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Diffstat (limited to 'dom/base/DOMIntersectionObserver.cpp')
| -rw-r--r-- | dom/base/DOMIntersectionObserver.cpp | 821 |
1 files changed, 821 insertions, 0 deletions
diff --git a/dom/base/DOMIntersectionObserver.cpp b/dom/base/DOMIntersectionObserver.cpp new file mode 100644 index 0000000000..12f7ee3029 --- /dev/null +++ b/dom/base/DOMIntersectionObserver.cpp @@ -0,0 +1,821 @@ +/* -*- 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/. */ + +#include "DOMIntersectionObserver.h" +#include "nsCSSPropertyID.h" +#include "nsIFrame.h" +#include "nsContainerFrame.h" +#include "nsIScrollableFrame.h" +#include "nsContentUtils.h" +#include "nsLayoutUtils.h" +#include "nsRefreshDriver.h" +#include "mozilla/PresShell.h" +#include "mozilla/StaticPrefs_dom.h" +#include "mozilla/StaticPrefs_layout.h" +#include "mozilla/ServoBindings.h" +#include "mozilla/dom/BrowserChild.h" +#include "mozilla/dom/BrowsingContext.h" +#include "mozilla/dom/DocumentInlines.h" +#include "mozilla/dom/HTMLImageElement.h" +#include "mozilla/dom/HTMLIFrameElement.h" +#include "Units.h" + +namespace mozilla::dom { + +NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DOMIntersectionObserverEntry) + NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY + NS_INTERFACE_MAP_ENTRY(nsISupports) +NS_INTERFACE_MAP_END + +NS_IMPL_CYCLE_COLLECTING_ADDREF(DOMIntersectionObserverEntry) +NS_IMPL_CYCLE_COLLECTING_RELEASE(DOMIntersectionObserverEntry) + +NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(DOMIntersectionObserverEntry, mOwner, + mRootBounds, mBoundingClientRect, + mIntersectionRect, mTarget) + +NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(DOMIntersectionObserver) + NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY + NS_INTERFACE_MAP_ENTRY(nsISupports) + NS_INTERFACE_MAP_ENTRY(DOMIntersectionObserver) +NS_INTERFACE_MAP_END + +NS_IMPL_CYCLE_COLLECTING_ADDREF(DOMIntersectionObserver) +NS_IMPL_CYCLE_COLLECTING_RELEASE(DOMIntersectionObserver) + +NS_IMPL_CYCLE_COLLECTION_CLASS(DOMIntersectionObserver) + +NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(DOMIntersectionObserver) + NS_IMPL_CYCLE_COLLECTION_TRACE_PRESERVED_WRAPPER +NS_IMPL_CYCLE_COLLECTION_TRACE_END + +NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(DOMIntersectionObserver) + NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER + tmp->Disconnect(); + NS_IMPL_CYCLE_COLLECTION_UNLINK(mOwner) + NS_IMPL_CYCLE_COLLECTION_UNLINK(mDocument) + if (tmp->mCallback.is<RefPtr<dom::IntersectionCallback>>()) { + ImplCycleCollectionUnlink( + tmp->mCallback.as<RefPtr<dom::IntersectionCallback>>()); + } + NS_IMPL_CYCLE_COLLECTION_UNLINK(mRoot) + NS_IMPL_CYCLE_COLLECTION_UNLINK(mQueuedEntries) +NS_IMPL_CYCLE_COLLECTION_UNLINK_END + +NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(DOMIntersectionObserver) + NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mOwner) + NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDocument) + if (tmp->mCallback.is<RefPtr<dom::IntersectionCallback>>()) { + ImplCycleCollectionTraverse( + cb, tmp->mCallback.as<RefPtr<dom::IntersectionCallback>>(), "mCallback", + 0); + } + NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRoot) + NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mQueuedEntries) +NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END + +DOMIntersectionObserver::DOMIntersectionObserver( + already_AddRefed<nsPIDOMWindowInner>&& aOwner, + dom::IntersectionCallback& aCb) + : mOwner(aOwner), + mDocument(mOwner->GetExtantDoc()), + mCallback(RefPtr<dom::IntersectionCallback>(&aCb)) {} + +already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor( + const GlobalObject& aGlobal, dom::IntersectionCallback& aCb, + ErrorResult& aRv) { + return