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Diffstat (limited to 'layout/generic/nsGfxScrollFrame.cpp')
| -rw-r--r-- | layout/generic/nsGfxScrollFrame.cpp | 7955 |
1 files changed, 7955 insertions, 0 deletions
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp new file mode 100644 index 0000000000..68aaafcc5f --- /dev/null +++ b/layout/generic/nsGfxScrollFrame.cpp @@ -0,0 +1,7955 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +/* rendering object to wrap rendering objects that should be scrollable */ + +#include "nsGfxScrollFrame.h" + +#include "mozilla/layers/LayersTypes.h" +#include "nsIXULRuntime.h" +#include "base/compiler_specific.h" +#include "DisplayItemClip.h" +#include "nsCOMPtr.h" +#include "nsIContentViewer.h" +#include "nsPresContext.h" +#include "nsView.h" +#include "nsViewportInfo.h" +#include "nsContainerFrame.h" +#include "nsGkAtoms.h" +#include "nsNameSpaceManager.h" +#include "mozilla/intl/BidiEmbeddingLevel.h" +#include "mozilla/dom/DocumentInlines.h" +#include "mozilla/gfx/gfxVars.h" +#include "nsFontMetrics.h" +#include "mozilla/dom/NodeInfo.h" +#include "nsScrollbarFrame.h" +#include "nsINode.h" +#include "nsIScrollbarMediator.h" +#include "nsITextControlFrame.h" +#include "nsILayoutHistoryState.h" +#include "nsNodeInfoManager.h" +#include "nsContentCreatorFunctions.h" +#include "nsStyleTransformMatrix.h" +#include "mozilla/PresState.h" +#include "nsContentUtils.h" +#include "nsDisplayList.h" +#include "nsHTMLDocument.h" +#include "nsLayoutUtils.h" +#include "nsBidiPresUtils.h" +#include "nsBidiUtils.h" +#include "nsDocShell.h" +#include "mozilla/ContentEvents.h" +#include "mozilla/DisplayPortUtils.h" +#include "mozilla/EventDispatcher.h" +#include "mozilla/Preferences.h" +#include "mozilla/PresShell.h" +#include "mozilla/ScopeExit.h" +#include "mozilla/ScrollbarPreferences.h" +#include "mozilla/ScrollingMetrics.h" +#include "mozilla/StaticPrefs_browser.h" +#include "mozilla/StaticPrefs_toolkit.h" +#include "mozilla/StaticPtr.h" +#include "mozilla/SVGOuterSVGFrame.h" +#include "mozilla/ViewportUtils.h" +#include "mozilla/LookAndFeel.h" +#include "mozilla/dom/Element.h" +#include "mozilla/dom/Event.h" +#include "mozilla/dom/HTMLMarqueeElement.h" +#include "mozilla/dom/ScrollTimeline.h" +#include <stdint.h> +#include "mozilla/MathAlgorithms.h" +#include "mozilla/Telemetry.h" +#include "nsSubDocumentFrame.h" +#include "mozilla/Attributes.h" +#include "ScrollbarActivity.h" +#include "nsRefreshDriver.h" +#include "nsStyleConsts.h" +#include "nsIScrollPositionListener.h" +#include "StickyScrollContainer.h" +#include "nsIFrameInlines.h" +#include "gfxPlatform.h" +#include "mozilla/StaticPrefs_apz.h" +#include "mozilla/StaticPrefs_general.h" +#include "mozilla/StaticPrefs_layers.h" +#include "mozilla/StaticPrefs_layout.h" +#include "mozilla/StaticPrefs_mousewheel.h" +#include "mozilla/ToString.h" +#include "ScrollAnimationPhysics.h" +#include "ScrollAnimationBezierPhysics.h" +#include "ScrollAnimationMSDPhysics.h" +#include "ScrollSnap.h" +#include "UnitTransforms.h" +#include "nsSliderFrame.h" +#include "ViewportFrame.h" +#include "mozilla/gfx/gfxVars.h" +#include "mozilla/layers/APZCCallbackHelper.h" +#include "mozilla/layers/APZPublicUtils.h" +#include "mozilla/layers/AxisPhysicsModel.h" +#include "mozilla/layers/AxisPhysicsMSDModel.h" +#include "mozilla/layers/ScrollingInteractionContext.h" +#include "mozilla/layers/ScrollLinkedEffectDetector.h" +#include "mozilla/Unused.h" +#include "MobileViewportManager.h" +#include "VisualViewport.h" +#include "WindowRenderer.h" +#include <algorithm> +#include <cstdlib> // for std::abs(int/long) +#include <cmath> // for std::abs(float/double) +#include <tuple> // for std::tie + +static mozilla::LazyLogModule sApzPaintSkipLog("apz.paintskip"); +#define PAINT_SKIP_LOG(...) \ + MOZ_LOG(sApzPaintSkipLog, LogLevel::Debug, (__VA_ARGS__)) +static mozilla::LazyLogModule sScrollRestoreLog("scrollrestore"); +#define SCROLLRESTORE_LOG(...) \ + MOZ_LOG(sScrollRestoreLog, LogLevel::Debug, (__VA_ARGS__)) +static mozilla::LazyLogModule sRootScrollbarsLog("rootscrollbars"); +#define ROOT_SCROLLBAR_LOG(...) \ + if (mIsRoot) { \ + MOZ_LOG(sRootScrollbarsLog, LogLevel::Debug, (__VA_ARGS__)); \ + } +static mozilla::LazyLogModule sDisplayportLog("apz.displayport"); + +using namespace mozilla; +using namespace mozilla::dom; +using namespace mozilla::gfx; +using namespace mozilla::layers; +using namespace mozilla::layout; +using nsStyleTransformMatrix::TransformReferenceBox; + +static ScrollDirections GetOverflowChange(const nsRect& aCurScrolledRect, + const nsRect& aPrevScrolledRect) { + ScrollDirections result; + if (aPrevScrolledRect.x != aCurScrolledRect.x || + aPrevScrolledRect.width != aCurScrolledRect.width) { + result += ScrollDirection::eHorizontal; + } + if (aPrevScrolledRect.y != aCurScrolledRect.y || + aPrevScrolledRect.height != aCurScrolledRect.height) { + result += ScrollDirection::eVertical; + } + return result; +} + +/** + * This class handles the dispatching of scroll events to content. + * + * Scroll events are posted to the refresh driver via + * nsRefreshDriver::PostScrollEvent(), and they are fired during a refresh + * driver tick, after running requestAnimationFrame callbacks but before + * the style flush. This allows rAF callbacks to perform scrolling and have + * that scrolling be reflected on the same refresh driver tick, while at + * the same time allowing scroll event listeners to make style changes and + * have those style changes be reflected on the same refresh driver tick. + * + * ScrollEvents cannot be refresh observers, because none of the existing + * categories of refresh observers (FlushType::Style, FlushType::Layout, + * and FlushType::Display) are run at the desired time in a refresh driver + * tick. They behave similarly to refresh observers in that their presence + * causes the refresh driver to tick. + * + * ScrollEvents are one-shot runnables; the refresh driver drops them after + * running them. + */ +class nsHTMLScrollFrame::ScrollEvent : public Runnable { + public: + NS_DECL_NSIRUNNABLE + explicit ScrollEvent(nsHTMLScrollFrame* aHelper, bool aDelayed); + void Revoke() { mHelper = nullptr; } + + private: + nsHTMLScrollFrame* mHelper; +}; + +class nsHTMLScrollFrame::ScrollEndEvent : public Runnable { + public: + NS_DECL_NSIRUNNABLE + explicit ScrollEndEvent(nsHTMLScrollFrame* aHelper); + void Revoke() { mHelper = nullptr; } + + private: + nsHTMLScrollFrame* mHelper; +}; + +class nsHTMLScrollFrame::AsyncScrollPortEvent : public Runnable { + public: + NS_DECL_NSIRUNNABLE + explicit AsyncScrollPortEvent(nsHTMLScrollFrame* helper) + : Runnable("nsHTMLScrollFrame::AsyncScrollPortEvent"), mHelper(helper) {} + void Revoke() { mHelper = nullptr; } + + private: + nsHTMLScrollFrame* mHelper; +}; + +class nsHTMLScrollFrame::ScrolledAreaEvent : public Runnable { + public: + NS_DECL_NSIRUNNABLE + explicit ScrolledAreaEvent(nsHTMLScrollFrame* helper) + : Runnable("nsHTMLScrollFrame::ScrolledAreaEvent"), mHelper(helper) {} + void Revoke() { mHelper = nullptr; } + + private: + nsHTMLScrollFrame* mHelper; +}; + +//---------------------------------------------------------------------- + +//----------nsHTMLScrollFrame------------------------------------------- + +class ScrollFrameActivityTracker final + : public nsExpirationTracker<nsHTMLScrollFrame, 4> { + public: + // Wait for 3-4s between scrolls before we remove our layers. + // That's 4 generations of 1s each. + enum { TIMEOUT_MS = 1000 }; + explicit ScrollFrameActivityTracker(nsIEventTarget* aEventTarget) + : nsExpirationTracker<nsHTMLScrollFrame, 4>( + TIMEOUT_MS, "ScrollFrameActivityTracker", aEventTarget) {} + ~ScrollFrameActivityTracker() { AgeAllGenerations(); } + + virtual void NotifyExpired(nsHTMLScrollFrame* aObject) override { + RemoveObject(aObject); + aObject->MarkNotRecentlyScrolled(); + } +}; +static StaticAutoPtr<ScrollFrameActivityTracker> gScrollFrameActivityTracker; + +nsHTMLScrollFrame* NS_NewHTMLScrollFrame(PresShell* aPresShell, + ComputedStyle* aStyle, bool aIsRoot) { + return new (aPresShell) + nsHTMLScrollFrame(aStyle, aPresShell->GetPresContext(), aIsRoot); +} + +NS_IMPL_FRAMEARENA_HELPERS(nsHTMLScrollFrame) + +nsHTMLScrollFrame::nsHTMLScrollFrame(ComputedStyle* aStyle, + nsPresContext* aPresContext, + nsIFrame::ClassID aID, bool aIsRoot) + : nsContainerFrame(aStyle, aPresContext, aID), + mHScrollbarBox(nullptr), + mVScrollbarBox(nullptr), + mScrolledFrame(nullptr), + mScrollCornerBox(nullptr), + mResizerBox(nullptr), + mReferenceFrameDuringPainting(nullptr), + mAsyncScroll(nullptr), + mAsyncSmoothMSDScroll(nullptr), + mLastScrollOrigin(ScrollOrigin::None), + mDestination(0, 0), + mRestorePos(-1, -1), + mLastPos(-1, -1), + mApzScrollPos(0, 0), + mLastUpdateFramesPos(-1, -1), + mDisplayPortAtLastFrameUpdate(), + mScrollParentID(mozilla::layers::ScrollableLayerGuid::NULL_SCROLL_ID), + mAnchor(this), + mCurrentAPZScrollAnimationType(APZScrollAnimationType::No), + mIsFirstScrollableFrameSequenceNumber(Nothing()), + mInScrollingGesture(InScrollingGesture::No), + mAllowScrollOriginDowngrade(false), + mHadDisplayPortAtLastFrameUpdate(false), + mHasVerticalScrollbar(false), + mHasHorizontalScrollbar(false), + mOnlyNeedVScrollbarToScrollVVInsideLV(false), + mOnlyNeedHScrollbarToScrollVVInsideLV(false), + mFrameIsUpdatingScrollbar(false), + mDidHistoryRestore(false), + mIsRoot(aIsRoot), + mSuppressScrollbarUpdate(false), + mSkippedScrollbarLayout(false), + mHadNonInitialReflow(false), + mFirstReflow(true), + mHorizontalOverflow(false), + mVerticalOverflow(false), + mPostedReflowCallback(false), + mMayHaveDirtyFixedChildren(false), + mUpdateScrollbarAttributes(false), + mHasBeenScrolledRecently(false), + mWillBuildScrollableLayer(false), + mIsParentToActiveScrollFrames(false), + mHasBeenScrolled(false), + mIgnoreMomentumScroll(false), + mTransformingByAPZ(false), + mScrollableByAPZ(false), + mZoomableByAPZ(false), + mHasOutOfFlowContentInsideFilter(false), + mSuppressScrollbarRepaints(false), + mIsUsingMinimumScaleSize(false), + mMinimumScaleSizeChanged(false), + mProcessingScrollEvent(false), + mApzAnimationRequested(false), + mApzAnimationTriggeredByScriptRequested(false), + mReclampVVOffsetInReflowFinished(false), + mMayScheduleScrollAnimations(false), +#ifdef MOZ_WIDGET_ANDROID + mHasVerticalOverflowForDynamicToolbar(false), +#endif + mVelocityQueue(PresContext()) { + AppendScrollUpdate(ScrollPositionUpdate::NewScrollframe(nsPoint())); + + if (UsesOverlayScrollbars()) { + mScrollbarActivity = new ScrollbarActivity(this); + } + + if (mIsRoot) { + mZoomableByAPZ = PresShell()->GetZoomableByAPZ(); + } +} + +nsHTMLScrollFrame::~nsHTMLScrollFrame() = default; + +void nsHTMLScrollFrame::ScrollbarActivityStarted() const { + if (mScrollbarActivity) { + mScrollbarActivity->ActivityStarted(); + } +} + +void nsHTMLScrollFrame::ScrollbarActivityStopped() const { + if (mScrollbarActivity) { + mScrollbarActivity->ActivityStopped(); + } +} + +void nsHTMLScrollFrame::Destroy(DestroyContext& aContext) { + DestroyAbsoluteFrames(aContext); + if (mIsRoot) { + PresShell()->ResetVisualViewportOffset(); + } + + mAnchor.Destroy(); + + if (mScrollbarActivity) { + mScrollbarActivity->Destroy(); + mScrollbarActivity = nullptr; + } + + // Unbind the content created in CreateAnonymousContent later... + aContext.AddAnonymousContent(mHScrollbarContent.forget()); + aContext.AddAnonymousContent(mVScrollbarContent.forget()); + aContext.AddAnonymousContent(mScrollCornerContent.forget()); + aContext.AddAnonymousContent(mResizerContent.forget()); + + if (mPostedReflowCallback) { + PresShell()->CancelReflowCallback(this); + mPostedReflowCallback = false; + } + + if (mDisplayPortExpiryTimer) { + mDisplayPortExpiryTimer->Cancel(); + mDisplayPortExpiryTimer = nullptr; + } + if (mActivityExpirationState.IsTracked()) { + gScrollFrameActivityTracker->RemoveObject(this); + } + if (gScrollFrameActivityTracker && gScrollFrameActivityTracker->IsEmpty()) { + gScrollFrameActivityTracker = nullptr; + } + + if (mScrollActivityTimer) { + mScrollActivityTimer->Cancel(); + mScrollActivityTimer = nullptr; + } + RemoveObservers(); + if (mScrollEvent) { + mScrollEvent->Revoke(); + } + if (mScrollEndEvent) { + mScrollEndEvent->Revoke(); + } + nsContainerFrame::Destroy(aContext); +} + +void nsHTMLScrollFrame::SetInitialChildList(ChildListID aListID, + nsFrameList&& aChildList) { + nsContainerFrame::SetInitialChildList(aListID, std::move(aChildList)); + ReloadChildFrames(); +} + +void nsHTMLScrollFrame::AppendFrames(ChildListID aListID, + nsFrameList&& aFrameList) { + NS_ASSERTION(aListID == FrameChildListID::Principal, + "Only main list supported"); + mFrames.AppendFrames(nullptr, std::move(aFrameList)); + ReloadChildFrames(); +} + +void nsHTMLScrollFrame::InsertFrames(ChildListID aListID, nsIFrame* aPrevFrame, + const nsLineList::iterator* aPrevFrameLine, + nsFrameList&& aFrameList) { + NS_ASSERTION(aListID == FrameChildListID::Principal, + "Only main list supported"); + NS_ASSERTION(!aPrevFrame || aPrevFrame->GetParent() == this, + "inserting after sibling frame with different parent"); + mFrames.InsertFrames(nullptr, aPrevFrame, std::move(aFrameList)); + ReloadChildFrames(); +} + +void nsHTMLScrollFrame::RemoveFrame(DestroyContext& aContext, + ChildListID aListID, nsIFrame* aOldFrame) { + NS_ASSERTION(aListID == FrameChildListID::Principal, + "Only main list supported"); + mFrames.DestroyFrame(aContext, aOldFrame); + ReloadChildFrames(); +} + +/** + HTML scrolling implementation + + All other things being equal, we prefer layouts with fewer scrollbars showing. +*/ + +namespace mozilla { + +enum class ShowScrollbar : uint8_t { + Auto, + Always, + // Never is a misnomer. We can still get a scrollbar if we need to scroll the + // visual viewport inside the layout viewport. Thus this enum is best thought + // of as value used by layout, which does not know about the visual viewport. + // The visual viewport does not affect any layout sizes, so this is sound. + Never, +}; + +static ShowScrollbar ShouldShowScrollbar(StyleOverflow aOverflow) { + switch (aOverflow) { + case StyleOverflow::Scroll: + return ShowScrollbar::Always; + case StyleOverflow::Hidden: + return ShowScrollbar::Never; + default: + case StyleOverflow::Auto: + return ShowScrollbar::Auto; + } +} + +struct MOZ_STACK_CLASS ScrollReflowInput { + // === Filled in by the constructor. Members in this section shouldn't change + // their values after the constructor. === + const ReflowInput& mReflowInput; + ShowScrollbar mHScrollbar; + // If the horizontal scrollbar is allowed (even if mHScrollbar == + // ShowScrollbar::Never) provided that it is for scrolling the visual viewport + // inside the layout viewport only. + bool mHScrollbarAllowedForScrollingVVInsideLV = true; + ShowScrollbar mVScrollbar; + // If the vertical scrollbar is allowed (even if mVScrollbar == + // ShowScrollbar::Never) provided that it is for scrolling the visual viewport + // inside the layout viewport only. + bool mVScrollbarAllowedForScrollingVVInsideLV = true; + nsMargin mComputedBorder; + + // === Filled in by ReflowScrolledFrame === + OverflowAreas mContentsOverflowAreas; + // The scrollbar gutter sizes used in the most recent reflow of + // mScrolledFrame. The writing-mode is the same as the scroll + // container. + LogicalMargin mScrollbarGutterFromLastReflow; + // True if the most recent reflow of mScrolledFrame is with the + // horizontal scrollbar. + bool mReflowedContentsWithHScrollbar = false; + // True if the most recent reflow of mScrolledFrame is with the + // vertical scrollbar. + bool mReflowedContentsWithVScrollbar = false; + + // === Filled in when TryLayout succeeds === + // The size of the inside-border area + nsSize mInsideBorderSize; + // Whether we decided to show the horizontal scrollbar in the most recent + // TryLayout. + bool mShowHScrollbar = false; + // Whether we decided to show the vertical scrollbar in the most recent + // TryLayout. + bool mShowVScrollbar = false; + // If mShow(H|V)Scrollbar is true then + // mOnlyNeed(V|H)ScrollbarToScrollVVInsideLV indicates if the only reason we + // need that scrollbar is to scroll the visual viewport inside the layout + // viewport. These scrollbars are special in that even if they are layout + // scrollbars they do not take up any layout space. + bool mOnlyNeedHScrollbarToScrollVVInsideLV = false; + bool mOnlyNeedVScrollbarToScrollVVInsideLV = false; + + ScrollReflowInput(nsHTMLScrollFrame* aFrame, const ReflowInput& aReflowInput); + + nscoord VScrollbarMinHeight() const { return mVScrollbarPrefSize.height; } + nscoord VScrollbarPrefWidth() const { return mVScrollbarPrefSize.width; } + nscoord HScrollbarMinWidth() const { return mHScrollbarPrefSize.width; } + nscoord HScrollbarPrefHeight() const { return mHScrollbarPrefSize.height; } + + // Returns the sizes occupied by the scrollbar gutters. If aShowVScroll or + // aShowHScroll is true, the sizes occupied by the scrollbars are also + // included. + nsMargin ScrollbarGutter(bool aShowVScrollbar, bool aShowHScrollbar, + bool aScrollbarOnRight) const { + if (mOverlayScrollbars) { + return mScrollbarGutter; + } + nsMargin gutter = mScrollbarGutter; + if (aShowVScrollbar && gutter.right == 0 && gutter.left == 0) { + const nscoord w = VScrollbarPrefWidth(); + if (aScrollbarOnRight) { + gutter.right = w; + } else { + gutter.left = w; + } + } + if (aShowHScrollbar && gutter.bottom == 0) { + // The horizontal scrollbar is always at the bottom side. + gutter.bottom = HScrollbarPrefHeight(); + } + return gutter; + } + + bool OverlayScrollbars() const { return mOverlayScrollbars; } + + private: + // Filled in by the constructor. Put variables here to keep them unchanged + // after initializing them in the constructor. + nsSize mVScrollbarPrefSize; + nsSize mHScrollbarPrefSize; + bool mOverlayScrollbars = false; + // The scrollbar gutter sizes resolved from the scrollbar-gutter and + // scrollbar-width property. + nsMargin mScrollbarGutter; +}; + +ScrollReflowInput::ScrollReflowInput(nsHTMLScrollFrame* aFrame, + const ReflowInput& aReflowInput) + : mReflowInput(aReflowInput), + mComputedBorder(aReflowInput.ComputedPhysicalBorderPadding() - + aReflowInput.ComputedPhysicalPadding()), + mScrollbarGutterFromLastReflow(aFrame->GetWritingMode()) { + ScrollStyles styles = aFrame->GetScrollStyles(); + mHScrollbar = ShouldShowScrollbar(styles.mHorizontal); + mVScrollbar = ShouldShowScrollbar(styles.mVertical); + mOverlayScrollbars = aFrame->UsesOverlayScrollbars(); + + if (nsScrollbarFrame* scrollbar = aFrame->GetScrollbarBox(false)) { + scrollbar->SetScrollbarMediatorContent(mReflowInput.mFrame->GetContent()); + mHScrollbarPrefSize = scrollbar->ScrollbarMinSize(); + // A zero minimum size is a bug with non-overlay scrollbars. That means + // we'll always try to place the scrollbar, even if it will ultimately not + // fit, see bug 1809630. XUL collapsing is the exception because the + // front-end uses it. + MOZ_ASSERT(mHScrollbarPrefSize.width && mHScrollbarPrefSize.height, + "Shouldn't have a zero horizontal scrollbar-size"); + } else { + mHScrollbar = ShowScrollbar::Never; + mHScrollbarAllowedForScrollingVVInsideLV = false; + } + if (nsScrollbarFrame* scrollbar = aFrame->GetScrollbarBox(true)) { + scrollbar->SetScrollbarMediatorContent(mReflowInput.mFrame->GetContent()); + mVScrollbarPrefSize = scrollbar->ScrollbarMinSize(); + // See above. + MOZ_ASSERT(mVScrollbarPrefSize.width && mVScrollbarPrefSize.height, + "Shouldn't have a zero vertical scrollbar-size"); + } else { + mVScrollbar = ShowScrollbar::Never; + mVScrollbarAllowedForScrollingVVInsideLV = false; + } + + const auto* scrollbarStyle = + nsLayoutUtils::StyleForScrollbar(mReflowInput.mFrame); + // Hide the scrollbar when the scrollbar-width is set to none. + // + // Note: In some cases this is unnecessary, because scrollbar-width:none + // makes us suppress scrollbars in CreateAnonymousContent. But if this frame + // initially had a non-'none' scrollbar-width and dynamically changed to + // 'none', then we'll need to handle it here. + if (scrollbarStyle->StyleUIReset()->ScrollbarWidth() == + StyleScrollbarWidth::None) { + mHScrollbar = ShowScrollbar::Never; + mHScrollbarAllowedForScrollingVVInsideLV = false; + mVScrollbar = ShowScrollbar::Never; + mVScrollbarAllowedForScrollingVVInsideLV = false; + } else if (const auto& scrollbarGutterStyle = + scrollbarStyle->StyleDisplay()->mScrollbarGutter; + scrollbarGutterStyle && !mOverlayScrollbars) { + const auto stable = + bool(scrollbarGutterStyle & StyleScrollbarGutter::STABLE); + const auto bothEdges = + bool(scrollbarGutterStyle & StyleScrollbarGutter::BOTH_EDGES); + + if (mReflowInput.GetWritingMode().IsVertical()) { + const nscoord h = HScrollbarPrefHeight(); + if (bothEdges) { + mScrollbarGutter.top = mScrollbarGutter.bottom = h; + } else if (stable) { + // The horizontal scrollbar gutter is always at the bottom side. + mScrollbarGutter.bottom = h; + } + } else { + const nscoord w = VScrollbarPrefWidth(); + if (bothEdges) { + mScrollbarGutter.left = mScrollbarGutter.right = w; + } else if (stable) { + if (aFrame->IsScrollbarOnRight()) { + mScrollbarGutter.right = w; + } else { + mScrollbarGutter.left = w; + } + } + } + } +} + +} // namespace mozilla + +// XXXldb Can this go away? +static nsSize ComputeInsideBorderSize(const ScrollReflowInput& aState, + const nsSize& aDesiredInsideBorderSize) { + // aDesiredInsideBorderSize is the frame size; i.e., it includes + // borders and padding (but the scrolled child doesn't have + // borders). The scrolled child has the same padding as us. + nscoord contentWidth = aState.mReflowInput.ComputedWidth(); + if (contentWidth == NS_UNCONSTRAINEDSIZE) { + contentWidth = aDesiredInsideBorderSize.width - + aState.mReflowInput.ComputedPhysicalPadding().LeftRight(); + } + nscoord contentHeight = aState.mReflowInput.ComputedHeight(); + if (contentHeight == NS_UNCONSTRAINEDSIZE) { + contentHeight = aDesiredInsideBorderSize.height - + aState.mReflowInput.ComputedPhysicalPadding().TopBottom(); + } + + contentWidth = aState.mReflowInput.ApplyMinMaxWidth(contentWidth); + contentHeight = aState.mReflowInput.ApplyMinMaxHeight(contentHeight); + return nsSize( + contentWidth + aState.mReflowInput.ComputedPhysicalPadding().LeftRight(), + contentHeight + + aState.mReflowInput.ComputedPhysicalPadding().TopBottom()); +} + +/** + * Assuming that we know the metrics for our wrapped frame and + * whether the horizontal and/or vertical scrollbars are present, + * compute the resulting layout and return true if the layout is + * consistent. If the layout is consistent then we fill in the + * computed fields of the ScrollReflowInput. + * + * The layout is consistent when both scrollbars are showing if and only + * if they should be showing. A horizontal scrollbar should be showing if all + * following conditions are met: + * 1) the style is not HIDDEN + * 2) our inside-border height is at least the scrollbar height (i.e., the + * scrollbar fits vertically) + * 3) the style is SCROLL, or the kid's overflow-area XMost is + * greater than the scrollport width + * + * @param aForce if true, then we just assume the layout is consistent. + */ +bool nsHTMLScrollFrame::TryLayout(ScrollReflowInput& aState, + ReflowOutput* aKidMetrics, + bool aAssumeHScroll, bool aAssumeVScroll, + bool aForce) { + if ((aState.mVScrollbar == ShowScrollbar::Never && aAssumeVScroll) || + (aState.mHScrollbar == ShowScrollbar::Never && aAssumeHScroll)) { + NS_ASSERTION(!aForce, "Shouldn't be forcing a hidden scrollbar to show!"); + return false; + } + + const auto wm = GetWritingMode(); + const nsMargin scrollbarGutter = aState.ScrollbarGutter( + aAssumeVScroll, aAssumeHScroll, IsScrollbarOnRight()); + const LogicalMargin logicalScrollbarGutter(wm, scrollbarGutter); + + const bool inlineEndsGutterChanged = + aState.mScrollbarGutterFromLastReflow.IStartEnd(wm) != + logicalScrollbarGutter.IStartEnd(wm); + const bool blockEndsGutterChanged = + aState.mScrollbarGutterFromLastReflow.BStartEnd(wm) != + logicalScrollbarGutter.BStartEnd(wm); + const bool shouldReflowScrolledFrame = + inlineEndsGutterChanged || + (blockEndsGutterChanged && ScrolledContentDependsOnBSize(aState)); + + if (shouldReflowScrolledFrame) { + if (blockEndsGutterChanged) { + nsLayoutUtils::MarkIntrinsicISizesDirtyIfDependentOnBSize(mScrolledFrame); + } + aKidMetrics->mOverflowAreas.Clear(); + ROOT_SCROLLBAR_LOG( + "TryLayout reflowing scrolled frame with scrollbars h=%d, v=%d\n", + aAssumeHScroll, aAssumeVScroll); + ReflowScrolledFrame(aState, aAssumeHScroll, aAssumeVScroll, aKidMetrics); + } + + const nsSize scrollbarGutterSize(scrollbarGutter.LeftRight(), + scrollbarGutter.TopBottom()); + + // First, compute our inside-border size and scrollport size + // XXXldb Can we depend more on ComputeSize here? + nsSize kidSize = GetContainSizeAxes().ContainSize( + aKidMetrics->PhysicalSize(), *aState.mReflowInput.mFrame); + const nsSize desiredInsideBorderSize = kidSize + scrollbarGutterSize; + aState.mInsideBorderSize = + ComputeInsideBorderSize(aState, desiredInsideBorderSize); + + nsSize layoutSize = + mIsUsingMinimumScaleSize ? mMinimumScaleSize : aState.mInsideBorderSize; + + const nsSize scrollPortSize = + Max(nsSize(0, 0), layoutSize - scrollbarGutterSize); + if (mIsUsingMinimumScaleSize) { + mICBSize = + Max(nsSize(0, 0), aState.mInsideBorderSize - scrollbarGutterSize); + } + + nsSize visualViewportSize = scrollPortSize; + ROOT_SCROLLBAR_LOG("TryLayout with VV %s\n", + ToString(visualViewportSize).c_str()); + mozilla::PresShell* presShell = PresShell(); + // Note: we check for a non-null MobileViepwortManager here, but ideally we + // should be able to drop that clause as well. It's just that in some cases + // with extension popups the composition size comes back as stale, because + // the content viewer is only resized after the popup contents are reflowed. + // That case also happens to have no APZ and no MVM, so we use that as a + // way to detect the scenario. Bug 1648669 tracks removing this clause. + if (mIsRoot && presShell->GetMobileViewportManager()) { + visualViewportSize = nsLayoutUtils::CalculateCompositionSizeForFrame( + this, false, &layoutSize); + visualViewportSize = + Max(nsSize(0, 0), visualViewportSize - scrollbarGutterSize); + + float resolution = presShell->GetResolution(); + visualViewportSize.width /= resolution; + visualViewportSize.height /= resolution; + ROOT_SCROLLBAR_LOG("TryLayout now with VV %s\n", + ToString(visualViewportSize).c_str()); + } + + nsRect overflowRect = aState.mContentsOverflowAreas.ScrollableOverflow(); + // If the content height expanded by the minimum-scale will be taller than + // the scrollable overflow area, we need to expand the area here to tell + // properly whether we need to render the overlay vertical scrollbar. + // NOTE: This expanded size should NOT be used for non-overley scrollbars + // cases since putting the vertical non-overlay scrollbar will make the + // content width narrow a little bit, which in turn the minimum scale value + // becomes a bit bigger than before, then the vertical scrollbar is no longer + // needed, which means the content width becomes the original width, then the + // minimum-scale is changed to the original one, and so forth. + if (UsesOverlayScrollbars() && mIsUsingMinimumScaleSize && + mMinimumScaleSize.height > overflowRect.YMost()) { + overflowRect.height += mMinimumScaleSize.height - overflowRect.YMost(); + } + nsRect scrolledRect = + GetUnsnappedScrolledRectInternal(overflowRect, scrollPortSize); + ROOT_SCROLLBAR_LOG( + "TryLayout scrolledRect:%s overflowRect:%s scrollportSize:%s\n", + ToString(scrolledRect).c_str(), ToString(overflowRect).c_str(), + ToString(scrollPortSize).c_str()); + nscoord oneDevPixel = PresContext()->DevPixelsToAppUnits(1); + + bool showHScrollbar = aAssumeHScroll; + bool showVScrollbar = aAssumeVScroll; + if (!aForce) { + nsSize sizeToCompare = visualViewportSize; + if (gfxPlatform::UseDesktopZoomingScrollbars()) { + sizeToCompare = scrollPortSize; + } + + // No need to compute showHScrollbar if we got ShowScrollbar::Never. + if (aState.mHScrollbar != ShowScrollbar::Never) { + showHScrollbar = + aState.mHScrollbar == ShowScrollbar::Always || + scrolledRect.XMost() >= sizeToCompare.width + oneDevPixel || + scrolledRect.x <= -oneDevPixel; + // TODO(emilio): This should probably check this scrollbar's minimum size + // in both axes, for consistency? + if (aState.mHScrollbar == ShowScrollbar::Auto && + scrollPortSize.width < aState.HScrollbarMinWidth()) { + showHScrollbar = false; + } + ROOT_SCROLLBAR_LOG("TryLayout wants H Scrollbar: %d =? %d\n", + showHScrollbar, aAssumeHScroll); + } + + // No need to compute showVScrollbar if we got ShowScrollbar::Never. + if (aState.mVScrollbar != ShowScrollbar::Never) { + showVScrollbar = + aState.mVScrollbar == ShowScrollbar::Always || + scrolledRect.YMost() >= sizeToCompare.height + oneDevPixel || + scrolledRect.y <= -oneDevPixel; + // TODO(emilio): This should probably check this scrollbar's minimum size + // in both axes, for consistency? + if (aState.mVScrollbar == ShowScrollbar::Auto && + scrollPortSize.height < aState.VScrollbarMinHeight()) { + showVScrollbar = false; + } + ROOT_SCROLLBAR_LOG("TryLayout wants V Scrollbar: %d =? %d\n", + showVScrollbar, aAssumeVScroll); + } + + if (showHScrollbar != aAssumeHScroll || showVScrollbar != aAssumeVScroll) { + const nsMargin wantedScrollbarGutter = aState.ScrollbarGutter( + showVScrollbar, showHScrollbar, IsScrollbarOnRight()); + // We report an inconsistent layout only when the desired visibility of + // the scrollbars can change the size of the scrollbar gutters. + if (scrollbarGutter != wantedScrollbarGutter) { + return false; + } + } + } + + // If we reach here, the layout is consistent. Record the desired visibility + // of the scrollbars. + aState.mShowHScrollbar = showHScrollbar; + aState.mShowVScrollbar = showVScrollbar; + const nsPoint scrollPortOrigin( + aState.mComputedBorder.left + scrollbarGutter.left, + aState.mComputedBorder.top + scrollbarGutter.top); + SetScrollPort(nsRect(scrollPortOrigin, scrollPortSize)); + + if (mIsRoot && gfxPlatform::UseDesktopZoomingScrollbars()) { + bool vvChanged = true; + const bool overlay = aState.OverlayScrollbars(); + // This loop can run at most twice since we can only add a scrollbar once. + // At this point we've already decided that this layout is consistent so we + // will return true. Scrollbars added here never take up layout space even + // if they are layout scrollbars so any changes made here will not make us + // return false. + while (vvChanged) { + vvChanged = false; + if (!aState.mShowHScrollbar && + aState.mHScrollbarAllowedForScrollingVVInsideLV) { + if (ScrollPort().width >= visualViewportSize.width + oneDevPixel && + (overlay || + visualViewportSize.width >= aState.HScrollbarMinWidth())) { + vvChanged = true; + if (!overlay) { + visualViewportSize.height -= aState.HScrollbarPrefHeight(); + } + aState.mShowHScrollbar = true; + aState.mOnlyNeedHScrollbarToScrollVVInsideLV = true; + ROOT_SCROLLBAR_LOG("TryLayout added H scrollbar for VV, VV now %s\n", + ToString(visualViewportSize).c_str()); + } + } + + if (!aState.mShowVScrollbar && + aState.mVScrollbarAllowedForScrollingVVInsideLV) { + if (ScrollPort().height >= visualViewportSize.height + oneDevPixel && + (overlay || + visualViewportSize.height >= aState.VScrollbarMinHeight())) { + vvChanged = true; + if (!overlay) { + visualViewportSize.width -= aState.VScrollbarPrefWidth(); + } + aState.mShowVScrollbar = true; + aState.mOnlyNeedVScrollbarToScrollVVInsideLV = true; + ROOT_SCROLLBAR_LOG("TryLayout added V scrollbar for VV, VV now %s\n", + ToString(visualViewportSize).c_str()); + } + } + } + } + + return true; +} + +bool nsHTMLScrollFrame::ScrolledContentDependsOnBSize( + const ScrollReflowInput& aState) const { + return mScrolledFrame->HasAnyStateBits( + NS_FRAME_CONTAINS_RELATIVE_BSIZE | + NS_FRAME_DESCENDANT_INTRINSIC_ISIZE_DEPENDS_ON_BSIZE) || + aState.mReflowInput.ComputedBSize() != NS_UNCONSTRAINEDSIZE || + aState.mReflowInput.ComputedMinBSize() > 0 || + aState.mReflowInput.ComputedMaxBSize() != NS_UNCONSTRAINEDSIZE; +} + +void nsHTMLScrollFrame::ReflowScrolledFrame(ScrollReflowInput& aState, + bool aAssumeHScroll, + bool aAssumeVScroll, + ReflowOutput* aMetrics) { + const WritingMode wm = GetWritingMode(); + + // these could be NS_UNCONSTRAINEDSIZE ... std::min arithmetic should + // be OK + LogicalMargin padding = aState.mReflowInput.ComputedLogicalPadding(wm); + nscoord availISize = + aState.mReflowInput.ComputedISize() + padding.IStartEnd(wm); + + nscoord computedBSize = aState.mReflowInput.ComputedBSize(); + nscoord computedMinBSize = aState.mReflowInput.ComputedMinBSize(); + nscoord computedMaxBSize = aState.mReflowInput.ComputedMaxBSize(); + if (!ShouldPropagateComputedBSizeToScrolledContent()) { + computedBSize = NS_UNCONSTRAINEDSIZE; + computedMinBSize = 0; + computedMaxBSize = NS_UNCONSTRAINEDSIZE; + } + + const LogicalMargin scrollbarGutter( + wm, aState.ScrollbarGutter(aAssumeVScroll, aAssumeHScroll, + IsScrollbarOnRight())); + if (const nscoord inlineEndsGutter = scrollbarGutter.IStartEnd(wm); + inlineEndsGutter > 0) { + availISize = std::max(0, availISize - inlineEndsGutter); + } + if (const nscoord blockEndsGutter = scrollbarGutter.BStartEnd(wm); + blockEndsGutter > 0) { + if (computedBSize != NS_UNCONSTRAINEDSIZE) { + computedBSize = std::max(0, computedBSize - blockEndsGutter); + } + computedMinBSize = std::max(0, computedMinBSize - blockEndsGutter); + if (computedMaxBSize != NS_UNCONSTRAINEDSIZE) { + computedMaxBSize = std::max(0, computedMaxBSize - blockEndsGutter); + } + } + + nsPresContext* presContext = PresContext(); + + // Pass InitFlags::CallerWillInit so we can pass in the correct padding. + ReflowInput kidReflowInput(presContext, aState.mReflowInput, mScrolledFrame, + LogicalSize(wm, availISize, NS_UNCONSTRAINEDSIZE), + Nothing(), ReflowInput::InitFlag::CallerWillInit); + const WritingMode kidWM = kidReflowInput.GetWritingMode(); + kidReflowInput.Init(presContext, Nothing(), Nothing(), + Some(padding.ConvertTo(kidWM, wm))); + kidReflowInput.mFlags.mAssumingHScrollbar = aAssumeHScroll; + kidReflowInput.mFlags.mAssumingVScrollbar = aAssumeVScroll; + kidReflowInput.mFlags.mTreatBSizeAsIndefinite = + aState.mReflowInput.mFlags.mTreatBSizeAsIndefinite; + kidReflowInput.SetComputedBSize(computedBSize); + kidReflowInput.SetComputedMinBSize(computedMinBSize); + kidReflowInput.SetComputedMaxBSize(computedMaxBSize); + if (aState.mReflowInput.IsBResizeForWM(kidWM)) { + kidReflowInput.SetBResize(true); + } + if (aState.mReflowInput.IsBResizeForPercentagesForWM(kidWM)) { + kidReflowInput.mFlags.mIsBResizeForPercentages = true; + } + + // Temporarily set mHasHorizontalScrollbar/mHasVerticalScrollbar to + // reflect our assumptions while we reflow the child. + bool didHaveHorizontalScrollbar = mHasHorizontalScrollbar; + bool didHaveVerticalScrollbar = mHasVerticalScrollbar; + mHasHorizontalScrollbar = aAssumeHScroll; + mHasVerticalScrollbar = aAssumeVScroll; + + nsReflowStatus status; + // No need to pass a true container-size to ReflowChild or + // FinishReflowChild, because it's only used there when positioning + // the frame (i.e. if ReflowChildFlags::NoMoveFrame isn't set) + const nsSize dummyContainerSize; + ReflowChild(mScrolledFrame, presContext, *aMetrics, kidReflowInput, wm, + LogicalPoint(wm), dummyContainerSize, + ReflowChildFlags::NoMoveFrame, status); + + mHasHorizontalScrollbar = didHaveHorizontalScrollbar; + mHasVerticalScrollbar = didHaveVerticalScrollbar; + + // Don't resize or position the view (if any) because we're going to resize + // it to the correct size anyway in PlaceScrollArea. Allowing it to + // resize here would size it to the natural height of the frame, + // which will usually be different from the scrollport height; + // invalidating the difference will cause unnecessary repainting. + FinishReflowChild( + mScrolledFrame, presContext, *aMetrics, &kidReflowInput, wm, + LogicalPoint(wm), dummyContainerSize, + ReflowChildFlags::NoMoveFrame | ReflowChildFlags::NoSizeView); + + if (mScrolledFrame->HasAnyStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE)) { + // Propagate NS_FRAME_CONTAINS_RELATIVE_BSIZE from our inner scrolled frame + // to ourselves so that our containing block is aware of it. + // + // Note: If the scrolled frame has any child whose block-size depends on the + // containing block's block-size, the NS_FRAME_CONTAINS_RELATIVE_BSIZE bit + // is set on the scrolled frame when initializing the child's ReflowInput in + // ReflowInput::InitResizeFlags(). Therefore, we propagate the bit here + // after we reflowed the scrolled frame. + AddStateBits(NS_FRAME_CONTAINS_RELATIVE_BSIZE); + } + + // XXX