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Diffstat (limited to 'layout/generic/TextOverflow.h')
| -rw-r--r-- | layout/generic/TextOverflow.h | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/layout/generic/TextOverflow.h b/layout/generic/TextOverflow.h new file mode 100644 index 0000000000..3f8e933c77 --- /dev/null +++ b/layout/generic/TextOverflow.h @@ -0,0 +1,305 @@ +/* -*- 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/. */ + +#ifndef TextOverflow_h_ +#define TextOverflow_h_ + +#include "nsDisplayList.h" +#include "nsTHashtable.h" +#include "mozilla/Attributes.h" +#include "mozilla/Likely.h" +#include "mozilla/UniquePtr.h" +#include "mozilla/WritingModes.h" +#include <algorithm> + +class nsIScrollableFrame; +class nsLineBox; + +namespace mozilla { +namespace css { + +/** + * A class for rendering CSS3 text-overflow. + * Usage: + * 1. allocate an object using WillProcessLines + * 2. then call ProcessLine for each line you are building display lists for + */ +class TextOverflow final { + public: + /** + * Allocate an object for text-overflow processing. + * @return nullptr if no processing is necessary. The caller owns the object. + */ + static Maybe<TextOverflow> WillProcessLines(nsDisplayListBuilder* aBuilder, + nsIFrame* aBlockFrame); + + /** + * Constructor, which client code SHOULD NOT use directly. Instead, clients + * should call WillProcessLines(), which is basically the factory function + * for TextOverflow instances. + */ + TextOverflow(nsDisplayListBuilder* aBuilder, nsIFrame* aBlockFrame); + + TextOverflow() = delete; + ~TextOverflow() = default; + TextOverflow(TextOverflow&&) = default; + TextOverflow(const TextOverflow&) = delete; + TextOverflow& operator=(TextOverflow&&) = default; + TextOverflow& operator=(const TextOverflow&) = delete; + + /** + * Analyze the display lists for text overflow and what kind of item is at + * the content edges. Add display items for text-overflow markers as needed + * and remove or clip items that would overlap a marker. + */ + void ProcessLine(const nsDisplayListSet& aLists, nsLineBox* aLine, + uint32_t aLineNumber); + + /** + * Get the resulting text-overflow markers (the list may be empty). + * @return a DisplayList containing any text-overflow markers. + */ + nsDisplayList& GetMarkers() { return mMarkerList; } + + // Returns whether aBlockFrame has text-overflow:clip on both sides. + static bool HasClippedTextOverflow(nsIFrame* aBlockFrame); + + // Returns whether aBlockFrame has a block ellipsis on one of its lines. + static bool HasBlockEllipsis(nsIFrame* aBlockFrame); + + // Returns whether aBlockFrame needs analysis for text overflow. + static bool CanHaveOverflowMarkers(nsIFrame* aBlockFrame); + + typedef nsTHashtable<nsPtrHashKey<nsIFrame>> FrameHashtable; + + private: + typedef mozilla::WritingMode WritingMode; + typedef mozilla::LogicalRect LogicalRect; + + // Edges to align the IStart and IEnd markers to. + struct AlignmentEdges { + AlignmentEdges() + : mIStart(0), mIEnd(0), mIEndOuter(0), mAssignedInner(false) {} + void AccumulateInner(WritingMode aWM, const LogicalRect& aRect) { + if (MOZ_LIKELY(mAssignedInner)) { + mIStart = std::min(mIStart, aRect.IStart(aWM)); + mIEnd = std::max(mIEnd, aRect.IEnd(aWM)); + } else { + mIStart = aRect.IStart(aWM); + mIEnd = aRect.IEnd(aWM); + mAssignedInner = true; + } + } + void AccumulateOuter(WritingMode aWM, const LogicalRect& aRect) { + mIEndOuter = std::max(mIEndOuter, aRect.IEnd(aWM)); + } + nscoord ISize() { return mIEnd - mIStart; } + + // The outermost edges of all text and atomic inline-level frames that are + // inside the area between the markers. + nscoord mIStart; + nscoord mIEnd; + + // The closest IEnd edge of all text and atomic inline-level frames that + // fall completely before the IStart edge of the content area. (Used to + // align a block ellipsis when there are no visible