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Diffstat (limited to 'layout/svg/SVGTextFrame.h')
| -rw-r--r-- | layout/svg/SVGTextFrame.h | 589 |
1 files changed, 589 insertions, 0 deletions
diff --git a/layout/svg/SVGTextFrame.h b/layout/svg/SVGTextFrame.h new file mode 100644 index 0000000000..6789e90c0f --- /dev/null +++ b/layout/svg/SVGTextFrame.h @@ -0,0 +1,589 @@ +/* -*- 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 LAYOUT_SVG_SVGTEXTFRAME_H_ +#define LAYOUT_SVG_SVGTEXTFRAME_H_ + +#include "mozilla/Attributes.h" +#include "mozilla/PresShellForwards.h" +#include "mozilla/RefPtr.h" +#include "mozilla/SVGContainerFrame.h" +#include "mozilla/gfx/2D.h" +#include "gfxMatrix.h" +#include "gfxRect.h" +#include "gfxTextRun.h" +#include "nsIContent.h" // for GetContent +#include "nsStubMutationObserver.h" +#include "nsTextFrame.h" + +class gfxContext; + +namespace mozilla { + +class CharIterator; +class DisplaySVGText; +class SVGTextFrame; +class TextFrameIterator; +class TextNodeCorrespondenceRecorder; +struct TextRenderedRun; +class TextRenderedRunIterator; + +namespace dom { +struct DOMPointInit; +class DOMSVGPoint; +class SVGRect; +class SVGGeometryElement; +} // namespace dom +} // namespace mozilla + +nsIFrame* NS_NewSVGTextFrame(mozilla::PresShell* aPresShell, + mozilla::ComputedStyle* aStyle); + +namespace mozilla { + +/** + * Information about the positioning for a single character in an SVG <text> + * element. + * + * During SVG text layout, we use infinity values to represent positions and + * rotations that are not explicitly specified with x/y/rotate attributes. + */ +struct CharPosition { + CharPosition() + : mAngle(0), + mHidden(false), + mUnaddressable(false), + mClusterOrLigatureGroupMiddle(false), + mRunBoundary(false), + mStartOfChunk(false) {} + + CharPosition(gfxPoint aPosition, double aAngle) + : mPosition(aPosition), + mAngle(aAngle), + mHidden(false), + mUnaddressable(false), + mClusterOrLigatureGroupMiddle(false), + mRunBoundary(false), + mStartOfChunk(false) {} + + static CharPosition Unspecified(bool aUnaddressable) { + CharPosition cp(UnspecifiedPoint(), UnspecifiedAngle()); + cp.mUnaddressable = aUnaddressable; + return cp; + } + + bool IsAngleSpecified() const { return mAngle != UnspecifiedAngle(); } + + bool IsXSpecified() const { return mPosition.x != UnspecifiedCoord(); } + + bool IsYSpecified() const { return mPosition.y != UnspecifiedCoord(); } + + gfxPoint mPosition; + double mAngle; + + // not displayed due to falling off the end of a <textPath> + bool mHidden; + + // skipped in positioning attributes due to being collapsed-away white space + bool mUnaddressable; + + // a preceding character is what positioning attributes address + bool mClusterOrLigatureGroupMiddle; + + // rendering is split here since an explicit position or rotation was given + bool mRunBoundary; + + // an anchored chunk begins here + bool mStartOfChunk; + + private: + static gfxFloat UnspecifiedCoord() { + return std::numeric_limits<gfxFloat>::infinity(); + } + + static double UnspecifiedAngle() { + return std::numeric_limits<double>::infinity(); + } + + static gfxPoint UnspecifiedPoint() { + return gfxPoint(UnspecifiedCoord(), UnspecifiedCoord()); + } +}; + +/** + * A runnable to mark glyph positions as needing to be recomputed + * and to invalid the bounds of the SVGTextFrame frame. + */ +class GlyphMetricsUpdater : public Runnable { + public: + NS_DECL_NSIRUNNABLE + explicit GlyphMetricsUpdater(SVGTextFrame* aFrame) + : Runnable("GlyphMetricsUpdater"), mFrame(aFrame) {} + static void Run(SVGTextFrame* aFrame); + void Revoke() { mFrame = nullptr; } + + private: + SVGTextFrame* mFrame; +}; + +/** + * Frame class for SVG <text> elements. + * + * An SVGTextFrame manages SVG text layout, painting and interaction for + * all descendent text content elements. The frame tree will look like this: + * + * SVGTextFrame -- for <text> + * <anonymous block frame> + * ns{Block,Inline,Text}Frames -- for text nodes, <tspan>s, <a>s, etc. + * + * SVG text layout is done by: + * + * 1. Reflowing the anonymous block frame. + * 2. Inspecting the (app unit) positions of the glyph for each character in + * the nsTextFrames underneath the anonymous block frame. + * 3. Determining the (user unit) positions for each character in the <text> + * using the x/y/dx/dy/rotate attributes on all the text content elements, + * and using the step 2 results to fill in any gaps. + * 