Some frames (e.g. nsFrameFrame, nsTextFrame) don't + // bother setting their mOverflowArea. This is wrong because every frame + // should always set mOverflowArea. In fact nsFrameFrame doesn't + // support the 'outline' property because of this. Rather than fix the + // world right now, just fix up the overflow area if necessary. Note that we + // don't check HasOverflowRect() because it could be set even though the + // overflow area doesn't include the frame bounds. + aMetrics->UnionOverflowAreasWithDesiredBounds(); + + auto* disp = StyleDisplay(); + if (MOZ_UNLIKELY(disp->mOverflowClipBoxInline == + StyleOverflowClipBox::ContentBox)) { + // The scrolled frame is scrollable in the inline axis with + // `overflow-clip-box:content-box`. To prevent its content from being + // clipped at the scroll container's padding edges, we inflate its + // children's scrollable overflow area with its inline padding, and union + // its scrollable overflow area with its children's inflated scrollable + // overflow area. + OverflowAreas childOverflow; + mScrolledFrame->UnionChildOverflow(childOverflow); + nsRect childScrollableOverflow = childOverflow.ScrollableOverflow(); + + const LogicalMargin inlinePadding = + padding.ApplySkipSides(LogicalSides(wm, eLogicalSideBitsBBoth)); + childScrollableOverflow.Inflate(inlinePadding.GetPhysicalMargin(wm)); + + nsRect& so = aMetrics->ScrollableOverflow(); + so = so.UnionEdges(childScrollableOverflow); + } + + aState.mContentsOverflowAreas = aMetrics->mOverflowAreas; + aState.mScrollbarGutterFromLastReflow = scrollbarGutter; + aState.mReflowedContentsWithHScrollbar = aAssumeHScroll; + aState.mReflowedContentsWithVScrollbar = aAssumeVScroll; +} + +bool nsHTMLScrollFrame::GuessHScrollbarNeeded(const ScrollReflowInput& aState) { + if (aState.mHScrollbar != ShowScrollbar::Auto) { + // no guessing required + return aState.mHScrollbar == ShowScrollbar::Always; + } + // We only care about scrollbars that might take up space when trying to guess + // if we need a scrollbar, so we ignore scrollbars only created to scroll the + // visual viewport inside the layout viewport because they take up no layout + // space. + return mHasHorizontalScrollbar && !mOnlyNeedHScrollbarToScrollVVInsideLV; +} + +bool nsHTMLScrollFrame::GuessVScrollbarNeeded(const ScrollReflowInput& aState) { + if (aState.mVScrollbar != ShowScrollbar::Auto) { + // no guessing required + return aState.mVScrollbar == ShowScrollbar::Always; + } + + // If we've had at least one non-initial reflow, then just assume + // the state of the vertical scrollbar will be what we determined + // last time. + if (mHadNonInitialReflow) { + // We only care about scrollbars that might take up space when trying to + // guess if we need a scrollbar, so we ignore scrollbars only created to + // scroll the visual viewport inside the layout viewport because they take + // up no layout space. + return mHasVerticalScrollbar && !mOnlyNeedVScrollbarToScrollVVInsideLV; + } + + // If this is the initial reflow, guess false because usually + // we have very little content by then. + if (InInitialReflow()) return false; + + if (mIsRoot) { + nsIFrame* f = mScrolledFrame->PrincipalChildList().FirstChild(); + if (f && f->IsSVGOuterSVGFrame() && + static_cast<SVGOuterSVGFrame*>(f)->VerticalScrollbarNotNeeded()) { + // Common SVG case - avoid a bad guess. + return false; + } + // Assume that there will be a scrollbar; it seems to me + // that 'most pages' do have a scrollbar, and anyway, it's cheaper + // to do an extra reflow for the pages that *don't* need a + // scrollbar (because on average they will have less content). + return true; + } + + // For non-viewports, just guess that we don't need a scrollbar. + // XXX I wonder if statistically this is the right idea; I'm + // basically guessing that there are a lot of overflow:auto DIVs + // that get their intrinsic size and don't overflow + return false; +} + +bool nsHTMLScrollFrame::InInitialReflow() const { + // We're in an initial reflow if NS_FRAME_FIRST_REFLOW is set, unless we're a + // root scrollframe. In that case we want to skip this clause altogether. + // The guess here is that there are lots of overflow:auto divs out there that + // end up auto-sizing so they don't overflow, and that the root basically + // always needs a scrollbar if it did last time we loaded this page (good + // assumption, because our initial reflow is no longer synchronous). + return !mIsRoot && HasAnyStateBits(NS_FRAME_FIRST_REFLOW); +} + +void nsHTMLScrollFrame::ReflowContents(ScrollReflowInput& aState, + const ReflowOutput& aDesiredSize) { + const WritingMode desiredWm = aDesiredSize.GetWritingMode(); + ReflowOutput kidDesiredSize(desiredWm); + ReflowScrolledFrame(aState, GuessHScrollbarNeeded(aState), + GuessVScrollbarNeeded(aState), &kidDesiredSize); + + // There's an important special case ... if the child appears to fit + // in the inside-border rect (but overflows the scrollport), we + // should try laying it out without a vertical scrollbar. It will + // usually fit because making the available-width wider will not + // normally make the child taller. (The only situation I can think + // of is when you have a line containing %-width inline replaced + // elements whose percentages sum to more than 100%, so increasing + // the available width makes the line break where it was fitting + // before.) If we don't treat this case specially, then we will + // decide that showing scrollbars is OK because the content + // overflows when we're showing scrollbars and we won't try to + // remove the vertical scrollbar. + + // Detecting when we enter this special case is important for when + // people design layouts that exactly fit the container "most of the + // time". + + // XXX Is this check really sufficient to catch all the incremental cases + // where the ideal case doesn't have a scrollbar? + if ((aState.mReflowedContentsWithHScrollbar || + aState.mReflowedContentsWithVScrollbar) && + aState.mVScrollbar != ShowScrollbar::Always && + aState.mHScrollbar != ShowScrollbar::Always) { + nsSize kidSize = GetContainSizeAxes().ContainSize( + kidDesiredSize.PhysicalSize(), *aState.mReflowInput.mFrame); + nsSize insideBorderSize = ComputeInsideBorderSize(aState, kidSize); + nsRect scrolledRect = GetUnsnappedScrolledRectInternal( + kidDesiredSize.ScrollableOverflow(), insideBorderSize); + if (nsRect(nsPoint(0, 0), insideBorderSize).Contains(scrolledRect)) { + // Let's pretend we had no scrollbars coming in here + kidDesiredSize.mOverflowAreas.Clear(); + ReflowScrolledFrame(aState, false, false, &kidDesiredSize); + } + } + + if (IsRootScrollFrameOfDocument()) { + UpdateMinimumScaleSize(aState.mContentsOverflowAreas.ScrollableOverflow(), + kidDesiredSize.PhysicalSize()); + } + + // Try vertical scrollbar settings that leave the vertical scrollbar + // unchanged. Do this first because changing the vertical scrollbar setting is + // expensive, forcing a reflow always. + + // Try leaving the horizontal scrollbar unchanged first. This will be more + // efficient. + ROOT_SCROLLBAR_LOG("Trying layout1 with %d, %d\n", + aState.mReflowedContentsWithHScrollbar, + aState.mReflowedContentsWithVScrollbar); + if (TryLayout(aState, &kidDesiredSize, aState.mReflowedContentsWithHScrollbar, + aState.mReflowedContentsWithVScrollbar, false)) { + return; + } + ROOT_SCROLLBAR_LOG("Trying layout2 with %d, %d\n", + !aState.mReflowedContentsWithHScrollbar, + aState.mReflowedContentsWithVScrollbar); + if (TryLayout(aState, &kidDesiredSize, + !aState.mReflowedContentsWithHScrollbar, + aState.mReflowedContentsWithVScrollbar, false)) { + return; + } + + // OK, now try toggling the vertical scrollbar. The performance advantage + // of trying the status-quo horizontal scrollbar state + // does not exist here (we'll have to reflow due to the vertical scrollbar + // change), so always try no horizontal scrollbar first. + bool newVScrollbarState = !aState.mReflowedContentsWithVScrollbar; + ROOT_SCROLLBAR_LOG("Trying layout3 with %d, %d\n", false, newVScrollbarState); + if (TryLayout(aState, &kidDesiredSize, false, newVScrollbarState, false)) { + return; + } + ROOT_SCROLLBAR_LOG("Trying layout4 with %d, %d\n", true, newVScrollbarState); + if (TryLayout(aState, &kidDesiredSize, true, newVScrollbarState, false)) { + return; + } + + // OK, we're out of ideas. Try again enabling whatever scrollbars we can + // enable and force the layout to stick even if it's inconsistent. + // This just happens sometimes. + ROOT_SCROLLBAR_LOG("Giving up, adding both scrollbars...\n"); + TryLayout(aState, &kidDesiredSize, aState.mHScrollbar != ShowScrollbar::Never, + aState.mVScrollbar != ShowScrollbar::Never, true); +} + +void nsHTMLScrollFrame::PlaceScrollArea(ScrollReflowInput& aState, + const nsPoint& aScrollPosition) { + nsIFrame* scrolledFrame = mScrolledFrame; + // Set the x,y of the scrolled frame to the correct value + scrolledFrame->SetPosition(ScrollPort().TopLeft() - aScrollPosition); + + // Recompute our scrollable overflow, taking perspective children into + // account. Note that this only recomputes the overflow areas stored on the + // helper (which are used to compute scrollable length and scrollbar thumb + // sizes) but not the overflow areas stored on the frame. This seems to work + // for now, but it's possible that we may need to update both in the future. + AdjustForPerspective(aState.mContentsOverflowAreas.ScrollableOverflow()); + + // Preserve the width or height of empty rects + const nsSize portSize = ScrollPort().Size(); + nsRect scrolledRect = GetUnsnappedScrolledRectInternal( + aState.mContentsOverflowAreas.ScrollableOverflow(), portSize); + nsRect scrolledArea = + scrolledRect.UnionEdges(nsRect(nsPoint(0, 0), portSize)); + + // Store the new overflow area. Note that this changes where an outline + // of the scrolled frame would be painted, but scrolled frames can't have + // outlines (the outline would go on this scrollframe instead). + // Using FinishAndStoreOverflow is needed so the overflow rect gets set + // correctly. It also messes with the overflow rect in the 'clip' case, but + // scrolled frames can't have 'overflow' either. + // This needs to happen before SyncFrameViewAfterReflow so + // HasOverflowRect() will return the correct value. + OverflowAreas overflow(scrolledArea, scrolledArea); + scrolledFrame->FinishAndStoreOverflow(overflow, scrolledFrame->GetSize()); + + // Note that making the view *exactly* the size of the scrolled area + // is critical, since the view scrolling code uses the size of the + // scrolled view to clamp scroll requests. + // Normally the scrolledFrame won't have a view but in some cases it + // might create its own. + nsContainerFrame::SyncFrameViewAfterReflow( + scrolledFrame->PresContext(), scrolledFrame, scrolledFrame->GetView(), + scrolledArea, ReflowChildFlags::Default); +} + +nscoord nsHTMLScrollFrame::IntrinsicScrollbarGutterSizeAtInlineEdges( + gfxContext* aRenderingContext) { + const bool isVerticalWM = GetWritingMode().IsVertical(); + nsScrollbarFrame* inlineEndScrollbarBox = + isVerticalWM ? mHScrollbarBox : mVScrollbarBox; + if (!inlineEndScrollbarBox) { + // No scrollbar box frame means no intrinsic size. + return 0; + } + + if (PresContext()->UseOverlayScrollbars()) { + return 0; + } + + const auto* styleForScrollbar = nsLayoutUtils::StyleForScrollbar(this); + if (styleForScrollbar->StyleUIReset()->ScrollbarWidth() == + StyleScrollbarWidth::None) { + // Scrollbar shouldn't appear at all with "scrollbar-width: none". + return 0; + } + + const auto& styleScrollbarGutter = + styleForScrollbar->StyleDisplay()->mScrollbarGutter; + ScrollStyles ss = GetScrollStyles(); + const StyleOverflow& inlineEndStyleOverflow = + isVerticalWM ? ss.mHorizontal : ss.mVertical; + + // Return the scrollbar-gutter size only if we have "overflow:scroll" or + // non-auto "scrollbar-gutter", so early-return here if the conditions aren't + // satisfied. + if (inlineEndStyleOverflow != StyleOverflow::Scroll && + styleScrollbarGutter == StyleScrollbarGutter::AUTO) { + return 0; + } + + // No need to worry about reflow depth here since it's just for scrollbars. + nsSize scrollbarPrefSize = inlineEndScrollbarBox->ScrollbarMinSize(); + const nscoord scrollbarSize = + isVerticalWM ? scrollbarPrefSize.height : scrollbarPrefSize.width; + const auto bothEdges = + bool(styleScrollbarGutter & StyleScrollbarGutter::BOTH_EDGES); + return bothEdges ? scrollbarSize * 2 : scrollbarSize; +} + +// Legacy, this sucks! +static bool IsMarqueeScrollbox(const nsIFrame& aScrollFrame) { + if (!aScrollFrame.GetContent()) { + return false; + } + if (MOZ_LIKELY(!aScrollFrame.GetContent()->HasBeenInUAWidget())) { + return false; + } + MOZ_ASSERT(aScrollFrame.GetParent() && + aScrollFrame.GetParent()->GetContent()); + return aScrollFrame.GetParent() && + HTMLMarqueeElement::FromNodeOrNull( + aScrollFrame.GetParent()->GetContent()); +} + +/* virtual */ +nscoord nsHTMLScrollFrame::GetMinISize(gfxContext* aRenderingContext) { + nscoord result = [&] { + if (const Maybe<nscoord> containISize = ContainIntrinsicISize()) { + return *containISize; + } + if (MOZ_UNLIKELY(IsMarqueeScrollbox(*this))) { + return 0; + } + return mScrolledFrame->GetMinISize(aRenderingContext); + }(); + + DISPLAY_MIN_INLINE_SIZE(this, result); + return result + IntrinsicScrollbarGutterSizeAtInlineEdges(aRenderingContext); +} + +/* virtual */ +nscoord nsHTMLScrollFrame::GetPrefISize(gfxContext* aRenderingContext) { + const Maybe<nscoord> containISize = ContainIntrinsicISize(); + nscoord result = containISize + ? *containISize + : mScrolledFrame->GetPrefISize(aRenderingContext); + DISPLAY_PREF_INLINE_SIZE(this, result); + return NSCoordSaturatingAdd( + result, IntrinsicScrollbarGutterSizeAtInlineEdges(aRenderingContext)); +} + +// When we have perspective set on the outer scroll frame, and transformed +// children (possibly with preserve-3d) then the effective transform on the +// child depends on the offset to the scroll frame, which changes as we scroll. +// This perspective transform can cause the element to move relative to the +// scrolled inner frame, which would cause the scrollable length changes during +// scrolling if we didn't account for it. Since we don't want scrollHeight/Width +// and the size of scrollbar thumbs to change during scrolling, we compute the +// scrollable overflow by determining the scroll position at which the child +// becomes completely visible within the scrollport rather than using the union +// of the overflow areas at their current position. +static void GetScrollableOverflowForPerspective( + nsIFrame* aScrolledFrame, nsIFrame* aCurrentFrame, const nsRect aScrollPort, + nsPoint aOffset, nsRect& aScrolledFrameOverflowArea) { + // Iterate over all children except pop-ups. + for (const auto& [list, listID] : aCurrentFrame->ChildLists()) { + if (listID == FrameChildListID::Popup) { + continue; + } + + for (nsIFrame* child : list) { + nsPoint offset = aOffset; + + // When we reach a direct child of the scroll, then we record the offset + // to convert from that frame's coordinate into the scroll frame's + // coordinates. Preserve-3d descendant frames use the same offset as their + // ancestors, since TransformRect already converts us into the coordinate + // space of the preserve-3d root. + if (aScrolledFrame == aCurrentFrame) { + offset = child->GetPosition(); + } + + if (child->Extend3DContext()) { + // If we're a preserve-3d frame, then recurse and include our + // descendants since overflow of preserve-3d frames is only included + // in the post-transform overflow area of the preserve-3d root frame. + GetScrollableOverflowForPerspective(aScrolledFrame, child, aScrollPort, + offset, aScrolledFrameOverflowArea); + } + + // If we're transformed, then we want to consider the possibility that + // this frame might move relative to the scrolled frame when scrolling. + // For preserve-3d, leaf frames have correct overflow rects relative to + // themselves. preserve-3d 'nodes' (intermediate frames and the root) have + // only their untransformed children included in their overflow relative + // to self, which is what we want to include here. + if (child->IsTransformed()) { + // Compute the overflow rect for this leaf transform frame in the + // coordinate space of the scrolled frame. + nsPoint scrollPos = aScrolledFrame->GetPosition(); + nsRect preScroll, postScroll; + { + // TODO: Can we reuse the reference box? + TransformReferenceBox refBox(child); + preScroll = nsDisplayTransform::TransformRect( + child->ScrollableOverflowRectRelativeToSelf(), child, refBox); + } + + // Temporarily override the scroll position of the scrolled frame by + // 10 CSS pixels, and then recompute what the overflow rect would be. + // This scroll position may not be valid, but that shouldn't matter + // for our calculations. + { + aScrolledFrame->SetPosition(scrollPos + nsPoint(600, 600)); + TransformReferenceBox refBox(child); + postScroll = nsDisplayTransform::TransformRect( + child->ScrollableOverflowRectRelativeToSelf(), child, refBox); + aScrolledFrame->SetPosition(scrollPos); + } + + // Compute how many app units the overflow rects moves by when we adjust + // the scroll position by 1 app unit. + double rightDelta = + (postScroll.XMost() - preScroll.XMost() + 600.0) / 600.0; + double bottomDelta = + (postScroll.YMost() - preScroll.YMost() + 600.0) / 600.0; + + // We can't ever have negative scrolling. + NS_ASSERTION(rightDelta > 0.0f && bottomDelta > 0.0f, + "Scrolling can't be reversed!"); + + // Move preScroll into the coordinate space of the scrollport. + preScroll += offset + scrollPos; + + // For each of the four edges of preScroll, figure out how far they + // extend beyond the scrollport. Ignore negative values since that means + // that side is already scrolled in to view and we don't need to add + // overflow to account for it. + nsMargin overhang(std::max(0, aScrollPort.Y() - preScroll.Y()), + std::max(0, preScroll.XMost() - aScrollPort.XMost()), + std::max(0, preScroll.YMost() - aScrollPort.YMost()), + std::max(0, aScrollPort.X() - preScroll.X())); + + // Scale according to rightDelta/bottomDelta to adjust for the different + // scroll rates. + overhang.top = NSCoordSaturatingMultiply( + overhang.top, static_cast<float>(1 / bottomDelta)); + overhang.right = NSCoordSaturatingMultiply( + overhang.right, static_cast<float>(1 / rightDelta)); + overhang.bottom = NSCoordSaturatingMultiply( + overhang.bottom, static_cast<float>(1 / bottomDelta)); + overhang.left = NSCoordSaturatingMultiply( + overhang.left, static_cast<float>(1 / rightDelta)); + + // Take the minimum overflow rect that would allow the current scroll + // position, using the size of the scroll port and offset by the + // inverse of the scroll position. + nsRect overflow = aScrollPort - scrollPos; + + // Expand it by our margins to get an overflow rect that would allow all + // edges of our transformed content to be scrolled into view. + overflow.Inflate(overhang); + + // Merge it with the combined overflow + aScrolledFrameOverflowArea.UnionRect(aScrolledFrameOverflowArea, + overflow); + } else if (aCurrentFrame == aScrolledFrame) { + aScrolledFrameOverflowArea.UnionRect( + aScrolledFrameOverflowArea, + child->ScrollableOverflowRectRelativeToParent()); + } + } + } +} + +BaselineSharingGroup nsHTMLScrollFrame::GetDefaultBaselineSharingGroup() const { + return mScrolledFrame->GetDefaultBaselineSharingGroup(); +} + +nscoord nsHTMLScrollFrame::SynthesizeFallbackBaseline( + mozilla::WritingMode aWM, BaselineSharingGroup aBaselineGroup) const { + // Marign-end even for central baselines. + if (aWM.IsLineInverted()) { + return -GetLogicalUsedMargin(aWM).BStart(aWM); + } + return aBaselineGroup == BaselineSharingGroup::First + ? BSize(aWM) + GetLogicalUsedMargin(aWM).BEnd(aWM) + : -GetLogicalUsedMargin(aWM).BEnd(aWM); +} + +Maybe<nscoord> nsHTMLScrollFrame::GetNaturalBaselineBOffset( + WritingMode aWM, BaselineSharingGroup aBaselineGroup, + BaselineExportContext aExportContext) const { + // Block containers that are scrollable always have a last baseline + // that are synthesized from block-end margin edge. + // Note(dshin): This behaviour is really only relevant to `inline-block` + // alignment context. In the context of table/flex/grid alignment, first/last + // baselines are calculated through `GetFirstLineBaseline`, which does + // calculations of its own. + // https://drafts.csswg.org/css-align/#baseline-export + if (aExportContext == BaselineExportContext::LineLayout && + aBaselineGroup == BaselineSharingGroup::Last && + mScrolledFrame->IsBlockFrameOrSubclass()) { + return Some(SynthesizeFallbackBaseline(aWM, aBaselineGroup)); + } + + if (StyleDisplay()->IsContainLayout()) { + return Nothing{}; + } + + // OK, here's where we defer to our scrolled frame. + return mScrolledFrame + ->GetNaturalBaselineBOffset(aWM, aBaselineGroup, aExportContext) + .map([this, aWM](nscoord aBaseline) { + // We have to add our border BStart thickness to whatever it returns, to + // produce an offset in our frame-rect's coordinate system. (We don't + // have to add padding, because the scrolled frame handles our padding.) + LogicalMargin border = GetLogicalUsedBorder(aWM); + const auto bSize = GetLogicalSize(aWM).BSize(aWM); + // Clamp the baseline to the border rect. See bug 1791069. + return std::clamp(border.BStart(aWM) + aBaseline, 0, bSize); + }); +} + +void nsHTMLScrollFrame::AdjustForPerspective(nsRect& aScrollableOverflow) { + // If we have perspective that is being applied to our children, then + // the effective transform on the child depends on the relative position + // of the child to us and changes during scrolling. + if (!ChildrenHavePerspective()) { + return; + } + aScrollableOverflow.SetEmpty(); + GetScrollableOverflowForPerspective(mScrolledFrame, mScrolledFrame, + ScrollPort(), nsPoint(), + aScrollableOverflow); +} + +void nsHTMLScrollFrame::Reflow(nsPresContext* aPresContext, + ReflowOutput& aDesiredSize, + const ReflowInput& aReflowInput, + nsReflowStatus& aStatus) { + MarkInReflow(); + DO_GLOBAL_REFLOW_COUNT("nsHTMLScrollFrame"); + DISPLAY_REFLOW(aPresContext, this, aReflowInput, aDesiredSize, aStatus); + MOZ_ASSERT(aStatus.IsEmpty(), "Caller should pass a fresh reflow status!"); + + HandleScrollbarStyleSwitching(); + + ScrollReflowInput state(this, aReflowInput); + + //------------ Handle Incremental Reflow ----------------- + bool reflowHScrollbar = true; + bool reflowVScrollbar = true; + bool reflowScrollCorner = true; + if (!aReflowInput.ShouldReflowAllKids()) { + auto NeedsReflow = [](const nsIFrame* aFrame) { + return aFrame && aFrame->IsSubtreeDirty(); + }; + + reflowHScrollbar = NeedsReflow(mHScrollbarBox); + reflowVScrollbar = NeedsReflow(mVScrollbarBox); + reflowScrollCorner = + NeedsReflow(mScrollCornerBox) || NeedsReflow(mResizerBox); + } + + if (mIsRoot) { + reflowScrollCorner = false; + } + + const nsRect oldScrollPort = ScrollPort(); + nsRect oldScrolledAreaBounds = + mScrolledFrame->ScrollableOverflowRectRelativeToParent(); + nsPoint oldScrollPosition = GetScrollPosition(); + + ReflowContents(state, aDesiredSize); + + nsSize layoutSize = + mIsUsingMinimumScaleSize ? mMinimumScaleSize : state.mInsideBorderSize; + aDesiredSize.Width() = layoutSize.width + state.mComputedBorder.LeftRight(); + aDesiredSize.Height() = layoutSize.height + state.mComputedBorder.TopBottom(); + + // Set the size of the frame now since computing the perspective-correct + // overflow (within PlaceScrollArea) can rely on it. + SetSize(aDesiredSize.GetWritingMode(), + aDesiredSize.Size(aDesiredSize.GetWritingMode())); + + // Restore the old scroll position, for now, even if that's not valid anymore + // because we changed size. We'll fix it up in a post-reflow callback, because + // our current size may only be temporary (e.g. we're compute XUL desired + // sizes). + PlaceScrollArea(state, oldScrollPosition); + if (!mPostedReflowCallback) { + // Make sure we'll try scrolling to restored position + PresShell()->PostReflowCallback(this); + mPostedReflowCallback = true; + } + + bool didOnlyHScrollbar = mOnlyNeedHScrollbarToScrollVVInsideLV; + bool didOnlyVScrollbar = mOnlyNeedVScrollbarToScrollVVInsideLV; + mOnlyNeedHScrollbarToScrollVVInsideLV = + state.mOnlyNeedHScrollbarToScrollVVInsideLV; + mOnlyNeedVScrollbarToScrollVVInsideLV = + state.mOnlyNeedVScrollbarToScrollVVInsideLV; + + bool didHaveHScrollbar = mHasHorizontalScrollbar; + bool didHaveVScrollbar = mHasVerticalScrollbar; + mHasHorizontalScrollbar = state.mShowHScrollbar; + mHasVerticalScrollbar = state.mShowVScrollbar; + const nsRect& newScrollPort = ScrollPort(); + nsRect newScrolledAreaBounds = + mScrolledFrame->ScrollableOverflowRectRelativeToParent(); + if (mSkippedScrollbarLayout || reflowHScrollbar || reflowVScrollbar || + reflowScrollCorner || HasAnyStateBits(NS_FRAME_IS_DIRTY) || + didHaveHScrollbar != state.mShowHScrollbar || + didHaveVScrollbar != state.mShowVScrollbar || + didOnlyHScrollbar != mOnlyNeedHScrollbarToScrollVVInsideLV || + didOnlyVScrollbar != mOnlyNeedVScrollbarToScrollVVInsideLV || + !oldScrollPort.IsEqualEdges(newScrollPort) || + !oldScrolledAreaBounds.IsEqualEdges(newScrolledAreaBounds)) { + if (!mSuppressScrollbarUpdate) { + mSkippedScrollbarLayout = false; + nsHTMLScrollFrame::SetScrollbarVisibility(mHScrollbarBox, + state.mShowHScrollbar); + nsHTMLScrollFrame::SetScrollbarVisibility(mVScrollbarBox, + state.mShowVScrollbar); + // place and reflow scrollbars + const nsRect insideBorderArea( + nsPoint(state.mComputedBorder.left, state.mComputedBorder.top), + layoutSize); + LayoutScrollbars(state, insideBorderArea, oldScrollPort); + } else { + mSkippedScrollbarLayout = true; + } + } + if (mIsRoot) { + if (RefPtr<MobileViewportManager> manager = + PresShell()->GetMobileViewportManager()) { + // Note that this runs during layout, and when we get here the root + // scrollframe has already been laid out. It may have added or removed + // scrollbars as a result of that layout, so we need to ensure the + // visual viewport is updated to account for that before we read the + // visual viewport size. + manager->UpdateVisualViewportSizeForPotentialScrollbarChange(); + } else if (oldScrollPort.Size() != newScrollPort.Size()) { + // We want to make sure to send a visual viewport resize event if the + // scrollport changed sizes for root scroll frames. The + // MobileViewportManager will do that, but if we don't have one (ie we + // aren't a root content document for example) we have to send one + // ourselves. + if (auto* window = nsGlobalWindowInner::Cast( + aPresContext->Document()->GetInnerWindow())) { + window->VisualViewport()->PostResizeEvent(); + } + } + } + + // Note that we need to do this after the + // UpdateVisualViewportSizeForPotentialScrollbarChange call above because that + // is what updates the visual viewport size and we need it to be up to date. + if (mIsRoot && !state.OverlayScrollbars() && + (didHaveHScrollbar != state.mShowHScrollbar || + didHaveVScrollbar != state.mShowVScrollbar || + didOnlyHScrollbar != mOnlyNeedHScrollbarToScrollVVInsideLV || + didOnlyVScrollbar != mOnlyNeedVScrollbarToScrollVVInsideLV) && + PresShell()->IsVisualViewportOffsetSet()) { + // Removing layout/classic scrollbars can make a previously valid vvoffset + // invalid. For example, if we are zoomed in on an overflow hidden document + // and then zoom back out, when apz reaches the initial resolution (ie 1.0) + // it won't know that we can remove the scrollbars, so the vvoffset can + // validly be upto the width/height of the scrollbars. After we reflow and + // remove the scrollbars the only valid vvoffset is (0,0). We could wait + // until we send the new frame metrics to apz and then have it reply with + // the new corrected vvoffset but having an inconsistent vvoffset causes + // problems so trigger the vvoffset to be re-set and re-clamped in + // ReflowFinished. + mReclampVVOffsetInReflowFinished = true; + } + + aDesiredSize.SetOverflowAreasToDesiredBounds(); + + UpdateSticky(); + FinishReflowWithAbsoluteFrames(aPresContext, aDesiredSize, aReflowInput, + aStatus); + + if (!InInitialReflow() && !mHadNonInitialReflow) { + mHadNonInitialReflow = true; + } + + if (mIsRoot && !oldScrolledAreaBounds.IsEqualEdges(newScrolledAreaBounds)) { + PostScrolledAreaEvent(); + } + + UpdatePrevScrolledRect(); + + aStatus.Reset(); // This type of frame can't be split. + PostOverflowEvent(); +} + +void nsHTMLScrollFrame::DidReflow(nsPresContext* aPresContext, + const ReflowInput* aReflowInput) { + nsContainerFrame::DidReflow(aPresContext, aReflowInput); + if (NeedsResnap()) { + PostPendingResnap(); + } else { + PresShell()->PostPendingScrollAnchorAdjustment(Anchor()); + } +} + +//////////////////////////////////////////////////////////////////////////////// + +#ifdef DEBUG_FRAME_DUMP +nsresult nsHTMLScrollFrame::GetFrameName(nsAString& aResult) const { + return MakeFrameName(u"HTMLScroll"_ns, aResult); +} +#endif + +#ifdef ACCESSIBILITY +a11y::AccType nsHTMLScrollFrame::AccessibleType() { + if (IsTableCaption()) { + return GetRect().IsEmpty() ? a11y::eNoType : a11y::eHTMLCaptionType; + } + + // Create an accessible regardless of focusable state because the state can be + // changed during frame life cycle without any notifications to accessibility. + if (mContent->IsRootOfNativeAnonymousSubtree() || + GetScrollStyles().IsHiddenInBothDirections()) { + return a11y::eNoType; + } + + return a11y::eHyperTextType; +} +#endif + +NS_QUERYFRAME_HEAD(nsHTMLScrollFrame) + NS_QUERYFRAME_ENTRY(nsIAnonymousContentCreator) + NS_QUERYFRAME_ENTRY(nsIScrollableFrame) + NS_QUERYFRAME_ENTRY(nsIStatefulFrame) + NS_QUERYFRAME_ENTRY(nsIScrollbarMediator) + NS_QUERYFRAME_ENTRY(nsHTMLScrollFrame) +NS_QUERYFRAME_TAIL_INHERITING(nsContainerFrame) + +nsMargin nsHTMLScrollFrame::GetDesiredScrollbarSizes() const { + nsPresContext* pc = PresContext(); + if (pc->UseOverlayScrollbars()) { + return {}; + } + + const auto& style = *nsLayoutUtils::StyleForScrollbar(this); + const auto scrollbarWidth = style.StyleUIReset()->ScrollbarWidth(); + if (scrollbarWidth == StyleScrollbarWidth::None) { + return {}; + } + + ScrollStyles styles = GetScrollStyles(); + nsMargin result(0, 0, 0, 0); + + auto size = pc->DevPixelsToAppUnits( + pc->Theme()->GetScrollbarSize(pc, scrollbarWidth, nsITheme::Overlay::No)); + if (styles.mVertical != StyleOverflow::Hidden) { + if (IsScrollbarOnRight()) + result.left = size; + else + result.right = size; + } + + if (styles.mHorizontal != StyleOverflow::Hidden) { + // We don't currently support any scripts that would require a scrollbar + // at the top. (Are there any?) + result.bottom = size; + } + + return result; +} + +nscoord nsIScrollableFrame::GetNondisappearingScrollbarWidth(nsPresContext* aPc, + WritingMode aWM) { + // We use this to size the combobox dropdown button. For that, we need to have + // the proper big, non-overlay scrollbar size, regardless of whether we're + // using e.g. scrollbar-width: thin, or overlay scrollbars. + auto size = aPc->Theme()->GetScrollbarSize(aPc, StyleScrollbarWidth::Auto, + nsITheme::Overlay::No); + return aPc->DevPixelsToAppUnits(size); +} + +void nsHTMLScrollFrame::HandleScrollbarStyleSwitching() { + // Check if we switched between scrollbar styles. + if (mScrollbarActivity && !UsesOverlayScrollbars()) { + mScrollbarActivity->Destroy(); + mScrollbarActivity = nullptr; + } else if (!mScrollbarActivity && UsesOverlayScrollbars()) { + mScrollbarActivity = new ScrollbarActivity(do_QueryFrame(this)); + } +} + +#if defined(MOZ_WIDGET_ANDROID) +static bool IsFocused(nsIContent* aContent) { + // Some content elements, like the GetContent() of a scroll frame + // for a text input field, are inside anonymous subtrees, but the focus + // manager always reports a non-anonymous element as the focused one, so + // walk up the tree until we reach a non-anonymous element. + while (aContent && aContent->IsInNativeAnonymousSubtree()) { + aContent = aContent->GetParent(); + } + + return aContent ? nsContentUtils::IsFocusedContent(aContent) : false; +} +#endif + +void nsHTMLScrollFrame::SetScrollableByAPZ(bool aScrollable) { + mScrollableByAPZ = aScrollable; +} + +void nsHTMLScrollFrame::SetZoomableByAPZ(bool aZoomable) { + if (!nsLayoutUtils::UsesAsyncScrolling(this)) { + // If APZ is disabled on this window, then we're never actually going to + // do any zooming. So we don't need to do any of the setup for it. Note + // that this function gets called from ZoomConstraintsClient even if APZ + // is disabled to indicate the zoomability of content. + aZoomable = false; + } + if (mZoomableByAPZ != aZoomable) { + // We might be changing the result of DecideScrollableLayer() so schedule a + // paint to make sure we pick up the result of that change. + mZoomableByAPZ = aZoomable; + SchedulePaint(); + } +} + +void nsHTMLScrollFrame::SetHasOutOfFlowContentInsideFilter() { + mHasOutOfFlowContentInsideFilter = true; +} + +bool nsHTMLScrollFrame::WantAsyncScroll() const { + ScrollStyles styles = GetScrollStyles(); + nscoord oneDevPixel = + GetScrolledFrame()->PresContext()->AppUnitsPerDevPixel(); + nsRect scrollRange = GetLayoutScrollRange(); + + // If the page has a visual viewport size that's different from + // the layout viewport size at the current zoom level, we need to be + // able to scroll the visual viewport inside the layout viewport + // even if the page is not zoomable. + if (!GetVisualScrollRange().IsEqualInterior(scrollRange)) { + return true; + } + + bool isVScrollable = (scrollRange.height >= oneDevPixel) && + (styles.mVertical != StyleOverflow::Hidden); + bool isHScrollable = (scrollRange.width >= oneDevPixel) && + (styles.mHorizontal != StyleOverflow::Hidden); + +#if defined(MOZ_WIDGET_ANDROID) + // Mobile platforms need focus to scroll text inputs. + bool canScrollWithoutScrollbars = + !IsForTextControlWithNoScrollbars() || IsFocused(GetContent()); +#else + bool canScrollWithoutScrollbars = true; +#endif + + // The check for scroll bars was added in bug 825692 to prevent layerization + // of text inputs for performance reasons. + bool isVAsyncScrollable = + isVScrollable && (mVScrollbarBox || canScrollWithoutScrollbars); + bool isHAsyncScrollable = + isHScrollable && (mHScrollbarBox || canScrollWithoutScrollbars); + return isVAsyncScrollable || isHAsyncScrollable; +} + +static nsRect GetOnePixelRangeAroundPoint(const nsPoint& aPoint, + bool aIsHorizontal) { + nsRect allowedRange(aPoint, nsSize()); + nscoord halfPixel = nsPresContext::CSSPixelsToAppUnits(0.5f); + if (aIsHorizontal) { + allowedRange.x = aPoint.x - halfPixel; + allowedRange.width = halfPixel * 2 - 1; + } else { + allowedRange.y = aPoint.y - halfPixel; + allowedRange.height = halfPixel * 2 - 1; + } + return allowedRange; +} + +void nsHTMLScrollFrame::ScrollByPage(nsScrollbarFrame* aScrollbar, + int32_t aDirection, + ScrollSnapFlags aSnapFlags) { + ScrollByUnit(aScrollbar, ScrollMode::Smooth, aDirection, ScrollUnit::PAGES, + aSnapFlags); +} + +void nsHTMLScrollFrame::ScrollByWhole(nsScrollbarFrame* aScrollbar, + int32_t aDirection, + ScrollSnapFlags aSnapFlags) { + ScrollByUnit(aScrollbar, ScrollMode::Instant, aDirection, ScrollUnit::WHOLE, + aSnapFlags); +} + +void nsHTMLScrollFrame::ScrollByLine(nsScrollbarFrame* aScrollbar, + int32_t aDirection, + ScrollSnapFlags aSnapFlags) { + bool isHorizontal = aScrollbar->IsHorizontal(); + nsIntPoint delta; + if (isHorizontal) { + const double kScrollMultiplier = + StaticPrefs::toolkit_scrollbox_horizontalScrollDistance(); + delta.x = aDirection * kScrollMultiplier; + if (GetLineScrollAmount().width * delta.x > GetPageScrollAmount().width) { + // The scroll frame is so small that the delta would be more + // than an entire page. Scroll by one page instead to maintain + // context. + ScrollByPage(aScrollbar, aDirection); + return; + } + } else { + const double kScrollMultiplier = + StaticPrefs::toolkit_scrollbox_verticalScrollDistance(); + delta.y = aDirection * kScrollMultiplier; + if (GetLineScrollAmount().height * delta.y > GetPageScrollAmount().height) { + // The scroll frame is so small that the delta would be more + // than an entire page. Scroll by one page instead to maintain + // context. + ScrollByPage(aScrollbar, aDirection); + return; + } + } + + nsIntPoint overflow; + ScrollBy(delta, ScrollUnit::LINES, ScrollMode::Smooth, &overflow, + ScrollOrigin::Other, nsIScrollableFrame::NOT_MOMENTUM, aSnapFlags); +} + +void nsHTMLScrollFrame::RepeatButtonScroll(nsScrollbarFrame* aScrollbar) { + aScrollbar->MoveToNewPosition(nsScrollbarFrame::ImplementsScrollByUnit::Yes); +} + +void nsHTMLScrollFrame::ThumbMoved(nsScrollbarFrame* aScrollbar, + nscoord aOldPos, nscoord aNewPos) { + MOZ_ASSERT(aScrollbar != nullptr); + bool isHorizontal = aScrollbar->IsHorizontal(); + nsPoint