frames to align to.) + nscoord mIEndOuter; + + bool mAssignedInner; + }; + + struct InnerClipEdges { + InnerClipEdges() + : mIStart(0), mIEnd(0), mAssignedIStart(false), mAssignedIEnd(false) {} + void AccumulateIStart(WritingMode aWM, const LogicalRect& aRect) { + if (MOZ_LIKELY(mAssignedIStart)) { + mIStart = std::max(mIStart, aRect.IStart(aWM)); + } else { + mIStart = aRect.IStart(aWM); + mAssignedIStart = true; + } + } + void AccumulateIEnd(WritingMode aWM, const LogicalRect& aRect) { + if (MOZ_LIKELY(mAssignedIEnd)) { + mIEnd = std::min(mIEnd, aRect.IEnd(aWM)); + } else { + mIEnd = aRect.IEnd(aWM); + mAssignedIEnd = true; + } + } + nscoord mIStart; + nscoord mIEnd; + bool mAssignedIStart; + bool mAssignedIEnd; + }; + + LogicalRect GetLogicalScrollableOverflowRectRelativeToBlock( + nsIFrame* aFrame) const { + return LogicalRect( + mBlockWM, + aFrame->ScrollableOverflowRect() + aFrame->GetOffsetTo(mBlock), + mBlockSize); + } + + /** + * Examines frames on the line to determine whether we should draw a left + * and/or right marker, and if so, which frames should be completely hidden + * and the bounds of what will be displayed between the markers. + * @param aLine the line we're processing + * @param aFramesToHide frames that should have their display items removed + * @param aAlignmentEdges edges the markers will be aligned to, including + * the outermost edges of all text and atomic inline-level frames that + * are inside the content area, and the closest IEnd edge of such a frame + * outside the content area + * @return the area inside which we should add any markers; + * this is the block's content area narrowed by any floats on this line. + */ + LogicalRect ExamineLineFrames(nsLineBox* aLine, FrameHashtable* aFramesToHide, + AlignmentEdges* aAlignmentEdges); + + /** + * LineHasOverflowingText calls this to analyze edges, both the block's + * content edges and the hypothetical marker edges aligned at the block edges. + * @param aFrame the descendant frame of mBlock that we're analyzing + * @param aContentArea the block's content area + * @param aInsideMarkersArea the rectangle between the markers + * @param aFramesToHide frames that should have their display items removed + * @param aAlignmentEdges edges the markers will be aligned to, including + * the outermost edges of all text and atomic inline-level frames that + * are inside the content area, and the closest IEnd edge of such a frame + * outside the content area + * @param aFoundVisibleTextOrAtomic is set to true if a text or atomic + * inline-level frame is visible between the marker edges + * @param aClippedMarkerEdges the innermost edges of all text and atomic + * inline-level frames that are clipped by the current marker width + */ + void ExamineFrameSubtree(nsIFrame* aFrame, const LogicalRect& aContentArea, + const LogicalRect& aInsideMarkersArea, + FrameHashtable* aFramesToHide, + AlignmentEdges* aAlignmentEdges, + bool* aFoundVisibleTextOrAtomic, + InnerClipEdges* aClippedMarkerEdges); + + /** + * ExamineFrameSubtree calls this to analyze a frame against the hypothetical + * marker edges (aInsideMarkersArea) for text frames and atomic inline-level + * elements. A text frame adds its extent inside aInsideMarkersArea where + * grapheme clusters are fully visible. An atomic adds its border box if + * it's fully inside aInsideMarkersArea, otherwise the frame is added to + * aFramesToHide. + * @param aFrame the descendant frame of mBlock that we're analyzing + * @param aFrameType aFrame's frame type + * @param aInsideMarkersArea the rectangle between the markers + * @param aFramesToHide frames that should have their display items removed + * @param aAlignmentEdges the outermost edges of all text and atomic + * inline-level frames that are inside the area between the markers + * inside aInsideMarkersArea + * @param aAlignmentEdges edges the markers will