Constructor(aGlobal, aCb, IntersectionObserverInit(), aRv); +} + +already_AddRefed<DOMIntersectionObserver> DOMIntersectionObserver::Constructor( + const GlobalObject& aGlobal, dom::IntersectionCallback& aCb, + const IntersectionObserverInit& aOptions, ErrorResult& aRv) { + nsCOMPtr<nsPIDOMWindowInner> window = + do_QueryInterface(aGlobal.GetAsSupports()); + if (!window) { + aRv.Throw(NS_ERROR_FAILURE); + return nullptr; + } + RefPtr<DOMIntersectionObserver> observer = + new DOMIntersectionObserver(window.forget(), aCb); + + if (!aOptions.mRoot.IsNull()) { + if (aOptions.mRoot.Value().IsElement()) { + observer->mRoot = aOptions.mRoot.Value().GetAsElement(); + } else { + MOZ_ASSERT(aOptions.mRoot.Value().IsDocument()); + observer->mRoot = aOptions.mRoot.Value().GetAsDocument(); + } + } + + if (!observer->SetRootMargin(aOptions.mRootMargin)) { + aRv.ThrowSyntaxError("rootMargin must be specified in pixels or percent."); + return nullptr; + } + + if (aOptions.mThreshold.IsDoubleSequence()) { + const Sequence<double>& thresholds = + aOptions.mThreshold.GetAsDoubleSequence(); + observer->mThresholds.SetCapacity(thresholds.Length()); + for (const auto& thresh : thresholds) { + if (thresh < 0.0 || thresh > 1.0) { + aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>(); + return nullptr; + } + observer->mThresholds.AppendElement(thresh); + } + observer->mThresholds.Sort(); + if (observer->mThresholds.IsEmpty()) { + observer->mThresholds.AppendElement(0.0); + } + } else { + double thresh = aOptions.mThreshold.GetAsDouble(); + if (thresh < 0.0 || thresh > 1.0) { + aRv.ThrowRangeError<dom::MSG_THRESHOLD_RANGE_ERROR>(); + return nullptr; + } + observer->mThresholds.AppendElement(thresh); + } + + return observer.forget(); +} + +static void LazyLoadCallback( + const Sequence<OwningNonNull<DOMIntersectionObserverEntry>>& aEntries) { + for (const auto& entry : aEntries) { + Element* target = entry->Target(); + if (entry->IsIntersecting()) { + if (auto* image = HTMLImageElement::FromNode(target)) { + image->StopLazyLoading(HTMLImageElement::StartLoading::Yes); + } else if (auto* iframe = HTMLIFrameElement::FromNode(target)) { + iframe->StopLazyLoading(); + } else { + MOZ_ASSERT_UNREACHABLE( + "Only <img> and <iframe> should be observed by lazy load observer"); + } + } + } +} + +static LengthPercentage PrefMargin(float aValue, bool aIsPercentage) { + return aIsPercentage ? LengthPercentage::FromPercentage(aValue / 100.0f) + : LengthPercentage::FromPixels(aValue); +} + +DOMIntersectionObserver::DOMIntersectionObserver(Document& aDocument, + NativeCallback aCallback) + : mOwner(aDocument.GetInnerWindow()), + mDocument(&aDocument), + mCallback(aCallback) {} + +already_AddRefed<DOMIntersectionObserver> +DOMIntersectionObserver::CreateLazyLoadObserver(Document& aDocument) { + RefPtr<DOMIntersectionObserver> observer = + new DOMIntersectionObserver(aDocument, LazyLoadCallback); + observer->mThresholds.AppendElement(0.0f); + +#define SET_MARGIN(side_, side_lower_) \ + observer->mRootMargin.Get(eSide##side_) = PrefMargin( \ + StaticPrefs::dom_image_lazy_loading_root_margin_##side_lower_(), \ + StaticPrefs:: \ + dom_image_lazy_loading_root_margin_##side_lower_##_percentage()); + SET_MARGIN(Top, top); + SET_MARGIN(Right, right); + SET_MARGIN(Bottom, bottom); + SET_MARGIN(Left, left); +#undef SET_MARGIN + + return observer.forget(); +} + +bool DOMIntersectionObserver::SetRootMargin(const nsACString& aString) { + return Servo_IntersectionObserverRootMargin_Parse(&aString, &mRootMargin); +} + +nsISupports* DOMIntersectionObserver::GetParentObject() const { return mOwner; } + +void DOMIntersectionObserver::GetRootMargin(nsACString& aRetVal) { + Servo_IntersectionObserverRootMargin_ToString(&mRootMargin, &aRetVal); +} + +void DOMIntersectionObserver::GetThresholds(nsTArray<double>& aRetVal) { + aRetVal = mThresholds.Clone(); +} + +void DOMIntersectionObserver::Observe(Element& aTarget) { + if (!mObservationTargetSet.EnsureInserted(&aTarget)) { + return; + } + aTarget.RegisterIntersectionObserver(this); + mObservationTargets.AppendElement(&aTarget); + + MOZ_ASSERT(mObservationTargets.Length() == mObservationTargetSet.Count()); + + Connect(); + if (mDocument) { + if (nsPresContext* pc = mDocument->GetPresContext()) { + pc->RefreshDriver()->EnsureIntersectionObservationsUpdateHappens(); + } + } +} + +void DOMIntersectionObserver::Unobserve(Element& aTarget) { + if (!mObservationTargetSet.EnsureRemoved(&aTarget)) { + return; + } + + mObservationTargets.RemoveElement(&aTarget); + aTarget.UnregisterIntersectionObserver(this); + + MOZ_ASSERT(mObservationTargets.Length() == mObservationTargetSet.Count()); + + if (mObservationTargets.IsEmpty()) { + Disconnect(); + } +} + +void DOMIntersectionObserver::UnlinkTarget(Element& aTarget) { + mObservationTargets.RemoveElement(&aTarget); + mObservationTargetSet.Remove(&aTarget); + if (mObservationTargets.IsEmpty()) { + Disconnect(); + } +} + +void DOMIntersectionObserver::Connect() { + if (mConnected) { + return; + } + + mConnected = true; + if (mDocument) { + mDocument->AddIntersectionObserver(this); + } +} + +void DOMIntersectionObserver::Disconnect() { + if (!mConnected) { + return; + } + + mConnected = false; + for (Element* target : mObservationTargets) { + target->UnregisterIntersectionObserver(this); + } + mObservationTargets.Clear(); + mObservationTargetSet.Clear(); + if (mDocument) { + mDocument->RemoveIntersectionObserver(this); + } +} + +void DOMIntersectionObserver::TakeRecords( + nsTArray<RefPtr<DOMIntersectionObserverEntry>>& aRetVal) { + aRetVal = std::move(mQueuedEntries); +} + +enum class BrowsingContextOrigin { Similar, Different }; + +// NOTE(emilio): Checking docgroup as per discussion in: +// https://github.com/w3c/IntersectionObserver/issues/161 +static BrowsingContextOrigin SimilarOrigin(const Element& aTarget, + const nsINode* aRoot) { + if (!aRoot) { + return BrowsingContextOrigin::Different; + } + return aTarget.OwnerDoc()->GetDocGroup() == aRoot->OwnerDoc()->GetDocGroup() + ? BrowsingContextOrigin::Similar + : BrowsingContextOrigin::Different; +} + +// NOTE: This returns nullptr if |aDocument| is in another process from the top +// level content document. +static const Document* GetTopLevelContentDocumentInThisProcess( + const Document& aDocument) { + auto* wc = aDocument.GetTopLevelWindowContext(); + return wc ? wc->GetExtantDoc() : nullptr; +} + +// https://w3c.github.io/IntersectionObserver/#compute-the-intersection +// +// TODO(emilio): Proof of this being equivalent to the spec welcome, seems +// reasonably close. +// +// Also, it's unclear to me why the spec talks about browsing context while +// discarding observations of targets of different documents. +// +// Both aRootBounds and the return value are relative to +// nsLayoutUtils::GetContainingBlockForClientRect(aRoot). +// +// In case of out-of-process document, aRemoteDocumentVisibleRect is a rectangle +// in the out-of-process document's coordinate system. +static Maybe<nsRect> ComputeTheIntersection( + nsIFrame* aTarget, nsIFrame* aRoot, const nsRect& aRootBounds, + const Maybe<nsRect>& aRemoteDocumentVisibleRect, + DOMIntersectionObserver::IsForProximityToViewport + aIsForProximityToViewport) { + nsIFrame* target = aTarget; + // 1. Let intersectionRect be the result of running the + // getBoundingClientRect() algorithm on the target. + // + // `intersectionRect` is kept relative to `target` during the loop. + auto inflowRect = nsLayoutUtils::GetAllInFlowRectsUnion( + target, target, nsLayoutUtils::RECTS_ACCOUNT_FOR_TRANSFORMS); + // For content-visibility, we need to observe the overflow clip edge, + // https://drafts.csswg.org/css-contain-2/#close-to-the-viewport + if (aIsForProximityToViewport == + DOMIntersectionObserver::IsForProximityToViewport::Yes) { + const auto& disp = *target->StyleDisplay(); + auto clipAxes = target->ShouldApplyOverflowClipping(&disp); + if (clipAxes != PhysicalAxes::None) { + inflowRect = OverflowAreas::GetOverflowClipRect( + inflowRect, inflowRect, clipAxes, + target->OverflowClipMargin(clipAxes)); + } + } + Maybe<nsRect> intersectionRect = Some(inflowRect); + + // 2. Let container be the containing block of the target. + // (We go through the parent chain and only look at scroll frames) + // + // FIXME(emilio): Spec uses containing blocks, we use scroll frames, but we + // only apply overflow-clipping, not clip-path, so it's ~fine. We do need to + // apply clip-path. + // + // 3. While container is not the intersection root: + nsIFrame* containerFrame = + nsLayoutUtils::GetCrossDocParentFrameInProcess(target); + while (containerFrame && containerFrame != aRoot) { + // FIXME(emilio): What about other scroll frames that inherit from + // nsHTMLScrollFrame but have a different type, like nsListControlFrame? + // This looks bogus in that case, but different bug. + if (nsIScrollableFrame* scrollFrame = do_QueryFrame(containerFrame)) { + if (containerFrame->GetParent() == aRoot && !aRoot->GetParent()) { + // This is subtle: if we're computing the intersection against the + // viewport (the root frame), and this is its scroll frame, we really + // want to skip this intersection (because we want to account for the + // root margin, which is already in aRootBounds). + break; + } + nsRect subFrameRect = scrollFrame->GetScrollPortRect(); + + // 3.1 Map intersectionRect to the coordinate space of container. + nsRect intersectionRectRelativeToContainer = + nsLayoutUtils::TransformFrameRectToAncestor( + target, intersectionRect.value(), containerFrame); + + // 3.2 If container has overflow clipping or a css clip-path property, + // update intersectionRect by applying container's clip. + // + // 3.3 is handled, looks like, by this same clipping, given the root + // scroll-frame cannot escape the viewport, probably? + intersectionRect = + intersectionRectRelativeToContainer.EdgeInclusiveIntersection( + subFrameRect); + if (!intersectionRect) { + return Nothing(); + } + target = containerFrame; + } else { + const auto& disp = *containerFrame->StyleDisplay(); + auto clipAxes = containerFrame->ShouldApplyOverflowClipping(&disp); + // 3.2 TODO: Apply clip-path. + if (clipAxes != PhysicalAxes::None) { + // 3.1 Map intersectionRect to the coordinate space of container. + const nsRect intersectionRectRelativeToContainer = + nsLayoutUtils::TransformFrameRectToAncestor( + target, intersectionRect.value(), containerFrame); + const nsRect clipRect = OverflowAreas::GetOverflowClipRect( + intersectionRectRelativeToContainer, + containerFrame->GetRectRelativeToSelf(), clipAxes, + containerFrame->OverflowClipMargin(clipAxes)); + intersectionRect = + intersectionRectRelativeToContainer.EdgeInclusiveIntersection( + clipRect); + if (!intersectionRect) { + return Nothing(); + } + target = containerFrame; + } + } + containerFrame = + nsLayoutUtils::GetCrossDocParentFrameInProcess(containerFrame); + } + MOZ_ASSERT(intersectionRect); + + // 4. Map intersectionRect to the coordinate space of the intersection root. + nsRect intersectionRectRelativeToRoot = + nsLayoutUtils::TransformFrameRectToAncestor( + target, intersectionRect.value(), + nsLayoutUtils::GetContainingBlockForClientRect(aRoot)); + + // 5.Update intersectionRect by intersecting it with the root intersection + // rectangle. + intersectionRect = + intersectionRectRelativeToRoot.EdgeInclusiveIntersection(aRootBounds); + if (intersectionRect.isNothing()) { + return Nothing(); + } + // 6. Map intersectionRect to the