current = GetScrollPosition(); + nsPoint dest = current; + if (isHorizontal) { + dest.x = IsPhysicalLTR() ? aNewPos : aNewPos - GetLayoutScrollRange().width; + } else { + dest.y = aNewPos; + } + nsRect allowedRange = GetOnePixelRangeAroundPoint(dest, isHorizontal); + + // Don't try to scroll if we're already at an acceptable place. + // Don't call Contains here since Contains returns false when the point is + // on the bottom or right edge of the rectangle. + if (allowedRange.ClampPoint(current) == current) { + return; + } + + ScrollToWithOrigin( + dest, &allowedRange, + ScrollOperationParams{ScrollMode::Instant, ScrollOrigin::Other}); +} + +void nsHTMLScrollFrame::ScrollbarReleased(nsScrollbarFrame* aScrollbar) { + // Scrollbar scrolling does not result in fling gestures, clear any + // accumulated velocity + mVelocityQueue.Reset(); + + // Perform scroll snapping, if needed. Scrollbar movement uses the same + // smooth scrolling animation as keyboard scrolling. + ScrollSnap(mDestination, ScrollMode::Smooth); +} + +void nsHTMLScrollFrame::ScrollByUnit(nsScrollbarFrame* aScrollbar, + ScrollMode aMode, int32_t aDirection, + ScrollUnit aUnit, + ScrollSnapFlags aSnapFlags) { + MOZ_ASSERT(aScrollbar != nullptr); + bool isHorizontal = aScrollbar->IsHorizontal(); + nsIntPoint delta; + if (isHorizontal) { + delta.x = aDirection; + } else { + delta.y = aDirection; + } + nsIntPoint overflow; + ScrollBy(delta, aUnit, aMode, &overflow, ScrollOrigin::Other, + nsIScrollableFrame::NOT_MOMENTUM, aSnapFlags); +} + +//-------------------- Helper ---------------------- + +// AsyncSmoothMSDScroll has ref counting. +class nsHTMLScrollFrame::AsyncSmoothMSDScroll final + : public nsARefreshObserver { + public: + AsyncSmoothMSDScroll(const nsPoint& aInitialPosition, + const nsPoint& aInitialDestination, + const nsSize& aInitialVelocity, const nsRect& aRange, + const mozilla::TimeStamp& aStartTime, + nsPresContext* aPresContext, + UniquePtr<ScrollSnapTargetIds> aSnapTargetIds, + ScrollTriggeredByScript aTriggeredByScript) + : mXAxisModel(aInitialPosition.x, aInitialDestination.x, + aInitialVelocity.width, + StaticPrefs::layout_css_scroll_behavior_spring_constant(), + StaticPrefs::layout_css_scroll_behavior_damping_ratio()), + mYAxisModel(aInitialPosition.y, aInitialDestination.y, + aInitialVelocity.height, + StaticPrefs::layout_css_scroll_behavior_spring_constant(), + StaticPrefs::layout_css_scroll_behavior_damping_ratio()), + mRange(aRange), + mStartPosition(aInitialPosition), + mLastRefreshTime(aStartTime), + mCallee(nullptr), + mOneDevicePixelInAppUnits(aPresContext->DevPixelsToAppUnits(1)), + mSnapTargetIds(std::move(aSnapTargetIds)), + mTriggeredByScript(aTriggeredByScript) { + Telemetry::SetHistogramRecordingEnabled( + Telemetry::FX_REFRESH_DRIVER_SYNC_SCROLL_FRAME_DELAY_MS, true); + } + + NS_INLINE_DECL_REFCOUNTING(AsyncSmoothMSDScroll, override) + + nsSize GetVelocity() { + // In nscoords per second + return nsSize(mXAxisModel.GetVelocity(), mYAxisModel.GetVelocity()); + } + + nsPoint GetPosition() { + // In nscoords + return nsPoint(NSToCoordRound(mXAxisModel.GetPosition()), + NSToCoordRound(mYAxisModel.GetPosition())); + } + + void SetDestination(const nsPoint& aDestination, + ScrollTriggeredByScript aTriggeredByScript) { + mXAxisModel.SetDestination(static_cast<int32_t>(aDestination.x)); + mYAxisModel.SetDestination(static_cast<int32_t>(aDestination.y)); + mTriggeredByScript = aTriggeredByScript; + } + + void SetRange(const nsRect& aRange) { mRange = aRange; } + + nsRect GetRange() { return mRange; } + + nsPoint GetStartPosition() { return mStartPosition; } + + void Simulate(const TimeDuration& aDeltaTime) { + mXAxisModel.Simulate(aDeltaTime); + mYAxisModel.Simulate(aDeltaTime); + + nsPoint desired = GetPosition(); + nsPoint clamped = mRange.ClampPoint(desired); + if (desired.x != clamped.x) { + // The scroll has hit the "wall" at the left or right edge of the allowed + // scroll range. + // Absorb the impact to avoid bounceback effect. + mXAxisModel.SetVelocity(0.0); + mXAxisModel.SetPosition(clamped.x); + } + + if (desired.y != clamped.y) { + // The scroll has hit the "wall" at the left or right edge of the allowed + // scroll range. + // Absorb the impact to avoid bounceback effect. + mYAxisModel.SetVelocity(0.0); + mYAxisModel.SetPosition(clamped.y); + } + } + + bool IsFinished() { + return mXAxisModel.IsFinished(mOneDevicePixelInAppUnits) && + mYAxisModel.IsFinished(mOneDevicePixelInAppUnits); + } + + virtual void WillRefresh(mozilla::TimeStamp aTime) override { + mozilla::TimeDuration deltaTime = aTime - mLastRefreshTime; + mLastRefreshTime = aTime; + + // The callback may release "this". + // We don't access members after returning, so no need for KungFuDeathGrip. + nsHTMLScrollFrame::AsyncSmoothMSDScrollCallback(mCallee, deltaTime); + } + + /* + * Set a refresh observer for smooth scroll iterations (and start observing). + * Should be used at most once during the lifetime of this object. + */ + void SetRefreshObserver(nsHTMLScrollFrame* aCallee) { + NS_ASSERTION(aCallee && !mCallee, + "AsyncSmoothMSDScroll::SetRefreshObserver - Invalid usage."); + + RefreshDriver(aCallee)->AddRefreshObserver(this, FlushType::Style, + "Smooth scroll (MSD) animation"); + mCallee = aCallee; + } + + /** + * The mCallee holds a strong ref to us since the refresh driver doesn't. + * Our dtor and mCallee's Destroy() method both call RemoveObserver() - + * whichever comes first removes us from the refresh driver. + */ + void RemoveObserver() { + if (mCallee) { + RefreshDriver(mCallee)->RemoveRefreshObserver(this, FlushType::Style); + mCallee = nullptr; + } + } + + UniquePtr<ScrollSnapTargetIds> TakeSnapTargetIds() { + return std::move(mSnapTargetIds); + } + + bool WasTriggeredByScript() const { + return mTriggeredByScript == ScrollTriggeredByScript::Yes; + } + + private: + // Private destructor, to discourage deletion outside of Release(): + ~AsyncSmoothMSDScroll() { + RemoveObserver(); + Telemetry::SetHistogramRecordingEnabled( + Telemetry::FX_REFRESH_DRIVER_SYNC_SCROLL_FRAME_DELAY_MS, false); + } + + nsRefreshDriver* RefreshDriver(nsHTMLScrollFrame* aCallee) { + return aCallee->PresContext()->RefreshDriver(); + } + + mozilla::layers::AxisPhysicsMSDModel mXAxisModel, mYAxisModel; + nsRect mRange; + nsPoint mStartPosition; + mozilla::TimeStamp mLastRefreshTime; + nsHTMLScrollFrame* mCallee; + nscoord mOneDevicePixelInAppUnits; + UniquePtr<ScrollSnapTargetIds> mSnapTargetIds; + ScrollTriggeredByScript mTriggeredByScript; +}; + +// AsyncScroll has ref counting. +class nsHTMLScrollFrame::AsyncScroll final : public nsARefreshObserver { + public: + typedef mozilla::TimeStamp TimeStamp; + typedef mozilla::TimeDuration TimeDuration; + + explicit AsyncScroll(UniquePtr<ScrollSnapTargetIds> aSnapTargetIds, + ScrollTriggeredByScript aTriggeredByScript) + : mOrigin(ScrollOrigin::NotSpecified), + mCallee(nullptr), + mSnapTargetIds(std::move(aSnapTargetIds)), + mTriggeredByScript(aTriggeredByScript) { + Telemetry::SetHistogramRecordingEnabled( + Telemetry::FX_REFRESH_DRIVER_SYNC_SCROLL_FRAME_DELAY_MS, true); + } + + private: + // Private destructor, to discourage deletion outside of Release(): + ~AsyncScroll() { + RemoveObserver(); + Telemetry::SetHistogramRecordingEnabled( + Telemetry::FX_REFRESH_DRIVER_SYNC_SCROLL_FRAME_DELAY_MS, false); + } + + public: + void InitSmoothScroll(TimeStamp aTime, nsPoint aInitialPosition, + nsPoint aDestination, ScrollOrigin aOrigin, + const nsRect& aRange, const nsSize& aCurrentVelocity); + void Init(nsPoint aInitialPosition, const nsRect& aRange) { + mAnimationPhysics = nullptr; + mRange = aRange; + mStartPosition = aInitialPosition; + } + + bool IsSmoothScroll() { return mAnimationPhysics != nullptr; } + + bool IsFinished(const TimeStamp& aTime) const { + MOZ_RELEASE_ASSERT(mAnimationPhysics); + return mAnimationPhysics->IsFinished(aTime); + } + + nsPoint PositionAt(const TimeStamp& aTime) const { + MOZ_RELEASE_ASSERT(mAnimationPhysics); + return mAnimationPhysics->PositionAt(aTime); + } + + nsSize VelocityAt(const TimeStamp& aTime) const { + MOZ_RELEASE_ASSERT(mAnimationPhysics); + return mAnimationPhysics->VelocityAt(aTime); + } + + nsPoint GetStartPosition() const { return mStartPosition; } + + // Most recent scroll origin. + ScrollOrigin mOrigin; + + // Allowed destination positions around mDestination + nsRect mRange; + + // Initial position where the async scroll was triggered. + nsPoint mStartPosition; + + private: + void InitPreferences(TimeStamp aTime, nsAtom* aOrigin); + + UniquePtr<ScrollAnimationPhysics> mAnimationPhysics; + + // The next section is observer/callback management + // Bodies of WillRefresh and RefreshDriver contain nsHTMLScrollFrame specific + // code. + public: + NS_INLINE_DECL_REFCOUNTING(AsyncScroll, override) + + /* + * Set a refresh observer for smooth scroll iterations (and start observing). + * Should be used at most once during the lifetime of this object. + */ + void SetRefreshObserver(nsHTMLScrollFrame* aCallee) { + NS_ASSERTION(aCallee && !mCallee, + "AsyncScroll::SetRefreshObserver - Invalid usage."); + + RefreshDriver(aCallee)->AddRefreshObserver(this, FlushType::Style, + "Smooth scroll animation"); + mCallee = aCallee; + auto* presShell = mCallee->PresShell(); + MOZ_ASSERT(presShell); + presShell->SuppressDisplayport(true); + } + + virtual void WillRefresh(mozilla::TimeStamp aTime) override { + // The callback may release "this". + // We don't access members after returning, so no need for KungFuDeathGrip. + nsHTMLScrollFrame::AsyncScrollCallback(mCallee, aTime); + } + + /** + * The mCallee holds a strong ref to us since the refresh driver doesn't. + * Our dtor and mCallee's Destroy() method both call RemoveObserver() - + * whichever comes first removes us from the refresh driver. + */ + void RemoveObserver() { + if (mCallee) { + RefreshDriver(mCallee)->RemoveRefreshObserver(this, FlushType::Style); + auto* presShell = mCallee->PresShell(); + MOZ_ASSERT(presShell); + presShell->SuppressDisplayport(false); + mCallee = nullptr; + } + } + + UniquePtr<ScrollSnapTargetIds> TakeSnapTargetIds() { + return std::move(mSnapTargetIds); + } + + bool WasTriggeredByScript() const { + return mTriggeredByScript == ScrollTriggeredByScript::Yes; + } + + private: + nsHTMLScrollFrame* mCallee; + UniquePtr<ScrollSnapTargetIds> mSnapTargetIds; + ScrollTriggeredByScript mTriggeredByScript; + + nsRefreshDriver* RefreshDriver(nsHTMLScrollFrame* aCallee) { + return aCallee->PresContext()->RefreshDriver(); + } +}; + +void nsHTMLScrollFrame::AsyncScroll::InitSmoothScroll( + TimeStamp aTime, nsPoint aInitialPosition, nsPoint aDestination, + ScrollOrigin aOrigin, const nsRect& aRange, + const nsSize& aCurrentVelocity) { + switch (aOrigin) { + case ScrollOrigin::NotSpecified: + case ScrollOrigin::Restore: + case ScrollOrigin::Relative: + // We don't have special prefs for "restore", just treat it as "other". + // "restore" scrolls are (for now) always instant anyway so unless + // something changes we should never have aOrigin == + // ScrollOrigin::Restore here. + aOrigin = ScrollOrigin::Other; + break; + case ScrollOrigin::Apz: + // Likewise we should never get APZ-triggered scrolls here, and if that + // changes something is likely broken somewhere. + MOZ_ASSERT(false); + break; + default: + break; + }; + + // Read preferences only on first iteration or for a different event origin. + if (!mAnimationPhysics || aOrigin != mOrigin) { + mOrigin = aOrigin; + if (StaticPrefs::general_smoothScroll_msdPhysics_enabled()) { + mAnimationPhysics = + MakeUnique<ScrollAnimationMSDPhysics>(aInitialPosition); + } else { + ScrollAnimationBezierPhysicsSettings settings = + layers::apz::ComputeBezierAnimationSettingsForOrigin(mOrigin); + mAnimationPhysics = + MakeUnique<ScrollAnimationBezierPhysics>(aInitialPosition, settings); + } + } + + mStartPosition = aInitialPosition; + mRange = aRange; + + mAnimationPhysics->Update(aTime, aDestination, aCurrentVelocity); +} + +/* + * Callback function from AsyncSmoothMSDScroll, used in + * nsHTMLScrollFrame::ScrollTo + */ +void nsHTMLScrollFrame::AsyncSmoothMSDScrollCallback( + nsHTMLScrollFrame* aInstance, mozilla::TimeDuration aDeltaTime) { + NS_ASSERTION(aInstance != nullptr, "aInstance must not be null"); + NS_ASSERTION(aInstance->mAsyncSmoothMSDScroll, + "Did not expect AsyncSmoothMSDScrollCallback without an active " + "MSD scroll."); + + nsRect range = aInstance->mAsyncSmoothMSDScroll->GetRange(); + aInstance->mAsyncSmoothMSDScroll->Simulate(aDeltaTime); + + if (!aInstance->mAsyncSmoothMSDScroll->IsFinished()) { + nsPoint destination = aInstance->mAsyncSmoothMSDScroll->GetPosition(); + // Allow this scroll operation to land on any pixel boundary within the + // allowed scroll range for this frame. + // If the MSD is under-dampened or the destination is changed rapidly, + // it is expected (and desired) that the scrolling may overshoot. + nsRect intermediateRange = nsRect(destination, nsSize()).UnionEdges(range); + aInstance->ScrollToImpl(destination, intermediateRange); + // 'aInstance' might be destroyed here + return; + } + + aInstance->CompleteAsyncScroll( + aInstance->mAsyncSmoothMSDScroll->GetStartPosition(), range, + aInstance->mAsyncSmoothMSDScroll->TakeSnapTargetIds()); +} + +/* + * Callback function from AsyncScroll, used in nsHTMLScrollFrame::ScrollTo + */ +void nsHTMLScrollFrame::AsyncScrollCallback(nsHTMLScrollFrame* aInstance, + mozilla::TimeStamp aTime) { + MOZ_ASSERT(aInstance != nullptr, "aInstance must not be null"); + MOZ_ASSERT( + aInstance->mAsyncScroll, + "Did not expect AsyncScrollCallback without an active async scroll."); + + if (!aInstance || !aInstance->mAsyncScroll) { + return; // XXX wallpaper bug 1107353 for now. + } + + nsRect range = aInstance->mAsyncScroll->mRange; + if (aInstance->mAsyncScroll->IsSmoothScroll()) { + if (!aInstance->mAsyncScroll->IsFinished(aTime)) { + nsPoint destination = aInstance->mAsyncScroll->PositionAt(aTime); + // Allow this scroll operation to land on any pixel boundary between the + // current position and the final allowed range. (We don't want + // intermediate steps to be more constrained than the final step!) + nsRect intermediateRange = + nsRect(aInstance->GetScrollPosition(), nsSize()).UnionEdges(range); + aInstance->ScrollToImpl(destination, intermediateRange); + // 'aInstance' might be destroyed here + return; + } + } + + aInstance->CompleteAsyncScroll(aInstance->mAsyncScroll->GetStartPosition(), + range, + aInstance->mAsyncScroll->TakeSnapTargetIds()); +} + +void nsHTMLScrollFrame::SetTransformingByAPZ(bool aTransforming) { + if (mTransformingByAPZ && !aTransforming) { + PostScrollEndEvent(); + } + mTransformingByAPZ = aTransforming; + if (!mozilla::css::TextOverflow::HasClippedTextOverflow(this) || + mozilla::css::TextOverflow::HasBlockEllipsis(mScrolledFrame)) { + // If the block has some overflow marker stuff we should kick off a paint + // because we have special behaviour for it when APZ scrolling is active. + SchedulePaint(); + } +} + +void nsHTMLScrollFrame::CompleteAsyncScroll( + const nsPoint& aStartPosition, const nsRect& aRange, + UniquePtr<ScrollSnapTargetIds> aSnapTargetIds, ScrollOrigin aOrigin) { + SetLastSnapTargetIds(std::move(aSnapTargetIds)); + + bool scrollPositionChanged = mDestination != aStartPosition; + bool isNotHandledByApz = + nsLayoutUtils::CanScrollOriginClobberApz(aOrigin) || + ScrollAnimationState().contains(AnimationState::MainThread); + + // Apply desired destination range since this is the last step of scrolling. + RemoveObservers(); + AutoWeakFrame weakFrame(this); + ScrollToImpl(mDestination, aRange, aOrigin); + if (!weakFrame.IsAlive()) { + return; + } + // We are done scrolling, set our destination to wherever we actually ended + // up scrolling to. + mDestination = GetScrollPosition(); + // Post a `scrollend` event for scrolling not handled by APZ, including: + // + // - programmatic instant scrolls + // - the end of a smooth scroll animation running on the main thread + // + // For scrolling handled by APZ, the `scrollend` event is posted in + // SetTransformingByAPZ() when the APZC is transitioning from a transforming + // to a non-transforming state (e.g. a transition from PANNING to NOTHING). + // The scrollend event should not be fired for a scroll that does not + // result in a scroll position change. + if (isNotHandledByApz && scrollPositionChanged) { + PostScrollEndEvent(); + } +} + +bool nsHTMLScrollFrame::HasBgAttachmentLocal() const { + const nsStyleBackground* bg = StyleBackground(); + return bg->HasLocalBackground(); +} + +void nsHTMLScrollFrame::ScrollToInternal( + nsPoint aScrollPosition, ScrollMode aMode, ScrollOrigin aOrigin, + const nsRect* aRange, ScrollSnapFlags aSnapFlags, + ScrollTriggeredByScript aTriggeredByScript) { + if (aOrigin == ScrollOrigin::NotSpecified) { + aOrigin = ScrollOrigin::Other; + } + ScrollToWithOrigin( + aScrollPosition, aRange, + ScrollOperationParams{aMode, aOrigin, aSnapFlags, aTriggeredByScript}); +} + +void nsHTMLScrollFrame::ScrollToCSSPixels(const CSSIntPoint& aScrollPosition, + ScrollMode aMode) { + CSSIntPoint currentCSSPixels = GetScrollPositionCSSPixels(); + // Transmogrify this scroll to a relative one if there's any on-going + // animation in APZ triggered by __user__. + // Bug 1740164: We will apply it for cases there's no animation in APZ. + + auto scrollAnimationState = ScrollAnimationState(); + bool isScrollAnimating = + scrollAnimationState.contains(AnimationState::MainThread) || + scrollAnimationState.contains(AnimationState::APZPending) || + scrollAnimationState.contains(AnimationState::APZRequested); + if (mCurrentAPZScrollAnimationType == + APZScrollAnimationType::TriggeredByUserInput && + !isScrollAnimating) { + CSSIntPoint delta = aScrollPosition - currentCSSPixels; + // This transmogrification need to be an intended end position scroll + // operation. + ScrollByCSSPixelsInternal(delta, aMode, + ScrollSnapFlags::IntendedEndPosition); + return; + } + + nscoord halfPixel = nsPresContext::CSSPixelsToAppUnits(0.5f); + nsPoint pt = CSSPoint::ToAppUnits(aScrollPosition); + nsRect range(pt.x - halfPixel, pt.y - halfPixel, 2 * halfPixel - 1, + 2 * halfPixel - 1); + // XXX I don't think the following blocks are needed anymore, now that + // ScrollToImpl simply tries to scroll an integer number of layer + // pixels from the current position + nsPoint current = GetScrollPosition(); + if (currentCSSPixels.x == aScrollPosition.x) { + pt.x = current.x; + range.x = pt.x; + range.width = 0; + } + if (currentCSSPixels.y == aScrollPosition.y) { + pt.y = current.y; + range.y = pt.y; + range.height = 0; + } + ScrollToWithOrigin( + pt, &range, + ScrollOperationParams{ + aMode, ScrollOrigin::Other, + // This ScrollToCSSPixels is used for Element.scrollTo, + // Element.scrollTop, Element.scrollLeft and for Window.scrollTo. + ScrollSnapFlags::IntendedEndPosition, ScrollTriggeredByScript::Yes}); + // 'this' might be destroyed here +} + +void nsHTMLScrollFrame::ScrollToCSSPixelsForApz( + const CSSPoint& aScrollPosition, ScrollSnapTargetIds&& aLastSnapTargetIds) { + nsPoint pt = CSSPoint::ToAppUnits(aScrollPosition); + nscoord halfRange = nsPresContext::CSSPixelsToAppUnits(1000); + nsRect range(pt.x - halfRange, pt.y - halfRange, 2 * halfRange - 1, + 2 * halfRange - 1); + ScrollToWithOrigin( + pt, &range, + ScrollOperationParams{ScrollMode::Instant, ScrollOrigin::Apz, + std::move(aLastSnapTargetIds)}); + // 'this' might be destroyed here +} + +CSSIntPoint nsHTMLScrollFrame::GetScrollPositionCSSPixels() { + return CSSIntPoint::FromAppUnitsRounded(GetScrollPosition()); +} + +/* + * this method wraps calls to ScrollToImpl(), either in one shot or + * incrementally, based on the setting of the smoothness scroll pref + */ +void nsHTMLScrollFrame::ScrollToWithOrigin(nsPoint aScrollPosition, + const nsRect* aRange, + ScrollOperationParams&& aParams) { + // None is never a valid scroll origin to be passed in. + MOZ_ASSERT(aParams.mOrigin != ScrollOrigin::None); + + if (aParams.mOrigin != ScrollOrigin::Restore) { + // If we're doing a non-restore scroll, we don't want to later + // override it by restoring our saved scroll position. + SCROLLRESTORE_LOG("%p: Clearing mRestorePos (cur=%s, dst=%s)\n", this, + ToString(GetScrollPosition()).c_str(), + ToString(aScrollPosition).c_str()); + mRestorePos.x = mRestorePos.y = -1; + } + + Maybe<SnapTarget> snapTarget; + if (!aParams.IsScrollSnapDisabled()) { + snapTarget = GetSnapPointForDestination(ScrollUnit::DEVICE_PIXELS, + aParams.mSnapFlags, mDestination, + aScrollPosition); + if (snapTarget) { + aScrollPosition = snapTarget->mPosition; + } + } + + nsRect scrollRange = GetLayoutScrollRange(); + mDestination = scrollRange.ClampPoint(aScrollPosition); + if (mDestination != aScrollPosition && + aParams.mOrigin == ScrollOrigin::Restore && + GetPageLoadingState() != LoadingState::Loading) { + // If we're doing a restore but the scroll position is clamped, promote + // the origin from one that APZ can clobber to one that it can't clobber. + aParams.mOrigin = ScrollOrigin::Other; + } + + nsRect range = aRange && snapTarget.isNothing() + ? *aRange + : nsRect(aScrollPosition, nsSize(0, 0)); + + UniquePtr<ScrollSnapTargetIds> snapTargetIds; + if (snapTarget) { + snapTargetIds = + MakeUnique<ScrollSnapTargetIds>(std::move(snapTarget->mTargetIds)); + } else { + snapTargetIds = + MakeUnique<ScrollSnapTargetIds>(std::move(aParams.mTargetIds)); + } + if (aParams.IsInstant()) { + // Asynchronous scrolling is not allowed, so we'll kill any existing + // async-scrolling process and do an instant scroll. + CompleteAsyncScroll(GetScrollPosition(), range, std::move(snapTargetIds), + aParams.mOrigin); + mApzSmoothScrollDestination = Nothing(); + return; + } + + if (!aParams.IsSmoothMsd()) { + // If we get a non-smooth-scroll, reset the cached APZ scroll destination, + // so that we know to process the next smooth-scroll destined for APZ. + mApzSmoothScrollDestination = Nothing(); + } + + nsPresContext* presContext = PresContext(); + TimeStamp now = + presContext->RefreshDriver()->IsTestControllingRefreshesEnabled() + ? presContext->RefreshDriver()->MostRecentRefresh() + : TimeStamp::Now(); + + nsSize currentVelocity(0, 0); + + if (aParams.IsSmoothMsd()) { + mIgnoreMomentumScroll = true; + if (!mAsyncSmoothMSDScroll) { + nsPoint sv = mVelocityQueue.GetVelocity(); + currentVelocity.width = sv.x; + currentVelocity.height = sv.y; + if (mAsyncScroll) { + if (mAsyncScroll->IsSmoothScroll()) { + currentVelocity = mAsyncScroll->VelocityAt(now); + } + mAsyncScroll = nullptr; + } + + if (nsLayoutUtils::AsyncPanZoomEnabled(this) && WantAsyncScroll() && + CanApzScrollInTheseDirections( + DirectionsInDelta(mDestination - GetScrollPosition()))) { + ApzSmoothScrollTo(mDestination, aParams.mOrigin, + aParams.mTriggeredByScript, std::move(snapTargetIds)); + return; + } + + mAsyncSmoothMSDScroll = new AsyncSmoothMSDScroll( + GetScrollPosition(), mDestination, currentVelocity, + GetLayoutScrollRange(), now, presContext, std::move(snapTargetIds), + aParams.mTriggeredByScript); + + mAsyncSmoothMSDScroll->SetRefreshObserver(this); + } else { + // A previous smooth MSD scroll is still in progress, so we just need to + // update its range and destination. + mAsyncSmoothMSDScroll->SetRange(GetLayoutScrollRange()); + mAsyncSmoothMSDScroll->SetDestination(mDestination, + aParams.mTriggeredByScript); + } + + return; + } + + if (mAsyncSmoothMSDScroll) { + currentVelocity = mAsyncSmoothMSDScroll->GetVelocity(); + mAsyncSmoothMSDScroll = nullptr; + } + + if (!mAsyncScroll) { + mAsyncScroll = + new AsyncScroll(std::move(snapTargetIds), aParams.mTriggeredByScript); + mAsyncScroll->SetRefreshObserver(this); + } + + const bool isSmoothScroll = + aParams.IsSmooth() && nsLayoutUtils::IsSmoothScrollingEnabled(); + if (isSmoothScroll) { + mAsyncScroll->InitSmoothScroll(now, GetScrollPosition(), mDestination, + aParams.mOrigin, range, currentVelocity); + } else { + mAsyncScroll->Init(GetScrollPosition(), range); + } +} + +// We can't use nsContainerFrame::PositionChildViews here because +// we don't want to invalidate views that have moved. +static void AdjustViews(nsIFrame* aFrame) { + nsView* view = aFrame->GetView(); + if (view) { + nsPoint pt; + aFrame->GetParent()->GetClosestView(&pt); + pt += aFrame->GetPosition(); + view->SetPosition(pt.x, pt.y); + + return; + } + + if (!aFrame->HasAnyStateBits(NS_FRAME_HAS_CHILD_WITH_VIEW)) { + return; + } + + // Call AdjustViews recursively for all child frames except the popup list as + // the views for popups are not scrolled. + for (const auto& [list, listID] : aFrame->ChildLists()) { + if (listID == FrameChildListID::Popup) { + continue; + } + for (nsIFrame* child : list) { + AdjustViews(child); + } + } +} + +void nsHTMLScrollFrame::MarkScrollbarsDirtyForReflow() const { + auto* presShell = PresShell(); + if (mVScrollbarBox) { + presShell->FrameNeedsReflow(mVScrollbarBox, + IntrinsicDirty::FrameAncestorsAndDescendants, + NS_FRAME_IS_DIRTY); + } + if (mHScrollbarBox) { + presShell->FrameNeedsReflow(mHScrollbarBox, + IntrinsicDirty::FrameAncestorsAndDescendants, + NS_FRAME_IS_DIRTY); + } +} + +void nsHTMLScrollFrame::InvalidateScrollbars() const { + if (mHScrollbarBox) { + mHScrollbarBox->InvalidateFrameSubtree(); + } + if (mVScrollbarBox) { + mVScrollbarBox->InvalidateFrameSubtree(); + } +} + +bool nsHTMLScrollFrame::IsAlwaysActive() const { + if (nsDisplayItem::ForceActiveLayers()) { + return true; + } + + // Unless this is the root scrollframe for a non-chrome document + // which is the direct child of a chrome document, we default to not + // being "active". + if (!(mIsRoot && PresContext()->IsRootContentDocumentCrossProcess())) { + return false; + } + + // If we have scrolled before, then we should stay active. + if (mHasBeenScrolled) { + return true; + } + + // If we're overflow:hidden, then start as inactive until + // we get scrolled manually. + ScrollStyles styles = GetScrollStyles(); + return (styles.mHorizontal != StyleOverflow::Hidden && + styles.mVertical != StyleOverflow::Hidden); +} + +static void RemoveDisplayPortCallback(nsITimer* aTimer, void* aClosure) { + nsHTMLScrollFrame* sf = static_cast<nsHTMLScrollFrame*>(aClosure); + + // This function only ever gets called from the expiry timer, so it must + // be non-null here. Set it to null here so that we don't keep resetting + // it unnecessarily in MarkRecentlyScrolled(). + MOZ_ASSERT(sf->mDisplayPortExpiryTimer); + sf->mDisplayPortExpiryTimer = nullptr; + + if (!sf->AllowDisplayPortExpiration() || sf->mIsParentToActiveScrollFrames) { + // If this is a scroll parent for some other scrollable frame, don't + // expire the displayport because it would break scroll handoff. Once the + // descendant scrollframes have their displayports expired, they will + // trigger the displayport expiration on this scrollframe as well, and + // mIsParentToActiveScrollFrames will presumably be false when that kicks + // in. + return; + } + + // Remove the displayport from this scrollframe if it's been a while + // since it's scrolled, except if it needs to be always active. Note that + // there is one scrollframe that doesn't fall under this general rule, and + // that is the one that nsLayoutUtils::MaybeCreateDisplayPort decides to put + // a displayport on (i.e. the first scrollframe that WantAsyncScroll()s). + // If that scrollframe is this one, we remove the displayport anyway, and + // as part of the next paint MaybeCreateDisplayPort will put another + // displayport back on it. Although the displayport will "flicker" off and + // back on, the layer itself should never disappear, because this all + // happens between actual painting. If the displayport is reset to a + // different position that's ok; this scrollframe hasn't been scrolled + // recently and so the reset should be correct. + + nsIContent* content = sf->GetContent(); + + if (nsHTMLScrollFrame::ShouldActivateAllScrollFrames()) { + // If we are activating all scroll frames then we only want to remove the + // regular display port and downgrade to a minimal display port. + MOZ_ASSERT(!content->GetProperty(nsGkAtoms::MinimalDisplayPort)); + content->SetProperty(nsGkAtoms::MinimalDisplayPort, + reinterpret_cast<void*>(true)); + } else { + content->RemoveProperty(nsGkAtoms::MinimalDisplayPort); + DisplayPortUtils::RemoveDisplayPort(content); + // Be conservative and unflag this this scrollframe as being scrollable by + // APZ. If it is still scrollable this will get flipped back soon enough. + sf->mScrollableByAPZ = false; + } + + DisplayPortUtils::ExpireDisplayPortOnAsyncScrollableAncestor(sf); + sf->SchedulePaint(); +} + +void nsHTMLScrollFrame::MarkEverScrolled() { + // Mark this frame as having been scrolled. If this is the root + // scroll frame of a content document, then IsAlwaysActive() + // will return true from now on and MarkNotRecentlyScrolled() won't + // have any effect. + mHasBeenScrolled = true; +} + +void nsHTMLScrollFrame::MarkNotRecentlyScrolled() { + if (!mHasBeenScrolledRecently) return; + + mHasBeenScrolledRecently = false; + SchedulePaint(); +} + +void nsHTMLScrollFrame::MarkRecentlyScrolled() { + mHasBeenScrolledRecently = true; + if (IsAlwaysActive()) { + return; + } + + if (mActivityExpirationState.IsTracked()) { + gScrollFrameActivityTracker->MarkUsed(this); + } else { + if (!gScrollFrameActivityTracker) { + gScrollFrameActivityTracker = + new ScrollFrameActivityTracker(GetMainThreadSerialEventTarget()); + } + gScrollFrameActivityTracker->AddObject(this); + } + + // If we just scrolled and there's a displayport expiry timer in place, + // reset the timer. + ResetDisplayPortExpiryTimer(); +} + +void nsHTMLScrollFrame::ResetDisplayPortExpiryTimer() { + if (mDisplayPortExpiryTimer) { + mDisplayPortExpiryTimer->InitWithNamedFuncCallback( + RemoveDisplayPortCallback, this, + StaticPrefs::apz_displayport_expiry_ms(), nsITimer::TYPE_ONE_SHOT, + "nsHTMLScrollFrame::ResetDisplayPortExpiryTimer"); + } +} + +bool nsHTMLScrollFrame::AllowDisplayPortExpiration() { + if (IsAlwaysActive()) { + return false; + } + + if (mIsRoot && PresContext()->IsRoot()) { + return false; + } + + // If this was the first scrollable frame found, this displayport should + // not expire. + if (IsFirstScrollableFrameSequenceNumber().isSome()) { + return false; + } + + if (ShouldActivateAllScrollFrames() && + GetContent()->GetProperty(nsGkAtoms::MinimalDisplayPort)) { + return false; + } + return true; +} + +void nsHTMLScrollFrame::TriggerDisplayPortExpiration() { + if (!AllowDisplayPortExpiration()) { + return; + } + + if (!StaticPrefs::apz_displayport_expiry_ms()) { + // a zero time disables the expiry + return; + } + + if (!mDisplayPortExpiryTimer) { + mDisplayPortExpiryTimer = NS_NewTimer(); + } + ResetDisplayPortExpiryTimer(); +} + +void nsHTMLScrollFrame::ScrollVisual() { + MarkEverScrolled(); + + AdjustViews(mScrolledFrame); + // We need to call this after fixing up the view positions + // to be consistent with the frame hierarchy. + MarkRecentlyScrolled(); +} + +/** + * Clamp desired scroll position aDesired and range [aDestLower, aDestUpper] + * to [aBoundLower, aBoundUpper] and then select the appunit value from among + * aBoundLower, aBoundUpper and those such that (aDesired - aCurrent) * + * aRes/aAppUnitsPerPixel is an integer (or as close as we can get + * modulo rounding to appunits) that is in [aDestLower, aDestUpper] and + * closest to aDesired. If no such value exists, return the nearest in + * [aDestLower, aDestUpper]. + */ +static nscoord ClampAndAlignWithPixels(nscoord aDesired, nscoord aBoundLower, + nscoord aBoundUpper, nscoord aDestLower, + nscoord aDestUpper, + nscoord aAppUnitsPerPixel, double aRes, + nscoord aCurrent) { + // Intersect scroll range with allowed range, by clamping the ends + // of aRange to be within bounds + nscoord destLower = clamped(aDestLower, aBoundLower, aBoundUpper); + nscoord destUpper = clamped(aDestUpper, aBoundLower, aBoundUpper); + + nscoord desired = clamped(aDesired, destLower, destUpper); + + double currentLayerVal = (aRes * aCurrent) / aAppUnitsPerPixel; + double desiredLayerVal = (aRes * desired) / aAppUnitsPerPixel; + double delta = desiredLayerVal - currentLayerVal; + double nearestLayerVal = NS_round(delta) + currentLayerVal; + + // Convert back from PaintedLayer space to appunits relative to the top-left + // of the scrolled frame. + nscoord aligned = + aRes == 0.0 + ? 0.0 + : NSToCoordRoundWithClamp(nearestLayerVal * aAppUnitsPerPixel / aRes); + + // Use a bound if it is within the allowed range and closer to desired than + // the nearest pixel-aligned value. + if (aBoundUpper == destUpper && + static_cast<decltype(Abs(desired))>(aBoundUpper - desired) < + Abs(desired - aligned)) { + return aBoundUpper; + } + + if (aBoundLower == destLower && + static_cast<decltype(Abs(desired))>(desired - aBoundLower) < + Abs(aligned - desired)) { + return aBoundLower; + } + + // Accept the nearest pixel-aligned value if it is within the allowed range. + if (aligned >= destLower && aligned <= destUpper) { + return aligned; + } + + // Check if opposite pixel boundary fits into allowed range. + double oppositeLayerVal = + nearestLayerVal + ((nearestLayerVal < desiredLayerVal) ? 1.0 : -1.0); + nscoord opposite = aRes == 0.0 + ? 