diff options
Diffstat (limited to 'gfx/layers/apz/util/DoubleTapToZoom.cpp')
| -rw-r--r-- | gfx/layers/apz/util/DoubleTapToZoom.cpp | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/gfx/layers/apz/util/DoubleTapToZoom.cpp b/gfx/layers/apz/util/DoubleTapToZoom.cpp new file mode 100644 index 0000000000..c40d79ced3 --- /dev/null +++ b/gfx/layers/apz/util/DoubleTapToZoom.cpp @@ -0,0 +1,376 @@ +/* -*- 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 "DoubleTapToZoom.h" + +#include <algorithm> // for std::min, std::max + +#include "mozilla/PresShell.h" +#include "mozilla/AlreadyAddRefed.h" +#include "mozilla/dom/Element.h" +#include "nsCOMPtr.h" +#include "nsIContent.h" +#include "mozilla/dom/Document.h" +#include "nsIFrame.h" +#include "nsIFrameInlines.h" +#include "nsIScrollableFrame.h" +#include "nsTableCellFrame.h" +#include "nsLayoutUtils.h" +#include "nsStyleConsts.h" +#include "mozilla/ViewportUtils.h" +#include "mozilla/EventListenerManager.h" + +namespace mozilla { +namespace layers { + +namespace { + +using FrameForPointOption = nsLayoutUtils::FrameForPointOption; + +static bool IsGeneratedContent(nsIContent* aContent) { + // We exclude marks because making them double tap targets does not seem + // desirable. + return aContent->IsGeneratedContentContainerForBefore() || + aContent->IsGeneratedContentContainerForAfter(); +} + +// Returns the DOM element found at |aPoint|, interpreted as being relative to +// the root frame of |aPresShell| in visual coordinates. If the point is inside +// a subdocument, returns an element inside the subdocument, rather than the +// subdocument element (and does so recursively). The implementation was adapted +// from DocumentOrShadowRoot::ElementFromPoint(), with the notable exception +// that we don't pass nsLayoutUtils::IGNORE_CROSS_DOC to GetFrameForPoint(), so +// as to get the behaviour described above in the presence of subdocuments. +static already_AddRefed<dom::Element> ElementFromPoint( + const RefPtr<PresShell>& aPresShell, const CSSPoint& aPoint) { + nsIFrame* rootFrame = aPresShell->GetRootFrame(); + if (!rootFrame) { + return nullptr; + } + nsIFrame* frame = nsLayoutUtils::GetFrameForPoint( + RelativeTo{rootFrame, ViewportType::Visual}, CSSPoint::ToAppUnits(aPoint), + {{FrameForPointOption::IgnorePaintSuppression}}); + while (frame && (!frame->GetContent() || + (frame->GetContent()->IsInNativeAnonymousSubtree() && + !IsGeneratedContent(frame->GetContent())))) { + frame = nsLayoutUtils::GetParentOrPlaceholderFor(frame); + } + if (!frame) { + return nullptr; + } + // FIXME(emilio): This should probably use the flattened tree, GetParent() is + // not guaranteed to be an element in presence of shadow DOM. + nsIContent* content = frame->GetContent(); + if (!content) { + return nullptr; + } + if (dom::Element* element = content->GetAsElementOrParentElement()) { + return do_AddRef(element); + } + return nullptr; +} + +// Get table cell from element, parent or grand parent. +static dom::Element* GetNearbyTableCell( + const nsCOMPtr<dom::Element>& aElement) { + nsTableCellFrame* tableCell = do_QueryFrame(aElement->GetPrimaryFrame()); + if (tableCell) { + return aElement.get(); + } + if (dom::Element* parent = aElement->GetFlattenedTreeParentElement()) { + nsTableCellFrame* tableCell = do_QueryFrame(parent->GetPrimaryFrame()); + if (tableCell) { + return parent; + } + if (dom::Element* grandParent = parent->GetFlattenedTreeParentElement()) { + tableCell = do_QueryFrame(grandParent->GetPrimaryFrame()); + if (tableCell) { + return grandParent; + } + } + } + return nullptr; +} + +static bool