4. Applying any other SVG specific text layout (anchoring and text paths) + * to the positions computed in step 3. + * + * Rendering of the text is done by splitting up each nsTextFrame into ranges + * that can be contiguously painted. (For example <text x="10 20">abcd</text> + * would have two contiguous ranges: one for the "a" and one for the "bcd".) + * Each range is called a "text rendered run", represented by a TextRenderedRun + * object. The TextRenderedRunIterator class performs that splitting and + * returns a TextRenderedRun for each bit of text to be painted separately. + * + * Each rendered run is painted by calling nsTextFrame::PaintText. If the text + * formatting is simple enough (solid fill, no stroking, etc.), PaintText will + * itself do the painting. Otherwise, a DrawPathCallback is passed to + * PaintText so that we can fill the text geometry with SVG paint servers. + */ +class SVGTextFrame final : public SVGDisplayContainerFrame { + friend nsIFrame* ::NS_NewSVGTextFrame(mozilla::PresShell* aPresShell, + ComputedStyle* aStyle); + + friend class CharIterator; + friend class DisplaySVGText; + friend class GlyphMetricsUpdater; + friend class MutationObserver; + friend class TextFrameIterator; + friend class TextNodeCorrespondenceRecorder; + friend struct TextRenderedRun; + friend class TextRenderedRunIterator; + + using Range = gfxTextRun::Range; + using DrawTarget = gfx::DrawTarget; + using Path = gfx::Path; + using Point = gfx::Point; + using Rect = gfx::Rect; + + protected: + explicit SVGTextFrame(ComputedStyle* aStyle, nsPresContext* aPresContext) + : SVGDisplayContainerFrame(aStyle, aPresContext, kClassID), + mTrailingUndisplayedCharacters(0), + mFontSizeScaleFactor(1.0f), + mLastContextScale(1.0f), + mLengthAdjustScaleFactor(1.0f) { + AddStateBits(NS_FRAME_SVG_LAYOUT | NS_FRAME_IS_SVG_TEXT | + NS_STATE_SVG_TEXT_CORRESPONDENCE_DIRTY | + NS_STATE_SVG_POSITIONING_DIRTY); + } + + ~SVGTextFrame() = default; + + public: + NS_DECL_QUERYFRAME + NS_DECL_FRAMEARENA_HELPERS(SVGTextFrame) + + // nsIFrame: + void Init(nsIContent* aContent, nsContainerFrame* aParent, + nsIFrame* aPrevInFlow) override; + + nsresult AttributeChanged(int32_t aNamespaceID, nsAtom* aAttribute, + int32_t aModType) override; + + nsContainerFrame* GetContentInsertionFrame() override { + return PrincipalChildList().FirstChild()->GetContentInsertionFrame(); + } + + void BuildDisplayList(nsDisplayListBuilder* aBuilder, + const nsDisplayListSet& aLists) override; + +#ifdef DEBUG_FRAME_DUMP + nsresult GetFrameName(nsAString& aResult) const override { + return MakeFrameName(u"SVGText"_ns, aResult); + } +#endif + + /** + * Finds the nsTextFrame for the closest rendered run to the specified point. + */ + void FindCloserFrameForSelection( + const nsPoint& aPoint, FrameWithDistance* aCurrentBestFrame) override; + + // ISVGDisplayableFrame interface: + void NotifySVGChanged(uint32_t aFlags) override; + void PaintSVG(gfxContext& aContext, const gfxMatrix& aTransform, + imgDrawingParams& aImgParams) override; + nsIFrame* GetFrameForPoint(const gfxPoint& aPoint) override; + void ReflowSVG() override; + SVGBBox GetBBoxContribution(const Matrix& aToBBoxUserspace, + uint32_t aFlags) override; + + // SVG DOM text methods: + uint32_t GetNumberOfChars(nsIContent* aContent); + float GetComputedTextLength(nsIContent* aContent); + MOZ_CAN_RUN_SCRIPT_BOUNDARY void SelectSubString(nsIContent* aContent, + uint32_t charnum, + uint32_t nchars, + ErrorResult& aRv); + bool RequiresSlowFallbackForSubStringLength(); + float GetSubStringLengthFastPath(nsIContent* aContent, uint32_t charnum, + uint32_t nchars, ErrorResult& aRv); + /** + * This fallback version of GetSubStringLength takes + * into account glyph positioning and requires us to have flushed layout + * before calling it. As per the SVG 2 spec, typically glyph + * positioning does not affect the results of getSubStringLength, but one + * exception is text in a textPath where we need to ignore characters that + * fall off the end of the textPath path. + */ + float GetSubStringLengthSlowFallback(nsIContent* aContent, uint32_t charnum, + uint32_t nchars, ErrorResult& aRv); + + int32_t GetCharNumAtPosition(nsIContent* aContent, + const dom::DOMPointInit& aPoint); + + already_AddRefed<dom::DOMSVGPoint> GetStartPositionOfChar( + nsIContent* aContent, uint32_t aCharNum, ErrorResult& aRv); + already_AddRefed<dom::DOMSVGPoint> GetEndPositionOfChar(nsIContent* aContent, + uint32_t