0.0 + : NSToCoordRoundWithClamp(oppositeLayerVal * + aAppUnitsPerPixel / aRes); + if (opposite >= destLower && opposite <= destUpper) { + return opposite; + } + + // No alignment available. + return desired; +} + +/** + * Clamp desired scroll position aPt to aBounds and then snap + * it to the same layer pixel edges as aCurrent, keeping it within aRange + * during snapping. aCurrent is the current scroll position. + */ +static nsPoint ClampAndAlignWithLayerPixels(const nsPoint& aPt, + const nsRect& aBounds, + const nsRect& aRange, + const nsPoint& aCurrent, + nscoord aAppUnitsPerPixel, + const MatrixScales& aScale) { + return nsPoint( + ClampAndAlignWithPixels(aPt.x, aBounds.x, aBounds.XMost(), aRange.x, + aRange.XMost(), aAppUnitsPerPixel, aScale.xScale, + aCurrent.x), + ClampAndAlignWithPixels(aPt.y, aBounds.y, aBounds.YMost(), aRange.y, + aRange.YMost(), aAppUnitsPerPixel, aScale.yScale, + aCurrent.y)); +} + +/* static */ +void nsHTMLScrollFrame::ScrollActivityCallback(nsITimer* aTimer, + void* anInstance) { + nsHTMLScrollFrame* self = static_cast<nsHTMLScrollFrame*>(anInstance); + + // Fire the synth mouse move. + self->mScrollActivityTimer->Cancel(); + self->mScrollActivityTimer = nullptr; + self->PresShell()->SynthesizeMouseMove(true); +} + +void nsHTMLScrollFrame::ScheduleSyntheticMouseMove() { + if (!mScrollActivityTimer) { + mScrollActivityTimer = NS_NewTimer( + PresContext()->Document()->EventTargetFor(TaskCategory::Other)); + if (!mScrollActivityTimer) { + return; + } + } + + mScrollActivityTimer->InitWithNamedFuncCallback( + ScrollActivityCallback, this, 100, nsITimer::TYPE_ONE_SHOT, + "nsHTMLScrollFrame::ScheduleSyntheticMouseMove"); +} + +void nsHTMLScrollFrame::NotifyApproximateFrameVisibilityUpdate( + bool aIgnoreDisplayPort) { + mLastUpdateFramesPos = GetScrollPosition(); + if (aIgnoreDisplayPort) { + mHadDisplayPortAtLastFrameUpdate = false; + mDisplayPortAtLastFrameUpdate = nsRect(); + } else { + mHadDisplayPortAtLastFrameUpdate = DisplayPortUtils::GetDisplayPort( + GetContent(), &mDisplayPortAtLastFrameUpdate); + } +} + +bool nsHTMLScrollFrame::GetDisplayPortAtLastApproximateFrameVisibilityUpdate( + nsRect* aDisplayPort) { + if (mHadDisplayPortAtLastFrameUpdate) { + *aDisplayPort = mDisplayPortAtLastFrameUpdate; + } + return mHadDisplayPortAtLastFrameUpdate; +} + +MatrixScales GetPaintedLayerScaleForFrame(nsIFrame* aFrame) { + MOZ_ASSERT(aFrame, "need a frame"); + + nsPresContext* presCtx = aFrame->PresContext()->GetRootPresContext(); + + if (!presCtx) { + presCtx = aFrame->PresContext(); + MOZ_ASSERT(presCtx); + } + + ParentLayerToScreenScale2D transformToAncestorScale = + ParentLayerToParentLayerScale( + presCtx->PresShell()->GetCumulativeResolution()) * + nsLayoutUtils::GetTransformToAncestorScaleCrossProcessForFrameMetrics( + aFrame); + + return transformToAncestorScale.ToUnknownScale(); +} + +void nsHTMLScrollFrame::ScrollToImpl( + nsPoint aPt, const nsRect& aRange, ScrollOrigin aOrigin, + ScrollTriggeredByScript aTriggeredByScript) { + // None is never a valid scroll origin to be passed in. + MOZ_ASSERT(aOrigin != ScrollOrigin::None); + + // Figure out the effective origin for this scroll request. + if (aOrigin == ScrollOrigin::NotSpecified) { + // If no origin was specified, we still want to set it to something that's + // non-unknown, so that we can use eUnknown to distinguish if the frame was + // scrolled at all. Default it to some generic placeholder. + aOrigin = ScrollOrigin::Other; + } + + // If this scroll is |relative|, but we've already had a user scroll that + // was not relative, promote this origin to |other|. This ensures that we + // may only transmit a relative update to APZ if all scrolls since the last + // transaction or repaint request have been relative. + if (aOrigin == ScrollOrigin::Relative && + (mLastScrollOrigin != ScrollOrigin::None && + mLastScrollOrigin != ScrollOrigin::NotSpecified && + mLastScrollOrigin != ScrollOrigin::Relative && + mLastScrollOrigin != ScrollOrigin::Apz)) { + aOrigin = ScrollOrigin::Other; + } + + // If the origin is a downgrade, and downgrades are allowed, process the + // downgrade even if we're going to early-exit because we're already at + // the correct scroll position. This ensures that if there wasn't a main- + // thread scroll update pending before a frame reconstruction (as indicated + // by mAllowScrollOriginDowngrade=true), then after the frame reconstruction + // the origin is downgraded to "restore" even if the layout scroll offset to + // be restored is (0,0) (which will take the early-exit below). This is + // important so that restoration of a *visual* scroll offset (which might be + // to something other than (0,0)) isn't clobbered. + bool isScrollOriginDowngrade = + nsLayoutUtils::CanScrollOriginClobberApz(mLastScrollOrigin) && + !nsLayoutUtils::CanScrollOriginClobberApz(aOrigin); + bool allowScrollOriginChange = + mAllowScrollOriginDowngrade && isScrollOriginDowngrade; + + if (allowScrollOriginChange) { + mLastScrollOrigin = aOrigin; + mAllowScrollOriginDowngrade = false; + } + + nsPresContext* presContext = PresContext(); + nscoord appUnitsPerDevPixel = presContext->AppUnitsPerDevPixel(); + // 'scale' is our estimate of the scale factor that will be applied + // when rendering the scrolled content to its own PaintedLayer. + MatrixScales scale = GetPaintedLayerScaleForFrame(mScrolledFrame); + nsPoint curPos = GetScrollPosition(); + + // Try to align aPt with curPos so they have an integer number of layer + // pixels between them. This gives us the best chance of scrolling without + // having to invalidate due to changes in subpixel rendering. + // Note that when we actually draw into a PaintedLayer, the coordinates + // that get mapped onto the layer buffer pixels are from the display list, + // which are relative to the display root frame's top-left increasing down, + // whereas here our coordinates are scroll positions which increase upward + // and are relative to the scrollport top-left. This difference doesn't + // actually matter since all we are about is that there be an integer number + // of layer pixels between pt and curPos. + nsPoint pt = ClampAndAlignWithLayerPixels(aPt, GetLayoutScrollRange(), aRange, + curPos, appUnitsPerDevPixel, scale); + if (pt == curPos) { + // Even if we are bailing out due to no-op main-thread scroll position + // change, we might need to cancel an APZ smooth scroll that we already + // kicked off. It might be reasonable to eventually remove the + // mApzSmoothScrollDestination clause from this if statement, as that + // may simplify this a bit and should be fine from the APZ side. + if (mApzSmoothScrollDestination && aOrigin != ScrollOrigin::Clamp) { + if (aOrigin == ScrollOrigin::Relative) { + AppendScrollUpdate( + ScrollPositionUpdate::NewRelativeScroll(mApzScrollPos, pt)); + mApzScrollPos = pt; + } else if (aOrigin != ScrollOrigin::Apz) { + ScrollOrigin origin = + (mAllowScrollOriginDowngrade || !isScrollOriginDowngrade) + ? aOrigin + : mLastScrollOrigin; + AppendScrollUpdate(ScrollPositionUpdate::NewScroll(origin, pt)); + } + } + return; + } + + // If we are scrolling the RCD-RSF, and a visual scroll update is pending, + // cancel it; otherwise, it will clobber this scroll. + if (IsRootScrollFrameOfDocument() && + presContext->IsRootContentDocumentCrossProcess()) { + auto* ps = presContext->GetPresShell(); + if (const auto& visualScrollUpdate = ps->GetPendingVisualScrollUpdate()) { + if (visualScrollUpdate->mVisualScrollOffset != aPt) { + // Only clobber if the scroll was originated by the main thread. + // Respect the priority of origins (an "eRestore" layout scroll should + // not clobber an "eMainThread" visual scroll.) + bool shouldClobber = + aOrigin == ScrollOrigin::Other || + (aOrigin == ScrollOrigin::Restore && + visualScrollUpdate->mUpdateType == FrameMetrics::eRestore); + if (shouldClobber) { + ps->AcknowledgePendingVisualScrollUpdate(); + ps->ClearPendingVisualScrollUpdate(); + } + } + } + } + + bool needFrameVisibilityUpdate = mLastUpdateFramesPos == nsPoint(-1, -1); + + nsPoint dist(std::abs(pt.x - mLastUpdateFramesPos.x), + std::abs(pt.y - mLastUpdateFramesPos.y)); + nsSize visualViewportSize = GetVisualViewportSize(); + nscoord horzAllowance = std::max( + visualViewportSize.width / + std::max( + StaticPrefs:: + layout_framevisibility_amountscrollbeforeupdatehorizontal(), + 1), + AppUnitsPerCSSPixel()); + nscoord vertAllowance = std::max( + visualViewportSize.height / + std::max( + StaticPrefs:: + layout_framevisibility_amountscrollbeforeupdatevertical(), + 1), + AppUnitsPerCSSPixel()); + if (dist.x >= horzAllowance || dist.y >= vertAllowance) { + needFrameVisibilityUpdate = true; + } + + // notify the listeners. + for (uint32_t i = 0; i < mListeners.Length(); i++) { + mListeners[i]->ScrollPositionWillChange(pt.x, pt.y); + } + + nsRect oldDisplayPort; + nsIContent* content = GetContent(); + DisplayPortUtils::GetDisplayPort(content, &oldDisplayPort); + oldDisplayPort.MoveBy(-mScrolledFrame->GetPosition()); + + // Update frame position for scrolling + mScrolledFrame->SetPosition(mScrollPort.TopLeft() - pt); + + // If |mLastScrollOrigin| is already set to something that can clobber APZ's + // scroll offset, then we don't want to change it to something that can't. + // If we allowed this, then we could end up in a state where APZ ignores + // legitimate scroll offset updates because the origin has been masked by + // a later change within the same refresh driver tick. + allowScrollOriginChange = + (mAllowScrollOriginDowngrade || !isScrollOriginDowngrade); + + if (allowScrollOriginChange) { + mLastScrollOrigin = aOrigin; + mAllowScrollOriginDowngrade = false; + } + + if (aOrigin == ScrollOrigin::Relative) { + MOZ_ASSERT(!isScrollOriginDowngrade); + MOZ_ASSERT(mLastScrollOrigin == ScrollOrigin::Relative); + AppendScrollUpdate( + ScrollPositionUpdate::NewRelativeScroll(mApzScrollPos, pt)); + mApzScrollPos = pt; + } else if (aOrigin != ScrollOrigin::Apz) { + AppendScrollUpdate(ScrollPositionUpdate::NewScroll(mLastScrollOrigin, pt)); + } + + if (mLastScrollOrigin == ScrollOrigin::Apz) { + mApzScrollPos = GetScrollPosition(); + } + + ScrollVisual(); + mAnchor.UserScrolled(); + + // Only report user-triggered scrolling interactions + bool jsOnStack = nsContentUtils::GetCurrentJSContext() != nullptr; + bool scrollingToAnchor = ScrollingInteractionContext::IsScrollingToAnchor(); + if (!jsOnStack && !scrollingToAnchor) { + nsPoint distanceScrolled(std::abs(pt.x - curPos.x), + std::abs(pt.y - curPos.y)); + ScrollingMetrics::OnScrollingInteraction( + CSSPoint::FromAppUnits(distanceScrolled).Length()); + } + + bool schedulePaint = true; + if (nsLayoutUtils::AsyncPanZoomEnabled(this) && + !nsLayoutUtils::ShouldDisableApzForElement(content) && + !content->GetProperty(nsGkAtoms::MinimalDisplayPort) && + StaticPrefs::apz_paint_skipping_enabled()) { + // If APZ is enabled with paint-skipping, there are certain conditions in + // which we can skip paints: + // 1) If APZ triggered this scroll, and the tile-aligned displayport is + // unchanged. + // 2) If non-APZ triggered this scroll, but we can handle it by just asking + // APZ to update the scroll position. Again we make this conditional on + // the tile-aligned displayport being unchanged. + // We do the displayport check first since it's common to all scenarios, + // and then if the displayport is unchanged, we check if APZ triggered, + // or can handle, this scroll. If so, we set schedulePaint to false and + // skip the paint. + // Because of bug 1264297, we also don't do paint-skipping for elements with + // perspective, because the displayport may not have captured everything + // that needs to be painted. So even if the final tile-aligned displayport + // is the same, we force a repaint for these elements. Bug 1254260 tracks + // fixing this properly. + nsRect displayPort; + bool usingDisplayPort = + DisplayPortUtils::GetDisplayPort(content, &displayPort); + displayPort.MoveBy(-mScrolledFrame->GetPosition()); + + PAINT_SKIP_LOG( + "New scrollpos %s usingDP %d dpEqual %d scrollableByApz " + "%d perspective %d bglocal %d filter %d\n", + ToString(CSSPoint::FromAppUnits(GetScrollPosition())).c_str(), + usingDisplayPort, displayPort.IsEqualEdges(oldDisplayPort), + mScrollableByAPZ, HasPerspective(), HasBgAttachmentLocal(), + mHasOutOfFlowContentInsideFilter); + if (usingDisplayPort && displayPort.IsEqualEdges(oldDisplayPort) && + !HasPerspective() && !HasBgAttachmentLocal() && + !mHasOutOfFlowContentInsideFilter) { + bool haveScrollLinkedEffects = + content->GetComposedDoc()->HasScrollLinkedEffect(); + bool apzDisabled = haveScrollLinkedEffects && + StaticPrefs::apz_disable_for_scroll_linked_effects(); + if (!apzDisabled) { + if (LastScrollOrigin() == ScrollOrigin::Apz) { + schedulePaint = false; + PAINT_SKIP_LOG("Skipping due to APZ scroll\n"); + } else if (mScrollableByAPZ) { + nsIWidget* widget = presContext->GetNearestWidget(); + WindowRenderer* renderer = + widget ? widget->GetWindowRenderer() : nullptr; + if (renderer) { + mozilla::layers::ScrollableLayerGuid::ViewID id; + bool success = nsLayoutUtils::FindIDFor(content, &id); + MOZ_ASSERT(success); // we have a displayport, we better have an ID + + // Schedule an empty transaction to carry over the scroll offset + // update, instead of a full transaction. This empty transaction + // might still get squashed into a full transaction if something + // happens to trigger one. + MOZ_ASSERT(!mScrollUpdates.IsEmpty()); + success = renderer->AddPendingScrollUpdateForNextTransaction( + id, mScrollUpdates.LastElement()); + if (success) { + schedulePaint = false; + SchedulePaint(nsIFrame::PAINT_COMPOSITE_ONLY); + PAINT_SKIP_LOG( + "Skipping due to APZ-forwarded main-thread scroll\n"); + } else { + PAINT_SKIP_LOG( + "Failed to set pending scroll update on layer manager\n"); + } + } + } + } + } + } + + // If the new scroll offset is going to clobber APZ's scroll offset, for + // the RCD-RSF this will have the effect of updating the visual viewport + // offset in a way that keeps the relative offset between the layout and + // visual viewports constant. This will cause APZ to send us a new visual + // viewport offset, but instead of waiting for that, just set the value + // we expect APZ will set ourselves, to minimize the chances of + // inconsistencies from querying a stale value. + if (mIsRoot && nsLayoutUtils::CanScrollOriginClobberApz(aOrigin)) { + AutoWeakFrame weakFrame(this); + AutoScrollbarRepaintSuppression repaintSuppression(this, weakFrame, + !schedulePaint); + + nsPoint visualViewportOffset = curPos; + if (presContext->PresShell()->IsVisualViewportOffsetSet()) { + visualViewportOffset = + presContext->PresShell()->GetVisualViewportOffset(); + } + nsPoint relativeOffset = visualViewportOffset - curPos; + + presContext->PresShell()->SetVisualViewportOffset(pt + relativeOffset, + curPos); + if (!weakFrame.IsAlive()) { + return; + } + } + + if (schedulePaint) { + SchedulePaint(); + + if (needFrameVisibilityUpdate) { + presContext->PresShell()->ScheduleApproximateFrameVisibilityUpdateNow(); + } + } + + if (ChildrenHavePerspective()) { + // The overflow areas of descendants may depend on the scroll position, + // so ensure they get updated. + + // First we recompute the overflow areas of the transformed children + // that use the perspective. FinishAndStoreOverflow only calls this + // if the size changes, so we need to do it manually. + RecomputePerspectiveChildrenOverflow(this); + + // Update the overflow for the scrolled frame to take any changes from the + // children into account. + mScrolledFrame->UpdateOverflow(); + + // Update the overflow for the outer so that we recompute scrollbars. + UpdateOverflow(); + } + + ScheduleSyntheticMouseMove(); + + nsAutoScriptBlocker scriptBlocker; + PresShell::AutoAssertNoFlush noFlush(*PresShell()); + + { // scope the AutoScrollbarRepaintSuppression + AutoWeakFrame weakFrame(this); + AutoScrollbarRepaintSuppression repaintSuppression(this, weakFrame, + !schedulePaint); + UpdateScrollbarPosition(); + if (!weakFrame.IsAlive()) { + return; + } + } + + presContext->RecordInteractionTime( + nsPresContext::InteractionType::ScrollInteraction, TimeStamp::Now()); + + PostScrollEvent(); + // If this is a viewport scroll, this could affect the relative offset + // between layout and visual viewport, so we might have to fire a visual + // viewport scroll event as well. + if (mIsRoot) { + if (auto* window = nsGlobalWindowInner::Cast( + PresContext()->Document()->GetInnerWindow())) { + window->VisualViewport()->PostScrollEvent( + presContext->PresShell()->GetVisualViewportOffset(), curPos); + } + } + + // Schedule the scroll-timelines linked to its scrollable frame. + // if `pt == curPos`, we early return, so the position must be changed at + // this moment. Therefore, we can schedule scroll animations directly. + ScheduleScrollAnimations(); + + // notify the listeners. + for (uint32_t i = 0; i < mListeners.Length(); i++) { + mListeners[i]->ScrollPositionDidChange(pt.x, pt.y); + } + + if (nsCOMPtr<nsIDocShell> docShell = presContext->GetDocShell()) { + docShell->NotifyScrollObservers(); + } +} + +// Finds the max z-index of the items in aList that meet the following +// conditions +// 1) have z-index auto or z-index >= 0, and +// 2) aFrame is a proper ancestor of the item's frame. +// Returns Nothing() if there is no such item. +static Maybe<int32_t> MaxZIndexInListOfItemsContainedInFrame( + nsDisplayList* aList, nsIFrame* aFrame) { + Maybe<int32_t> maxZIndex = Nothing(); + for (nsDisplayItem* item : *aList) { + int32_t zIndex = item->ZIndex(); + if (zIndex < 0 || + !nsLayoutUtils::IsProperAncestorFrame(aFrame, item->Frame())) { + continue; + } + if (!maxZIndex) { + maxZIndex = Some(zIndex); + } else { + maxZIndex = Some(std::max(maxZIndex.value(), zIndex)); + } + } + return maxZIndex; +} + +template <class T> +static void AppendInternalItemToTop(const nsDisplayListSet& aLists, T* aItem, + const Maybe<int32_t>& aZIndex) { + if (aZIndex) { + aItem->SetOverrideZIndex(aZIndex.value()); + aLists.PositionedDescendants()->AppendToTop(aItem); + } else { + aLists.Content()->AppendToTop(aItem); + } +} + +static const uint32_t APPEND_OWN_LAYER = 0x1; +static const uint32_t APPEND_POSITIONED = 0x2; +static const uint32_t APPEND_SCROLLBAR_CONTAINER = 0x4; +static const uint32_t APPEND_OVERLAY = 0x8; +static const uint32_t APPEND_TOP = 0x10; + +static void AppendToTop(nsDisplayListBuilder* aBuilder, + const nsDisplayListSet& aLists, nsDisplayList* aSource, + nsIFrame* aSourceFrame, nsIFrame* aScrollFrame, + uint32_t aFlags) { + if (aSource->IsEmpty()) { + return; + } + + nsDisplayWrapList* newItem; + const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot(); + if (aFlags & APPEND_OWN_LAYER) { + ScrollbarData scrollbarData; + if (aFlags & APPEND_SCROLLBAR_CONTAINER) { + scrollbarData = ScrollbarData::CreateForScrollbarContainer( + aBuilder->GetCurrentScrollbarDirection(), + aBuilder->GetCurrentScrollbarTarget()); + // Direction should be set + MOZ_ASSERT(scrollbarData.mDirection.isSome()); + } + + newItem = MakeDisplayItemWithIndex<nsDisplayOwnLayer>( + aBuilder, aSourceFrame, + /* aIndex = */ nsDisplayOwnLayer::OwnLayerForScrollbar, aSource, asr, + nsDisplayOwnLayerFlags::None, scrollbarData, true, false); + } else { + // Build the wrap list with an index of 1, since the scrollbar frame itself + // might have already built an nsDisplayWrapList. + newItem = MakeDisplayItemWithIndex<nsDisplayWrapper>( + aBuilder, aSourceFrame, 1, aSource, asr, false); + } + if (!newItem) { + return; + } + + if (aFlags & APPEND_POSITIONED) { + // We want overlay scrollbars to always be on top of the scrolled content, + // but we don't want them to unnecessarily cover overlapping elements from + // outside our scroll frame. + Maybe<int32_t> zIndex = Nothing(); + if (aFlags & APPEND_TOP) { + zIndex = Some(INT32_MAX); + } else if (aFlags & APPEND_OVERLAY) { + zIndex = MaxZIndexInListOfItemsContainedInFrame( + aLists.PositionedDescendants(), aScrollFrame); + } else if (aSourceFrame->StylePosition()->mZIndex.IsInteger()) { + zIndex = Some(aSourceFrame->StylePosition()->mZIndex.integer._0); + } + AppendInternalItemToTop(aLists, newItem, zIndex); + } else { + aLists.BorderBackground()->AppendToTop(newItem); + } +} + +struct HoveredStateComparator { + static bool Hovered(const nsIFrame* aFrame) { + return aFrame->GetContent()->IsElement() && + aFrame->GetContent()->AsElement()->HasAttr(kNameSpaceID_None, + nsGkAtoms::hover); + } + + bool Equals(nsIFrame* A, nsIFrame* B) const { + return Hovered(A) == Hovered(B); + } + + bool LessThan(nsIFrame* A, nsIFrame* B) const { + return !Hovered(A) && Hovered(B); + } +}; + +void nsHTMLScrollFrame::AppendScrollPartsTo(nsDisplayListBuilder* aBuilder, + const nsDisplayListSet& aLists, + bool aCreateLayer, + bool aPositioned) { + const bool overlayScrollbars = UsesOverlayScrollbars(); + + AutoTArray<nsIFrame*, 3> scrollParts; + for (nsIFrame* kid : PrincipalChildList()) { + if (kid == mScrolledFrame || + (kid->IsAbsPosContainingBlock() || overlayScrollbars) != aPositioned) { + continue; + } + + scrollParts.AppendElement(kid); + } + if (scrollParts.IsEmpty()) { + return; + } + + // We can't check will-change budget during display list building phase. + // This means that we will build scroll bar layers for out of budget + // will-change: scroll position. + const mozilla::layers::ScrollableLayerGuid::ViewID scrollTargetId = + IsScrollingActive() + ? nsLayoutUtils::FindOrCreateIDFor(mScrolledFrame->GetContent()) + : mozilla::layers::ScrollableLayerGuid::NULL_SCROLL_ID; + + scrollParts.Sort(HoveredStateComparator()); + + DisplayListClipState::AutoSaveRestore clipState(aBuilder); + // Don't let scrollparts extent outside our frame's border-box, if these are + // viewport scrollbars. They would create layerization problems. This wouldn't + // normally be an issue but themes can add overflow areas to scrollbar parts. + if (mIsRoot) { + nsRect scrollPartsClip(aBuilder->ToReferenceFrame(this), + TrueOuterSize(aBuilder)); + clipState.ClipContentDescendants(scrollPartsClip); + } + + for (uint32_t i = 0; i < scrollParts.Length(); ++i) { + MOZ_ASSERT(scrollParts[i]); + Maybe<ScrollDirection> scrollDirection; + uint32_t appendToTopFlags = 0; + if (scrollParts[i] == mVScrollbarBox) { + scrollDirection.emplace(ScrollDirection::eVertical); + appendToTopFlags |= APPEND_SCROLLBAR_CONTAINER; + } + if (scrollParts[i] == mHScrollbarBox) { + MOZ_ASSERT(!scrollDirection.isSome()); + scrollDirection.emplace(ScrollDirection::eHorizontal); + appendToTopFlags |= APPEND_SCROLLBAR_CONTAINER; + } + + // The display port doesn't necessarily include the scrollbars, so just + // include all of the scrollbars if we are in a RCD-RSF. We only do + // this for the root scrollframe of the root content document, which is + // zoomable, and where the scrollbar sizes are bounded by the widget. + const nsRect visible = + mIsRoot && PresContext()->IsRootContentDocumentCrossProcess() + ? scrollParts[i]->InkOverflowRectRelativeToParent() + : aBuilder->GetVisibleRect(); + if (visible.IsEmpty()) { + continue; + } + const nsRect dirty = + mIsRoot && PresContext()->IsRootContentDocumentCrossProcess() + ? scrollParts[i]->InkOverflowRectRelativeToParent() + : aBuilder->GetDirtyRect(); + + // Always create layers for overlay scrollbars so that we don't create a + // giant layer covering the whole scrollport if both scrollbars are visible. + const bool isOverlayScrollbar = + scrollDirection.isSome() && overlayScrollbars; + const bool createLayer = + aCreateLayer || isOverlayScrollbar || + StaticPrefs::layout_scrollbars_always_layerize_track(); + + nsDisplayListCollection partList(aBuilder); + { + nsDisplayListBuilder::AutoBuildingDisplayList buildingForChild( + aBuilder, this, visible, dirty); + + nsDisplayListBuilder::AutoCurrentScrollbarInfoSetter infoSetter( + aBuilder, scrollTargetId, scrollDirection, createLayer); + BuildDisplayListForChild( + aBuilder, scrollParts[i], partList, + nsIFrame::DisplayChildFlag::ForceStackingContext); + } + + // DisplayChildFlag::ForceStackingContext put everything into + // partList.PositionedDescendants(). + if (partList.PositionedDescendants()->IsEmpty()) { + continue; + } + + if (createLayer) { + appendToTopFlags |= APPEND_OWN_LAYER; + } + if (aPositioned) { + appendToTopFlags |= APPEND_POSITIONED; + } + + if (isOverlayScrollbar || scrollParts[i] == mResizerBox) { + if (isOverlayScrollbar && mIsRoot) { + appendToTopFlags |= APPEND_TOP; + } else { + appendToTopFlags |= APPEND_OVERLAY; + aBuilder->SetDisablePartialUpdates(true); + } + } + + { + nsDisplayListBuilder::AutoBuildingDisplayList buildingForChild( + aBuilder, scrollParts[i], visible + GetOffsetTo(scrollParts[i]), + dirty + GetOffsetTo(scrollParts[i])); + if (scrollParts[i]->IsTransformed()) { + nsPoint toOuterReferenceFrame; + const nsIFrame* outerReferenceFrame = aBuilder->FindReferenceFrameFor( + scrollParts[i]->GetParent(), &toOuterReferenceFrame); + toOuterReferenceFrame += scrollParts[i]->GetPosition(); + + buildingForChild.SetReferenceFrameAndCurrentOffset( + outerReferenceFrame, toOuterReferenceFrame); + } + nsDisplayListBuilder::AutoCurrentScrollbarInfoSetter infoSetter( + aBuilder, scrollTargetId, scrollDirection, createLayer); + + ::AppendToTop(aBuilder, aLists, partList.PositionedDescendants(), + scrollParts[i], this, appendToTopFlags); + } + } +} + +nsRect nsHTMLScrollFrame::ExpandRectToNearlyVisible(const nsRect& aRect) const { + // We don't want to expand a rect in a direction that we can't scroll, so we + // check the scroll range. + nsRect scrollRange = GetLayoutScrollRange(); + nsPoint scrollPos = GetScrollPosition(); + nsMargin expand(0, 0, 0, 0); + + nscoord vertShift = + StaticPrefs::layout_framevisibility_numscrollportheights() * aRect.height; + if (scrollRange.y < scrollPos.y) { + expand.top = vertShift; + } + if (scrollPos.y < scrollRange.YMost()) { + expand.bottom = vertShift; + } + + nscoord horzShift = + StaticPrefs::layout_framevisibility_numscrollportwidths() * aRect.width; + if (scrollRange.x < scrollPos.x) { + expand.left = horzShift; + } + if (scrollPos.x < scrollRange.XMost()) { + expand.right = horzShift; + } + + nsRect rect = aRect; + rect.Inflate(expand); + return rect; +} + +static bool ShouldBeClippedByFrame(nsIFrame* aClipFrame, + nsIFrame* aClippedFrame) { + return nsLayoutUtils::IsProperAncestorFrame(aClipFrame, aClippedFrame); +} + +static void ClipItemsExceptCaret( + nsDisplayList* aList, nsDisplayListBuilder* aBuilder, nsIFrame* aClipFrame, + const DisplayItemClipChain* aExtraClip, + nsTHashMap<nsPtrHashKey<const DisplayItemClipChain>, + const DisplayItemClipChain*>& aCache) { + for (nsDisplayItem* i : *aList) { + if (!ShouldBeClippedByFrame(aClipFrame, i->Frame())) { + continue; + } + + const DisplayItemType type = i->GetType(); + if (type != DisplayItemType::TYPE_CARET && + type != DisplayItemType::TYPE_CONTAINER) { + const DisplayItemClipChain* clip = i->GetClipChain(); + const DisplayItemClipChain* intersection = nullptr; + if (aCache.Get(clip, &intersection)) { + i->SetClipChain(intersection, true); + } else { + i->IntersectClip(aBuilder, aExtraClip, true); + aCache.InsertOrUpdate(clip, i->GetClipChain()); + } + } + nsDisplayList* children = i->GetSameCoordinateSystemChildren(); + if (children) { + ClipItemsExceptCaret(children, aBuilder, aClipFrame, aExtraClip, aCache); + } + } +} + +static void ClipListsExceptCaret(nsDisplayListCollection* aLists, + nsDisplayListBuilder* aBuilder, + nsIFrame* aClipFrame, + const DisplayItemClipChain* aExtraClip) { + nsTHashMap<nsPtrHashKey<const DisplayItemClipChain>, + const DisplayItemClipChain*> + cache; + ClipItemsExceptCaret(aLists->BorderBackground(), aBuilder, aClipFrame, + aExtraClip, cache); + ClipItemsExceptCaret(aLists->BlockBorderBackgrounds(), aBuilder, aClipFrame, + aExtraClip, cache); + ClipItemsExceptCaret(aLists->Floats(), aBuilder, aClipFrame, aExtraClip, + cache); + ClipItemsExceptCaret(aLists->PositionedDescendants(), aBuilder, aClipFrame, + aExtraClip, cache); + ClipItemsExceptCaret(aLists->Outlines(), aBuilder, aClipFrame, aExtraClip, + cache); + ClipItemsExceptCaret(aLists->Content(), aBuilder, aClipFrame, aExtraClip, + cache); +} + +// This is similar to a "save-restore" RAII class for +// DisplayListBuilder::ContainsBlendMode(), with a slight enhancement. +// If this class is put on the stack and then unwound, the DL builder's +// ContainsBlendMode flag will be effectively the same as if this class wasn't +// put on the stack. However, if the CaptureContainsBlendMode method is called, +// there will be a difference - the blend mode in the descendant display lists +// will be "captured" and extracted. +// The main goal here is to allow conditionally capturing the flag that +// indicates whether or not a blend mode was encountered in the descendant part +// of the display list. +class MOZ_RAII AutoContainsBlendModeCapturer { + nsDisplayListBuilder& mBuilder; + bool mSavedContainsBlendMode; + + public: + explicit AutoContainsBlendModeCapturer(nsDisplayListBuilder& aBuilder) + : mBuilder(aBuilder), + mSavedContainsBlendMode(aBuilder.ContainsBlendMode()) { + mBuilder.SetContainsBlendMode(false); + } + + bool CaptureContainsBlendMode() { + // "Capture" the flag by extracting and clearing the ContainsBlendMode flag + // on the builder. + bool capturedBlendMode = mBuilder.ContainsBlendMode(); + mBuilder.SetContainsBlendMode(false); + return capturedBlendMode; + } + + ~AutoContainsBlendModeCapturer() { + // If CaptureContainsBlendMode() was called, the descendant blend mode was + // "captured" and so uncapturedContainsBlendMode will be false. If + // CaptureContainsBlendMode() wasn't called, then no capture occurred, and + // uncapturedContainsBlendMode may be true if there was a descendant blend + // mode. In that case, we set the flag on the DL builder so that we restore + // state to what it would have been without this RAII class on the stack. + bool uncapturedContainsBlendMode = mBuilder.ContainsBlendMode(); + mBuilder.SetContainsBlendMode(mSavedContainsBlendMode || + uncapturedContainsBlendMode); + } +}; + +void nsHTMLScrollFrame::MaybeCreateTopLayerAndWrapRootItems( + nsDisplayListBuilder* aBuilder, nsDisplayListCollection& aSet, + bool aCreateAsyncZoom, + AutoContainsBlendModeCapturer* aAsyncZoomBlendCapture, + const nsRect& aAsyncZoomClipRect, nscoord* aRadii) { + if (!mIsRoot) { + return; + } + + // Create any required items for the 'top layer' and check if they'll be + // opaque over the entire area of the viewport. If they are, then we can + // skip building display items for the rest of the page. + if (ViewportFrame* viewport = do_QueryFrame(GetParent())) { + bool topLayerIsOpaque = false; + if (nsDisplayWrapList* topLayerWrapList = + viewport->BuildDisplayListForTopLayer(aBuilder, + &topLayerIsOpaque)) { + // If the top layer content is opaque, and we're the root content document + // in the process, we can drop the display items behind it. We only + // support doing this for the root content document in the process, since + // the top layer content might have fixed position items that have a + // scrolltarget referencing the APZ data for the document. APZ builds this + // data implicitly for the root content document in the process, but + // subdocuments etc need their display items to generate it, so we can't + // cull those. + if (topLayerIsOpaque && PresContext()->IsRootContentDocumentInProcess()) { + aSet.DeleteAll(aBuilder); + } + aSet.PositionedDescendants()->AppendToTop(topLayerWrapList); + } + } + + nsDisplayList rootResultList(aBuilder); + + bool serializedList = false; + auto SerializeList = [&] { + if (!serializedList) { + serializedList = true; + aSet.SerializeWithCorrectZOrder(&rootResultList, GetContent()); + } + }; + + if (nsIFrame* rootStyleFrame = GetFrameForStyle()) { + bool usingBackdropFilter = + rootStyleFrame->StyleEffects()->HasBackdropFilters() && + rootStyleFrame->IsVisibleForPainting(); + + if (rootStyleFrame->StyleEffects()->HasFilters() && + !aBuilder->IsForGenerateGlyphMask()) { + SerializeList(); + rootResultList.AppendNewToTop<nsDisplayFilters>( + aBuilder, this, &rootResultList, rootStyleFrame, usingBackdropFilter); + } + + if (usingBackdropFilter) { + SerializeList(); + DisplayListClipState::AutoSaveRestore clipState(aBuilder); + nsRect backdropRect = + GetRectRelativeToSelf() + aBuilder->ToReferenceFrame(this); + rootResultList.AppendNewToTop<nsDisplayBackdropFilters>( + aBuilder, this, &rootResultList, backdropRect, rootStyleFrame); + } + } + + if (aCreateAsyncZoom) { + MOZ_ASSERT(mIsRoot); + + // Wrap all our scrolled contents in an nsDisplayAsyncZoom. This will be + // the layer that gets scaled for APZ zooming. It does not have the + // scrolled ASR, but it does have the composition bounds clip applied to + // it. The children have the layout viewport clip applied to them (above). + // Effectively we are double clipping to the viewport, at potentially + // different async scales. + SerializeList(); + + if (aAsyncZoomBlendCapture->CaptureContainsBlendMode()) { + // The async zoom contents contain a mix-blend mode, so let's wrap all + // those contents into a blend container, and then wrap the blend + // container in the async zoom container. Otherwise the blend container + // ends up outside the zoom container which results in blend failure for + // WebRender. + nsDisplayItem* blendContainer = + nsDisplayBlendContainer::CreateForMixBlendMode( + aBuilder, this, &rootResultList, + aBuilder->CurrentActiveScrolledRoot()); + rootResultList.AppendToTop(blendContainer); + + // Blend containers can be created or omitted during partial updates + // depending on the dirty rect. So we basically can't do partial updates + // if there's a blend container involved. There is equivalent code to this + // in the BuildDisplayListForStackingContext function as well, with a more + // detailed comment explaining things better. + if (aBuilder->IsRetainingDisplayList()) { + if (aBuilder->IsPartialUpdate()) { + aBuilder->SetPartialBuildFailed(true); + } else { + aBuilder->SetDisablePartialUpdates(true); + } + } + } + + mozilla::layers::FrameMetrics::ViewID viewID = + nsLayoutUtils::FindOrCreateIDFor(mScrolledFrame->GetContent()); + + DisplayListClipState::AutoSaveRestore clipState(aBuilder); + clipState.ClipContentDescendants(aAsyncZoomClipRect, aRadii); + + rootResultList.AppendNewToTop<nsDisplayAsyncZoom>( + aBuilder, this, &rootResultList, aBuilder->CurrentActiveScrolledRoot(), + viewID); + } + + if (serializedList) { + aSet.Content()->AppendToTop(&rootResultList); + } +} + +void nsHTMLScrollFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder, + const nsDisplayListSet& aLists) { + SetAndNullOnExit<const nsIFrame> tmpBuilder( + mReferenceFrameDuringPainting, aBuilder->GetCurrentReferenceFrame()); + if (aBuilder->IsForFrameVisibility()) { + NotifyApproximateFrameVisibilityUpdate(false); + } + + DisplayBorderBackgroundOutline(aBuilder, aLists); + + const bool isRootContent = + mIsRoot && PresContext()->IsRootContentDocumentCrossProcess(); + + nsRect effectiveScrollPort = mScrollPort; + if (isRootContent && PresContext()->HasDynamicToolbar()) { + // Expand the scroll port to the size including the area covered by dynamic + // toolbar in the case where the dynamic toolbar is being used since + // position:fixed elements attached to this root scroller might be taller + // than its scroll port (e.g 100vh). Even if the dynamic toolbar covers the + // taller area, it doesn't mean the area is clipped by the toolbar because + // the dynamic toolbar is laid out outside of our topmost window and it + // transitions without changing our topmost window size. + effectiveScrollPort.SizeTo(nsLayoutUtils::ExpandHeightForDynamicToolbar( + PresContext(), effectiveScrollPort.Size())); + } + + // It's safe to get this value before the DecideScrollableLayer call below + // because that call cannot create a displayport for root scroll frames, + // and hence it cannot create an ignore scroll frame. + const bool ignoringThisScrollFrame = aBuilder->GetIgnoreScrollFrame() == this; + + // Overflow clipping can never clip frames outside our subtree, so there + // is no need to worry about whether we are a moving frame that might clip + // non-moving frames. + // Not all our descendants will be clipped by overflow clipping, but all + // the ones that aren't clipped will be out of flow frames that have already + // had dirty rects saved for them by their parent frames calling + // MarkOutOfFlowChildrenForDisplayList, so it's safe to restrict our + // dirty rect here. + nsRect visibleRect = aBuilder->GetVisibleRect(); + nsRect dirtyRect = aBuilder->GetDirtyRect(); + if (!ignoringThisScrollFrame) { + visibleRect = visibleRect.Intersect(effectiveScrollPort); + dirtyRect = dirtyRect.Intersect(effectiveScrollPort); + } + + bool dirtyRectHasBeenOverriden = false; + Unused << DecideScrollableLayer(aBuilder, &visibleRect, &dirtyRect, + /* aSetBase = */ !mIsRoot, + &dirtyRectHasBeenOverriden); + + if (aBuilder->IsForFrameVisibility()) { + // We expand the dirty rect to catch frames just outside of the scroll port. + // We use the dirty rect instead of the whole scroll port to prevent + // too much expansion in the presence of very large (bigger than the + // viewport) scroll ports. + dirtyRect = ExpandRectToNearlyVisible(dirtyRect); + visibleRect = dirtyRect; + } + + // We put non-overlay scrollbars in their own layers when this is the root + // scroll frame and we are a toplevel content document. In this situation, + // the scrollbar(s) would normally be assigned their own layer anyway, since + // they're not scrolled with the rest of the document. But when both + // scrollbars are visible, the layer's visible rectangle would be the size + // of the viewport, so most layer implementations would create a layer buffer + // that's much larger than necessary. Creating independent layers for each + // scrollbar works around the problem. + const bool createLayersForScrollbars = isRootContent; + + nsDisplayListCollection set(aBuilder); + + if (ignoringThisScrollFrame) { + // If we are a root scroll frame that has a display port we want to add + // scrollbars, they will be children of the scrollable layer, but they get + // adjusted by the APZC automatically. + bool addScrollBars = + mIsRoot && mWillBuildScrollableLayer && aBuilder->IsPaintingToWindow(); + + if (addScrollBars) { + // Add classic scrollbars. + AppendScrollPartsTo(aBuilder, set, createLayersForScrollbars, false); + } + + { + nsDisplayListBuilder::AutoBuildingDisplayList building( + aBuilder, this, visibleRect, dirtyRect); + + // Don't clip the scrolled child, and don't paint scrollbars/scrollcorner. + // The scrolled frame shouldn't have its own background/border, so we + // can just pass aLists directly. + BuildDisplayListForChild(aBuilder, mScrolledFrame, set); + } + + MaybeCreateTopLayerAndWrapRootItems(aBuilder, set, + /* aCreateAsyncZoom = */ false, nullptr, + nsRect(), nullptr); + + if (addScrollBars) { + // Add overlay scrollbars. + AppendScrollPartsTo(aBuilder, set, createLayersForScrollbars, true); + } + + set.MoveTo(aLists); + return; + } + + // Whether we might want to build a scrollable layer for this scroll frame + // at some point in the future. This controls whether we add the information + // to the layer tree (a scroll info layer if necessary, and add the right + // area to the dispatch to content layer event regions) necessary to activate + // a scroll frame so it creates a scrollable layer. + const bool couldBuildLayer = [&] { + if (!aBuilder->IsPaintingToWindow()) { + return false; + } + if (mWillBuildScrollableLayer) { + return true; + } + return StyleVisibility()->IsVisible() && + nsLayoutUtils::AsyncPanZoomEnabled(this) && WantAsyncScroll(); + }(); + + // Now display the scrollbars and scrollcorner. These parts are drawn + // in the border-background layer, on top of our own background and + // borders and underneath borders and backgrounds of later elements + // in the tree. + // Note that this does not apply for overlay scrollbars; those are drawn + // in the positioned-elements layer on top of everything else by the call + // to AppendScrollPartsTo(..., true) further