ShouldZoomToElement( + const nsCOMPtr<dom::Element>& aElement, + const RefPtr<dom::Document>& aRootContentDocument, + nsIScrollableFrame* aRootScrollFrame, const FrameMetrics& aMetrics) { + if (nsIFrame* frame = aElement->GetPrimaryFrame()) { + if (frame->StyleDisplay()->IsInlineFlow() && + // Replaced elements are suitable zoom targets because they act like + // inline-blocks instead of inline. (textarea's are the specific reason + // we do this) + !frame->IsFrameOfType(nsIFrame::eReplaced)) { + return false; + } + } + // Trying to zoom to the html element will just end up scrolling to the start + // of the document, return false and we'll run out of elements and just + // zoomout (without scrolling to the start). + if (aElement->OwnerDoc() == aRootContentDocument && + aElement->IsHTMLElement(nsGkAtoms::html)) { + return false; + } + if (aElement->IsAnyOfHTMLElements(nsGkAtoms::li, nsGkAtoms::q)) { + return false; + } + + // Ignore elements who are table cells or their parents are table cells, and + // they take up less than 30% of page rect width because they are likely cells + // in data tables (as opposed to tables used for layout purposes), and we + // don't want to zoom to them. This heuristic is quite naive and leaves a lot + // to be desired. + if (dom::Element* tableCell = GetNearbyTableCell(aElement)) { + CSSRect rect = + nsLayoutUtils::GetBoundingContentRect(tableCell, aRootScrollFrame); + if (rect.width < 0.3 * aMetrics.GetScrollableRect().width) { + return false; + } + } + + return true; +} + +// Calculates if zooming to aRect would have almost the same zoom level as +// aCompositedArea currently has. If so we would want to zoom out instead. +static bool RectHasAlmostSameZoomLevel(const CSSRect& aRect, + const CSSRect& aCompositedArea) { + // This functions checks to see if the area of the rect visible in the + // composition bounds (i.e. the overlapArea variable below) is approximately + // the max area of the rect we can show. + + // AsyncPanZoomController::ZoomToRect will adjust the zoom and scroll offset + // so that the zoom to rect fills the composited area. If after adjusting the + // scroll offset _only_ the rect would fill the composited area we want to + // zoom out (we don't want to _just_ scroll, we want to do some amount of + // zooming, either in or out it doesn't matter which). So translate both rects + // to the same origin and then compute their overlap, which is what the + // following calculation does. + + float overlapArea = std::min(aRect.width, aCompositedArea.width) * + std::min(aRect.height, aCompositedArea.height); + float availHeight = std::min( + aRect.Width() * aCompositedArea.Height() / aCompositedArea.Width(), + aRect.Height()); + float showing = overlapArea / (aRect.Width() * availHeight); + float ratioW = aRect.Width() / aCompositedArea.Width(); + float ratioH = aRect.Height() / aCompositedArea.Height(); + + return showing > 0.9 && (ratioW > 0.9 || ratioH > 0.9); +} + +} // namespace + +static CSSRect AddHMargin(const CSSRect& aRect, const CSSCoord& aMargin, + const FrameMetrics& aMetrics) { + CSSRect rect = + CSSRect(std::max(aMetrics.GetScrollableRect().X(), aRect.X() - aMargin), + aRect.Y(), aRect.Width() + 2 * aMargin, aRect.Height()); + // Constrict the rect to the screen's right edge + rect.SetWidth( + std::min(rect.Width(), aMetrics.GetScrollableRect().XMost() - rect.X())); + return rect; +} + +static CSSRect AddVMargin(const CSSRect& aRect, const CSSCoord& aMargin, + const FrameMetrics& aMetrics) { + CSSRect rect = + CSSRect(aRect.X(), + std::max(aMetrics.GetScrollableRect().Y(), aRect.Y() - aMargin), + aRect.Width(), aRect.Height() + 