aCharNum, + ErrorResult& aRv); + already_AddRefed<dom::SVGRect> GetExtentOfChar(nsIContent* aContent, + uint32_t aCharNum, + ErrorResult& aRv); + float GetRotationOfChar(nsIContent* aContent, uint32_t aCharNum, + ErrorResult& aRv); + + // SVGTextFrame methods: + + /** + * Handles a base or animated attribute value change to a descendant + * text content element. + */ + void HandleAttributeChangeInDescendant(dom::Element* aElement, + int32_t aNameSpaceID, + nsAtom* aAttribute); + + /** + * Calls ScheduleReflowSVGNonDisplayText if this is a non-display frame, + * and SVGUtils::ScheduleReflowSVG otherwise. + */ + void ScheduleReflowSVG(); + + /** + * Reflows the anonymous block frame of this non-display SVGTextFrame. + * + * When we are under SVGDisplayContainerFrame::ReflowSVG, we need to + * reflow any SVGTextFrame frames in the subtree in case they are + * being observed (by being for example in a <mask>) and the change + * that caused the reflow would not already have caused a reflow. + * + * Note that displayed SVGTextFrames are reflowed as needed, when PaintSVG + * is called or some SVG DOM method is called on the element. + */ + void ReflowSVGNonDisplayText(); + + /** + * This is a function that behaves similarly to SVGUtils::ScheduleReflowSVG, + * but which will skip over any ancestor non-display container frames on the + * way to the SVGOuterSVGFrame. It exists for the situation where a + * non-display <text> element has changed and needs to ensure ReflowSVG will + * be called on its closest display container frame, so that + * SVGDisplayContainerFrame::ReflowSVG will call ReflowSVGNonDisplayText on + * it. + * + * We have to do this in two cases: in response to a style change on a + * non-display <text>, where aReason will be + * IntrinsicDirty::FrameAncestorsAndDescendants (the common case), and also in + * response to glyphs changes on non-display <text> (i.e., animated + * SVG-in-OpenType glyphs), in which case aReason will be None, since layout + * doesn't need to be recomputed. + */ + void ScheduleReflowSVGNonDisplayText(IntrinsicDirty aReason); + + /** + * Updates the mFontSizeScaleFactor value by looking at the range of + * font-sizes used within the <text>. + * + * @return Whether mFontSizeScaleFactor changed. + */ + bool UpdateFontSizeScaleFactor(); + + double GetFontSizeScaleFactor() const; + + /** + * Takes a point from the <text> element's user space and + * converts it to the appropriate frame user space of aChildFrame, + * according to which rendered run the point hits. + */ + Point TransformFramePointToTextChild(const Point& aPoint, + const nsIFrame* aChildFrame); + + /** + * Takes an app unit rectangle in the coordinate space of a given descendant + * frame of this frame, and returns a rectangle in the <text> element's user + * space that covers all parts of rendered runs that intersect with the + * rectangle. + */ + gfxRect TransformFrameRectFromTextChild(const nsRect& aRect, + const nsIFrame* aChildFrame); + + /** As above, but taking and returning a device px rect. */ + Rect TransformFrameRectFromTextChild(const Rect& aRect, + const nsIFrame* aChildFrame); + + /** As above, but with a single point */ + Point TransformFramePointFromTextChild(const Point& aPoint, + const nsIFrame* aChildFrame); + + // Return our ::-moz-svg-text anonymous box. + void AppendDirectlyOwnedAnonBoxes(nsTArray<OwnedAnonBox>& aResult) override; + + private: + /** + * Mutation observer used to watch for text positioning attribute changes + * on descendent text content elements (like <tspan>s). + */ + class MutationObserver final : public nsStubMutationObserver { + public: + explicit MutationObserver(SVGTextFrame* aFrame) : mFrame(aFrame) { + MOZ_ASSERT(mFrame, "MutationObserver needs a non-null frame"); + mFrame->GetContent()->AddMutationObserver(this); + } + + // nsISupports + NS_DECL_ISUPPORTS + + // nsIMutationObserver + NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED + NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED + NS_DECL_NSIMUTATIONOBSERVER_CONTENTREMOVED + NS_DECL_NSIMUTATIONOBSERVER_CHARACTERDATACHANGED + NS_DECL_NSIMUTATIONOBSERVER_ATTRIBUTECHANGED + + private: + ~MutationObserver() { mFrame->GetContent()->RemoveMutationObserver(this); } + + SVGTextFrame* const mFrame; + }; + + /** + * Resolves Bidi for the anonymous block child if it needs it. + */ + void MaybeResolveBidiForAnonymousBlockChild(); + + /** + * Reflows the anonymous