down. + AppendScrollPartsTo(aBuilder, aLists, createLayersForScrollbars, false); + + const nsStyleDisplay* disp = StyleDisplay(); + if (aBuilder->IsForPainting() && + disp->mWillChange.bits & StyleWillChangeBits::SCROLL) { + aBuilder->AddToWillChangeBudget(this, GetVisualViewportSize()); + } + + mScrollParentID = aBuilder->GetCurrentScrollParentId(); + + Maybe<nsRect> contentBoxClip; + Maybe<const DisplayItemClipChain*> extraContentBoxClipForNonCaretContent; + if (MOZ_UNLIKELY( + disp->mOverflowClipBoxBlock == StyleOverflowClipBox::ContentBox || + disp->mOverflowClipBoxInline == StyleOverflowClipBox::ContentBox)) { + WritingMode wm = mScrolledFrame->GetWritingMode(); + bool cbH = (wm.IsVertical() ? disp->mOverflowClipBoxBlock + : disp->mOverflowClipBoxInline) == + StyleOverflowClipBox::ContentBox; + bool cbV = (wm.IsVertical() ? disp->mOverflowClipBoxInline + : disp->mOverflowClipBoxBlock) == + StyleOverflowClipBox::ContentBox; + // We only clip if there is *scrollable* overflow, to avoid clipping + // *ink* overflow unnecessarily. + nsRect clipRect = effectiveScrollPort + aBuilder->ToReferenceFrame(this); + nsMargin padding = GetUsedPadding(); + if (!cbH) { + padding.left = padding.right = nscoord(0); + } + if (!cbV) { + padding.top = padding.bottom = nscoord(0); + } + clipRect.Deflate(padding); + + nsRect so = mScrolledFrame->ScrollableOverflowRect(); + if ((cbH && (clipRect.width != so.width || so.x < 0)) || + (cbV && (clipRect.height != so.height || so.y < 0))) { + // The non-inflated clip needs to be set on all non-caret items. + // We prepare an extra DisplayItemClipChain here that will be intersected + // with those items after they've been created. + const ActiveScrolledRoot* asr = aBuilder->CurrentActiveScrolledRoot(); + + DisplayItemClip newClip; + newClip.SetTo(clipRect); + + const DisplayItemClipChain* extraClip = + aBuilder->AllocateDisplayItemClipChain(newClip, asr, nullptr); + + extraContentBoxClipForNonCaretContent = Some(extraClip); + + nsIFrame* caretFrame = aBuilder->GetCaretFrame(); + // Avoid clipping it in a zero-height line box (heuristic only). + if (caretFrame && caretFrame->GetRect().height != 0) { + nsRect caretRect = aBuilder->GetCaretRect(); + // Allow the caret to stick out of the content box clip by half the + // caret height on the top, and its full width on the right. + nsRect inflatedClip = clipRect; + inflatedClip.Inflate( + nsMargin(caretRect.height / 2, caretRect.width, 0, 0)); + contentBoxClip = Some(inflatedClip); + } + } + } + + AutoContainsBlendModeCapturer blendCapture(*aBuilder); + + const bool willBuildAsyncZoomContainer = + mWillBuildScrollableLayer && aBuilder->ShouldBuildAsyncZoomContainer() && + isRootContent; + + nsRect scrollPortClip = + effectiveScrollPort + aBuilder->ToReferenceFrame(this); + nsRect clipRect = scrollPortClip; + // Our override of GetBorderRadii ensures we never have a radius at + // the corners where we have a scrollbar. + nscoord radii[8]; + const bool haveRadii = GetPaddingBoxBorderRadii(radii); + if (mIsRoot) { + clipRect.SizeTo(nsLayoutUtils::CalculateCompositionSizeForFrame( + this, true /* aSubtractScrollbars */, + nullptr /* aOverrideScrollPortSize */, + // With the dynamic toolbar, this CalculateCompositionSizeForFrame call + // basically expands the region being covered up by the dynamic toolbar, + // but if the root scroll container is not scrollable, e.g. the root + // element has `overflow: hidden` or `position: fixed`, the function + // doesn't expand the region since expanding the region in such cases + // will prevent the content from restoring zooming to 1.0 zoom level + // such as bug 1652190. That said, this `clipRect` which will be used + // for the async zoom container needs to be expanded because zoomed-in + // contents can be scrollable __visually__ so that the region under the + // dynamic toolbar area will be revealed. + nsLayoutUtils::IncludeDynamicToolbar::Force)); + + // The composition size is essentially in visual coordinates. + // If we are hit-testing in layout coordinates, transform the clip rect + // to layout coordinates to match. + if (aBuilder->IsRelativeToLayoutViewport() && isRootContent) { + clipRect = ViewportUtils::VisualToLayout(clipRect, PresShell()); + } + } + + { + DisplayListClipState::AutoSaveRestore clipState(aBuilder); + + // If we're building an async zoom container, clip the contents inside + // to the layout viewport (scrollPortClip). The composition bounds clip + // (clipRect) will be applied to the zoom container itself in + // MaybeCreateTopLayerAndWrapRootItems. + nsRect clipRectForContents = + willBuildAsyncZoomContainer ? scrollPortClip : clipRect; + if (mIsRoot) { + clipState.ClipContentDescendants(clipRectForContents, + haveRadii ? radii : nullptr); + } else { + clipState.ClipContainingBlockDescendants(clipRectForContents, + haveRadii ? radii : nullptr); + } + + Maybe<DisplayListClipState::AutoSaveRestore> contentBoxClipState; + if (contentBoxClip) { + contentBoxClipState.emplace(aBuilder); + if (mIsRoot) { + contentBoxClipState->ClipContentDescendants(*contentBoxClip); + } else { + contentBoxClipState->ClipContainingBlockDescendants(*contentBoxClip); + } + } + + nsDisplayListBuilder::AutoCurrentActiveScrolledRootSetter asrSetter( + aBuilder); + + if (mWillBuildScrollableLayer && aBuilder->IsPaintingToWindow()) { + // If this scroll frame has a first scrollable frame sequence number, + // ensure that it matches the current paint sequence number. If it does + // not, reset it so that we can expire the displayport. The stored + // sequence number will not match that of the current paint if the dom + // was mutated in some way that alters the order of scroll frames. + if (IsFirstScrollableFrameSequenceNumber().isSome() && + *IsFirstScrollableFrameSequenceNumber() != + nsDisplayListBuilder::GetPaintSequenceNumber()) { + SetIsFirstScrollableFrameSequenceNumber(Nothing()); + } + asrSetter.EnterScrollFrame(this); + } + + if (couldBuildLayer && mScrolledFrame->GetContent()) { + asrSetter.SetCurrentScrollParentId( + nsLayoutUtils::FindOrCreateIDFor(mScrolledFrame->GetContent())); + } + + if (mWillBuildScrollableLayer && aBuilder->BuildCompositorHitTestInfo()) { + // Create a hit test info item for the scrolled content that's not + // clipped to the displayport. This ensures that within the bounds + // of the scroll frame, the scrolled content is always hit, even + // if we are checkerboarding. + CompositorHitTestInfo info = + mScrolledFrame->GetCompositorHitTestInfo(aBuilder); + + if (info != CompositorHitTestInvisibleToHit) { + auto* hitInfo = + MakeDisplayItemWithIndex<nsDisplayCompositorHitTestInfo>( + aBuilder, mScrolledFrame, 1); + if (hitInfo) { + aBuilder->SetCompositorHitTestInfo(info); + set.BorderBackground()->AppendToTop(hitInfo); + } + } + } + + { + // Clip our contents to the unsnapped scrolled rect. This makes sure + // that we don't have display items over the subpixel seam at the edge + // of the scrolled area. + DisplayListClipState::AutoSaveRestore scrolledRectClipState(aBuilder); + nsRect scrolledRectClip = + GetUnsnappedScrolledRectInternal( + mScrolledFrame->ScrollableOverflowRect(), mScrollPort.Size()) + + mScrolledFrame->GetPosition(); + bool clippedToDisplayPort = false; + if (mWillBuildScrollableLayer && aBuilder->IsPaintingToWindow()) { + // Clip the contents to the display port. + // The dirty rect already acts kind of like a clip, in that + // FrameLayerBuilder intersects item bounds and opaque regions with + // it, but it doesn't have the consistent snapping behavior of a + // true clip. + // For a case where this makes a difference, imagine the following + // scenario: The display port has an edge that falls on a fractional + // layer pixel, and there's an opaque display item that covers the + // whole display port up until that fractional edge, and there is a + // transparent display item that overlaps the edge. We want to prevent + // this transparent item from enlarging the scrolled layer's visible + // region beyond its opaque region. The dirty rect doesn't do that - + // it gets rounded out, whereas a true clip gets rounded to nearest + // pixels. + // If there is no display port, we don't need this because the clip + // from the scroll port is still applied. + scrolledRectClip = scrolledRectClip.Intersect(visibleRect); + clippedToDisplayPort = scrolledRectClip.IsEqualEdges(visibleRect); + } + scrolledRectClipState.ClipContainingBlockDescendants( + scrolledRectClip + aBuilder->ToReferenceFrame(this)); + if (clippedToDisplayPort) { + // We have to do this after the ClipContainingBlockDescendants call + // above, otherwise that call will clobber the flag set by this call + // to SetClippedToDisplayPort. + scrolledRectClipState.SetClippedToDisplayPort(); + } + + nsRect visibleRectForChildren = visibleRect; + nsRect dirtyRectForChildren = dirtyRect; + + // If we are entering the RCD-RSF, we are crossing the async zoom + // container boundary, and need to convert from visual to layout + // coordinates. + if (willBuildAsyncZoomContainer && aBuilder->IsForEventDelivery()) { + MOZ_ASSERT(ViewportUtils::IsZoomedContentRoot(mScrolledFrame)); + visibleRectForChildren = + ViewportUtils::VisualToLayout(visibleRectForChildren, PresShell()); + dirtyRectForChildren = + ViewportUtils::VisualToLayout(dirtyRectForChildren, PresShell()); + } + + nsDisplayListBuilder::AutoBuildingDisplayList building( + aBuilder, this, visibleRectForChildren, dirtyRectForChildren); + + BuildDisplayListForChild(aBuilder, mScrolledFrame, set); + + if (dirtyRectHasBeenOverriden && + StaticPrefs::layout_display_list_show_rebuild_area()) { + nsDisplaySolidColor* color = MakeDisplayItem<nsDisplaySolidColor>( + aBuilder, this, + dirtyRect + aBuilder->GetCurrentFrameOffsetToReferenceFrame(), + NS_RGBA(0, 0, 255, 64), false); + if (color) { + color->SetOverrideZIndex(INT32_MAX); + set.PositionedDescendants()->AppendToTop(color); + } + } + } + + if (extraContentBoxClipForNonCaretContent) { + // The items were built while the inflated content box clip was in + // effect, so that the caret wasn't clipped unnecessarily. We apply + // the non-inflated clip to the non-caret items now, by intersecting + // it with their existing clip. + ClipListsExceptCaret(&set, aBuilder, mScrolledFrame, + *extraContentBoxClipForNonCaretContent); + } + + if (aBuilder->IsPaintingToWindow()) { + mIsParentToActiveScrollFrames = + ShouldActivateAllScrollFrames() + ? asrSetter.GetContainsNonMinimalDisplayPort() + : asrSetter.ShouldForceLayerForScrollParent(); + } + + if (asrSetter.ShouldForceLayerForScrollParent()) { + // Note that forcing layerization of scroll parents follows the scroll + // handoff chain which is subject to the out-of-flow-frames caveat noted + // above (where the asrSetter variable is created). + MOZ_ASSERT(couldBuildLayer && mScrolledFrame->GetContent() && + aBuilder->IsPaintingToWindow()); + if (!mWillBuildScrollableLayer) { + // Set a displayport so next paint we don't have to force layerization + // after the fact. It's ok to pass DoNotRepaint here, since we've + // already painted the change and we're just optimizing it to be + // detected earlier. We also won't confuse RetainedDisplayLists + // with the silent change, since we explicitly request partial updates + // to be disabled on the next paint. + DisplayPortUtils::SetDisplayPortMargins( + GetContent(), PresShell(), DisplayPortMargins::Empty(GetContent()), + DisplayPortUtils::ClearMinimalDisplayPortProperty::Yes, 0, + DisplayPortUtils::RepaintMode::DoNotRepaint); + // Call DecideScrollableLayer to recompute mWillBuildScrollableLayer + // and recompute the current animated geometry root if needed. It's + // too late to change the dirty rect so pass a copy. + nsRect copyOfDirtyRect = dirtyRect; + nsRect copyOfVisibleRect = visibleRect; + Unused << DecideScrollableLayer(aBuilder, ©OfVisibleRect, + ©OfDirtyRect, + /* aSetBase = */ false, nullptr); + if (mWillBuildScrollableLayer) { + asrSetter.InsertScrollFrame(this); + aBuilder->SetDisablePartialUpdates(true); + } + } + } + } + + if (mWillBuildScrollableLayer && aBuilder->IsPaintingToWindow()) { + aBuilder->ForceLayerForScrollParent(); + } + + MaybeCreateTopLayerAndWrapRootItems( + aBuilder, set, willBuildAsyncZoomContainer, &blendCapture, clipRect, + haveRadii ? radii : nullptr); + + // We want to call SetContainsNonMinimalDisplayPort if + // mWillBuildScrollableLayer is true for any reason other than having a + // minimal display port. + if (aBuilder->IsPaintingToWindow()) { + if (DisplayPortUtils::HasNonMinimalDisplayPort(GetContent()) || + mZoomableByAPZ || nsContentUtils::HasScrollgrab(GetContent())) { + aBuilder->SetContainsNonMinimalDisplayPort(); + } + } + + if (couldBuildLayer) { + CompositorHitTestInfo info(CompositorHitTestFlags::eVisibleToHitTest, + CompositorHitTestFlags::eInactiveScrollframe); + // If the scroll frame has non-default overscroll-behavior, instruct + // APZ to require a target confirmation before processing events that + // hit this scroll frame (that is, to drop the events if a + // confirmation does not arrive within the timeout period). Otherwise, + // APZ's fallback behaviour of scrolling the enclosing scroll frame + // would violate the specified overscroll-behavior. + auto overscroll = GetOverscrollBehaviorInfo(); + if (overscroll.mBehaviorX != OverscrollBehavior::Auto || + overscroll.mBehaviorY != OverscrollBehavior::Auto) { + info += CompositorHitTestFlags::eRequiresTargetConfirmation; + } + + nsRect area = effectiveScrollPort + aBuilder->ToReferenceFrame(this); + + // Make sure that APZ will dispatch events back to content so we can + // create a displayport for this frame. We'll add the item later on. + if (!mWillBuildScrollableLayer && aBuilder->BuildCompositorHitTestInfo()) { + // Make sure the z-index of the inactive item is at least zero. + // Otherwise, it will end up behind non-positioned items in the scrolled + // content. + int32_t zIndex = MaxZIndexInListOfItemsContainedInFrame( + set.PositionedDescendants(), this) + .valueOr(0); + if (aBuilder->IsPartialUpdate()) { + for (nsDisplayItem* item : mScrolledFrame->DisplayItems()) { + if (item->GetType() == + DisplayItemType::TYPE_COMPOSITOR_HITTEST_INFO) { + auto* hitTestItem = + static_cast<nsDisplayCompositorHitTestInfo*>(item); + if (hitTestItem->GetHitTestInfo().Info().contains( + CompositorHitTestFlags::eInactiveScrollframe)) { + zIndex = std::max(zIndex, hitTestItem->ZIndex()); + item->SetCantBeReused(); + } + } + } + } + nsDisplayCompositorHitTestInfo* hitInfo = + MakeDisplayItemWithIndex<nsDisplayCompositorHitTestInfo>( + aBuilder, mScrolledFrame, 1, area, info); + if (hitInfo) { + AppendInternalItemToTop(set, hitInfo, Some(zIndex)); + aBuilder->SetCompositorHitTestInfo(info); + } + } + + if (aBuilder->ShouldBuildScrollInfoItemsForHoisting()) { + aBuilder->AppendNewScrollInfoItemForHoisting( + MakeDisplayItem<nsDisplayScrollInfoLayer>(aBuilder, mScrolledFrame, + this, info, area)); + } + } + + // Now display overlay scrollbars and the resizer, if we have one. + AppendScrollPartsTo(aBuilder, set, createLayersForScrollbars, true); + + set.MoveTo(aLists); +} + +nsRect nsHTMLScrollFrame::RestrictToRootDisplayPort( + const nsRect& aDisplayportBase) { + // This function clips aDisplayportBase so that it is no larger than the + // root frame's displayport (or the root composition bounds, if we can't + // obtain the root frame's displayport). This is useful for ensuring that + // the displayport of a tall scrollframe doesn't gobble up all the memory. + + nsPresContext* pc = PresContext(); + const nsPresContext* rootPresContext = + pc->GetInProcessRootContentDocumentPresContext(); + if (!rootPresContext) { + rootPresContext = pc->GetRootPresContext(); + } + if (!rootPresContext) { + return aDisplayportBase; + } + const mozilla::PresShell* const rootPresShell = rootPresContext->PresShell(); + nsIFrame* rootFrame = rootPresShell->GetRootScrollFrame(); + if (!rootFrame) { + rootFrame = rootPresShell->GetRootFrame(); + } + if (!rootFrame) { + return aDisplayportBase; + } + + // Make sure we aren't trying to restrict to our own displayport, which is a + // circular dependency. + MOZ_ASSERT(!mIsRoot || rootPresContext != pc); + + nsRect rootDisplayPort; + bool hasDisplayPort = + rootFrame->GetContent() && DisplayPortUtils::GetDisplayPort( + rootFrame->GetContent(), &rootDisplayPort); + if (hasDisplayPort) { + // The display port of the root frame already factors in it's callback + // transform, so subtract it out here, the GetCumulativeApzCallbackTransform + // call below will add it back. + MOZ_LOG(sDisplayportLog, LogLevel::Verbose, + ("RestrictToRootDisplayPort: Existing root displayport is %s\n", + ToString(rootDisplayPort).c_str())); + if (nsIContent* content = rootFrame->GetContent()) { + if (void* property = + content->GetProperty(nsGkAtoms::apzCallbackTransform)) { + rootDisplayPort -= + CSSPoint::ToAppUnits(*static_cast<CSSPoint*>(property)); + } + } + } else { + // If we don't have a display port on the root frame let's fall back to + // the root composition bounds instead. + nsRect rootCompBounds = + nsRect(nsPoint(0, 0), + nsLayoutUtils::CalculateCompositionSizeForFrame(rootFrame)); + + // If rootFrame is the RCD-RSF then + // CalculateCompositionSizeForFrame did not take the document's + // resolution into account, so we must. + if (rootPresContext->IsRootContentDocumentCrossProcess() && + rootFrame == rootPresShell->GetRootScrollFrame()) { + MOZ_LOG( + sDisplayportLog, LogLevel::Verbose, + ("RestrictToRootDisplayPort: Removing resolution %f from root " + "composition bounds %s\n", + rootPresShell->GetResolution(), ToString(rootCompBounds).c_str())); + rootCompBounds = + rootCompBounds.RemoveResolution(rootPresShell->GetResolution()); + } + + rootDisplayPort = rootCompBounds; + } + MOZ_LOG(sDisplayportLog, LogLevel::Verbose, + ("RestrictToRootDisplayPort: Intermediate root displayport %s\n", + ToString(rootDisplayPort).c_str())); + + // We want to convert the root display port from the + // coordinate space of |rootFrame| to the coordinate space of + // |this|. We do that with the TransformRect call below. + // However, since we care about the root display port + // relative to what the user is actually seeing, we also need to + // incorporate the APZ callback transforms into this. Most of the + // time those transforms are negligible, but in some cases (e.g. + // when a zoom is applied on an overflow:hidden document) it is + // not (see bug 1280013). + // XXX: Eventually we may want to create a modified version of + // TransformRect that includes the APZ callback transforms + // directly. + nsLayoutUtils::TransformRect(rootFrame, this, rootDisplayPort); + MOZ_LOG(sDisplayportLog, LogLevel::Verbose, + ("RestrictToRootDisplayPort: Transformed root displayport %s\n", + ToString(rootDisplayPort).c_str())); + rootDisplayPort += CSSPoint::ToAppUnits( + nsLayoutUtils::GetCumulativeApzCallbackTransform(this)); + MOZ_LOG(sDisplayportLog, LogLevel::Verbose, + ("RestrictToRootDisplayPort: Final root displayport %s\n", + ToString(rootDisplayPort).c_str())); + + // We want to limit aDisplayportBase to be no larger than + // rootDisplayPort on either axis, but we don't want to just + // blindly intersect the two, because rootDisplayPort might be + // offset from where aDisplayportBase is (see bug 1327095 comment + // 8). Instead, we translate rootDisplayPort so as to maximize the + // overlap with aDisplayportBase, and *then* do the intersection. + if (rootDisplayPort.x > aDisplayportBase.x && + rootDisplayPort.XMost() > aDisplayportBase.XMost()) { + // rootDisplayPort is at a greater x-position for both left and + // right, so translate it such that the XMost() values are the + // same. This will line up the right edge of the two rects, and + // might mean that rootDisplayPort.x is smaller than + // aDisplayportBase.x. We can avoid that by taking the min of the + // x delta and XMost() delta, but it doesn't really matter + // because the intersection between the two rects below will end + // up the same. + rootDisplayPort.x -= (rootDisplayPort.XMost() - aDisplayportBase.XMost()); + } else if (rootDisplayPort.x < aDisplayportBase.x && + rootDisplayPort.XMost() < aDisplayportBase.XMost()) { + // Analaogous code for when the rootDisplayPort is at a smaller + // x-position. + rootDisplayPort.x = aDisplayportBase.x; + } + // Do the same for y-axis + if (rootDisplayPort.y > aDisplayportBase.y && + rootDisplayPort.YMost() > aDisplayportBase.YMost()) { + rootDisplayPort.y -= (rootDisplayPort.YMost() - aDisplayportBase.YMost()); + } else if (rootDisplayPort.y < aDisplayportBase.y && + rootDisplayPort.YMost() < aDisplayportBase.YMost()) { + rootDisplayPort.y = aDisplayportBase.y; + } + MOZ_LOG( + sDisplayportLog, LogLevel::Verbose, + ("RestrictToRootDisplayPort: Root displayport translated to %s to " + "better enclose %s\n", + ToString(rootDisplayPort).c_str(), ToString(aDisplayportBase).c_str())); + + // Now we can do the intersection + return aDisplayportBase.Intersect(rootDisplayPort); +} + +/* static */ bool nsHTMLScrollFrame::ShouldActivateAllScrollFrames() { + return (StaticPrefs::apz_wr_activate_all_scroll_frames() || + (StaticPrefs::apz_wr_activate_all_scroll_frames_when_fission() && + FissionAutostart())); +} + +bool nsHTMLScrollFrame::DecideScrollableLayer( + nsDisplayListBuilder* aBuilder, nsRect* aVisibleRect, nsRect* aDirtyRect, + bool aSetBase, bool* aDirtyRectHasBeenOverriden) { + nsIContent* content = GetContent(); + // For hit testing purposes with fission we want to create a + // minimal display port for every scroll frame that could be active. (We only + // do this when aSetBase is true because we only want to do this the first + // time this function is called for the same scroll frame.) + if (ShouldActivateAllScrollFrames() && + !DisplayPortUtils::HasDisplayPort(content) && + nsLayoutUtils::AsyncPanZoomEnabled(this) && WantAsyncScroll() && + aBuilder->IsPaintingToWindow() && aSetBase) { + // SetDisplayPortMargins calls TriggerDisplayPortExpiration which starts a + // display port expiry timer for display ports that do expire. However + // minimal display ports do not expire, so the display port has to be + // marked before the SetDisplayPortMargins call so the expiry timer + // doesn't get started. + content->SetProperty(nsGkAtoms::MinimalDisplayPort, + reinterpret_cast<void*>(true)); + + DisplayPortUtils::SetDisplayPortMargins( + content, PresShell(), DisplayPortMargins::Empty(content), + DisplayPortUtils::ClearMinimalDisplayPortProperty::No, 0, + DisplayPortUtils::RepaintMode::DoNotRepaint); + } + + bool usingDisplayPort = DisplayPortUtils::HasDisplayPort(content); + if (aBuilder->IsPaintingToWindow()) { + if (aSetBase) { + nsRect displayportBase = *aVisibleRect; + nsPresContext* pc = PresContext(); + + bool isContentRootDoc = pc->IsRootContentDocumentCrossProcess(); + bool isChromeRootDoc = + !pc->Document()->IsContentDocument() && !pc->GetParentPresContext(); + + if (mIsRoot && (isContentRootDoc || isChromeRootDoc)) { + displayportBase = + nsRect(nsPoint(0, 0), + nsLayoutUtils::CalculateCompositionSizeForFrame(this)); + } else { + // Make the displayport base equal to the visible rect restricted to + // the scrollport and the root composition bounds, relative to the + // scrollport. + displayportBase = aVisibleRect->Intersect(mScrollPort); + + mozilla::layers::ScrollableLayerGuid::ViewID viewID = + mozilla::layers::ScrollableLayerGuid::NULL_SCROLL_ID; + if (MOZ_LOG_TEST(sDisplayportLog, LogLevel::Verbose)) { + nsLayoutUtils::FindIDFor(GetContent(), &viewID); + MOZ_LOG( + sDisplayportLog, LogLevel::Verbose, + ("Scroll id %" PRIu64 " has visible rect %s, scroll port %s\n", + viewID, ToString(*aVisibleRect).c_str(), + ToString(mScrollPort).c_str())); + } + + // Only restrict to the root displayport bounds if necessary, + // as the required coordinate transformation is expensive. + // And don't call RestrictToRootDisplayPort if we would be trying to + // restrict to our own display port, which doesn't make sense (ie if we + // are a root scroll frame in a process root prescontext). + if (usingDisplayPort && (!mIsRoot || pc->GetParentPresContext())) { + displayportBase = RestrictToRootDisplayPort(displayportBase); + MOZ_LOG(sDisplayportLog, LogLevel::Verbose, + ("Scroll id %" PRIu64 " has restricted base %s\n", viewID, + ToString(displayportBase).c_str())); + } + displayportBase -= mScrollPort.TopLeft(); + } + + DisplayPortUtils::SetDisplayPortBase(GetContent(), displayportBase); + } + + // If we don't have aSetBase == true then should have already + // been called with aSetBase == true which should have set a + // displayport base. + MOZ_ASSERT(content->GetProperty(nsGkAtoms::DisplayPortBase)); + nsRect displayPort; + usingDisplayPort = DisplayPortUtils::GetDisplayPort( + content, &displayPort, + DisplayPortOptions().With(DisplayportRelativeTo::ScrollFrame)); + + auto OverrideDirtyRect = [&](const nsRect& aRect) { + *aDirtyRect = aRect; + if (aDirtyRectHasBeenOverriden) { + *aDirtyRectHasBeenOverriden = true; + } + }; + + if (usingDisplayPort) { + // Override the dirty rectangle if the displayport has been set. + *aVisibleRect = displayPort; + if (aBuilder->IsReusingStackingContextItems() || + !aBuilder->IsPartialUpdate() || aBuilder->InInvalidSubtree() || + IsFrameModified()) { + OverrideDirtyRect(displayPort); + } else if (HasOverrideDirtyRegion()) { + nsRect* rect = GetProperty( + nsDisplayListBuilder::DisplayListBuildingDisplayPortRect()); + if (rect) { + OverrideDirtyRect(*rect); + } + } + } else if (mIsRoot) { + // The displayPort getter takes care of adjusting for resolution. So if + // we have resolution but no displayPort then we need to adjust for + // resolution here. + auto* presShell = PresShell(); + *aVisibleRect = + aVisibleRect->RemoveResolution(presShell->GetResolution()); + *aDirtyRect = aDirtyRect->RemoveResolution(presShell->GetResolution()); + } + } + + // Since making new layers is expensive, only create a scrollable layer + // for some scroll frames. + // When a displayport is being used, force building of a layer so that + // the compositor can find the scrollable layer for async scrolling. + // If the element is marked 'scrollgrab', also force building of a layer + // so that APZ can implement scroll grabbing. + mWillBuildScrollableLayer = usingDisplayPort || + nsContentUtils::HasScrollgrab(content) || + mZoomableByAPZ; + return mWillBuildScrollableLayer; +} + +void nsHTMLScrollFrame::NotifyApzTransaction() { + mAllowScrollOriginDowngrade = true; + mApzScrollPos = GetScrollPosition(); + mApzAnimationRequested = IsLastScrollUpdateAnimating(); + mApzAnimationTriggeredByScriptRequested = + IsLastScrollUpdateTriggeredByScriptAnimating(); + mScrollUpdates.Clear(); + if (mIsRoot) { + PresShell()->SetResolutionUpdated(false); + } +} + +Maybe<ScrollMetadata> nsHTMLScrollFrame::ComputeScrollMetadata( + WebRenderLayerManager* aLayerManager, const nsIFrame* aItemFrame, + const nsPoint& aOffsetToReferenceFrame) const { + if (!mWillBuildScrollableLayer) { + return Nothing(); + } + + bool isRootContent = + mIsRoot && PresContext()->IsRootContentDocumentCrossProcess(); + + MOZ_ASSERT(mScrolledFrame->GetContent()); + + return Some(nsLayoutUtils::ComputeScrollMetadata( + mScrolledFrame, this, GetContent(), aItemFrame, aOffsetToReferenceFrame, + aLayerManager, mScrollParentID, mScrollPort.Size(), isRootContent)); +} + +bool nsHTMLScrollFrame::IsRectNearlyVisible(const nsRect& aRect) const { + // Use the right rect depending on if a display port is set. + nsRect displayPort; + bool usingDisplayport = DisplayPortUtils::GetDisplayPort( + GetContent(), &displayPort, + DisplayPortOptions().With(DisplayportRelativeTo::ScrollFrame)); + + if (mIsRoot && !usingDisplayport && + PresContext()->IsRootContentDocumentInProcess() && + !PresContext()->IsRootContentDocumentCrossProcess()) { + // In the case of the root scroller of OOP iframes, there are cases where + // any display port value isn't set, e.g. the iframe element is out of view + // in the parent document. In such cases we'd consider the iframe is not + // visible. + return false; + } + + return aRect.Intersects( + ExpandRectToNearlyVisible(usingDisplayport ? displayPort : mScrollPort)); +} + +OverscrollBehaviorInfo nsHTMLScrollFrame::GetOverscrollBehaviorInfo() const { + nsIFrame* frame = GetFrameForStyle(); + if (!frame) { + return {}; + } + + auto& disp = *frame->StyleDisplay(); + return OverscrollBehaviorInfo::FromStyleConstants(disp.mOverscrollBehaviorX, + disp.mOverscrollBehaviorY); +} + +ScrollStyles nsHTMLScrollFrame::GetScrollStyles() const { + nsPresContext* presContext = PresContext(); + if (!presContext->IsDynamic() && + !(mIsRoot && presContext->HasPaginatedScrolling())) { + return ScrollStyles(StyleOverflow::Hidden, StyleOverflow::Hidden); + } + + if (!mIsRoot) { + return ScrollStyles(*StyleDisplay(), + ScrollStyles::MapOverflowToValidScrollStyle); + } + + ScrollStyles result = presContext->GetViewportScrollStylesOverride(); + if (nsDocShell* ds = presContext->GetDocShell()) { + switch (ds->ScrollbarPreference()) { + case ScrollbarPreference::Auto: + break; + case ScrollbarPreference::Never: + result.mHorizontal = result.mVertical = StyleOverflow::Hidden; + break; + } + } + return result; +} + +nsRect nsHTMLScrollFrame::GetLayoutScrollRange() const { + return GetScrollRange(mScrollPort.width, mScrollPort.height); +} + +nsRect nsHTMLScrollFrame::GetScrollRange(nscoord aWidth, + nscoord aHeight) const { + nsRect range = GetScrolledRect(); + range.width = std::max(range.width - aWidth, 0); + range.height = std::max(range.height - aHeight, 0); + return range; +} + +nsRect nsHTMLScrollFrame::GetVisualScrollRange() const { + nsSize visualViewportSize = GetVisualViewportSize(); + return GetScrollRange(visualViewportSize.width, visualViewportSize.height); +} + +nsSize nsHTMLScrollFrame::GetVisualViewportSize() const { + auto* presShell = PresShell(); + if (mIsRoot && presShell->IsVisualViewportSizeSet()) { + return presShell->GetVisualViewportSize(); + } + return mScrollPort.Size(); +} + +nsPoint nsHTMLScrollFrame::GetVisualViewportOffset() const { + if (mIsRoot) { + auto* presShell = PresShell(); + if (auto pendingUpdate = presShell->GetPendingVisualScrollUpdate()) { + // The pending visual scroll update on the PresShell contains a raw, + // unclamped offset (basically, whatever was passed to ScrollToVisual()). + // It will be clamped on the APZ side, but if we use it as the + // main-thread's visual viewport offset we need to clamp it ourselves. + // Use GetScrollRangeForUserInputEvents() to do the clamping because this + // the scroll range that APZ will use. + return GetScrollRangeForUserInputEvents().ClampPoint( + pendingUpdate->mVisualScrollOffset); + } + return presShell->GetVisualViewportOffset(); + } + return GetScrollPosition(); +} + +bool nsHTMLScrollFrame::SetVisualViewportOffset(const nsPoint& aOffset, + bool aRepaint) { + MOZ_ASSERT(mIsRoot); + AutoWeakFrame weakFrame(this); + AutoScrollbarRepaintSuppression repaintSuppression(this, weakFrame, + !aRepaint); + + bool retVal = + PresShell()->SetVisualViewportOffset(aOffset, GetScrollPosition()); + if (!weakFrame.IsAlive()) { + return false; + } + return retVal; +} + +nsRect nsHTMLScrollFrame::GetVisualOptimalViewingRect() const { + auto* presShell = PresShell(); + nsRect rect = mScrollPort; + if (mIsRoot && presShell->IsVisualViewportSizeSet() && + presShell->IsVisualViewportOffsetSet()) { + rect = nsRect(mScrollPort.TopLeft() - GetScrollPosition() + + presShell->GetVisualViewportOffset(), + presShell->GetVisualViewportSize()); + } + // NOTE: We intentionally resolve scroll-padding percentages against the + // scrollport even when the visual viewport is set, see + // https://github.com/w3c/csswg-drafts/issues/4393. + rect.Deflate(GetScrollPadding()); + return rect; +} + +static void AdjustDestinationForWholeDelta(const nsIntPoint& aDelta, + const nsRect& aScrollRange, + nsPoint& aPoint) { + if (aDelta.x < 0) { + aPoint.x = aScrollRange.X(); + } else if (aDelta.x > 0) { + aPoint.x = aScrollRange.XMost(); + } + if (aDelta.y < 0) { + aPoint.y = aScrollRange.Y(); + } else if (aDelta.y > 0) { + aPoint.y = aScrollRange.YMost(); + } +} + +/** + * Calculate lower/upper scrollBy range in given direction. + * @param aDelta specifies scrollBy direction, if 0 then range will be 0 size + * @param aPos desired destination in AppUnits + * @param aNeg/PosTolerance defines relative range distance + * below and above of aPos point + * @param aMultiplier used for conversion of tolerance into appUnis + */ +static void CalcRangeForScrollBy(int32_t aDelta, nscoord aPos, + float aNegTolerance, float aPosTolerance, + nscoord aMultiplier, nscoord* aLower, + nscoord* aUpper) { + if (!aDelta) { + *aLower = *aUpper = aPos; + return; + } + *aLower = aPos - NSToCoordRound(aMultiplier * + (aDelta > 0 ? aNegTolerance : aPosTolerance)); + *aUpper = aPos + NSToCoordRound(aMultiplier * + (aDelta > 0 ? aPosTolerance : aNegTolerance)); +} + +void nsHTMLScrollFrame::ScrollBy(nsIntPoint aDelta, ScrollUnit aUnit, + ScrollMode aMode, nsIntPoint* aOverflow, + ScrollOrigin aOrigin, + nsIScrollableFrame::ScrollMomentum aMomentum, + ScrollSnapFlags aSnapFlags) { + // When a smooth scroll is being processed on a frame, mouse wheel and + // trackpad momentum scroll event updates must notcancel the SMOOTH or + // SMOOTH_MSD scroll animations, enabling Javascript that depends on them to + // be responsive without forcing the user to wait for the fling animations to + // completely stop. + switch (aMomentum) { + case nsIScrollableFrame::NOT_MOMENTUM: + mIgnoreMomentumScroll = false; + break; + case nsIScrollableFrame::SYNTHESIZED_MOMENTUM_EVENT: + if (mIgnoreMomentumScroll) { + return; + } + break; + } + + if (mAsyncSmoothMSDScroll != nullptr) { + // When CSSOM-View scroll-behavior smooth scrolling is interrupted, + // the scroll is not completed to avoid non-smooth snapping to the + // prior smooth scroll's destination. + mDestination = GetScrollPosition(); + } + + nsSize deltaMultiplier; + float negativeTolerance; + float positiveTolerance; + if (aOrigin == ScrollOrigin::NotSpecified) { + aOrigin = ScrollOrigin::Other; + } + bool isGenericOrigin = (aOrigin == ScrollOrigin::Other); + + bool askApzToDoTheScroll = false; + if ((aSnapFlags == ScrollSnapFlags::Disabled || !NeedsScrollSnap()) && + gfxPlatform::UseDesktopZoomingScrollbars() && + nsLayoutUtils::AsyncPanZoomEnabled(this) && + !nsLayoutUtils::ShouldDisableApzForElement(GetContent()) && + (WantAsyncScroll() || mZoomableByAPZ) && + CanApzScrollInTheseDirections(DirectionsInDelta(aDelta))) { + askApzToDoTheScroll = true; + } + + switch (aUnit) { + case ScrollUnit::DEVICE_PIXELS: { + nscoord appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel(); + deltaMultiplier = nsSize(appUnitsPerDevPixel, appUnitsPerDevPixel); + if (isGenericOrigin) { + aOrigin = ScrollOrigin::Pixels; + } + negativeTolerance = positiveTolerance = 0.5f; + break; + } + case ScrollUnit::LINES: { + deltaMultiplier = GetLineScrollAmount(); + if (isGenericOrigin) { + aOrigin = ScrollOrigin::Lines; + } + negativeTolerance = positiveTolerance = 0.1f; + break; + } + case ScrollUnit::PAGES: { + deltaMultiplier = GetPageScrollAmount(); + if (isGenericOrigin) { + aOrigin = ScrollOrigin::Pages; + } + negativeTolerance = 0.05f; + positiveTolerance = 0; + break; + } + case ScrollUnit::WHOLE: { + if (askApzToDoTheScroll) { + MOZ_ASSERT(aDelta.x >= -1 && aDelta.x <= 1 && aDelta.y >= -1 && + aDelta.y <= 1); + deltaMultiplier = GetScrollRangeForUserInputEvents().Size(); + break; + } else { + nsPoint pos = GetScrollPosition(); + AdjustDestinationForWholeDelta(aDelta, GetLayoutScrollRange(), pos); + ScrollToWithOrigin( + pos, nullptr /* range */, + ScrollOperationParams{aMode, ScrollOrigin::Other, aSnapFlags, + ScrollTriggeredByScript::No}); + // 'this' might be destroyed here + if (aOverflow) { + *aOverflow = nsIntPoint(0, 0); + } + return; + } + } + default: + NS_ERROR("Invalid scroll mode"); + return; + } + + if (askApzToDoTheScroll) { + nsPoint delta( + NSCoordSaturatingNonnegativeMultiply(aDelta.x, deltaMultiplier.width), + NSCoordSaturatingNonnegativeMultiply(aDelta.y, deltaMultiplier.height)); + + AppendScrollUpdate( + ScrollPositionUpdate::NewPureRelativeScroll(aOrigin, aMode, delta)); + + nsIContent* content = GetContent(); + if (!DisplayPortUtils::HasNonMinimalNonZeroDisplayPort(content)) { + if (MOZ_LOG_TEST(sDisplayportLog, LogLevel::Debug)) { + mozilla::layers::ScrollableLayerGuid::ViewID viewID = + mozilla::layers::ScrollableLayerGuid::NULL_SCROLL_ID; + nsLayoutUtils::FindIDFor(content, &viewID); + MOZ_LOG( + sDisplayportLog, LogLevel::Debug, + ("ScrollBy setting displayport on scrollId=%" PRIu64 "\n", viewID)); + } + + DisplayPortUtils::CalculateAndSetDisplayPortMargins( + GetScrollTargetFrame(), DisplayPortUtils::RepaintMode::Repaint); + nsIFrame* frame = do_QueryFrame(GetScrollTargetFrame()); + DisplayPortUtils::SetZeroMarginDisplayPortOnAsyncScrollableAncestors( + frame); + } + + SchedulePaint(); + return; + } + + nsPoint newPos(NSCoordSaturatingAdd(mDestination.x, + NSCoordSaturatingNonnegativeMultiply( + aDelta.x, deltaMultiplier.width)), + NSCoordSaturatingAdd(mDestination.y, + NSCoordSaturatingNonnegativeMultiply( + aDelta.y, deltaMultiplier.height))); + + Maybe<SnapTarget> snapTarget; + if (aSnapFlags != ScrollSnapFlags::Disabled) { + if (NeedsScrollSnap()) { + nscoord appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel(); + deltaMultiplier = nsSize(appUnitsPerDevPixel, appUnitsPerDevPixel); + negativeTolerance = 0.1f; + positiveTolerance = 0; + ScrollUnit snapUnit = aUnit; + if (aOrigin == ScrollOrigin::MouseWheel) { + // When using a clicky scroll wheel, snap point selection works the same + // as keyboard up/down/left/right navigation, but with varying amounts + // of scroll delta. + snapUnit = ScrollUnit::LINES; + } + snapTarget = GetSnapPointForDestination(snapUnit, aSnapFlags, + mDestination, newPos); + if (snapTarget) { + newPos = snapTarget->mPosition; + } + } + } + + // Calculate desired range values. + nscoord rangeLowerX, rangeUpperX, rangeLowerY, rangeUpperY; + CalcRangeForScrollBy(aDelta.x, newPos.x, negativeTolerance, positiveTolerance, + deltaMultiplier.width, &rangeLowerX, &rangeUpperX); + CalcRangeForScrollBy(aDelta.y, newPos.y, negativeTolerance, positiveTolerance, + deltaMultiplier.height, &rangeLowerY, &rangeUpperY); + nsRect range(rangeLowerX, rangeLowerY, rangeUpperX - rangeLowerX, + rangeUpperY - rangeLowerY); + AutoWeakFrame weakFrame(this); + ScrollToWithOrigin( + newPos, &range, + snapTarget ? ScrollOperationParams{aMode, aOrigin, + std::move(snapTarget->mTargetIds)} + : ScrollOperationParams{aMode, aOrigin}); + if (!weakFrame.IsAlive()) { + return; + } + + if (aOverflow) { + nsPoint clampAmount = newPos - mDestination; + float appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel(); + *aOverflow = + nsIntPoint(NSAppUnitsToIntPixels(clampAmount.x, appUnitsPerDevPixel), + NSAppUnitsToIntPixels(clampAmount.y, appUnitsPerDevPixel)); + } + + if (aUnit == ScrollUnit::DEVICE_PIXELS && + !nsLayoutUtils::AsyncPanZoomEnabled(this)) { + // When APZ is disabled, we must track the velocity + // on the main thread; otherwise, the APZC will manage this. + mVelocityQueue.Sample(GetScrollPosition()); + } +} + +void nsHTMLScrollFrame::ScrollByCSSPixelsInternal(const CSSIntPoint& aDelta, + ScrollMode aMode, + ScrollSnapFlags aSnapFlags) { + nsPoint current = GetScrollPosition(); + // `current` value above might be a value which was aligned to in + // layer-pixels, so starting from such points will make the difference between + // the given position in script (e.g. scrollTo) and the aligned position + // larger, in the worst case the difference can be observed in CSS pixels. + // To avoid it, we use the current position in CSS pixels as the start + // position. Hopefully it exactly matches the position where it was given by + // the previous scrolling operation, but there may be some edge cases where + // the current position in CSS pixels differs from the given position, the + // cases should be fixed in bug 1556685. + CSSIntPoint currentCSSPixels = GetScrollPositionCSSPixels(); + nsPoint pt = CSSPoint::ToAppUnits(currentCSSPixels + aDelta); + + nscoord halfPixel = nsPresContext::CSSPixelsToAppUnits(0.5f); + nsRect range(pt.x - halfPixel, pt.y - halfPixel, 2 * halfPixel - 1, + 2 * halfPixel - 1); + // XXX I don't think the following blocks are needed anymore, now that + // ScrollToImpl simply tries to scroll an integer number of layer + // pixels from the current position + if (aDelta.x == 0.0f) { + pt.x = current.x; + range.x = pt.x; + range.width = 0; + } + if (aDelta.y == 0.0f) { + pt.y = current.y; + range.y = pt.y; + range.height = 0; + } + ScrollToWithOrigin( + pt, &range, + ScrollOperationParams{aMode, ScrollOrigin::Relative, aSnapFlags, + ScrollTriggeredByScript::Yes}); + // 'this' might be destroyed here +} + +void nsHTMLScrollFrame::ScrollSnap(ScrollMode aMode) { + float flingSensitivity = + StaticPrefs::layout_css_scroll_snap_prediction_sensitivity(); + int maxVelocity = + StaticPrefs::layout_css_scroll_snap_prediction_max_velocity(); + maxVelocity = nsPresContext::CSSPixelsToAppUnits(maxVelocity); + int maxOffset = maxVelocity * flingSensitivity; + nsPoint velocity = mVelocityQueue.GetVelocity(); + // Multiply each component individually to avoid integer multiply + nsPoint predictedOffset = + nsPoint(velocity.x * flingSensitivity, velocity.y * flingSensitivity); + predictedOffset.Clamp(maxOffset); + nsPoint pos = GetScrollPosition(); + nsPoint destinationPos = pos + predictedOffset; + ScrollSnap(destinationPos, aMode); +} + +void nsHTMLScrollFrame::ScrollSnap(const nsPoint& aDestination, + ScrollMode aMode) { + nsRect scrollRange = GetLayoutScrollRange(); + nsPoint pos = GetScrollPosition(); + nsPoint snapDestination = scrollRange.ClampPoint(aDestination); + ScrollSnapFlags snapFlags = ScrollSnapFlags::IntendedEndPosition; + if (mVelocityQueue.GetVelocity() != nsPoint()) { + snapFlags |= ScrollSnapFlags::IntendedDirection; + } + + // Bug 1776624 : Consider using mDestination as |aStartPos| argument for this + // GetSnapPointForDestination call, this function call is the only one call + // site using `GetScrollPosition()` as |aStartPos|. + if (auto snapTarget = GetSnapPointForDestination( + ScrollUnit::DEVICE_PIXELS, snapFlags, pos, snapDestination)) { + snapDestination = snapTarget->mPosition; + ScrollToWithOrigin( + snapDestination, nullptr /* range */, + ScrollOperationParams{aMode, ScrollOrigin::Other, + std::move(snapTarget->mTargetIds)}); + } +} + +nsSize nsHTMLScrollFrame::GetLineScrollAmount() const { + RefPtr<nsFontMetrics> fm = + nsLayoutUtils::GetInflatedFontMetricsForFrame(this); + NS_ASSERTION(fm, "FontMetrics is null, assuming fontHeight == 1 appunit"); + int32_t appUnitsPerDevPixel = PresContext()->AppUnitsPerDevPixel(); + nscoord minScrollAmountInAppUnits = + std::max(1, StaticPrefs::mousewheel_min_line_scroll_amount()) * + appUnitsPerDevPixel; + nscoord horizontalAmount = fm ? fm->AveCharWidth() : 0; + nscoord verticalAmount = fm ? fm->MaxHeight() : 0; + return nsSize(std::max(horizontalAmount, minScrollAmountInAppUnits), + std::max(verticalAmount, minScrollAmountInAppUnits)); +} + +/** + * Compute the scrollport size excluding any fixed-pos and sticky-pos (that are + * stuck) headers and footers. A header or footer is an box that spans that + * entire width of the viewport and touches the top (or bottom, respectively) of + * the viewport. We also want to consider fixed/sticky elements that stack or + * overlap to effectively create a larger header or footer. Headers and footers + * that cover more than a third of the the viewport are ignored since they + * probably aren't true headers and footers and we don't want to restrict + * scrolling too much in such cases. This is a bit conservative --- some + * pages use elements as headers or footers that don't span the entire width + * of the viewport --- but it should be a good start. + * + * If aViewportFrame is non-null then the scroll frame is the root scroll + * frame and we should consider fixed-pos items. + */ +struct TopAndBottom { + TopAndBottom(nscoord aTop, nscoord aBottom) : top(aTop), bottom(aBottom) {} + + nscoord top, bottom; +}; +struct TopComparator { + bool Equals(const TopAndBottom& A, const TopAndBottom& B) const { + return A.top == B.top; + } + bool LessThan(const TopAndBottom& A, const TopAndBottom& B) const { + return A.top < B.top; + } +}; +struct ReverseBottomComparator { + bool Equals(const TopAndBottom& A, const TopAndBottom& B) const { + return A.bottom == B.bottom; + } + bool LessThan(const TopAndBottom& A, const TopAndBottom& B) const { + return A.bottom > B.bottom; + } +}; + +static void AddToListIfHeaderFooter(nsIFrame* aFrame, + nsIFrame* aScrollPortFrame, + const nsRect& aScrollPort, + nsTArray<TopAndBottom>& aList) { + nsRect r = aFrame->GetRectRelativeToSelf(); + r = nsLayoutUtils::TransformFrameRectToAncestor(aFrame, r, aScrollPortFrame); + r = r.Intersect(aScrollPort); + if ((r.width >= aScrollPort.width / 2 || + r.width >= NSIntPixelsToAppUnits(800, AppUnitsPerCSSPixel())) && + r.height <= aScrollPort.height / 3) { + aList.AppendElement(TopAndBottom(r.y, r.YMost())); + } +} + +static nsSize GetScrollPortSizeExcludingHeadersAndFooters( + nsIFrame* aScrollFrame, nsIFrame* aViewportFrame, + const nsRect& aScrollPort) { + AutoTArray<TopAndBottom, 10> list; + if (aViewportFrame) { + for (nsIFrame* f : aViewportFrame->GetChildList(FrameChildListID::Fixed)) { + AddToListIfHeaderFooter(f, aViewportFrame, aScrollPort, list); + } + } + + // Add sticky frames that are currently in "fixed" positions + StickyScrollContainer* ssc = + StickyScrollContainer::GetStickyScrollContainerForScrollFrame( + aScrollFrame); + if (ssc) { + const nsTArray<nsIFrame*>& stickyFrames = ssc->GetFrames(); + for (nsIFrame* f : stickyFrames) { + // If it's acting like fixed position. + if (ssc->IsStuckInYDirection(f)) { + AddToListIfHeaderFooter(f, aScrollFrame, aScrollPort, list); + } + } + } + + list.Sort(TopComparator()); + nscoord headerBottom = 0; + for (uint32_t i = 0; i < list.Length(); ++i) { + if (list[i].top <= headerBottom) { + headerBottom = std::max(headerBottom, list[i].bottom); + } + } + + list.Sort(ReverseBottomComparator()); + nscoord footerTop = aScrollPort.height; + for (uint32_t i = 0; i < list.Length(); ++i) { + if (list[i].bottom >= footerTop) { + footerTop = std::min(footerTop, list[i].top); + } + } + + headerBottom = std::min(aScrollPort.height / 3, headerBottom); + footerTop = std::max(aScrollPort.height - aScrollPort.height / 3, footerTop); + + return nsSize(aScrollPort.width, footerTop - headerBottom); +} + +nsSize nsHTMLScrollFrame::GetPageScrollAmount() const { + nsSize effectiveScrollPortSize; + + if (GetVisualViewportSize() != mScrollPort.Size()) { + // We want to use the visual viewport size if one is set. + // The headers/footers adjustment is too complicated to do if there is a + // visual viewport that differs from the layout viewport, this is probably + // okay. + effectiveScrollPortSize = GetVisualViewportSize(); + } else { + // Reduce effective scrollport height by the height of any + // fixed-pos/sticky-pos headers or footers + effectiveScrollPortSize = GetScrollPortSizeExcludingHeadersAndFooters( + const_cast<nsHTMLScrollFrame*>(this), + mIsRoot ? PresShell()->GetRootFrame() : nullptr, mScrollPort); + } + + nsSize lineScrollAmount = GetLineScrollAmount(); + + // The page increment is the size of the page, minus the smaller of + // 10% of the size or 2 lines. + return nsSize(effectiveScrollPortSize.width - + std::min(effectiveScrollPortSize.width / 10, + 2 * lineScrollAmount.width), + effectiveScrollPortSize.height - + std::min(effectiveScrollPortSize.height / 10, + 2 * lineScrollAmount.height)); +} + +/** + * this code is resposible for restoring the scroll position back to some + * saved position. if the user has not moved the scroll position manually + * we keep scrolling down until we get to our original position. keep in + * mind that content could incrementally be coming in. we only want to stop + * when we reach our new position. + */ +void nsHTMLScrollFrame::ScrollToRestoredPosition() { + if (mRestorePos.y == -1 || mLastPos.x == -1 || mLastPos.y == -1) { + return; + } + // make sure our scroll position did not change for where we last put + // it. if it does then the user must have moved it, and we no longer + // need to restore. + // + // In the RTL case, we check whether the scroll position changed using the + // logical scroll position, but we scroll to the physical scroll position in + // all cases + + // The layout offset we want to restore is the same as the visual offset + // (for now, may change in bug 1499210), but clamped to the layout scroll + // range (which can be a subset of the visual scroll range). + // Note that we can't do the clamping when initializing mRestorePos in + // RestoreState(), since the scrollable rect (which the clamping depends + // on) can change over the course of the restoration process. + nsPoint layoutRestorePos = GetLayoutScrollRange().ClampPoint(mRestorePos); + nsPoint visualRestorePos = GetVisualScrollRange().ClampPoint(mRestorePos); + + // Continue restoring until both the layout and visual scroll positions + // reach the destination. (Note that the two can only be different for + // the root content document's root scroll frame, and when zoomed in). + // This is necessary to avoid situations where the two offsets get stuck + // at different values and nothing reconciles them (see bug 1519621 comment + // 8). + nsPoint logicalLayoutScrollPos = GetLogicalScrollPosition(); + + SCROLLRESTORE_LOG( + "%p: ScrollToRestoredPosition (mRestorePos=%s, mLastPos=%s, " + "layoutRestorePos=%s, visualRestorePos=%s, " + "logicalLayoutScrollPos=%s, " + "GetLogicalVisualViewportOffset()=%s)\n", + this, ToString(mRestorePos).c_str(), ToString(mLastPos).c_str(), + ToString(layoutRestorePos).c_str(), ToString(visualRestorePos).c_str(), + ToString(logicalLayoutScrollPos).c_str(), + ToString(GetLogicalVisualViewportOffset()).c_str()); + + // if we didn't move, we still need to restore + if (GetLogicalVisualViewportOffset() == mLastPos || + logicalLayoutScrollPos == mLastPos) { + // if our desired position is different to the scroll position, scroll. + // remember that we could be incrementally loading so we may enter + // and scroll many times. + if (mRestorePos != mLastPos /* GetLogicalVisualViewportOffset() */ || + layoutRestorePos != logicalLayoutScrollPos) { + LoadingState state = GetPageLoadingState(); + if (state == LoadingState::Stopped && !IsSubtreeDirty()) { + return; + } + nsPoint visualScrollToPos = visualRestorePos; + nsPoint layoutScrollToPos = layoutRestorePos; + if (!IsPhysicalLTR()) { + // convert from logical to physical scroll position + visualScrollToPos.x -= + (GetVisualViewportSize().width - mScrolledFrame->GetRect().width); + layoutScrollToPos.x -= + (GetVisualViewportSize().width - mScrolledFrame->GetRect().width); + } + AutoWeakFrame weakFrame(this); + // It's very important to pass ScrollOrigin::Restore here, so + // ScrollToWithOrigin won't clear out mRestorePos. + ScrollToWithOrigin( + layoutScrollToPos, nullptr, + ScrollOperationParams{ScrollMode::Instant, ScrollOrigin::Restore}); + if (!weakFrame.IsAlive()) { + return; + } + if (mIsRoot) { + PresShell()->ScrollToVisual(visualScrollToPos, FrameMetrics::eRestore, + ScrollMode::Instant); + } + if (state == LoadingState::Loading || IsSubtreeDirty()) { + // If we're trying to do a history scroll restore, then we want to + // keep trying this until we succeed, because the page can be loading + // incrementally. So re-get the scroll position for the next iteration, + // it might not be exactly equal to mRestorePos due to rounding and + // clamping. + mLastPos = GetLogicalVisualViewportOffset(); + return; + } + } + // If we get here, either we reached the desired position (mLastPos == + // mRestorePos) or we're not trying to do a history scroll restore, so + // we can stop after the scroll attempt above. + mRestorePos.y = -1; + mLastPos.x = -1; + mLastPos.y = -1; + } else { + // user moved the position, so we won't need to restore + mLastPos.x = -1; + mLastPos.y = -1; + } +} + +auto nsHTMLScrollFrame::GetPageLoadingState() -> LoadingState { + bool loadCompleted = false, stopped = false; + nsCOMPtr<nsIDocShell> ds = GetContent()->GetComposedDoc()->GetDocShell(); + if (ds) { + nsCOMPtr<nsIContentViewer> cv; + ds->GetContentViewer(getter_AddRefs(cv)); + if (cv) { + loadCompleted = cv->GetLoadCompleted(); + stopped = cv->GetIsStopped(); + } + } + return loadCompleted + ? (stopped ? LoadingState::Stopped : LoadingState::Loaded) + : LoadingState::Loading; +} + +nsHTMLScrollFrame::OverflowState nsHTMLScrollFrame::GetOverflowState() const { + nsSize scrollportSize = mScrollPort.Size(); + nsSize childSize = GetScrolledRect().Size(); + + OverflowState result = OverflowState::None; + + if (childSize.height > scrollportSize.height) { + result |= OverflowState::Vertical; + } + + if (childSize.width > scrollportSize.width) { + result |= OverflowState::Horizontal; + } + + return result; +} + +nsresult nsHTMLScrollFrame::FireScrollPortEvent() { + mAsyncScrollPortEvent.Forget(); + + // TODO(emilio): why do we need the whole WillPaintObserver infrastructure and + // can't use AddScriptRunner & co? I guess it made sense when we used + // WillPaintObserver for scroll events too, or when this used to flush. + // + // Should we remove this? + + OverflowState overflowState = GetOverflowState(); + + bool newVerticalOverflow = !!(overflowState & OverflowState::Vertical); + bool vertChanged = mVerticalOverflow != newVerticalOverflow; + + bool newHorizontalOverflow = !!(overflowState & OverflowState::Horizontal); + bool horizChanged = mHorizontalOverflow != newHorizontalOverflow; + + if (!vertChanged && !horizChanged) { + return NS_OK; + } + + // If both either overflowed or underflowed then we dispatch only one + // DOM event. + bool both = vertChanged && horizChanged && + newVerticalOverflow == newHorizontalOverflow; + InternalScrollPortEvent::OrientType orient; + if (both) { + orient = InternalScrollPortEvent::eBoth; + mHorizontalOverflow = newHorizontalOverflow; + mVerticalOverflow = newVerticalOverflow; + } else if (vertChanged) { + orient = InternalScrollPortEvent::eVertical; + mVerticalOverflow = newVerticalOverflow; + if (horizChanged) { + // We need to dispatch a separate horizontal DOM event. Do that the next + // time around since dispatching the vertical DOM event might destroy + // the frame. + PostOverflowEvent(); + } + } else { + orient = InternalScrollPortEvent::eHorizontal; + mHorizontalOverflow = newHorizontalOverflow; + } + + InternalScrollPortEvent event( + true, + (orient == InternalScrollPortEvent::eHorizontal ? mHorizontalOverflow + : mVerticalOverflow) + ? eScrollPortOverflow + : eScrollPortUnderflow, + nullptr); + event.mOrient = orient; + + RefPtr<nsIContent> content = GetContent(); + RefPtr<nsPresContext> presContext = PresContext(); + return EventDispatcher::Dispatch(content, presContext, &event); +} + +void nsHTMLScrollFrame::PostScrollEndEvent() { + if (mScrollEndEvent) { + return; + } + + // The ScrollEndEvent constructor registers itself with the refresh driver. + mScrollEndEvent = new ScrollEndEvent(this); +} + +void nsHTMLScrollFrame::FireScrollEndEvent() { + MOZ_ASSERT(GetContent()); + MOZ_ASSERT(mScrollEndEvent); + + RefPtr<nsPresContext> presContext = PresContext(); + mScrollEndEvent->Revoke(); + mScrollEndEvent = nullptr; + + nsEventStatus status = nsEventStatus_eIgnore; + WidgetGUIEvent event(true, eScrollend, nullptr); + event.mFlags.mBubbles = mIsRoot; + event.mFlags.mCancelable = false; + // If apz.scrollend-event.content.enabled is not set, the event should + // only be dispatched to the browser chrome. + event.mFlags.mOnlyChromeDispatch = + !StaticPrefs::apz_scrollend_event_content_enabled(); + RefPtr<nsINode> target = + mIsRoot ? static_cast<nsINode*>(presContext->Document()) : GetContent(); + EventDispatcher::Dispatch(target, presContext, &event, nullptr, &status); +} + +void nsHTMLScrollFrame::ReloadChildFrames() { + mScrolledFrame = nullptr; + mHScrollbarBox = nullptr; + mVScrollbarBox = nullptr; + mScrollCornerBox = nullptr; + mResizerBox = nullptr; + + for (nsIFrame* frame : PrincipalChildList()) { + nsIContent* content = frame->GetContent(); + if (content == GetContent()) { + NS_ASSERTION(!mScrolledFrame, "Already found the scrolled frame"); + mScrolledFrame = frame; + } else { + nsAutoString value; + if (content->IsElement()) { + content->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::orient, + value); + } + if (!value.IsEmpty()) { + // probably a scrollbar then + if (value.LowerCaseEqualsLiteral("horizontal")) { + NS_ASSERTION(!mHScrollbarBox, + "Found multiple horizontal scrollbars?"); + mHScrollbarBox = do_QueryFrame(frame); + MOZ_ASSERT(mHScrollbarBox, "Not a scrollbar?"); + } else { + NS_ASSERTION(!mVScrollbarBox, "Found multiple vertical scrollbars?"); + mVScrollbarBox = do_QueryFrame(frame); + MOZ_ASSERT(mVScrollbarBox, "Not a scrollbar?"); + } + } else if (content->IsXULElement(nsGkAtoms::resizer)) { + NS_ASSERTION(!mResizerBox, "Found multiple resizers"); + mResizerBox = frame; + } else if (content->IsXULElement(nsGkAtoms::scrollcorner)) { + // probably a scrollcorner + NS_ASSERTION(!mScrollCornerBox, "Found multiple scrollcorners"); + mScrollCornerBox = frame; + } + } + } +} + +already_AddRefed<Element> nsHTMLScrollFrame::MakeScrollbar( + NodeInfo* aNodeInfo, bool aVertical, AnonymousContentKey& aKey) { + MOZ_ASSERT(aNodeInfo); + MOZ_ASSERT( + aNodeInfo->Equals(nsGkAtoms::scrollbar, nullptr, kNameSpaceID_XUL)); + + static constexpr nsLiteralString kOrientValues[2] = { + u"horizontal"_ns, + u"vertical"_ns, + }; + + aKey = AnonymousContentKey::Type_Scrollbar; + if (aVertical) { + aKey |= AnonymousContentKey::Flag_Vertical; + } + + RefPtr<Element> e; + NS_TrustedNewXULElement(getter_AddRefs(e), do_AddRef(aNodeInfo)); + +#ifdef DEBUG + // Scrollbars can get restyled by theme changes. Whether such a restyle + // will actually reconstruct them correctly if it involves a frame + // reconstruct... I don't know. :( + e->SetProperty(nsGkAtoms::restylableAnonymousNode, + reinterpret_cast<void*>(true)); +#endif // DEBUG + + e->SetAttr(kNameSpaceID_None, nsGkAtoms::orient, kOrientValues[aVertical], + false); + + if (mIsRoot) { + e->SetProperty(nsGkAtoms::docLevelNativeAnonymousContent, + reinterpret_cast<void*>(true)); + e->SetAttr(kNameSpaceID_None, nsGkAtoms::root_, u"true"_ns, false); + + // Don't bother making style caching take [root="true"] styles into account. + aKey = AnonymousContentKey::None; + } + + return e.forget(); +} + +bool nsHTMLScrollFrame::IsForTextControlWithNoScrollbars() const { + // FIXME(emilio): we should probably make the scroller inside <input> an + // internal pseudo-element, and then this would be simpler. + // + // Also, this could just use scrollbar-width these days. + auto* content = GetContent(); + if (!content) { + return false; + } + auto* input = content->GetClosestNativeAnonymousSubtreeRootParentOrHost(); + return input && input->IsHTMLElement(nsGkAtoms::input); +} + +auto nsHTMLScrollFrame::GetCurrentAnonymousContent() const + -> EnumSet<AnonymousContentType> { + EnumSet<AnonymousContentType> result; + if (mHScrollbarContent) { + result += AnonymousContentType::HorizontalScrollbar; + } + if (mVScrollbarContent) { + result += AnonymousContentType::VerticalScrollbar; + } + if (mResizerContent) { + result += AnonymousContentType::Resizer; + } + return result; +} + +auto nsHTMLScrollFrame::GetNeededAnonymousContent() const + -> EnumSet<AnonymousContentType> { + nsPresContext* pc = PresContext(); + + // Don't create scrollbars if we're an SVG document being used as an image, + // or if we're printing/print previewing. + // (In the printing case, we allow scrollbars if this is the child of the + // viewport & paginated scrolling is enabled, because then we must be the + // scroll frame for the print preview window, & that does need scrollbars.) + if (pc->Document()->IsBeingUsedAsImage() || + (!pc->IsDynamic() && !(mIsRoot && pc->HasPaginatedScrolling()))) { + return {}; + } + + if (IsForTextControlWithNoScrollbars()) { + return {}; + } + + EnumSet<AnonymousContentType> result; + // If we're the scrollframe for the root, then we want to construct our + // scrollbar frames no matter what. That way later dynamic changes to + // propagated overflow styles will show or hide scrollbars on the viewport + // without requiring frame reconstruction of the viewport (good!). + // + // TODO(emilio): Figure out if we can remove this special-case now that we + // have more targeted optimizations. + if (mIsRoot) { + result += AnonymousContentType::HorizontalScrollbar; + result += AnonymousContentType::VerticalScrollbar; + // If scrollbar-width is none, don't generate scrollbars. + } else if (StyleUIReset()->ScrollbarWidth() != StyleScrollbarWidth::None) { + ScrollStyles styles = GetScrollStyles(); + if (styles.mHorizontal != StyleOverflow::Hidden) { + result += AnonymousContentType::HorizontalScrollbar; + } + if (styles.mVertical != StyleOverflow::Hidden) { + result += AnonymousContentType::VerticalScrollbar; + } + + // If we have scrollbar-gutter, construct the scrollbar frames to query its + // size to reserve the gutter space at the inline start or end edges. + if (StyleDisplay()->mScrollbarGutter & StyleScrollbarGutter::STABLE) { + result += GetWritingMode().IsVertical() + ? AnonymousContentType::HorizontalScrollbar + : AnonymousContentType::VerticalScrollbar; + } + } + + // Check if the frame is resizable. Note: + // "The effect of the resize property on generated content is undefined. + // Implementations should not apply the resize property to generated + // content." [1] + // For info on what is generated content, see [2]. + // [1]: https://drafts.csswg.org/css-ui/#resize + // [2]: https://www.w3.org/TR/CSS2/generate.html#content + auto resizeStyle = StyleDisplay()->mResize; + if (resizeStyle != StyleResize::None && + !HasAnyStateBits(NS_FRAME_GENERATED_CONTENT)) { + result += AnonymousContentType::Resizer; + } + + return result; +} + +nsresult nsHTMLScrollFrame::CreateAnonymousContent( + nsTArray<nsIAnonymousContentCreator::ContentInfo>& aElements) { + typedef nsIAnonymousContentCreator::ContentInfo ContentInfo; + + nsPresContext* presContext = PresContext(); + nsNodeInfoManager* nodeInfoManager = + presContext->Document()->NodeInfoManager(); + + auto neededAnonContent = GetNeededAnonymousContent(); + if (neededAnonContent.isEmpty()) { + return NS_OK; + } + + { + RefPtr<NodeInfo> nodeInfo = nodeInfoManager->GetNodeInfo( + nsGkAtoms::scrollbar, nullptr, kNameSpaceID_XUL, nsINode::ELEMENT_NODE); + NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY); + + if (neededAnonContent.contains(AnonymousContentType::HorizontalScrollbar)) { + AnonymousContentKey key; + mHScrollbarContent = MakeScrollbar(nodeInfo, /* aVertical */ false, key); + aElements.AppendElement(ContentInfo(mHScrollbarContent, key)); + } + + if (neededAnonContent.contains(AnonymousContentType::VerticalScrollbar)) { + AnonymousContentKey key; + mVScrollbarContent = MakeScrollbar(nodeInfo, /* aVertical */ true, key); + aElements.AppendElement(ContentInfo(mVScrollbarContent, key)); + } + } + + if (neededAnonContent.contains(AnonymousContentType::Resizer)) { + MOZ_ASSERT(!mIsRoot, "Root scroll frame shouldn't be resizable"); + + RefPtr<NodeInfo> nodeInfo; + nodeInfo = nodeInfoManager->GetNodeInfo( + nsGkAtoms::resizer, nullptr, kNameSpaceID_XUL, nsINode::ELEMENT_NODE); + NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY); + + NS_TrustedNewXULElement(getter_AddRefs(mResizerContent), nodeInfo.forget()); + + nsAutoString dir; + switch (StyleDisplay()->mResize) { + case StyleResize::Horizontal: + if (IsScrollbarOnRight()) { + dir.AssignLiteral("right"); + } else { + dir.AssignLiteral("left"); + } + break; + case StyleResize::Vertical: + dir.AssignLiteral("bottom"); + if (!IsScrollbarOnRight()) { + mResizerContent->SetAttr(kNameSpaceID_None, nsGkAtoms::flip, u""_ns, + false); + } + break; + case StyleResize::Both: + if (IsScrollbarOnRight()) { + dir.AssignLiteral("bottomright"); + } else { + dir.AssignLiteral("bottomleft"); + } + break; + default: + NS_WARNING("only resizable types should have resizers"); + } + mResizerContent->SetAttr(kNameSpaceID_None, nsGkAtoms::dir, dir, false); + aElements.AppendElement(mResizerContent); + } + + if (neededAnonContent.contains(AnonymousContentType::HorizontalScrollbar) && + neededAnonContent.contains(AnonymousContentType::VerticalScrollbar)) { + AnonymousContentKey key = AnonymousContentKey::Type_ScrollCorner; + + RefPtr<NodeInfo> nodeInfo = + nodeInfoManager->GetNodeInfo(nsGkAtoms::scrollcorner, nullptr, + kNameSpaceID_XUL, nsINode::ELEMENT_NODE); + NS_TrustedNewXULElement(getter_AddRefs(mScrollCornerContent), + nodeInfo.forget()); + if (mIsRoot) { + mScrollCornerContent->SetProperty( + nsGkAtoms::docLevelNativeAnonymousContent, + reinterpret_cast<void*>(true)); + mScrollCornerContent->SetAttr(kNameSpaceID_None, nsGkAtoms::root_, + u"true"_ns, false); + + // Don't bother making style caching take [root="true"] styles into + // account. + key = AnonymousContentKey::None; + } + aElements.AppendElement(ContentInfo(mScrollCornerContent, key)); + } + + // Don't cache styles if we are a child of a <select> element, since we have + // some UA style sheet rules that depend on the <select>'s attributes. + if (GetContent()->IsHTMLElement(nsGkAtoms::select)) { + for (auto& info : aElements) { + info.mKey = AnonymousContentKey::None; + } + } + + return NS_OK; +} + +void nsHTMLScrollFrame::AppendAnonymousContentTo( + nsTArray<nsIContent*>& aElements, uint32_t aFilter) { + if (mHScrollbarContent) { + aElements.AppendElement(mHScrollbarContent); + } + + if (mVScrollbarContent) { + aElements.AppendElement(mVScrollbarContent); + } + + if (mScrollCornerContent) { + aElements.AppendElement(mScrollCornerContent); + } + + if (mResizerContent) { + aElements.AppendElement(mResizerContent); + } +} + +void nsHTMLScrollFrame::DidSetComputedStyle(ComputedStyle* aOldComputedStyle) { + nsContainerFrame::DidSetComputedStyle(aOldComputedStyle); + if (aOldComputedStyle && !mIsRoot && + StyleDisplay()->mScrollSnapType != + aOldComputedStyle->StyleDisplay()->mScrollSnapType) { + PostPendingResnap(); + } +} + +void nsHTMLScrollFrame::RemoveObservers() { + if (mAsyncScroll) { + mAsyncScroll->RemoveObserver(); + mAsyncScroll = nullptr; + } + if (mAsyncSmoothMSDScroll) { + mAsyncSmoothMSDScroll->RemoveObserver(); + mAsyncSmoothMSDScroll = nullptr; + } +} + +/** + * Called when we want to update the scrollbar position, either because + * scrolling happened or the user moved the scrollbar position and we need to + * undo that (e.g., when the user clicks to scroll and we're using smooth + * scrolling, so we need to put the thumb back to its initial position for the + * start of the smooth sequence). + */ +void nsHTMLScrollFrame::UpdateScrollbarPosition() { + AutoWeakFrame weakFrame(this); + mFrameIsUpdatingScrollbar = true; + + nsPoint pt = GetScrollPosition(); + nsRect scrollRange = GetVisualScrollRange(); + + if (gfxPlatform::UseDesktopZoomingScrollbars()) { + pt = GetVisualViewportOffset(); + scrollRange = GetScrollRangeForUserInputEvents(); + } + + if (mVScrollbarBox) { + SetCoordAttribute(mVScrollbarBox->GetContent()->AsElement(), + nsGkAtoms::curpos, pt.y - scrollRange.y); + if (!weakFrame.IsAlive()) { + return; + } + } + if (mHScrollbarBox) { + SetCoordAttribute(mHScrollbarBox->GetContent()->AsElement(), + nsGkAtoms::curpos, pt.x - scrollRange.x); + if (!weakFrame.IsAlive()) { + return; + } + } + + mFrameIsUpdatingScrollbar = false; +} + +void nsHTMLScrollFrame::CurPosAttributeChangedInternal(nsIContent* aContent, + bool aDoScroll) { + NS_ASSERTION(aContent, "aContent must not be null"); + NS_ASSERTION((mHScrollbarBox && mHScrollbarBox->GetContent() == aContent) || + (mVScrollbarBox && mVScrollbarBox->GetContent() == aContent), + "unexpected child"); + MOZ_ASSERT(aContent->IsElement()); + + // Attribute changes on the scrollbars happen in one of three ways: + // 1) The scrollbar changed the attribute in response to some user event + // 2) We changed the attribute in response to a ScrollPositionDidChange + // callback from the scrolling view + // 3) We changed the attribute to adjust the scrollbars for the start + // of a smooth scroll operation + // + // In cases 2 and 3 we do not need to scroll because we're just + // updating our scrollbar. + if (mFrameIsUpdatingScrollbar) { + return; + } + + nsRect scrollRange = GetVisualScrollRange(); + + nsPoint current = GetScrollPosition() - scrollRange.TopLeft(); + + if (gfxPlatform::UseDesktopZoomingScrollbars()) { + scrollRange = GetScrollRangeForUserInputEvents(); + current = GetVisualViewportOffset() - scrollRange.TopLeft(); + } + + nsPoint dest; + nsRect allowedRange; + dest.x = GetCoordAttribute(mHScrollbarBox, nsGkAtoms::curpos, current.x, + &allowedRange.x, &allowedRange.width); + dest.y = GetCoordAttribute(mVScrollbarBox, nsGkAtoms::curpos, current.y, + &allowedRange.y, &allowedRange.height); + current += scrollRange.TopLeft(); + dest += scrollRange.TopLeft(); + allowedRange += scrollRange.TopLeft(); + + // Don't try to scroll if we're already at an acceptable place. + // Don't call Contains here since Contains returns false when the point is + // on the bottom or right edge of the rectangle. + if (allowedRange.ClampPoint(current) == current) { + return; + } + + if (mScrollbarActivity && + (mHasHorizontalScrollbar || mHasVerticalScrollbar)) { + RefPtr<ScrollbarActivity> scrollbarActivity(mScrollbarActivity); + scrollbarActivity->ActivityOccurred(); + } + + const bool isSmooth = aContent->AsElement()->HasAttr(nsGkAtoms::smooth); + if (isSmooth) { + // Make sure an attribute-setting callback occurs even if the view + // didn't actually move yet. We need to make sure other listeners + // see that the scroll position is not (yet) what they thought it + // was. + AutoWeakFrame weakFrame(this); + UpdateScrollbarPosition(); + if (!weakFrame.IsAlive()) { + return; + } + } + + if (aDoScroll) { + ScrollToWithOrigin(dest, &allowedRange, + ScrollOperationParams{ + isSmooth ? ScrollMode::Smooth : ScrollMode::Instant, + ScrollOrigin::Scrollbars}); + } + // 'this' might be destroyed here +} + +/* ============= Scroll events ========== */ + +nsHTMLScrollFrame::ScrollEvent::ScrollEvent(nsHTMLScrollFrame* aHelper, + bool aDelayed) + : Runnable("nsHTMLScrollFrame::ScrollEvent"), mHelper(aHelper) { + mHelper->PresContext()->RefreshDriver()->PostScrollEvent(this, aDelayed); +} + +// TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398) +MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP +nsHTMLScrollFrame::ScrollEvent::Run() { + if (mHelper) { + mHelper->FireScrollEvent(); + } + return NS_OK; +} + +nsHTMLScrollFrame::ScrollEndEvent::ScrollEndEvent(nsHTMLScrollFrame* aHelper) + : Runnable("nsHTMLScrollFrame::ScrollEndEvent"), mHelper(aHelper) { + mHelper->PresContext()->RefreshDriver()->PostScrollEvent(this); +} + +MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP +nsHTMLScrollFrame::ScrollEndEvent::Run() { + if (mHelper) { + mHelper->FireScrollEndEvent(); + } + return NS_OK; +} + +void nsHTMLScrollFrame::FireScrollEvent() { + RefPtr<nsIContent> content = GetContent(); + RefPtr<nsPresContext> presContext = PresContext(); + AUTO_PROFILER_TRACING_MARKER_DOCSHELL("Paint", "FireScrollEvent", GRAPHICS, + presContext->GetDocShell()); + + MOZ_ASSERT(mScrollEvent); + mScrollEvent->Revoke(); + mScrollEvent = nullptr; + + // If event handling is suppressed, keep posting the scroll event to the + // refresh driver until it is unsuppressed. The event is marked as delayed so + // that the refresh driver does not continue ticking. + if (content->GetComposedDoc() && + content->GetComposedDoc()->EventHandlingSuppressed()) { + content->GetComposedDoc()->SetHasDelayedRefreshEvent(); + PostScrollEvent(/* aDelayed = */ true); + return; + } + + bool oldProcessing = mProcessingScrollEvent; + AutoWeakFrame weakFrame(this); + auto RestoreProcessingScrollEvent = mozilla::MakeScopeExit([&] { + if (weakFrame.IsAlive()) { // Otherwise `this` will be dead too. + mProcessingScrollEvent = oldProcessing; + } + }); + + mProcessingScrollEvent = true; + + WidgetGUIEvent event(true, eScroll, nullptr); + nsEventStatus status = nsEventStatus_eIgnore; + // Fire viewport scroll events at the document (where they + // will bubble to the window) + mozilla::layers::ScrollLinkedEffectDetector detector( + content->GetComposedDoc(), + presContext->RefreshDriver()->MostRecentRefresh()); + if (mIsRoot) { + if (RefPtr<Document> doc = content->GetUncomposedDoc()) { + // TODO: Bug 1506441 + EventDispatcher::Dispatch(MOZ_KnownLive(ToSupports(doc)), presContext, + &event, nullptr, &status); + } + } else { + // scroll events fired at elements don't bubble (although scroll events + // fired at documents do, to the window) + event.mFlags.mBubbles = false; + EventDispatcher::Dispatch(content, presContext, &event, nullptr, &status); + } +} + +void nsHTMLScrollFrame::PostScrollEvent(bool aDelayed) { + if (mScrollEvent) { + return; + } + + // The ScrollEvent constructor registers itself with the refresh driver. + mScrollEvent = new ScrollEvent(this, aDelayed); +} + +// TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398) +MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP +nsHTMLScrollFrame::AsyncScrollPortEvent::Run() { + return mHelper ? mHelper->FireScrollPortEvent() : NS_OK; +} + +void nsHTMLScrollFrame::PostOverflowEvent() { + if (mAsyncScrollPortEvent.IsPending()) { + return; + } + + OverflowState overflowState = GetOverflowState(); + + bool newVerticalOverflow = !!