coordinate space of the viewport of the + // Document containing the target. + // + // FIXME(emilio): I think this may not be correct if the root is explicit + // and in the same document, since then the rectangle may not be relative to + // the viewport already (but it's in the same document). + nsRect rect = intersectionRect.value(); + if (aTarget->PresContext() != aRoot->PresContext()) { + if (nsIFrame* rootScrollFrame = + aTarget->PresShell()->GetRootScrollFrame()) { + nsLayoutUtils::TransformRect(aRoot, rootScrollFrame, rect); + } + } + + // In out-of-process iframes we need to take an intersection with the remote + // document visible rect which was already clipped by ancestor document's + // viewports. + if (aRemoteDocumentVisibleRect) { + MOZ_ASSERT(aRoot->PresContext()->IsRootContentDocumentInProcess() && + !aRoot->PresContext()->IsRootContentDocumentCrossProcess()); + + intersectionRect = + rect.EdgeInclusiveIntersection(*aRemoteDocumentVisibleRect); + if (intersectionRect.isNothing()) { + return Nothing(); + } + rect = intersectionRect.value(); + } + + return Some(rect); +} + +struct OopIframeMetrics { + nsIFrame* mInProcessRootFrame = nullptr; + nsRect mInProcessRootRect; + nsRect mRemoteDocumentVisibleRect; +}; + +static Maybe<OopIframeMetrics> GetOopIframeMetrics( + const Document& aDocument, const Document* aRootDocument) { + const Document* rootDoc = + nsContentUtils::GetInProcessSubtreeRootDocument(&aDocument); + MOZ_ASSERT(rootDoc); + + if (rootDoc->IsTopLevelContentDocument()) { + return Nothing(); + } + + if (aRootDocument && + rootDoc == + nsContentUtils::GetInProcessSubtreeRootDocument(aRootDocument)) { + // aRootDoc, if non-null, is either the implicit root + // (top-level-content-document) or a same-origin document passed explicitly. + // + // In the former case, we should've returned above if there are no iframes + // in between. This condition handles the explicit, same-origin root + // document, when both are embedded in an OOP iframe. + return Nothing(); + } + + PresShell* rootPresShell = rootDoc->GetPresShell(); + if (!rootPresShell || rootPresShell->IsDestroying()) { + return Some(OopIframeMetrics{}); + } + + nsIFrame* inProcessRootFrame = rootPresShell->GetRootFrame(); + if (!inProcessRootFrame) { + return Some(OopIframeMetrics{}); + } + + BrowserChild* browserChild = BrowserChild::GetFrom(rootDoc->GetDocShell()); + if (!browserChild) { + return Some(OopIframeMetrics{}); + } + + if (MOZ_UNLIKELY(browserChild->IsTopLevel())) { + // FIXME(bug 1772083): This can be hit, but it's unclear how... When can we + // have a top-level BrowserChild for a document that isn't a top-level + // content document? + MOZ_ASSERT_UNREACHABLE("Top level BrowserChild w/ non-top level Document?"); + return Nothing(); + } + + nsRect inProcessRootRect; + if (nsIScrollableFrame* scrollFrame = + rootPresShell->GetRootScrollFrameAsScrollable()) { + inProcessRootRect = scrollFrame->GetScrollPortRect(); + } + + Maybe<LayoutDeviceRect> remoteDocumentVisibleRect = + browserChild->GetTopLevelViewportVisibleRectInSelfCoords(); + if (!remoteDocumentVisibleRect) { + return Some(OopIframeMetrics{}); + } + + return Some(OopIframeMetrics{ + inProcessRootFrame, + inProcessRootRect, + LayoutDeviceRect::ToAppUnits( + *remoteDocumentVisibleRect, + rootPresShell->GetPresContext()->AppUnitsPerDevPixel()), + }); +} + +// https://w3c.github.io/IntersectionObserver/#update-intersection-observations-algo +// step 2.1 +IntersectionInput DOMIntersectionObserver::ComputeInput( + const Document& aDocument, const nsINode* aRoot, + const StyleRect<LengthPercentage>* aRootMargin) { + // 1 - Let rootBounds be observer's root intersection rectangle. + // ... but since the intersection rectangle depends on the target, we defer + // the inflation until later. + // NOTE: |rootRect| and |rootFrame| will be root in the same process. In + // out-of-process iframes, they are NOT root ones of the top level content + // document. + nsRect rootRect; + nsIFrame* rootFrame = nullptr; + const nsINode* root = aRoot; + const bool isImplicitRoot = !aRoot; + Maybe<nsRect> remoteDocumentVisibleRect; + if (aRoot && aRoot->IsElement()) { + if ((rootFrame = aRoot->AsElement()->GetPrimaryFrame())) { + nsRect rootRectRelativeToRootFrame; + if (nsIScrollableFrame* scrollFrame = do_QueryFrame(rootFrame)) { + // rootRectRelativeToRootFrame should be the content rect of rootFrame, + // not including the scrollbars. + rootRectRelativeToRootFrame = scrollFrame->GetScrollPortRect(); + } else { + // rootRectRelativeToRootFrame should be the border rect of rootFrame. + rootRectRelativeToRootFrame = rootFrame->GetRectRelativeToSelf(); + } + nsIFrame* containingBlock = + nsLayoutUtils::GetContainingBlockForClientRect(rootFrame); + rootRect = nsLayoutUtils::TransformFrameRectToAncestor( + rootFrame, rootRectRelativeToRootFrame, containingBlock); + } + } else { + MOZ_ASSERT(!aRoot || aRoot->IsDocument()); + const Document* rootDocument = + aRoot ? aRoot->AsDocument() + : GetTopLevelContentDocumentInThisProcess(aDocument); + root = rootDocument; + + if (rootDocument) { + // We're in the same process as the root document, though note that there + // could be an out-of-process iframe in between us and the root. Grab the + // root frame and the root rect. + // + // Note that the root rect is always good (we assume no DPI changes in + // between the two documents, and we don't need to convert coordinates). + // + // The root frame however we may need to tweak in the block below, if + // there's any OOP iframe in between `rootDocument` and `aDocument`, to + // handle the OOP iframe positions. + if (PresShell* presShell = rootDocument->GetPresShell()) { + rootFrame = presShell->GetRootFrame(); + // We use the root scrollable frame's scroll port to account the + // scrollbars in rootRect, if needed. + if (nsIScrollableFrame* scrollFrame = + presShell->GetRootScrollFrameAsScrollable()) { + rootRect = scrollFrame->GetScrollPortRect(); + } else if (rootFrame) { + rootRect = rootFrame->GetRectRelativeToSelf(); + } + } + } + + if (Maybe<OopIframeMetrics> metrics = + GetOopIframeMetrics(aDocument, rootDocument)) { + rootFrame = metrics->mInProcessRootFrame; + if (!rootDocument) { + rootRect = metrics->mInProcessRootRect; + } + remoteDocumentVisibleRect = Some(metrics->mRemoteDocumentVisibleRect); + } + } + + nsMargin rootMargin; // This root margin is NOT applied in `implicit root` + // case, e.g. in out-of-process iframes. + if (aRootMargin) { + for (const auto side : mozilla::AllPhysicalSides()) { + nscoord basis = side == eSideTop || side == eSideBottom + ? rootRect.Height() + : rootRect.Width(); + rootMargin.Side(side) = aRootMargin->Get(side).Resolve( + basis, static_cast<nscoord (*)(float)>(NSToCoordRoundWithClamp)); + } + } + return {isImplicitRoot, root, rootFrame, + rootRect, rootMargin, remoteDocumentVisibleRect}; +} + +// https://w3c.github.io/IntersectionObserver/#update-intersection-observations-algo +// (steps 2.1 - 2.5) +IntersectionOutput DOMIntersectionObserver::Intersect( + const IntersectionInput& aInput, const Element& aTarget, + IsForProximityToViewport aIsForProximityToViewport) { + const bool isSimilarOrigin = SimilarOrigin(aTarget, aInput.mRootNode) == + BrowsingContextOrigin::Similar; + nsIFrame* targetFrame = aTarget.GetPrimaryFrame(); + if (!targetFrame || !aInput.mRootFrame) { + return {isSimilarOrigin}; + } + + // "From the perspective of an IntersectionObserver, the skipped contents + // of an element are never intersecting the intersection root. This is + // true even if both the root and the target elements are in the skipped + // contents." + // https://drafts.csswg.org/css-contain/#cv-notes + // + // Skip the intersection if the element is hidden, unless this is the + // specifically to determine the proximity to the viewport for + // `content-visibility: auto` elements. + if (aIsForProximityToViewport == IsForProximityToViewport::No && + targetFrame->IsHiddenByContentVisibilityOnAnyAncestor()) { + return {isSimilarOrigin}; + } + + // 2.2. If the intersection root is not the implicit root, and target is + // not in the same Document as the intersection root, skip to step 11. + if (!aInput.mIsImplicitRoot && + aInput.mRootNode->OwnerDoc() != aTarget.OwnerDoc()) { + return {isSimilarOrigin}; + } + + // 2.3. If the intersection root is an element and target is not a descendant + // of the intersection root in the containing block chain, skip to step 11. + // + // NOTE(emilio): We also do this if target is the implicit root, pending + // clarification in + // https://github.com/w3c/IntersectionObserver/issues/456. + if (aInput.mRootFrame == targetFrame || + !nsLayoutUtils::IsAncestorFrameCrossDocInProcess(aInput.mRootFrame, + targetFrame)) { + return {isSimilarOrigin}; + } + + nsRect rootBounds = aInput.mRootRect; + if (isSimilarOrigin) { + rootBounds.Inflate(aInput.mRootMargin); + } + + // 2.4. Set targetRect to the DOMRectReadOnly obtained by running the + // getBoundingClientRect() algorithm on target. + nsRect targetRect = targetFrame->GetBoundingClientRect(); + // For content-visibility, we need to observe the overflow clip edge, + // https://drafts.csswg.org/css-contain-2/#close-to-the-viewport + if (aIsForProximityToViewport == IsForProximityToViewport::Yes) { + const auto& disp = *targetFrame->StyleDisplay(); + auto clipAxes = targetFrame->ShouldApplyOverflowClipping(&disp); + if (clipAxes != PhysicalAxes::None) { + targetRect = OverflowAreas::GetOverflowClipRect( + targetRect, targetRect, clipAxes, + targetFrame->OverflowClipMargin(clipAxes)); + } + } + + // 2.5. Let intersectionRect be the result of running the compute the + // intersection algorithm on target and observer’s intersection root. + Maybe<nsRect> intersectionRect = ComputeTheIntersection( + targetFrame, aInput.mRootFrame, rootBounds, + aInput.mRemoteDocumentVisibleRect, aIsForProximityToViewport); + + return {isSimilarOrigin, rootBounds, targetRect, intersectionRect}; +} + +IntersectionOutput DOMIntersectionObserver::Intersect( + const IntersectionInput& aInput, const nsRect& aTargetRect) { + nsRect rootBounds = aInput.mRootRect; + rootBounds.Inflate(aInput.mRootMargin); + auto intersectionRect = + aInput.mRootRect.EdgeInclusiveIntersection(aTargetRect); + if (intersectionRect && aInput.mRemoteDocumentVisibleRect) { + intersectionRect = intersectionRect->EdgeInclusiveIntersection( + *aInput.mRemoteDocumentVisibleRect); + } + return {true, rootBounds, aTargetRect, intersectionRect}; +} + +// https://w3c.github.io/IntersectionObserver/#update-intersection-observations-algo +// (step 2) +void DOMIntersectionObserver::Update(Document& aDocument, + DOMHighResTimeStamp time) { + auto input = ComputeInput(aDocument, mRoot, &mRootMargin); + + // 2. For each target in observer’s internal [[ObservationTargets]] slot, + // processed in the same order that observe() was called on each target: + for (Element* target : mObservationTargets) { + // 2.1 - 2.4. + IntersectionOutput output = Intersect(input, *target); + + // 2.5. Let targetArea be targetRect’s area. + int64_t targetArea = (int64_t)output.mTargetRect.Width() * + (int64_t)output.mTargetRect.Height(); + + // 2.6. Let intersectionArea be intersectionRect’s area. + int64_t intersectionArea = + !output.mIntersectionRect + ? 