be aligned to, including + * the outermost edges of all text and atomic inline-level frames that + * are inside aInsideMarkersArea, and the closest IEnd edge of such a frame + * outside the content area + * @param aFoundVisibleTextOrAtomic is set to true if a text or atomic + * inline-level frame is visible between the marker edges + * @param aClippedMarkerEdges the innermost edges of all text and atomic + * inline-level frames that are clipped by the current marker width + */ + void AnalyzeMarkerEdges(nsIFrame* aFrame, mozilla::LayoutFrameType aFrameType, + const LogicalRect& aInsideMarkersArea, + FrameHashtable* aFramesToHide, + AlignmentEdges* aAlignmentEdges, + bool* aFoundVisibleTextOrAtomic, + InnerClipEdges* aClippedMarkerEdges); + + /** + * Clip or remove items given the final marker edges. ("clip" here just means + * assigning mVisIStartEdge/mVisIEndEdge for any nsCharClipDisplayItem that + * needs it; see nsDisplayList.h for a description of that item). + * @param aFramesToHide remove display items for these frames + * @param aInsideMarkersArea is the area inside the markers + */ + void PruneDisplayListContents(nsDisplayList* aList, + const FrameHashtable& aFramesToHide, + const LogicalRect& aInsideMarkersArea); + + /** + * ProcessLine calls this to create display items for the markers and insert + * them into mMarkerList. + * @param aLine the line we're processing + * @param aCreateIStart if true, create a marker on the inline start side + * @param aCreateIEnd if true, create a marker on the inline end side + * @param aInsideMarkersArea is the area inside the markers + * @param aContentArea is the area inside which we should add the markers; + * this is the block's content area narrowed by any floats on this line. + */ + void CreateMarkers(const nsLineBox* aLine, bool aCreateIStart, + bool aCreateIEnd, const LogicalRect& aInsideMarkersArea, + const LogicalRect& aContentArea, uint32_t aLineNumber); + + LogicalRect mContentArea; + nsDisplayListBuilder* mBuilder; + nsIFrame* mBlock; + nsIScrollableFrame* mScrollableFrame; + nsDisplayList mMarkerList; + nsSize mBlockSize; + WritingMode mBlockWM; + bool mCanHaveInlineAxisScrollbar; + bool mAdjustForPixelSnapping; + + class Marker { + public: + void Init(const StyleTextOverflowSide& aStyle) { + mInitialized = false; + mISize = 0; + mStyle = &aStyle; + mIntrinsicISize = 0; + mHasOverflow = false; + mHasBlockEllipsis = false; + mActive = false; + mEdgeAligned = false; + } + + /** + * Setup the marker string and calculate its size, if not done already. + */ + void SetupString(nsIFrame* aFrame); + + bool IsSuppressed() const { return !mHasBlockEllipsis && mStyle->IsClip(); } + bool IsNeeded() const { return mHasOverflow || mHasBlockEllipsis; } + void Reset() { + mHasOverflow = false; + mHasBlockEllipsis = false; + mEdgeAligned = false; + } + + // The current width of the marker, the range is [0 .. mIntrinsicISize]. + nscoord mISize; + // The intrinsic width of the marker. + nscoord mIntrinsicISize; + // The text-overflow style for this side. Ignored if we're rendering a + // block ellipsis. + const StyleTextOverflowSide* mStyle; + // True if there is visible overflowing inline content on this side. + bool mHasOverflow; + // True if this side has a block ellipsis (from -webkit-line-clamp). + bool mHasBlockEllipsis; + // True if mISize and mIntrinsicISize have been setup from style. + bool mInitialized; + // True if the style is not text-overflow:clip on this side and the marker + // won't cause the line to become empty. + bool mActive; + // True if this marker is aligned to the edge of the content box, so that + // when scrolling the marker doesn't jump around. + bool mEdgeAligned; + }; + + Marker mIStart; // the inline start marker + Marker mIEnd; // the inline end marker +}; + +} // namespace css +} // namespace mozilla + +#endif /* !defined(TextOverflow_h_) */ |