(overflowState & OverflowState::Vertical); + bool vertChanged = mVerticalOverflow != newVerticalOverflow; + + bool newHorizontalOverflow = !!(overflowState & OverflowState::Horizontal); + bool horizChanged = mHorizontalOverflow != newHorizontalOverflow; + + if (!vertChanged && !horizChanged) { + return; + } + + nsRootPresContext* rpc = PresContext()->GetRootPresContext(); + if (!rpc) { + return; + } + + mAsyncScrollPortEvent = new AsyncScrollPortEvent(this); + rpc->AddWillPaintObserver(mAsyncScrollPortEvent.get()); +} + +nsIFrame* nsHTMLScrollFrame::GetFrameForStyle() const { + nsIFrame* styleFrame = nullptr; + if (mIsRoot) { + if (const Element* rootElement = + PresContext()->Document()->GetRootElement()) { + styleFrame = rootElement->GetPrimaryFrame(); + } + } else { + styleFrame = const_cast<nsHTMLScrollFrame*>(this); + } + + return styleFrame; +} + +bool nsHTMLScrollFrame::NeedsScrollSnap() const { + nsIFrame* scrollSnapFrame = GetFrameForStyle(); + if (!scrollSnapFrame) { + return false; + } + return scrollSnapFrame->StyleDisplay()->mScrollSnapType.strictness != + StyleScrollSnapStrictness::None; +} + +nsSize nsHTMLScrollFrame::GetSnapportSize() const { + nsRect snapport = GetScrollPortRect(); + nsMargin scrollPadding = GetScrollPadding(); + snapport.Deflate(scrollPadding); + return snapport.Size(); +} + +bool nsHTMLScrollFrame::IsScrollbarOnRight() const { + nsPresContext* presContext = PresContext(); + + // The position of the scrollbar in top-level windows depends on the pref + // layout.scrollbar.side. For non-top-level elements, it depends only on the + // directionaliy of the element (equivalent to a value of "1" for the pref). + if (!mIsRoot) { + return IsPhysicalLTR(); + } + switch (presContext->GetCachedIntPref(kPresContext_ScrollbarSide)) { + default: + case 0: // UI directionality + return presContext->GetCachedIntPref(kPresContext_BidiDirection) == + IBMBIDI_TEXTDIRECTION_LTR; + case 1: // Document / content directionality + return IsPhysicalLTR(); + case 2: // Always right + return true; + case 3: // Always left + return false; + } +} + +bool nsHTMLScrollFrame::IsScrollingActive() const { + const nsStyleDisplay* disp = StyleDisplay(); + if (disp->mWillChange.bits & StyleWillChangeBits::SCROLL) { + return true; + } + + nsIContent* content = GetContent(); + return mHasBeenScrolledRecently || IsAlwaysActive() || + DisplayPortUtils::HasDisplayPort(content) || + nsContentUtils::HasScrollgrab(content); +} + +void nsHTMLScrollFrame::FinishReflowForScrollbar(Element* aElement, + nscoord aMinXY, nscoord aMaxXY, + nscoord aCurPosXY, + nscoord aPageIncrement, + nscoord aIncrement) { + // Scrollbars assume zero is the minimum position, so translate for them. + SetCoordAttribute(aElement, nsGkAtoms::curpos, aCurPosXY - aMinXY); + SetScrollbarEnabled(aElement, aMaxXY - aMinXY); + SetCoordAttribute(aElement, nsGkAtoms::maxpos, aMaxXY - aMinXY); + SetCoordAttribute(aElement, nsGkAtoms::pageincrement, aPageIncrement); + SetCoordAttribute(aElement, nsGkAtoms::increment, aIncrement); +} + +class MOZ_RAII AutoMinimumScaleSizeChangeDetector final { + public: + explicit AutoMinimumScaleSizeChangeDetector( + nsHTMLScrollFrame* ansHTMLScrollFrame) + : mHelper(ansHTMLScrollFrame) { + MOZ_ASSERT(mHelper); + MOZ_ASSERT(mHelper->mIsRoot); + + mPreviousMinimumScaleSize = ansHTMLScrollFrame->mMinimumScaleSize; + mPreviousIsUsingMinimumScaleSize = + ansHTMLScrollFrame->mIsUsingMinimumScaleSize; + } + ~AutoMinimumScaleSizeChangeDetector() { + if (mPreviousMinimumScaleSize != mHelper->mMinimumScaleSize || + mPreviousIsUsingMinimumScaleSize != mHelper->mIsUsingMinimumScaleSize) { + mHelper->mMinimumScaleSizeChanged = true; + } + } + + private: + nsHTMLScrollFrame* mHelper; + + nsSize mPreviousMinimumScaleSize; + bool mPreviousIsUsingMinimumScaleSize; +}; + +nsSize nsHTMLScrollFrame::TrueOuterSize(nsDisplayListBuilder* aBuilder) const { + if (!PresShell()->UsesMobileViewportSizing()) { + return GetSize(); + } + + RefPtr<MobileViewportManager> manager = + PresShell()->GetMobileViewportManager(); + MOZ_ASSERT(manager); + + LayoutDeviceIntSize displaySize = manager->DisplaySize(); + + MOZ_ASSERT(aBuilder); + // In case of WebRender, we expand the outer size to include the dynamic + // toolbar area here. + // In case of non WebRender, we expand the size dynamically in + // MoveScrollbarForLayerMargin in AsyncCompositionManager.cpp. + WebRenderLayerManager* layerManager = aBuilder->GetWidgetLayerManager(); + if (layerManager) { + displaySize.height += ViewAs<LayoutDevicePixel>( + PresContext()->GetDynamicToolbarMaxHeight(), + PixelCastJustification::LayoutDeviceIsScreenForBounds); + } + + return LayoutDeviceSize::ToAppUnits(displaySize, + PresContext()->AppUnitsPerDevPixel()); +} + +void nsHTMLScrollFrame::UpdateMinimumScaleSize( + const nsRect& aScrollableOverflow, const nsSize& aICBSize) { + MOZ_ASSERT(mIsRoot); + + AutoMinimumScaleSizeChangeDetector minimumScaleSizeChangeDetector(this); + + mIsUsingMinimumScaleSize = false; + + if (!PresShell()->UsesMobileViewportSizing()) { + return; + } + + nsPresContext* pc = PresContext(); + MOZ_ASSERT(pc->IsRootContentDocumentCrossProcess(), + "The pres context should be for the root content document"); + + RefPtr<MobileViewportManager> manager = + PresShell()->GetMobileViewportManager(); + MOZ_ASSERT(manager); + + ScreenIntSize displaySize = ViewAs<ScreenPixel>( + manager->DisplaySize(), + PixelCastJustification::LayoutDeviceIsScreenForBounds); + if (displaySize.width == 0 || displaySize.height == 0) { + return; + } + if (aScrollableOverflow.IsEmpty()) { + // Bail if the scrollable overflow rect is empty, as we're going to be + // dividing by it. + return; + } + + Document* doc = pc->Document(); + MOZ_ASSERT(doc, "The document should be valid"); + if (doc->GetFullscreenElement()) { + // Don't use the minimum scale size in the case of fullscreen state. + // FIXME: 1508177: We will no longer need this. + return; + } + + nsViewportInfo viewportInfo = doc->GetViewportInfo(displaySize); + if (!viewportInfo.IsZoomAllowed()) { + // Don't apply the minimum scale size if user-scalable=no is specified. + return; + } + + // The intrinsic minimum scale is the scale that fits the entire content + // width into the visual viewport. + CSSToScreenScale intrinsicMinScale( + displaySize.width / CSSRect::FromAppUnits(aScrollableOverflow).XMost()); + + // The scale used to compute the minimum-scale size is the larger of the + // intrinsic minimum and the min-scale from the meta viewport tag. + CSSToScreenScale minScale = + std::max(intrinsicMinScale, viewportInfo.GetMinZoom()); + + // The minimum-scale size is the size of the visual viewport when zoomed + // to be the minimum scale. + mMinimumScaleSize = CSSSize::ToAppUnits(ScreenSize(displaySize) / minScale); + + // Ensure the minimum-scale size is never smaller than the ICB size. + // That could happen if a page has a meta viewport tag with large explicitly + // specified viewport dimensions (making the ICB large) and also a large + // minimum scale (making the min-scale size small). + mMinimumScaleSize = Max(aICBSize, mMinimumScaleSize); + + mIsUsingMinimumScaleSize = true; +} + +bool nsHTMLScrollFrame::ReflowFinished() { + mPostedReflowCallback = false; + + TryScheduleScrollAnimations(); + + if (mIsRoot) { + if (mMinimumScaleSizeChanged && PresShell()->UsesMobileViewportSizing() && + !PresShell()->IsResolutionUpdatedByApz()) { + RefPtr<MobileViewportManager> manager = + PresShell()->GetMobileViewportManager(); + MOZ_ASSERT(manager); + + manager->ShrinkToDisplaySizeIfNeeded(); + mMinimumScaleSizeChanged = false; + } + + if (!UsesOverlayScrollbars()) { + // Layout scrollbars may have added or removed during reflow, so let's + // update the visual viewport accordingly. Note that this may be a no-op + // because we might have recomputed the visual viewport size during the + // reflow itself, just before laying out the fixed-pos items. But there + // might be cases where that code doesn't run, so this is a sort of + // backstop to ensure we do that recomputation. + if (RefPtr<MobileViewportManager> manager = + PresShell()->GetMobileViewportManager()) { + manager->UpdateVisualViewportSizeForPotentialScrollbarChange(); + } + } + +#if defined(MOZ_WIDGET_ANDROID) + const bool hasVerticalOverflow = + GetOverflowState() & OverflowState::Vertical && + GetScrollStyles().mVertical != StyleOverflow::Hidden; + if (!mFirstReflow && mHasVerticalOverflowForDynamicToolbar && + !hasVerticalOverflow) { + PresShell()->MaybeNotifyShowDynamicToolbar(); + } + mHasVerticalOverflowForDynamicToolbar = hasVerticalOverflow; +#endif // defined(MOZ_WIDGET_ANDROID) + } + + bool doScroll = true; + if (IsSubtreeDirty()) { + // We will get another call after the next reflow and scrolling + // later is less janky. + doScroll = false; + } + + if (mFirstReflow) { + nsPoint currentScrollPos = GetScrollPosition(); + if (!mScrollUpdates.IsEmpty() && + mScrollUpdates.LastElement().GetOrigin() == ScrollOrigin::None && + currentScrollPos != nsPoint()) { + // With frame reconstructions, the reconstructed frame may have a nonzero + // scroll position by the end of the reflow, but without going through + // RestoreState. In particular this can happen with RTL XUL scrollframes, + // see https://bugzilla.mozilla.org/show_bug.cgi?id=1664638#c14. + // Upon construction, the nsHTMLScrollFrame constructor will have inserted + // a ScrollPositionUpdate into mScrollUpdates with origin None and a zero + // scroll position, but here we update that to hold the correct scroll + // position. Otherwise APZ may end up resetting the scroll position to + // zero incorrectly. If we ever hit this codepath, it must be on a reflow + // immediately following the scrollframe construction, so there should be + // exactly one ScrollPositionUpdate in mScrollUpdates. + MOZ_ASSERT(mScrollUpdates.Length() == 1); + MOZ_ASSERT(mScrollUpdates.LastElement().GetGeneration() == + mScrollGeneration); + MOZ_ASSERT(mScrollUpdates.LastElement().GetDestination() == CSSPoint()); + SCROLLRESTORE_LOG("%p: updating initial SPU to pos %s\n", this, + ToString(currentScrollPos).c_str()); + mScrollUpdates.Clear(); + AppendScrollUpdate( + ScrollPositionUpdate::NewScrollframe(currentScrollPos)); + } + + mFirstReflow = false; + } + + nsAutoScriptBlocker scriptBlocker; + + if (mReclampVVOffsetInReflowFinished) { + MOZ_ASSERT(mIsRoot && PresShell()->IsVisualViewportOffsetSet()); + mReclampVVOffsetInReflowFinished = false; + AutoWeakFrame weakFrame(this); + PresShell()->SetVisualViewportOffset(PresShell()->GetVisualViewportOffset(), + GetScrollPosition()); + NS_ENSURE_TRUE(weakFrame.IsAlive(), false); + } + + if (doScroll) { + ScrollToRestoredPosition(); + + // Clamp current scroll position to new bounds. Normally this won't + // do anything. + nsPoint currentScrollPos = GetScrollPosition(); + ScrollToImpl(currentScrollPos, nsRect(currentScrollPos, nsSize(0, 0)), + ScrollOrigin::Clamp); + if (ScrollAnimationState().isEmpty()) { + // We need to have mDestination track the current scroll position, + // in case it falls outside the new reflow area. mDestination is used + // by ScrollBy as its starting position. + mDestination = GetScrollPosition(); + } + } + + if (!mUpdateScrollbarAttributes) { + return false; + } + mUpdateScrollbarAttributes = false; + + // Update scrollbar attributes. + if (mMayHaveDirtyFixedChildren) { + mMayHaveDirtyFixedChildren = false; + nsIFrame* parentFrame = GetParent(); + for (nsIFrame* fixedChild = + parentFrame->GetChildList(FrameChildListID::Fixed).FirstChild(); + fixedChild; fixedChild = fixedChild->GetNextSibling()) { + // force a reflow of the fixed child + PresShell()->FrameNeedsReflow(fixedChild, IntrinsicDirty::None, + NS_FRAME_HAS_DIRTY_CHILDREN); + } + } + + // Suppress handling of the curpos attribute changes we make here. + NS_ASSERTION(!mFrameIsUpdatingScrollbar, "We shouldn't be reentering here"); + mFrameIsUpdatingScrollbar = true; + + // FIXME(emilio): Why this instead of mHScrollbarContent / mVScrollbarContent? + RefPtr<Element> vScroll = + mVScrollbarBox ? mVScrollbarBox->GetContent()->AsElement() : nullptr; + RefPtr<Element> hScroll = + mHScrollbarBox ? mHScrollbarBox->GetContent()->AsElement() : nullptr; + + // Note, in some cases this may get deleted while finishing reflow + // for scrollbars. XXXmats is this still true now that we have a script + // blocker in this scope? (if not, remove the weak frame checks below). + if (vScroll || hScroll) { + nsSize visualViewportSize = GetVisualViewportSize(); + nsRect scrollRange = GetVisualScrollRange(); + nsPoint scrollPos = GetScrollPosition(); + nsSize lineScrollAmount = GetLineScrollAmount(); + + if (gfxPlatform::UseDesktopZoomingScrollbars()) { + scrollRange = GetScrollRangeForUserInputEvents(); + scrollPos = GetVisualViewportOffset(); + } + + // If modifying the logic here, be sure to modify the corresponding + // compositor-side calculation in ScrollThumbUtils::ApplyTransformForAxis(). + AutoWeakFrame weakFrame(this); + if (vScroll) { + const double kScrollMultiplier = + StaticPrefs::toolkit_scrollbox_verticalScrollDistance(); + nscoord increment = lineScrollAmount.height * kScrollMultiplier; + // We normally use (visualViewportSize.height - increment) for height of + // page scrolling. However, it is too small when increment is very large. + // (If increment is larger than visualViewportSize.height, direction of + // scrolling will be opposite). To avoid it, we use + // (float(visualViewportSize.height) * 0.8) as lower bound value of height + // of page scrolling. (bug 383267) + // XXX shouldn't we use GetPageScrollAmount here? + nscoord pageincrement = nscoord(visualViewportSize.height - increment); + nscoord pageincrementMin = + nscoord(float(visualViewportSize.height) * 0.8); + FinishReflowForScrollbar( + vScroll, scrollRange.y, scrollRange.YMost(), scrollPos.y, + std::max(pageincrement, pageincrementMin), increment); + } + if (hScroll) { + const double kScrollMultiplier = + StaticPrefs::toolkit_scrollbox_horizontalScrollDistance(); + nscoord increment = lineScrollAmount.width * kScrollMultiplier; + FinishReflowForScrollbar( + hScroll, scrollRange.x, scrollRange.XMost(), scrollPos.x, + nscoord(float(visualViewportSize.width) * 0.8), increment); + } + NS_ENSURE_TRUE(weakFrame.IsAlive(), false); + } + + mFrameIsUpdatingScrollbar = false; + // We used to rely on the curpos attribute changes above to scroll the + // view. However, for scrolling to the left of the viewport, we + // rescale the curpos attribute, which means that operations like + // resizing the window while it is scrolled all the way to the left + // hold the curpos attribute constant at 0 while still requiring + // scrolling. So we suppress the effect of the changes above with + // mFrameIsUpdatingScrollbar and call CurPosAttributeChanged here. + // (It actually even works some of the time without this, thanks to + // nsSliderFrame::AttributeChanged's handling of maxpos, but not when + // we hide the scrollbar on a large size change, such as + // maximization.) + if (!mHScrollbarBox && !mVScrollbarBox) { + return false; + } + CurPosAttributeChangedInternal( + mVScrollbarBox ? mVScrollbarBox->GetContent()->AsElement() + : mHScrollbarBox->GetContent()->AsElement(), + doScroll); + return doScroll; +} + +void nsHTMLScrollFrame::ReflowCallbackCanceled() { + mPostedReflowCallback = false; +} + +bool nsHTMLScrollFrame::ComputeCustomOverflow(OverflowAreas& aOverflowAreas) { + ScrollStyles ss = GetScrollStyles(); + + // Reflow when the change in overflow leads to one of our scrollbars + // changing or might require repositioning the scrolled content due to + // reduced extents. + nsRect scrolledRect = GetScrolledRect(); + ScrollDirections overflowChange = + GetOverflowChange(scrolledRect, mPrevScrolledRect); + mPrevScrolledRect = scrolledRect; + + bool needReflow = false; + nsPoint scrollPosition = GetScrollPosition(); + if (overflowChange.contains(ScrollDirection::eHorizontal)) { + if (ss.mHorizontal != StyleOverflow::Hidden || scrollPosition.x) { + needReflow = true; + } + } + if (overflowChange.contains(ScrollDirection::eVertical)) { + if (ss.mVertical != StyleOverflow::Hidden || scrollPosition.y) { + needReflow = true; + } + } + + if (needReflow) { + // If there are scrollbars, or we're not at the beginning of the pane, + // the scroll position may change. In this case, mark the frame as + // needing reflow. Don't use NS_FRAME_IS_DIRTY as dirty as that means + // we have to reflow the frame and all its descendants, and we don't + // have to do that here. Only this frame needs to be reflowed. + PresShell()->FrameNeedsReflow(this, IntrinsicDirty::None, + NS_FRAME_HAS_DIRTY_CHILDREN); + // Ensure that next time nsHTMLScrollFrame::Reflow runs, we don't skip + // updating the scrollbars. (Because the overflow area of the scrolled + // frame has probably just been updated, Reflow won't see it change.) + mSkippedScrollbarLayout = true; + return false; // reflowing will update overflow + } + PostOverflowEvent(); + return nsContainerFrame::ComputeCustomOverflow(aOverflowAreas); +} + +void nsHTMLScrollFrame::UpdateSticky() { + StickyScrollContainer* ssc = + StickyScrollContainer::GetStickyScrollContainerForScrollFrame(this); + if (ssc) { + ssc->UpdatePositions(GetScrollPosition(), this); + } +} + +void nsHTMLScrollFrame::UpdatePrevScrolledRect() { + // The layout scroll range is determinated by the scrolled rect and the scroll + // port, so if the scrolled rect is updated, we may have to schedule the + // associated scroll-driven animations' restyles. + nsRect currScrolledRect = GetScrolledRect(); + if (!currScrolledRect.IsEqualEdges(mPrevScrolledRect)) { + mMayScheduleScrollAnimations = true; + } + mPrevScrolledRect = currScrolledRect; +} + +void nsHTMLScrollFrame::AdjustScrollbarRectForResizer( + nsIFrame* aFrame, nsPresContext* aPresContext, nsRect& aRect, + bool aHasResizer, ScrollDirection aDirection) { + if ((aDirection == ScrollDirection::eVertical ? aRect.width : aRect.height) == + 0) { + return; + } + + // if a content resizer is present, use its size. Otherwise, check if the + // widget has a resizer. + nsRect resizerRect; + if (aHasResizer) { + resizerRect = mResizerBox->GetRect(); + } else { + nsPoint offset; + nsIWidget* widget = aFrame->GetNearestWidget(offset); + LayoutDeviceIntRect widgetRect; + if (!widget || !widget->ShowsResizeIndicator(&widgetRect)) { + return; + } + + resizerRect = + nsRect(aPresContext->DevPixelsToAppUnits(widgetRect.x) - offset.x, + aPresContext->DevPixelsToAppUnits(widgetRect.y) - offset.y, + aPresContext->DevPixelsToAppUnits(widgetRect.width), + aPresContext->DevPixelsToAppUnits(widgetRect.height)); + } + + if (resizerRect.Contains(aRect.BottomRight() - nsPoint(1, 1))) { + switch (aDirection) { + case ScrollDirection::eVertical: + aRect.height = std::max(0, resizerRect.y - aRect.y); + break; + case ScrollDirection::eHorizontal: + aRect.width = std::max(0, resizerRect.x - aRect.x); + break; + } + } else if (resizerRect.Contains(aRect.BottomLeft() + nsPoint(1, -1))) { + switch (aDirection) { + case ScrollDirection::eVertical: + aRect.height = std::max(0, resizerRect.y - aRect.y); + break; + case ScrollDirection::eHorizontal: { + nscoord xmost = aRect.XMost(); + aRect.x = std::max(aRect.x, resizerRect.XMost()); + aRect.width = xmost - aRect.x; + break; + } + } + } +} + +static void AdjustOverlappingScrollbars(nsRect& aVRect, nsRect& aHRect) { + if (aVRect.IsEmpty() || aHRect.IsEmpty()) return; + + const nsRect oldVRect = aVRect; + const nsRect oldHRect = aHRect; + if (oldVRect.Contains(oldHRect.BottomRight() - nsPoint(1, 1))) { + aHRect.width = std::max(0, oldVRect.x - oldHRect.x); + } else if (oldVRect.Contains(oldHRect.BottomLeft() - nsPoint(0, 1))) { + nscoord overlap = std::min(oldHRect.width, oldVRect.XMost() - oldHRect.x); + aHRect.x += overlap; + aHRect.width -= overlap; + } + if (oldHRect.Contains(oldVRect.BottomRight() - nsPoint(1, 1))) { + aVRect.height = std::max(0, oldHRect.y - oldVRect.y); + } +} + +void nsHTMLScrollFrame::LayoutScrollbarPartAtRect( + const ScrollReflowInput& aState, ReflowInput& aKidReflowInput, + const nsRect& aRect) { + nsPresContext* pc = PresContext(); + nsIFrame* kid = aKidReflowInput.mFrame; + const auto wm = kid->GetWritingMode(); + ReflowOutput desiredSize(wm); + MOZ_ASSERT(!wm.IsVertical(), + "Scrollbar parts should have writing-mode: initial"); + MOZ_ASSERT(!wm.IsInlineReversed(), + "Scrollbar parts should have writing-mode: initial"); + // XXX Maybe get a meaningful container size or something. Shouldn't matter + // given our asserts above. + const nsSize containerSize; + aKidReflowInput.SetComputedISize(aRect.Width()); + aKidReflowInput.SetComputedBSize(aRect.Height()); + + const LogicalPoint pos(wm, aRect.TopLeft(), containerSize); + const auto flags = ReflowChildFlags::Default; + nsReflowStatus status; + ReflowOutput kidDesiredSize(wm); + ReflowChild(kid, pc, kidDesiredSize, aKidReflowInput, wm, pos, containerSize, + flags, status); + FinishReflowChild(kid, pc, kidDesiredSize, &aKidReflowInput, wm, pos, + containerSize, flags); +} + +void nsHTMLScrollFrame::LayoutScrollbars(ScrollReflowInput& aState, + const nsRect& aInsideBorderArea, + const nsRect& aOldScrollPort) { + NS_ASSERTION(!mSuppressScrollbarUpdate, "This should have been suppressed"); + + const bool scrollbarOnLeft = !IsScrollbarOnRight(); + const bool overlayScrollbars = UsesOverlayScrollbars(); + const bool overlayScrollBarsOnRoot = overlayScrollbars && mIsRoot; + const bool showVScrollbar = mVScrollbarBox && mHasVerticalScrollbar; + const bool showHScrollbar = mHScrollbarBox && mHasHorizontalScrollbar; + + nsSize compositionSize = mScrollPort.Size(); + if (overlayScrollBarsOnRoot) { + compositionSize = nsLayoutUtils::CalculateCompositionSizeForFrame( + this, false, &compositionSize); + } + + nsPresContext* presContext = mScrolledFrame->PresContext(); + nsRect vRect; + if (showVScrollbar) { + vRect.height = + overlayScrollBarsOnRoot ? compositionSize.height : mScrollPort.height; + vRect.y = mScrollPort.y; + if (scrollbarOnLeft) { + vRect.width = mScrollPort.x - aInsideBorderArea.x; + vRect.x = aInsideBorderArea.x; + } else { + vRect.width = aInsideBorderArea.XMost() - mScrollPort.XMost(); + vRect.x = mScrollPort.x + compositionSize.width; + } + if (overlayScrollbars || mOnlyNeedVScrollbarToScrollVVInsideLV) { + const nscoord width = aState.VScrollbarPrefWidth(); + // There is no space reserved for the layout scrollbar, it is currently + // not visible because it is positioned just outside the scrollport. But + // we know that it needs to be made visible so we shift it back in. + vRect.width += width; + if (!scrollbarOnLeft) { + vRect.x -= width; + } + } + } + + nsRect hRect; + if (showHScrollbar) { + hRect.width = + overlayScrollBarsOnRoot ? compositionSize.width : mScrollPort.width; + hRect.x = mScrollPort.x; + hRect.height = aInsideBorderArea.YMost() - mScrollPort.YMost(); + hRect.y = mScrollPort.y + compositionSize.height; + + if (overlayScrollbars || mOnlyNeedHScrollbarToScrollVVInsideLV) { + const nscoord height = aState.HScrollbarPrefHeight(); + hRect.height += height; + // There is no space reserved for the layout scrollbar, it is currently + // not visible because it is positioned just outside the scrollport. But + // we know that it needs to be made visible so we shift it back in. + hRect.y -= height; + } + } + + const bool hasVisualOnlyScrollbarsOnBothDirections = + !overlayScrollbars && showHScrollbar && + mOnlyNeedHScrollbarToScrollVVInsideLV && showVScrollbar && + mOnlyNeedVScrollbarToScrollVVInsideLV; + nsPresContext* pc = PresContext(); + + // place the scrollcorner + if (mScrollCornerBox) { + nsRect r(0, 0, 0, 0); + if (scrollbarOnLeft) { + // scrollbar (if any) on left + r.width = showVScrollbar ? mScrollPort.x - aInsideBorderArea.x : 0; + r.x = aInsideBorderArea.x; + } else { + // scrollbar (if any) on right + r.width = + showVScrollbar ? aInsideBorderArea.XMost() - mScrollPort.XMost() : 0; + r.x = aInsideBorderArea.XMost() - r.width; + } + NS_ASSERTION(r.width >= 0, "Scroll area should be inside client rect"); + + if (showHScrollbar) { + // scrollbar (if any) on bottom + // Note we don't support the horizontal scrollbar at the top side. + r.height = aInsideBorderArea.YMost() - mScrollPort.YMost(); + NS_ASSERTION(r.height >= 0, "Scroll area should be inside client rect"); + } + r.y = aInsideBorderArea.YMost() - r.height; + + // If we have layout scrollbars and both scrollbars are present and both are + // only needed to scroll the VV inside the LV then we need a scrollcorner + // but the above calculation will result in an empty rect, so adjust it. + if (r.IsEmpty() && hasVisualOnlyScrollbarsOnBothDirections) { + r.width = vRect.width; + r.height = hRect.height; + r.x = scrollbarOnLeft ? mScrollPort.x : mScrollPort.XMost() - r.width; + r.y = mScrollPort.YMost() - r.height; + } + + ReflowInput scrollCornerRI( + pc, aState.mReflowInput, mScrollCornerBox, + LogicalSize(mScrollCornerBox->GetWritingMode(), r.Size())); + LayoutScrollbarPartAtRect(aState, scrollCornerRI, r); + } + + if (mResizerBox) { + // If a resizer is present, get its size. + // + // TODO(emilio): Should this really account for scrollbar-width? + auto scrollbarWidth = nsLayoutUtils::StyleForScrollbar(this) + ->StyleUIReset() + ->ScrollbarWidth(); + auto scrollbarSize = pc->Theme()->GetScrollbarSize(pc, scrollbarWidth, + nsITheme::Overlay::No); + ReflowInput resizerRI(pc, aState.mReflowInput, mResizerBox, + LogicalSize(mResizerBox->GetWritingMode())); + nsSize resizerMinSize = {resizerRI.ComputedMinWidth(), + resizerRI.ComputedMinHeight()}; + + nsRect r; + nscoord vScrollbarWidth = pc->DevPixelsToAppUnits(scrollbarSize); + r.width = + std::max(std::max(r.width, vScrollbarWidth), resizerMinSize.width); + r.x = scrollbarOnLeft ? aInsideBorderArea.x + : aInsideBorderArea.XMost() - r.width; + + nscoord hScrollbarHeight = pc->DevPixelsToAppUnits(scrollbarSize); + r.height = + std::max(std::max(r.height, hScrollbarHeight), resizerMinSize.height); + r.y = aInsideBorderArea.YMost() - r.height; + + LayoutScrollbarPartAtRect(aState, resizerRI, r); + } + + // Note that AdjustScrollbarRectForResizer has to be called after the + // resizer has been laid out immediately above this because it gets the rect + // of the resizer frame. + if (mVScrollbarBox) { + AdjustScrollbarRectForResizer(this, presContext, vRect, mResizerBox, + ScrollDirection::eVertical); + } + if (mHScrollbarBox) { + AdjustScrollbarRectForResizer(this, presContext, hRect, mResizerBox, + ScrollDirection::eHorizontal); + } + + // Layout scrollbars can overlap at this point if they are both present and + // both only needed to scroll the VV inside the LV. + if (!LookAndFeel::GetInt(LookAndFeel::IntID::AllowOverlayScrollbarsOverlap) || + hasVisualOnlyScrollbarsOnBothDirections) { + AdjustOverlappingScrollbars(vRect, hRect); + } + if (mVScrollbarBox) { + ReflowInput vScrollbarRI( + pc, aState.mReflowInput, mVScrollbarBox, + LogicalSize(mVScrollbarBox->GetWritingMode(), vRect.Size())); + LayoutScrollbarPartAtRect(aState, vScrollbarRI, vRect); + } + if (mHScrollbarBox) { + ReflowInput hScrollbarRI( + pc, aState.mReflowInput, mHScrollbarBox, + LogicalSize(mHScrollbarBox->GetWritingMode(), hRect.Size())); + LayoutScrollbarPartAtRect(aState, hScrollbarRI, hRect); + } + + // may need to update fixed position children of the viewport, + // if the client area changed size because of an incremental + // reflow of a descendant. (If the outer frame is dirty, the fixed + // children will be re-laid out anyway) + if (aOldScrollPort.Size() != mScrollPort.Size() && + !HasAnyStateBits(NS_FRAME_IS_DIRTY) && mIsRoot) { + mMayHaveDirtyFixedChildren = true; + } + + // post reflow callback to modify scrollbar attributes + mUpdateScrollbarAttributes = true; + if (!mPostedReflowCallback) { + PresShell()->PostReflowCallback(this); + mPostedReflowCallback = true; + } +} + +#if DEBUG +static bool ShellIsAlive(nsWeakPtr& aWeakPtr) { + RefPtr<PresShell> presShell = do_QueryReferent(aWeakPtr); + return !!presShell; +} +#endif + +void nsHTMLScrollFrame::SetScrollbarEnabled(Element* aElement, + nscoord aMaxPos) { + DebugOnly<nsWeakPtr> weakShell(do_GetWeakReference(PresShell())); + if (aMaxPos) { + aElement->UnsetAttr(kNameSpaceID_None, nsGkAtoms::disabled, true); + } else { + aElement->SetAttr(kNameSpaceID_None, nsGkAtoms::disabled, u"true"_ns, true); + } + MOZ_ASSERT(ShellIsAlive(weakShell), "pres shell was destroyed by scrolling"); +} + +void nsHTMLScrollFrame::SetCoordAttribute(Element* aElement, nsAtom* aAtom, + nscoord aSize) { + DebugOnly<nsWeakPtr> weakShell(do_GetWeakReference(PresShell())); + // convert to pixels + int32_t pixelSize = nsPresContext::AppUnitsToIntCSSPixels(aSize); + + // only set the attribute if it changed. + + nsAutoString newValue; + newValue.AppendInt(pixelSize); + + if (aElement->AttrValueIs(kNameSpaceID_None, aAtom, newValue, eCaseMatters)) { + return; + } + + AutoWeakFrame weakFrame(this); + RefPtr<Element> kungFuDeathGrip = aElement; + aElement->SetAttr(kNameSpaceID_None, aAtom, newValue, true); + MOZ_ASSERT(ShellIsAlive(weakShell), "pres shell was destroyed by scrolling"); + if (!weakFrame.IsAlive()) { + return; + } + + if (mScrollbarActivity && + (mHasHorizontalScrollbar || mHasVerticalScrollbar)) { + RefPtr<ScrollbarActivity> scrollbarActivity(mScrollbarActivity); + scrollbarActivity->ActivityOccurred(); + } +} + +static void ReduceRadii(nscoord aXBorder, nscoord aYBorder, nscoord& aXRadius, + nscoord& aYRadius) { + // In order to ensure that the inside edge of the border has no + // curvature, we need at least one of its radii to be zero. + if (aXRadius <= aXBorder || aYRadius <= aYBorder) return; + + // For any corner where we reduce the radii, preserve the corner's shape. + double ratio = + std::max(double(aXBorder) / aXRadius, double(aYBorder) / aYRadius); + aXRadius *= ratio; + aYRadius *= ratio; +} + +/** + * Implement an override for nsIFrame::GetBorderRadii to ensure that + * the clipping region for the border radius does not clip the scrollbars. + * + * In other words, we require that the border radius be reduced until the + * inner border radius at the inner edge of the border is 0 wherever we + * have scrollbars. + */ +bool nsHTMLScrollFrame::GetBorderRadii(const nsSize& aFrameSize, + const nsSize& aBorderArea, + Sides aSkipSides, + nscoord aRadii[8]) const { + if (!nsContainerFrame::GetBorderRadii(aFrameSize, aBorderArea, aSkipSides, + aRadii)) { + return false; + } + + // Since we can use GetActualScrollbarSizes (rather than + // GetDesiredScrollbarSizes) since this doesn't affect reflow, we + // probably should. + nsMargin sb = GetActualScrollbarSizes(); + nsMargin border = GetUsedBorder(); + + if (sb.left > 0 || sb.top > 0) { + ReduceRadii(border.left, border.top, aRadii[eCornerTopLeftX], + aRadii[eCornerTopLeftY]); + } + + if (sb.top > 0 || sb.right > 0) { + ReduceRadii(border.right, border.top, aRadii[eCornerTopRightX], + aRadii[eCornerTopRightY]); + } + + if (sb.right > 0 || sb.bottom > 0) { + ReduceRadii(border.right, border.bottom, aRadii[eCornerBottomRightX], + aRadii[eCornerBottomRightY]); + } + + if (sb.bottom > 0 || sb.left > 0) { + ReduceRadii(border.left, border.bottom, aRadii[eCornerBottomLeftX], + aRadii[eCornerBottomLeftY]); + } + + return true; +} + +static nscoord SnapCoord(nscoord aCoord, double aRes, + nscoord aAppUnitsPerPixel) { + double snappedToLayerPixels = NS_round((aRes * aCoord) / aAppUnitsPerPixel); + return NSToCoordRoundWithClamp(snappedToLayerPixels * aAppUnitsPerPixel / + aRes); +} + +nsRect nsHTMLScrollFrame::GetScrolledRect() const { + nsRect result = GetUnsnappedScrolledRectInternal( + mScrolledFrame->ScrollableOverflowRect(), mScrollPort.Size()); + +#if 0 + // This happens often enough. + if (result.width < mScrollPort.width || result.height < mScrollPort.height) { + NS_WARNING("Scrolled rect smaller than scrollport?"); + } +#endif + + // Expand / contract the result by up to half a layer pixel so that scrolling + // to the right / bottom edge does not change the layer pixel alignment of + // the scrolled contents. + + if (result.x == 0 && result.y == 0 && result.width == mScrollPort.width && + result.height == mScrollPort.height) { + // The edges that we would snap are already aligned with the scroll port, + // so we can skip all the work below. + return result; + } + + // For that, we first convert the scroll port and the scrolled rect to rects + // relative to the reference frame, since that's the space where painting does + // snapping. + nsSize visualViewportSize = GetVisualViewportSize(); + const nsIFrame* referenceFrame = + mReferenceFrameDuringPainting ? mReferenceFrameDuringPainting + : nsLayoutUtils::GetReferenceFrame( + const_cast<nsHTMLScrollFrame*>(this)); + nsPoint toReferenceFrame = GetOffsetToCrossDoc(referenceFrame); + nsRect scrollPort(mScrollPort.TopLeft() + toReferenceFrame, + visualViewportSize); + nsRect scrolledRect = result + scrollPort.TopLeft(); + + if (scrollPort.Overflows() || scrolledRect.Overflows()) { + return result; + } + + // Now, snap the bottom right corner of both of these rects. + // We snap to layer pixels, so we need to respect the layer's scale. + nscoord appUnitsPerDevPixel = + mScrolledFrame->PresContext()->AppUnitsPerDevPixel(); + MatrixScales scale = GetPaintedLayerScaleForFrame(mScrolledFrame); + if (scale.xScale == 0 || scale.yScale == 0) { + scale = MatrixScales(); + } + + // Compute bounds for the scroll position, and computed the snapped scrolled + // rect from the scroll position bounds. + nscoord snappedScrolledAreaBottom = + SnapCoord(scrolledRect.YMost(), scale.yScale, appUnitsPerDevPixel); + nscoord snappedScrollPortBottom = + SnapCoord(scrollPort.YMost(), scale.yScale, appUnitsPerDevPixel); + nscoord maximumScrollOffsetY = + snappedScrolledAreaBottom - snappedScrollPortBottom; + result.SetBottomEdge(scrollPort.height + maximumScrollOffsetY); + + if (GetScrolledFrameDir() == StyleDirection::Ltr) { + nscoord snappedScrolledAreaRight = + SnapCoord(scrolledRect.XMost(), scale.xScale, appUnitsPerDevPixel); + nscoord snappedScrollPortRight = + SnapCoord(scrollPort.XMost(), scale.xScale, appUnitsPerDevPixel); + nscoord maximumScrollOffsetX = + snappedScrolledAreaRight - snappedScrollPortRight; + result.SetRightEdge(scrollPort.width + maximumScrollOffsetX); + } else { + // In RTL, the scrolled area's right edge is at scrollPort.XMost(), + // and the scrolled area's x position is zero or negative. We want + // the right edge to stay flush with the scroll port, so we snap the + // left edge. + nscoord snappedScrolledAreaLeft = + SnapCoord(scrolledRect.x, scale.xScale, appUnitsPerDevPixel); + nscoord snappedScrollPortLeft = + SnapCoord(scrollPort.x, scale.xScale, appUnitsPerDevPixel); + nscoord minimumScrollOffsetX = + snappedScrolledAreaLeft - snappedScrollPortLeft; + result.SetLeftEdge(minimumScrollOffsetX); + } + + return result; +} + +StyleDirection nsHTMLScrollFrame::GetScrolledFrameDir() const { + // If the scrolled frame has unicode-bidi: plaintext, the paragraph + // direction set by the text content overrides the direction of the frame + if (mScrolledFrame->StyleTextReset()->mUnicodeBidi == + StyleUnicodeBidi::Plaintext) { + if (nsIFrame* child = mScrolledFrame->PrincipalChildList().FirstChild()) { + return nsBidiPresUtils::ParagraphDirection(child) == + mozilla::intl::BidiDirection::LTR + ? StyleDirection::Ltr + : StyleDirection::Rtl; + } + } + return IsBidiLTR() ? StyleDirection::Ltr : StyleDirection::Rtl; +} + +nsRect nsHTMLScrollFrame::GetUnsnappedScrolledRectInternal( + const nsRect& aScrolledOverflowArea, const nsSize& aScrollPortSize) const { + return nsLayoutUtils::GetScrolledRect(mScrolledFrame, aScrolledOverflowArea, + aScrollPortSize, GetScrolledFrameDir()); +} + +nsMargin nsHTMLScrollFrame::GetActualScrollbarSizes( + nsIScrollableFrame::ScrollbarSizesOptions + aOptions /* = nsIScrollableFrame::ScrollbarSizesOptions::NONE */) + const { + nsRect r = GetPaddingRectRelativeToSelf(); + + nsMargin m(mScrollPort.y - r.y, r.XMost() - mScrollPort.XMost(), + r.YMost() - mScrollPort.YMost(), mScrollPort.x - r.x); + + if (aOptions == nsIScrollableFrame::ScrollbarSizesOptions:: + INCLUDE_VISUAL_VIEWPORT_SCROLLBARS && + !UsesOverlayScrollbars()) { + // If we are using layout scrollbars and they only exist to scroll the + // visual viewport then they do not take up any layout space (so the + // scrollport is the same as the padding