0 + : (int64_t)output.mIntersectionRect->Width() * + (int64_t)output.mIntersectionRect->Height(); + + // 2.7. Let isIntersecting be true if targetRect and rootBounds intersect or + // are edge-adjacent, even if the intersection has zero area (because + // rootBounds or targetRect have zero area); otherwise, let isIntersecting + // be false. + const bool isIntersecting = output.Intersects(); + + // 2.8. If targetArea is non-zero, let intersectionRatio be intersectionArea + // divided by targetArea. Otherwise, let intersectionRatio be 1 if + // isIntersecting is true, or 0 if isIntersecting is false. + double intersectionRatio; + if (targetArea > 0.0) { + intersectionRatio = + std::min((double)intersectionArea / (double)targetArea, 1.0); + } else { + intersectionRatio = isIntersecting ? 1.0 : 0.0; + } + + // 2.9 Let thresholdIndex be the index of the first entry in + // observer.thresholds whose value is greater than intersectionRatio, or the + // length of observer.thresholds if intersectionRatio is greater than or + // equal to the last entry in observer.thresholds. + int32_t thresholdIndex = -1; + + // If not intersecting, we can just shortcut, as we know that the thresholds + // are always between 0 and 1. + if (isIntersecting) { + thresholdIndex = mThresholds.IndexOfFirstElementGt(intersectionRatio); + if (thresholdIndex == 0) { + // Per the spec, we should leave threshold at 0 and distinguish between + // "less than all thresholds and intersecting" and "not intersecting" + // (queuing observer entries as both cases come to pass). However, + // neither Chrome nor the WPT tests expect this behavior, so treat these + // two cases as one. + // + // See https://github.com/w3c/IntersectionObserver/issues/432 about + // this. + thresholdIndex = -1; + } + } + + // Steps 2.10 - 2.15. + if (target->UpdateIntersectionObservation(this, thresholdIndex)) { + // See https://github.com/w3c/IntersectionObserver/issues/432 about + // why we use thresholdIndex > 0 rather than isIntersecting for the + // entry's isIntersecting value. + QueueIntersectionObserverEntry( + target, time, + output.mIsSimilarOrigin ? Some(output.mRootBounds) : Nothing(), + output.mTargetRect, output.mIntersectionRect, thresholdIndex > 0, + intersectionRatio); + } + } +} + +void DOMIntersectionObserver::QueueIntersectionObserverEntry( + Element* aTarget, DOMHighResTimeStamp time, const Maybe<nsRect>& aRootRect, + const nsRect& aTargetRect, const Maybe<nsRect>& aIntersectionRect, + bool aIsIntersecting, double aIntersectionRatio) { + RefPtr<DOMRect> rootBounds; + if (aRootRect.isSome()) { + rootBounds = new DOMRect(mOwner); + rootBounds->SetLayoutRect(aRootRect.value()); + } + RefPtr<DOMRect> boundingClientRect = new DOMRect(mOwner); + boundingClientRect->SetLayoutRect(aTargetRect); + RefPtr<DOMRect> intersectionRect = new DOMRect(mOwner); + if (aIntersectionRect.isSome()) { + intersectionRect->SetLayoutRect(aIntersectionRect.value()); + } + RefPtr<DOMIntersectionObserverEntry> entry = new DOMIntersectionObserverEntry( + mOwner, time, rootBounds.forget(), boundingClientRect.forget(), + intersectionRect.forget(), aIsIntersecting, aTarget, aIntersectionRatio); + mQueuedEntries.AppendElement(entry.forget()); +} + +void DOMIntersectionObserver::Notify() { + if (!mQueuedEntries.Length()) { + return; + } + Sequence<OwningNonNull<DOMIntersectionObserverEntry>> entries; + if (entries.SetCapacity(mQueuedEntries.Length(), mozilla::fallible)) { + for (size_t i = 0; i < mQueuedEntries.Length(); ++i) { + RefPtr<DOMIntersectionObserverEntry> next = mQueuedEntries[i]; + *entries.AppendElement(mozilla::fallible) = next; + } + } + mQueuedEntries.Clear(); + + if (mCallback.is<RefPtr<dom::IntersectionCallback>>()) { + RefPtr<dom::IntersectionCallback> callback( + mCallback.as<RefPtr<dom::IntersectionCallback>>()); + callback->Call(this, entries, *this); + } else { + mCallback.as<NativeCallback>()(entries); + } +} + +} // namespace mozilla::dom |