2 * aMargin); + // Constrict the rect to the screen's bottom edge + rect.SetHeight( + std::min(rect.Height(), aMetrics.GetScrollableRect().YMost() - rect.Y())); + return rect; +} + +static bool IsReplacedElement(const nsCOMPtr<dom::Element>& aElement) { + if (nsIFrame* frame = aElement->GetPrimaryFrame()) { + if (frame->IsFrameOfType(nsIFrame::eReplaced)) { + return true; + } + } + return false; +} + +static bool HasNonPassiveWheelListenerOnAncestor(nsIContent* aContent) { + for (nsIContent* content = aContent; content; + content = content->GetFlattenedTreeParent()) { + EventListenerManager* elm = content->GetExistingListenerManager(); + if (elm && elm->HasNonPassiveWheelListener()) { + return true; + } + } + return false; +} + +ZoomTarget CalculateRectToZoomTo( + const RefPtr<dom::Document>& aRootContentDocument, const CSSPoint& aPoint) { + // Ensure the layout information we get is up-to-date. + aRootContentDocument->FlushPendingNotifications(FlushType::Layout); + + // An empty rect as return value is interpreted as "zoom out". + const CSSRect zoomOut; + + RefPtr<PresShell> presShell = aRootContentDocument->GetPresShell(); + if (!presShell) { + return ZoomTarget{zoomOut, CantZoomOutBehavior::ZoomIn}; + } + + nsIScrollableFrame* rootScrollFrame = + presShell->GetRootScrollFrameAsScrollable(); + if (!rootScrollFrame) { + return ZoomTarget{zoomOut, CantZoomOutBehavior::ZoomIn}; + } + + CSSPoint documentRelativePoint = + CSSPoint::FromAppUnits(ViewportUtils::VisualToLayout( + CSSPoint::ToAppUnits(aPoint), presShell)) + + CSSPoint::FromAppUnits(rootScrollFrame->GetScrollPosition()); + + nsCOMPtr<dom::Element> element = ElementFromPoint(presShell, aPoint); + if (!element) { + return ZoomTarget{zoomOut, CantZoomOutBehavior::ZoomIn, Nothing(), + Some(documentRelativePoint)}; + } + + CantZoomOutBehavior cantZoomOutBehavior = + HasNonPassiveWheelListenerOnAncestor(element) + ? CantZoomOutBehavior::Nothing + : CantZoomOutBehavior::ZoomIn; + + FrameMetrics metrics = + nsLayoutUtils::CalculateBasicFrameMetrics(rootScrollFrame); + + while (element && !ShouldZoomToElement(element, aRootContentDocument, + rootScrollFrame, metrics)) { + element = element->GetFlattenedTreeParentElement(); + } + + if (!element) { + return ZoomTarget{zoomOut, cantZoomOutBehavior, Nothing(), + Some(documentRelativePoint)}; + } + + CSSPoint visualScrollOffset = metrics.GetVisualScrollOffset(); + CSSRect compositedArea(visualScrollOffset, + metrics.CalculateCompositedSizeInCssPixels()); + Maybe<CSSRect> nearestScrollClip; + CSSRect rect = nsLayoutUtils::GetBoundingContentRect(element, rootScrollFrame, + &nearestScrollClip); + + // In some cases, like overflow: visible and overflowing content, the bounding + // client rect of the targeted element won't contain the point the user double + // tapped on. In that case we use the scrollable overflow rect if it contains + // the user point. + if (!rect.Contains(documentRelativePoint)) { + if (nsIFrame* scrolledFrame = rootScrollFrame->GetScrolledFrame()) { + if (nsIFrame* f = element->GetPrimaryFrame()) { + nsRect overflowRect = f->ScrollableOverflowRect(); + nsLayoutUtils::TransformResult res = + nsLayoutUtils::TransformRect(f, scrolledFrame, overflowRect); + MOZ_ASSERT(res == nsLayoutUtils::TRANSFORM_SUCCEEDED || + res == nsLayoutUtils::NONINVERTIBLE_TRANSFORM); + if (res == nsLayoutUtils::TRANSFORM_SUCCEEDED) { + CSSRect overflowRectCSS = CSSRect::FromAppUnits(overflowRect); + if (nearestScrollClip.isSome()) { + overflowRectCSS = nearestScrollClip->Intersect(overflowRectCSS); + } + if (overflowRectCSS.Contains(documentRelativePoint)) { + rect = overflowRectCSS; + } + } + } + } + } + + CSSRect elementBoundingRect = rect; + + // Generally we zoom to the width of some element, but sometimes we zoom to + // the height. We set this to true when that happens so that we can add a + // vertical margin to the rect, otherwise it looks weird. + bool heightConstrained = false; + + // If the element is taller than the visible area of the page scale + // the height of the |rect| so that it has the same aspect ratio as + // the root frame. The clipped |rect| is centered on the y value of + // the touch point. This allows tall narrow elements to be zoomed. + if (!rect.IsEmpty() && compositedArea.Width() > 0.0f && + compositedArea.Height() > 0.0f) { + // Calculate the height of the rect if it had the same aspect ratio as + // compositedArea. + const float widthRatio = rect.Width() / compositedArea.Width(); + float targetHeight = compositedArea.Height() * widthRatio; + + // We don't want to cut off the top or bottoms of replaced elements that are + // square or wider in aspect ratio. + + // If it's a replaced element and we would otherwise trim it's height below + if (IsReplacedElement(element) && targetHeight < rect.Height() && + // If the target rect is at most 1.1x away from being square or wider + // aspect ratio + rect.Height() < 1.1 * rect.Width() && + // and our compositedArea is wider than it is tall + compositedArea.Width() >= compositedArea.Height()) { + heightConstrained = true; + // Expand the width of the rect so that it fills compositedArea so that if + // we are already zoomed to this element then the IsRectZoomedIn call + // below returns true so that we zoom out. This won't change what we + // actually zoom to as we are just making the rect the same aspect ratio + // as compositedArea. + float targetWidth = + rect.Height() * compositedArea.Width() / compositedArea.Height(); + MOZ_ASSERT(targetWidth > rect.Width()); + if (targetWidth > rect.Width()) { + rect.x -= (targetWidth - rect.Width()) / 2; + rect.SetWidth(targetWidth); + // keep elementBoundingRect containing rect + elementBoundingRect = rect; + } + + } else if (targetHeight < rect.Height()) { + // Trim the height so that the target rect has the same aspect ratio as + // compositedArea, centering it around the user tap point. + float newY = documentRelativePoint.y - (targetHeight * 0.5f); + if ((newY + targetHeight) > rect.YMost()) { + rect.MoveByY(rect.Height() - targetHeight); + } else if (newY > rect.Y()) { + rect.MoveToY(newY); + } + rect.SetHeight(targetHeight); + } + } + + const CSSCoord margin = 15; + rect = AddHMargin(rect, margin, metrics); + + if (heightConstrained) { + rect = AddVMargin(rect, margin, metrics); + } + + // If the rect is already taking up most of the visible area and is + // stretching the width of the page, then we want to zoom out instead. + if (RectHasAlmostSameZoomLevel(rect, compositedArea)) { + return ZoomTarget{zoomOut, cantZoomOutBehavior, Nothing(), + Some(documentRelativePoint)}; + } + + elementBoundingRect = AddHMargin(elementBoundingRect, margin, metrics); + + // Unlike rect, elementBoundingRect is the full height of the element we are + // zooming to. If we zoom to it without a margin it can look a weird, so give + // it a vertical margin. + elementBoundingRect = AddVMargin(elementBoundingRect, margin, metrics); + + rect.Round(); + elementBoundingRect.Round(); + return ZoomTarget{rect, cantZoomOutBehavior, Some(elementBoundingRect), + Some(documentRelativePoint)}; +} + +} // namespace layers +} // namespace mozilla |