rect) but they do cover everything + // below them so some callers may want to include this special type of + // scrollbars in the returned value. + if (mHScrollbarBox && mHasHorizontalScrollbar && + mOnlyNeedHScrollbarToScrollVVInsideLV) { + m.bottom += mHScrollbarBox->GetRect().height; + } + if (mVScrollbarBox && mHasVerticalScrollbar && + mOnlyNeedVScrollbarToScrollVVInsideLV) { + if (IsScrollbarOnRight()) { + m.right += mVScrollbarBox->GetRect().width; + } else { + m.left += mVScrollbarBox->GetRect().width; + } + } + } + + return m; +} + +void nsHTMLScrollFrame::SetScrollbarVisibility(nsIFrame* aScrollbar, + bool aVisible) { + nsScrollbarFrame* scrollbar = do_QueryFrame(aScrollbar); + if (scrollbar) { + // See if we have a mediator. + nsIScrollbarMediator* mediator = scrollbar->GetScrollbarMediator(); + if (mediator) { + // Inform the mediator of the visibility change. + mediator->VisibilityChanged(aVisible); + } + } +} + +nscoord nsHTMLScrollFrame::GetCoordAttribute(nsIFrame* aBox, nsAtom* aAtom, + nscoord aDefaultValue, + nscoord* aRangeStart, + nscoord* aRangeLength) { + if (aBox) { + nsIContent* content = aBox->GetContent(); + + nsAutoString value; + if (content->IsElement()) { + content->AsElement()->GetAttr(kNameSpaceID_None, aAtom, value); + } + if (!value.IsEmpty()) { + nsresult error; + // convert it to appunits + nscoord result = + nsPresContext::CSSPixelsToAppUnits(value.ToInteger(&error)); + nscoord halfPixel = nsPresContext::CSSPixelsToAppUnits(0.5f); + // Any nscoord value that would round to the attribute value when + // converted to CSS pixels is allowed. + *aRangeStart = result - halfPixel; + *aRangeLength = halfPixel * 2 - 1; + return result; + } + } + + // Only this exact default value is allowed. + *aRangeStart = aDefaultValue; + *aRangeLength = 0; + return aDefaultValue; +} + +bool nsHTMLScrollFrame::IsLastScrollUpdateAnimating() const { + if (!mScrollUpdates.IsEmpty()) { + switch (mScrollUpdates.LastElement().GetMode()) { + case ScrollMode::Smooth: + case ScrollMode::SmoothMsd: + return true; + case ScrollMode::Instant: + case ScrollMode::Normal: + break; + } + } + return false; +} + +bool nsHTMLScrollFrame::IsLastScrollUpdateTriggeredByScriptAnimating() const { + if (!mScrollUpdates.IsEmpty()) { + const ScrollPositionUpdate& lastUpdate = mScrollUpdates.LastElement(); + if (lastUpdate.WasTriggeredByScript() && + (mScrollUpdates.LastElement().GetMode() == ScrollMode::Smooth || + mScrollUpdates.LastElement().GetMode() == ScrollMode::SmoothMsd)) { + return true; + } + } + return false; +} + +using AnimationState = nsIScrollableFrame::AnimationState; +EnumSet<AnimationState> nsHTMLScrollFrame::ScrollAnimationState() const { + EnumSet<AnimationState> retval; + if (IsApzAnimationInProgress()) { + retval += AnimationState::APZInProgress; + if (mCurrentAPZScrollAnimationType == + APZScrollAnimationType::TriggeredByScript) { + retval += AnimationState::TriggeredByScript; + } + } + + if (mApzAnimationRequested) { + retval += AnimationState::APZRequested; + if (mApzAnimationTriggeredByScriptRequested) { + retval += AnimationState::TriggeredByScript; + } + } + + if (IsLastScrollUpdateAnimating()) { + retval += AnimationState::APZPending; + if (IsLastScrollUpdateTriggeredByScriptAnimating()) { + retval += AnimationState::TriggeredByScript; + } + } + if (mAsyncScroll) { + retval += AnimationState::MainThread; + if (mAsyncScroll->WasTriggeredByScript()) { + retval += AnimationState::TriggeredByScript; + } + } + + if (mAsyncSmoothMSDScroll) { + retval += AnimationState::MainThread; + if (mAsyncSmoothMSDScroll->WasTriggeredByScript()) { + retval += AnimationState::TriggeredByScript; + } + } + return retval; +} + +void nsHTMLScrollFrame::ResetScrollInfoIfNeeded( + const MainThreadScrollGeneration& aGeneration, + const APZScrollGeneration& aGenerationOnApz, + APZScrollAnimationType aAPZScrollAnimationType, + InScrollingGesture aInScrollingGesture) { + if (aGeneration == mScrollGeneration) { + mLastScrollOrigin = ScrollOrigin::None; + mApzAnimationRequested = false; + mApzAnimationTriggeredByScriptRequested = false; + } + + mScrollGenerationOnApz = aGenerationOnApz; + // We can reset this regardless of scroll generation, as this is only set + // here, as a response to APZ requesting a repaint. + mCurrentAPZScrollAnimationType = aAPZScrollAnimationType; + + mInScrollingGesture = aInScrollingGesture; +} + +UniquePtr<PresState> nsHTMLScrollFrame::SaveState() { + nsIScrollbarMediator* mediator = do_QueryFrame(GetScrolledFrame()); + if (mediator) { + // child handles its own scroll state, so don't bother saving state here + return nullptr; + } + + // Don't store a scroll state if we never have been scrolled or restored + // a previous scroll state, and we're not in the middle of a smooth scroll. + auto scrollAnimationState = ScrollAnimationState(); + bool isScrollAnimating = + scrollAnimationState.contains(AnimationState::MainThread) || + scrollAnimationState.contains(AnimationState::APZPending) || + scrollAnimationState.contains(AnimationState::APZRequested); + if (!mHasBeenScrolled && !mDidHistoryRestore && !isScrollAnimating) { + return nullptr; + } + + UniquePtr<PresState> state = NewPresState(); + bool allowScrollOriginDowngrade = + !nsLayoutUtils::CanScrollOriginClobberApz(mLastScrollOrigin) || + mAllowScrollOriginDowngrade; + // Save mRestorePos instead of our actual current scroll position, if it's + // valid and we haven't moved since the last update of mLastPos (same check + // that ScrollToRestoredPosition uses). This ensures if a reframe occurs + // while we're in the process of loading content to scroll to a restored + // position, we'll keep trying after the reframe. Similarly, if we're in the + // middle of a smooth scroll, store the destination so that when we restore + // we'll jump straight to the end of the scroll animation, rather than + // effectively dropping it. Note that the mRestorePos will override the + // smooth scroll destination if both are present. + nsPoint pt = GetLogicalVisualViewportOffset(); + if (isScrollAnimating) { + pt = mDestination; + allowScrollOriginDowngrade = false; + } + SCROLLRESTORE_LOG("%p: SaveState, pt=%s, mLastPos=%s, mRestorePos=%s\n", this, + ToString(pt).c_str(), ToString(mLastPos).c_str(), + ToString(mRestorePos).c_str()); + if (mRestorePos.y != -1 && pt == mLastPos) { + pt = mRestorePos; + } + state->scrollState() = pt; + state->allowScrollOriginDowngrade() = allowScrollOriginDowngrade; + if (mIsRoot) { + // Only save resolution properties for root scroll frames + state->resolution() = PresShell()->GetResolution(); + } + return state; +} + +NS_IMETHODIMP nsHTMLScrollFrame::RestoreState(PresState* aState) { + mRestorePos = aState->scrollState(); + MOZ_ASSERT(mLastScrollOrigin == ScrollOrigin::None); + mAllowScrollOriginDowngrade = aState->allowScrollOriginDowngrade(); + // When restoring state, we promote mLastScrollOrigin to a stronger value + // from the default of eNone, to restore the behaviour that existed when + // the state was saved. If mLastScrollOrigin was a weaker value previously, + // then mAllowScrollOriginDowngrade will be true, and so the combination of + // mAllowScrollOriginDowngrade and the stronger mLastScrollOrigin will allow + // the same types of scrolls as before. It might be possible to also just + // save and restore the mAllowScrollOriginDowngrade and mLastScrollOrigin + // values directly without this sort of fiddling. Something to try in the + // future or if we tinker with this code more. + mLastScrollOrigin = ScrollOrigin::Other; + mDidHistoryRestore = true; + mLastPos = mScrolledFrame ? GetLogicalVisualViewportOffset() : nsPoint(0, 0); + SCROLLRESTORE_LOG("%p: RestoreState, set mRestorePos=%s mLastPos=%s\n", this, + ToString(mRestorePos).c_str(), ToString(mLastPos).c_str()); + + // Resolution properties should only exist on root scroll frames. + MOZ_ASSERT(mIsRoot || aState->resolution() == 1.0); + + if (mIsRoot) { + PresShell()->SetResolutionAndScaleTo( + aState->resolution(), ResolutionChangeOrigin::MainThreadRestore); + } + return NS_OK; +} + +void nsHTMLScrollFrame::PostScrolledAreaEvent() { + if (mScrolledAreaEvent.IsPending()) { + return; + } + mScrolledAreaEvent = new ScrolledAreaEvent(this); + nsContentUtils::AddScriptRunner(mScrolledAreaEvent.get()); +} + +//////////////////////////////////////////////////////////////////////////////// +// ScrolledArea change event dispatch + +// TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230, bug 1535398) +MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP +nsHTMLScrollFrame::ScrolledAreaEvent::Run() { + if (mHelper) { + mHelper->FireScrolledAreaEvent(); + } + return NS_OK; +} + +void nsHTMLScrollFrame::FireScrolledAreaEvent() { + mScrolledAreaEvent.Forget(); + + InternalScrollAreaEvent event(true, eScrolledAreaChanged, nullptr); + RefPtr<nsPresContext> presContext = PresContext(); + nsIContent* content = GetContent(); + + event.mArea = mScrolledFrame->ScrollableOverflowRectRelativeToParent(); + if (RefPtr<Document> doc = content->GetUncomposedDoc()) { + // TODO: Bug 1506441 + EventDispatcher::Dispatch(MOZ_KnownLive(ToSupports(doc)), presContext, + &event, nullptr); + } +} + +ScrollDirections nsIScrollableFrame::GetAvailableScrollingDirections() const { + nscoord oneDevPixel = + GetScrolledFrame()->PresContext()->AppUnitsPerDevPixel(); + ScrollDirections directions; + nsRect scrollRange = GetScrollRange(); + if (scrollRange.width >= oneDevPixel) { + directions += ScrollDirection::eHorizontal; + } + if (scrollRange.height >= oneDevPixel) { + directions += ScrollDirection::eVertical; + } + return directions; +} + +nsRect nsHTMLScrollFrame::GetScrollRangeForUserInputEvents() const { + // This function computes a scroll range based on a scrolled rect and scroll + // port defined as follows: + // scrollable rect = overflow:hidden ? layout viewport : scrollable rect + // scroll port = have visual viewport ? visual viewport : layout viewport + // The results in the same notion of scroll range that APZ uses (the combined + // effect of FrameMetrics::CalculateScrollRange() and + // nsLayoutUtils::CalculateScrollableRectForFrame). + + ScrollStyles ss = GetScrollStyles(); + + nsPoint scrollPos = GetScrollPosition(); + + nsRect scrolledRect = GetScrolledRect(); + if (StyleOverflow::Hidden == ss.mHorizontal) { + scrolledRect.width = mScrollPort.width; + scrolledRect.x = scrollPos.x; + } + if (StyleOverflow::Hidden == ss.mVertical) { + scrolledRect.height = mScrollPort.height; + scrolledRect.y = scrollPos.y; + } + + nsSize scrollPort = GetVisualViewportSize(); + + nsRect scrollRange = scrolledRect; + scrollRange.width = std::max(scrolledRect.width - scrollPort.width, 0); + scrollRange.height = std::max(scrolledRect.height - scrollPort.height, 0); + + return scrollRange; +} + +ScrollDirections +nsHTMLScrollFrame::GetAvailableScrollingDirectionsForUserInputEvents() const { + nsRect scrollRange = GetScrollRangeForUserInputEvents(); + + // We check if there is at least one half of a screen pixel of scroll range to + // roughly match what apz does when it checks if the change in scroll position + // in screen pixels round to zero or not. + // (https://searchfox.org/mozilla-central/rev/2f09184ec781a2667feec87499d4b81b32b6c48e/gfx/layers/apz/src/AsyncPanZoomController.cpp#3210) + // This isn't quite half a screen pixel, it doesn't take into account CSS + // transforms, but should be good enough. + float halfScreenPixel = + GetScrolledFrame()->PresContext()->AppUnitsPerDevPixel() / + (PresShell()->GetCumulativeResolution() * 2.f); + ScrollDirections directions; + if (scrollRange.width >= halfScreenPixel) { + directions += ScrollDirection::eHorizontal; + } + if (scrollRange.height >= halfScreenPixel) { + directions += ScrollDirection::eVertical; + } + return directions; +} + +/** + * Append scroll positions for valid snap positions into |aSnapInfo| if + * applicable. + */ +static void AppendScrollPositionsForSnap( + const nsIFrame* aFrame, const nsIFrame* aScrolledFrame, + const nsRect& aScrolledRect, const nsMargin& aScrollPadding, + const nsRect& aScrollRange, WritingMode aWritingModeOnScroller, + ScrollSnapInfo& aSnapInfo, nsHTMLScrollFrame::SnapTargetSet* aSnapTargets) { + ScrollSnapTargetId targetId = ScrollSnapUtils::GetTargetIdFor(aFrame); + + nsRect snapArea = + ScrollSnapUtils::GetSnapAreaFor(aFrame, aScrolledFrame, aScrolledRect); + // Use the writing-mode on the target element if the snap area is larger than + // the snapport. + // https://drafts.csswg.org/css-scroll-snap/#snap-scope + WritingMode writingMode = ScrollSnapUtils::NeedsToRespectTargetWritingMode( + snapArea.Size(), aSnapInfo.mSnapportSize) + ? aFrame->GetWritingMode() + : aWritingModeOnScroller; + + // These snap range shouldn't be involved with scroll-margin since we just + // need the visible range of the target element. + if (snapArea.width > aSnapInfo.mSnapportSize.width) { + aSnapInfo.mXRangeWiderThanSnapport.AppendElement( + ScrollSnapInfo::ScrollSnapRange(snapArea.X(), snapArea.XMost(), + targetId)); + } + if (snapArea.height > aSnapInfo.mSnapportSize.height) { + aSnapInfo.mYRangeWiderThanSnapport.AppendElement( + ScrollSnapInfo::ScrollSnapRange(snapArea.Y(), snapArea.YMost(), + targetId)); + } + + // Shift target rect position by the scroll padding to get the padded + // position thus we don't need to take account scroll-padding values in + // ScrollSnapUtils::GetSnapPointForDestination() when it gets called from + // the compositor thread. + snapArea.y -= aScrollPadding.top; + snapArea.x -= aScrollPadding.left; + + LogicalRect logicalTargetRect(writingMode, snapArea, aSnapInfo.mSnapportSize); + LogicalSize logicalSnapportRect(writingMode, aSnapInfo.mSnapportSize); + LogicalRect logicalScrollRange(aWritingModeOnScroller, aScrollRange, + // The origin of this logical coordinate system + // what we need here is (0, 0), so we use an + // empty size. + nsSize()); + + Maybe<nscoord> blockDirectionPosition; + const nsStyleDisplay* styleDisplay = aFrame->StyleDisplay(); + nscoord containerBSize = logicalSnapportRect.BSize(writingMode); + switch (styleDisplay->mScrollSnapAlign.block) { + case StyleScrollSnapAlignKeyword::None: + break; + case StyleScrollSnapAlignKeyword::Start: + blockDirectionPosition.emplace( + writingMode.IsVerticalRL() ? -logicalTargetRect.BStart(writingMode) + : logicalTargetRect.BStart(writingMode)); + break; + case StyleScrollSnapAlignKeyword::End: { + nscoord candidate = std::clamp( + // What we need here is the scroll position instead of the snap + // position itself, so we need, for example, the top edge of the + // scroll port on horizontal-tb when the frame is positioned at + // the bottom edge of the scroll port. For this reason we subtract + // containerBSize from BEnd of the target and clamp it inside the + // scrollable range. + logicalTargetRect.BEnd(writingMode) - containerBSize, + logicalScrollRange.BStart(writingMode), + logicalScrollRange.BEnd(writingMode)); + blockDirectionPosition.emplace(writingMode.IsVerticalRL() ? -candidate + : candidate); + break; + } + case StyleScrollSnapAlignKeyword::Center: { + nscoord targetCenter = (logicalTargetRect.BStart(writingMode) + + logicalTargetRect.BEnd(writingMode)) / + 2; + nscoord halfSnapportSize = containerBSize / 2; + // Get the center of the target to align with the center of the snapport + // depending on direction. + nscoord candidate = std::clamp(targetCenter - halfSnapportSize, + logicalScrollRange.BStart(writingMode), + logicalScrollRange.BEnd(writingMode)); + blockDirectionPosition.emplace(writingMode.IsVerticalRL() ? -candidate + : candidate); + break; + } + } + + Maybe<nscoord> inlineDirectionPosition; + nscoord containerISize = logicalSnapportRect.ISize(writingMode); + switch (styleDisplay->mScrollSnapAlign.inline_) { + case StyleScrollSnapAlignKeyword::None: + break; + case StyleScrollSnapAlignKeyword::Start: + inlineDirectionPosition.emplace( + writingMode.IsInlineReversed() + ? -logicalTargetRect.IStart(writingMode) + : logicalTargetRect.IStart(writingMode)); + break; + case StyleScrollSnapAlignKeyword::End: { + nscoord candidate = std::clamp( + // Same as above BEnd case, we subtract containerISize. + // + // Note that the logical scroll range is mapped to [0, x] range even + // if it's in RTL contents. So for example, if the physical range is + // [-200, 0], it's mapped to [0, 200], i.e. IStart() is 0, IEnd() is + // 200. So we can just use std::clamp with the same arguments in both + // RTL/LTR cases. + logicalTargetRect.IEnd(writingMode) - containerISize, + logicalScrollRange.IStart(writingMode), + logicalScrollRange.IEnd(writingMode)); + inlineDirectionPosition.emplace( + writingMode.IsInlineReversed() ? -candidate : candidate); + break; + } + case StyleScrollSnapAlignKeyword::Center: { + nscoord targetCenter = (logicalTargetRect.IStart(writingMode) + + logicalTargetRect.IEnd(writingMode)) / + 2; + nscoord halfSnapportSize = containerISize / 2; + // Get the center of the target to align with the center of the snapport + // depending on direction. + nscoord candidate = std::clamp(targetCenter - halfSnapportSize, + logicalScrollRange.IStart(writingMode), + logicalScrollRange.IEnd(writingMode)); + inlineDirectionPosition.emplace( + writingMode.IsInlineReversed() ? -candidate : candidate); + break; + } + } + + if (blockDirectionPosition || inlineDirectionPosition) { + aSnapInfo.mSnapTargets.AppendElement( + writingMode.IsVertical() + ? ScrollSnapInfo::SnapTarget( + std::move(blockDirectionPosition), + std::move(inlineDirectionPosition), std::move(snapArea), + styleDisplay->mScrollSnapStop, targetId) + : ScrollSnapInfo::SnapTarget( + std::move(inlineDirectionPosition), + std::move(blockDirectionPosition), std::move(snapArea), + styleDisplay->mScrollSnapStop, targetId)); + if (aSnapTargets) { + aSnapTargets->EnsureInserted(aFrame->GetContent()); + } + } +} + +/** + * Collect the scroll positions corresponding to snap positions of frames in the + * subtree rooted at |aFrame|, relative to |aScrolledFrame|, into |aSnapInfo|. + */ +static void CollectScrollPositionsForSnap( + nsIFrame* aFrame, nsIFrame* aScrolledFrame, const nsRect& aScrolledRect, + const nsMargin& aScrollPadding, const nsRect& aScrollRange, + WritingMode aWritingModeOnScroller, ScrollSnapInfo& aSnapInfo, + nsHTMLScrollFrame::SnapTargetSet* aSnapTargets) { + // Snap positions only affect the nearest ancestor scroll container on the + // element's containing block chain. + nsIScrollableFrame* sf = do_QueryFrame(aFrame); + if (sf) { + return; + } + + for (const auto& childList : aFrame->ChildLists()) { + for (nsIFrame* f : childList.mList) { + const nsStyleDisplay* styleDisplay = f->StyleDisplay(); + if (styleDisplay->mScrollSnapAlign.inline_ != + StyleScrollSnapAlignKeyword::None || + styleDisplay->mScrollSnapAlign.block != + StyleScrollSnapAlignKeyword::None) { + AppendScrollPositionsForSnap( + f, aScrolledFrame, aScrolledRect, aScrollPadding, aScrollRange, + aWritingModeOnScroller, aSnapInfo, aSnapTargets); + } + CollectScrollPositionsForSnap( + f, aScrolledFrame, aScrolledRect, aScrollPadding, aScrollRange, + aWritingModeOnScroller, aSnapInfo, aSnapTargets); + } + } +} + +static nscoord ResolveScrollPaddingStyleValue( + const StyleRect<mozilla::NonNegativeLengthPercentageOrAuto>& + aScrollPaddingStyle, + Side aSide, const nsSize& aScrollPortSize) { + if (aScrollPaddingStyle.Get(aSide).IsAuto()) { + // https://drafts.csswg.org/css-scroll-snap-1/#valdef-scroll-padding-auto + return 0; + } + + nscoord percentageBasis; + switch (aSide) { + case eSideTop: + case eSideBottom: + percentageBasis = aScrollPortSize.height; + break; + case eSideLeft: + case eSideRight: + percentageBasis = aScrollPortSize.width; + break; + } + + return aScrollPaddingStyle.Get(aSide).AsLengthPercentage().Resolve( + percentageBasis); +} + +static nsMargin ResolveScrollPaddingStyle( + const StyleRect<mozilla::NonNegativeLengthPercentageOrAuto>& + aScrollPaddingStyle, + const nsSize& aScrollPortSize) { + return nsMargin(ResolveScrollPaddingStyleValue(aScrollPaddingStyle, eSideTop, + aScrollPortSize), + ResolveScrollPaddingStyleValue(aScrollPaddingStyle, + eSideRight, aScrollPortSize), + ResolveScrollPaddingStyleValue(aScrollPaddingStyle, + eSideBottom, aScrollPortSize), + ResolveScrollPaddingStyleValue(aScrollPaddingStyle, eSideLeft, + aScrollPortSize)); +} + +nsMargin nsHTMLScrollFrame::GetScrollPadding() const { + nsIFrame* styleFrame = GetFrameForStyle(); + if (!styleFrame) { + return nsMargin(); + } + + // The spec says percentage values are relative to the scroll port size. + // https://drafts.csswg.org/css-scroll-snap-1/#scroll-padding + return ResolveScrollPaddingStyle(styleFrame->StylePadding()->mScrollPadding, + GetScrollPortRect().Size()); +} + +layers::ScrollSnapInfo nsHTMLScrollFrame::ComputeScrollSnapInfo() { + ScrollSnapInfo result; + + nsIFrame* scrollSnapFrame = GetFrameForStyle(); + if (!scrollSnapFrame) { + return result; + } + + const nsStyleDisplay* disp = scrollSnapFrame->StyleDisplay(); + if (disp->mScrollSnapType.strictness == StyleScrollSnapStrictness::None) { + // We won't be snapping, short-circuit the computation. + return result; + } + + WritingMode writingMode = GetWritingMode(); + result.InitializeScrollSnapStrictness(writingMode, disp); + + result.mSnapportSize = GetSnapportSize(); + CollectScrollPositionsForSnap( + mScrolledFrame, mScrolledFrame, GetScrolledRect(), GetScrollPadding(), + GetLayoutScrollRange(), writingMode, result, &mSnapTargets); + return result; +} + +layers::ScrollSnapInfo nsHTMLScrollFrame::GetScrollSnapInfo() { + // TODO(botond): Should we cache it? + return ComputeScrollSnapInfo(); +} + +Maybe<SnapTarget> nsHTMLScrollFrame::GetSnapPointForDestination( + ScrollUnit aUnit, ScrollSnapFlags aFlags, const nsPoint& aStartPos, + const nsPoint& aDestination) { + // We can release the strong references for the previous snap target + // elements here since calling this ComputeScrollSnapInfo means we are going + // to evaluate new snap points, thus there's no chance to generating + // nsIContent instances in between this function call and the function call + // for the (re-)evaluation. + mSnapTargets.Clear(); + return ScrollSnapUtils::GetSnapPointForDestination( + ComputeScrollSnapInfo(), aUnit, aFlags, GetLayoutScrollRange(), aStartPos, + aDestination); +} + +Maybe<SnapTarget> nsHTMLScrollFrame::GetSnapPointForResnap() { + // Same as in GetSnapPointForDestination, We can release the strong references + // for the previous snap targets here. + mSnapTargets.Clear(); + nsIContent* focusedContent = + GetContent()->GetComposedDoc()->GetUnretargetedFocusedContent(); + return ScrollSnapUtils::GetSnapPointForResnap( + ComputeScrollSnapInfo(), GetLayoutScrollRange(), GetScrollPosition(), + mLastSnapTargetIds, focusedContent); +} + +bool nsHTMLScrollFrame::NeedsResnap() { + nsIContent* focusedContent = + GetContent()->GetComposedDoc()->GetUnretargetedFocusedContent(); + return ScrollSnapUtils::GetSnapPointForResnap( + ComputeScrollSnapInfo(), GetLayoutScrollRange(), + GetScrollPosition(), mLastSnapTargetIds, focusedContent) + .isSome(); +} + +void nsHTMLScrollFrame::SetLastSnapTargetIds( + UniquePtr<ScrollSnapTargetIds> aIds) { + if (!aIds) { + mLastSnapTargetIds = nullptr; + return; + } + + // This SetLastSnapTargetIds gets called asynchronously so that there's a race + // condition something like; + // 1) an async scroll operation triggered snapping to a point on an element + // 2) during the async scroll operation, the element got removed from this + // scroll container + // 3) re-snapping triggered + // 4) this SetLastSnapTargetIds got called + // In such case |aIds| are stale, we shouldn't use it. + for (const auto* idList : {&aIds->mIdsOnX, &aIds->mIdsOnY}) { + for (const auto id : *idList) { + if (!mSnapTargets.Contains(reinterpret_cast<nsIContent*>(id))) { + mLastSnapTargetIds = nullptr; + return; + } + } + } + + mLastSnapTargetIds = std::move(aIds); +} + +bool nsHTMLScrollFrame::IsLastSnappedTarget(const nsIFrame* aFrame) const { + ScrollSnapTargetId id = ScrollSnapUtils::GetTargetIdFor(aFrame); + MOZ_ASSERT(id != ScrollSnapTargetId::None, + "This function is supposed to be called for contents"); + + if (!mLastSnapTargetIds) { + return false; + } + + return mLastSnapTargetIds->mIdsOnX.Contains(id) || + mLastSnapTargetIds->mIdsOnY.Contains(id); +} + +void nsHTMLScrollFrame::TryResnap() { + // If there's any async scroll is running or we are processing pan/touch + // gestures or scroll thumb dragging, don't clobber the scroll. + if (!ScrollAnimationState().isEmpty() || + mInScrollingGesture == InScrollingGesture::Yes) { + return; + } + + if (auto snapTarget = GetSnapPointForResnap()) { + // We are going to re-snap so that we need to clobber scroll anchoring. + mAnchor.UserScrolled(); + + // Snap to the nearest snap position if exists. + ScrollToWithOrigin( + snapTarget->mPosition, nullptr /* range */, + ScrollOperationParams{ + IsSmoothScroll(ScrollBehavior::Auto) ? ScrollMode::SmoothMsd + : ScrollMode::Instant, + ScrollOrigin::Other, std::move(snapTarget->mTargetIds)}); + } +} + +void nsHTMLScrollFrame::PostPendingResnapIfNeeded(const nsIFrame* aFrame) { + if (!IsLastSnappedTarget(aFrame)) { + return; + } + + PostPendingResnap(); +} + +void nsHTMLScrollFrame::PostPendingResnap() { + PresShell()->PostPendingScrollResnap(this); +} + +nsIScrollableFrame::PhysicalScrollSnapAlign +nsHTMLScrollFrame::GetScrollSnapAlignFor(const nsIFrame* aFrame) const { + StyleScrollSnapAlignKeyword alignForY = StyleScrollSnapAlignKeyword::None; + StyleScrollSnapAlignKeyword alignForX = StyleScrollSnapAlignKeyword::None; + + nsIFrame* styleFrame = GetFrameForStyle(); + if (!styleFrame) { + return {alignForX, alignForY}; + } + + if (styleFrame->StyleDisplay()->mScrollSnapType.strictness == + StyleScrollSnapStrictness::None) { + return {alignForX, alignForY}; + } + + const nsStyleDisplay* styleDisplay = aFrame->StyleDisplay(); + if (styleDisplay->mScrollSnapAlign.inline_ == + StyleScrollSnapAlignKeyword::None && + styleDisplay->mScrollSnapAlign.block == + StyleScrollSnapAlignKeyword::None) { + return {alignForX, alignForY}; + } + + nsSize snapAreaSize = + ScrollSnapUtils::GetSnapAreaFor(aFrame, mScrolledFrame, GetScrolledRect()) + .Size(); + const WritingMode writingMode = + ScrollSnapUtils::NeedsToRespectTargetWritingMode(snapAreaSize, + GetSnapportSize()) + ? aFrame->GetWritingMode() + : styleFrame->GetWritingMode(); + + switch (styleFrame->StyleDisplay()->mScrollSnapType.axis) { + case StyleScrollSnapAxis::X: + alignForX = writingMode.IsVertical() + ? styleDisplay->mScrollSnapAlign.block + : styleDisplay->mScrollSnapAlign.inline_; + break; + case StyleScrollSnapAxis::Y: + alignForY = writingMode.IsVertical() + ? styleDisplay->mScrollSnapAlign.inline_ + : styleDisplay->mScrollSnapAlign.block; + break; + case StyleScrollSnapAxis::Block: + if (writingMode.IsVertical()) { + alignForX = styleDisplay->mScrollSnapAlign.block; + } else { + alignForY = styleDisplay->mScrollSnapAlign.block; + } + break; + case StyleScrollSnapAxis::Inline: + if (writingMode.IsVertical()) { + alignForY = styleDisplay->mScrollSnapAlign.inline_; + } else { + alignForX = styleDisplay->mScrollSnapAlign.inline_; + } + break; + case StyleScrollSnapAxis::Both: + if (writingMode.IsVertical()) { + alignForX = styleDisplay->mScrollSnapAlign.block; + alignForY = styleDisplay->mScrollSnapAlign.inline_; + } else { + alignForX = styleDisplay->mScrollSnapAlign.inline_; + alignForY = styleDisplay->mScrollSnapAlign.block; + } + break; + } + + return {alignForX, alignForY}; +} + +bool nsHTMLScrollFrame::UsesOverlayScrollbars() const { + return PresContext()->UseOverlayScrollbars(); +} + +bool nsHTMLScrollFrame::DragScroll(WidgetEvent* aEvent) { + // Dragging is allowed while within a 20 pixel border. Note that device pixels + // are used so that the same margin is used even when zoomed in or out. + nscoord margin = 20 * PresContext()->AppUnitsPerDevPixel(); + + // Don't drag scroll for small scrollareas. + if (mScrollPort.width < margin * 2 || mScrollPort.height < margin * 2) { + return false; + } + + // If willScroll is computed as false, then the frame is already scrolled as + // far as it can go in both directions. Return false so that an ancestor + // scrollframe can scroll instead. + bool willScroll = false; + nsPoint pnt = + nsLayoutUtils::GetEventCoordinatesRelativeTo(aEvent, RelativeTo{this}); + nsPoint scrollPoint = GetScrollPosition(); + nsRect rangeRect = GetLayoutScrollRange(); + + // Only drag scroll when a scrollbar is present. + nsPoint offset; + if (mHasHorizontalScrollbar) { + if (pnt.x >= mScrollPort.x && pnt.x <= mScrollPort.x + margin) { + offset.x = -margin; + if (scrollPoint.x > 0) { + willScroll = true; + } + } else if (pnt.x >= mScrollPort.XMost() - margin && + pnt.x <= mScrollPort.XMost()) { + offset.x = margin; + if (scrollPoint.x < rangeRect.width) { + willScroll = true; + } + } + } + + if (mHasVerticalScrollbar) { + if (pnt.y >= mScrollPort.y && pnt.y <= mScrollPort.y + margin) { + offset.y = -margin; + if (scrollPoint.y > 0) { + willScroll = true; + } + } else if (pnt.y >= mScrollPort.YMost() - margin && + pnt.y <= mScrollPort.YMost()) { + offset.y = margin; + if (scrollPoint.y < rangeRect.height) { + willScroll = true; + } + } + } + + if (offset.x || offset.y) { + ScrollToWithOrigin( + GetScrollPosition() + offset, nullptr /* range */, + ScrollOperationParams{ScrollMode::Normal, ScrollOrigin::Other}); + } + + return willScroll; +} + +static nsSliderFrame* GetSliderFrame(nsIFrame* aScrollbarFrame) { + if (!aScrollbarFrame) { + return nullptr; + } + + for (const auto& childList : aScrollbarFrame->ChildLists()) { + for (nsIFrame* frame : childList.mList) { + if (nsSliderFrame* sliderFrame = do_QueryFrame(frame)) { + return sliderFrame; + } + } + } + return nullptr; +} + +static void AsyncScrollbarDragInitiated(uint64_t aDragBlockId, + nsIFrame* aScrollbar) { + if (nsSliderFrame* sliderFrame = GetSliderFrame(aScrollbar)) { + sliderFrame->AsyncScrollbarDragInitiated(aDragBlockId); + } +} + +void nsHTMLScrollFrame::AsyncScrollbarDragInitiated( + uint64_t aDragBlockId, ScrollDirection aDirection) { + switch (aDirection) { + case ScrollDirection::eVertical: + ::AsyncScrollbarDragInitiated(aDragBlockId, mVScrollbarBox); + break; + case ScrollDirection::eHorizontal: + ::AsyncScrollbarDragInitiated(aDragBlockId, mHScrollbarBox); + break; + } +} + +static void AsyncScrollbarDragRejected(nsIFrame* aScrollbar) { + if (nsSliderFrame* sliderFrame = GetSliderFrame(aScrollbar)) { + sliderFrame->AsyncScrollbarDragRejected(); + } +} + +void nsHTMLScrollFrame::AsyncScrollbarDragRejected() { + // We don't get told which scrollbar requested the async drag, + // so we notify both. + ::AsyncScrollbarDragRejected(mHScrollbarBox); + ::AsyncScrollbarDragRejected(mVScrollbarBox); +} + +void nsHTMLScrollFrame::ApzSmoothScrollTo( + const nsPoint& aDestination, ScrollOrigin aOrigin, + ScrollTriggeredByScript aTriggeredByScript, + UniquePtr<ScrollSnapTargetIds> aSnapTargetIds) { + if (mApzSmoothScrollDestination == Some(aDestination)) { + // If we already sent APZ a smooth-scroll request to this + // destination (i.e. it was the last request + // we sent), then don't send another one because it is redundant. + // This is to avoid a scenario where pages do repeated scrollBy + // calls, incrementing the generation counter, and blocking APZ from + // syncing the scroll offset back to the main thread. + // Note that if we get two smooth-scroll requests to the same + // destination with some other scroll in between, + // mApzSmoothScrollDestination will get reset to Nothing() and so + // we shouldn't have the problem where this check discards a + // legitimate smooth-scroll. + return; + } + + // The animation will be handled in the compositor, pass the + // information needed to start the animation and skip the main-thread + // animation for this scroll. + MOZ_ASSERT(aOrigin != ScrollOrigin::None); + mApzSmoothScrollDestination = Some(aDestination); + AppendScrollUpdate(ScrollPositionUpdate::NewSmoothScroll( + aOrigin, aDestination, aTriggeredByScript, std::move(aSnapTargetIds))); + + nsIContent* content = GetContent(); + if (!DisplayPortUtils::HasNonMinimalNonZeroDisplayPort(content)) { + // If this frame doesn't have a displayport then there won't be an + // APZC instance for it and so there won't be anything to process + // this smooth scroll request. We should set a displayport on this + // frame to force an APZC which can handle the request. + if (MOZ_LOG_TEST(sDisplayportLog, LogLevel::Debug)) { + mozilla::layers::ScrollableLayerGuid::ViewID viewID = + mozilla::layers::ScrollableLayerGuid::NULL_SCROLL_ID; + nsLayoutUtils::FindIDFor(content, &viewID); + MOZ_LOG( + sDisplayportLog, LogLevel::Debug, + ("ApzSmoothScrollTo setting displayport on scrollId=%" PRIu64 "\n", + viewID)); + } + + DisplayPortUtils::CalculateAndSetDisplayPortMargins( + GetScrollTargetFrame(), DisplayPortUtils::RepaintMode::Repaint); + nsIFrame* frame = do_QueryFrame(GetScrollTargetFrame()); + DisplayPortUtils::SetZeroMarginDisplayPortOnAsyncScrollableAncestors(frame); + } + + // Schedule a paint to ensure that the frame metrics get updated on + // the compositor thread. + SchedulePaint(); +} + +bool nsHTMLScrollFrame::CanApzScrollInTheseDirections( + ScrollDirections aDirections) { + ScrollStyles styles = GetScrollStyles(); + if (aDirections.contains(ScrollDirection::eHorizontal) && + styles.mHorizontal == StyleOverflow::Hidden) + return false; + if (aDirections.contains(ScrollDirection::eVertical) && + styles.mVertical == StyleOverflow::Hidden) + return false; + return true; +} + +bool nsHTMLScrollFrame::SmoothScrollVisual( + const nsPoint& aVisualViewportOffset, + FrameMetrics::ScrollOffsetUpdateType aUpdateType) { + bool canDoApzSmoothScroll = + nsLayoutUtils::AsyncPanZoomEnabled(this) && WantAsyncScroll(); + if (!canDoApzSmoothScroll) { + return false; + } + + // Clamp the destination to the visual scroll range. + // There is a potential issue here, where |mDestination| is usually + // clamped to the layout scroll range, and so e.g. a subsequent + // window.scrollBy() may have an undesired effect. However, as this function + // is only called internally, this should not be a problem in practice. + // If it turns out to be, the fix would be: + // - add a new "destination" field that doesn't have to be clamped to + // the layout scroll range + // - clamp mDestination to the layout scroll range here + // - make sure ComputeScrollMetadata() picks up the former as the + // smooth scroll destination to send to APZ. + mDestination = GetVisualScrollRange().ClampPoint(aVisualViewportOffset); + + UniquePtr<ScrollSnapTargetIds> snapTargetIds; + // Perform the scroll. + ApzSmoothScrollTo(mDestination, + aUpdateType == FrameMetrics::eRestore + ? ScrollOrigin::Restore + : ScrollOrigin::Other, + ScrollTriggeredByScript::No, std::move(snapTargetIds)); + return true; +} + +bool nsHTMLScrollFrame::IsSmoothScroll(dom::ScrollBehavior aBehavior) const { + // The user smooth scrolling preference should be honored for any requested + // smooth scrolls. A requested smooth scroll when smooth scrolling is + // disabled should be equivalent to an instant scroll. + if (aBehavior == dom::ScrollBehavior::Instant || + !nsLayoutUtils::IsSmoothScrollingEnabled()) { + return false; + } + + if (aBehavior == dom::ScrollBehavior::Smooth) { + return true; + } + + nsIFrame* styleFrame = GetFrameForStyle(); + if (!styleFrame) { + return false; + } + return (aBehavior == dom::ScrollBehavior::Auto && + styleFrame->StyleDisplay()->mScrollBehavior == + StyleScrollBehavior::Smooth); +} + +nsTArray<ScrollPositionUpdate> nsHTMLScrollFrame::GetScrollUpdates() const { + return mScrollUpdates.Clone(); +} + +void nsHTMLScrollFrame::AppendScrollUpdate( + const ScrollPositionUpdate& aUpdate) { + mScrollGeneration = aUpdate.GetGeneration(); + mScrollUpdates.AppendElement(aUpdate); +} + +void nsHTMLScrollFrame::ScheduleScrollAnimations() { + nsIContent* content = GetContent(); + MOZ_ASSERT(content && content->IsElement(), + "The nsIScrollableFrame should have the element."); + + const Element* elementOrPseudo = content->AsElement(); + PseudoStyleType pseudo = elementOrPseudo->GetPseudoElementType(); + if (pseudo != PseudoStyleType::NotPseudo && + !AnimationUtils::IsSupportedPseudoForAnimations(pseudo)) { + // This is not an animatable pseudo element, and so we don't generate + // scroll-timeline for it. + return; + } + + const auto [element, type] = + AnimationUtils::GetElementPseudoPair(elementOrPseudo); + const auto* scheduler = ProgressTimelineScheduler::Get(element, type); + if (!scheduler) { + // We don't have scroll timelines associated with this frame. + return; + } + + scheduler->ScheduleAnimations(); +} |