block child if it is dirty or has dirty + * children, or if the SVGTextFrame itself is dirty. + */ + void MaybeReflowAnonymousBlockChild(); + + /** + * Performs the actual work of reflowing the anonymous block child. + */ + void DoReflow(); + + /** + * Schedules mPositions to be recomputed and the covered region to be + * updated. + */ + void NotifyGlyphMetricsChange(bool aUpdateTextCorrespondence); + + /** + * Recomputes mPositions by calling DoGlyphPositioning if this information + * is out of date. + */ + void UpdateGlyphPositioning(); + + /** + * Populates mPositions with positioning information for each character + * within the <text>. + */ + void DoGlyphPositioning(); + + /** + * Converts the specified index into mPositions to an addressable + * character index (as can be used with the SVG DOM text methods) + * relative to the specified text child content element. + * + * @param aIndex The global character index. + * @param aContent The descendant text child content element that + * the returned addressable index will be relative to; null + * means the same as the <text> element. + * @return The addressable index, or -1 if the index cannot be + * represented as an addressable index relative to aContent. + */ + int32_t ConvertTextElementCharIndexToAddressableIndex(int32_t aIndex, + nsIContent* aContent); + + /** + * Recursive helper for ResolvePositions below. + * + * @param aContent The current node. + * @param aIndex (in/out) The current character index. + * @param aInTextPath Whether we are currently under a <textPath> element. + * @param aForceStartOfChunk (in/out) Whether the next character we find + * should start a new anchored chunk. + * @param aDeltas (in/out) Receives the resolved dx/dy values for each + * character. + * @return false if we discover that mPositions did not have enough + * elements; true otherwise. + */ + bool ResolvePositionsForNode(nsIContent* aContent, uint32_t& aIndex, + bool aInTextPath, bool& aForceStartOfChunk, + nsTArray<gfxPoint>& aDeltas); + + /** + * Initializes mPositions with character position information based on + * x/y/rotate attributes, leaving unspecified values in the array if a + * position was not given for that character. Also fills aDeltas with values + * based on dx/dy attributes. + * + * @param aDeltas (in/out) Receives the resolved dx/dy values for each + * character. + * @param aRunPerGlyph Whether mPositions should record that a new run begins + * at each glyph. + * @return false if we did not record any positions (due to having no + * displayed characters) or if we discover that mPositions did not have + * enough elements; true otherwise. + */ + bool ResolvePositions(nsTArray<gfxPoint>& aDeltas, bool aRunPerGlyph); + + /** + * Determines the position, in app units, of each character in the <text> as + * laid out by reflow, and appends them to aPositions. Any characters that + * are undisplayed or trimmed away just get the last position. + */ + void DetermineCharPositions(nsTArray<nsPoint>& aPositions); + + /** + * Sets mStartOfChunk to true for each character in mPositions that starts a + * line of text. + */ + void AdjustChunksForLineBreaks(); + + /** + * Adjusts recorded character positions in mPositions to account for glyph + * boundaries. Four things are done: + * + * 1. mClusterOrLigatureGroupMiddle is set to true for all such characters. + * + * 2. Any run and anchored chunk boundaries that begin in the middle of a + * cluster/ligature group get moved to the start of the next + * cluster/ligature group. + * + * 3. The position of any character in the middle of a cluster/ligature + * group is updated to take into account partial ligatures and any + * rotation the glyph as a whole has. (The values that come out of + * DetermineCharPositions which then get written into mPositions in + * ResolvePositions store the same position value for each part of the + * ligature.) + * + * 4. The rotation of any character in the middle of a cluster/ligature + * group is set to the rotation of the first character. + */ + void AdjustPositionsForClusters(); + + /** + * Updates the character positions stored in mPositions to account for + * text anchoring. + */ + void DoAnchoring(); + + /** + * Updates character positions in mPositions for those characters inside a + * <textPath>. + */ + void DoTextPathLayout(); + + /** + * Returns whether we need to render the text using + * nsTextFrame::DrawPathCallbacks rather than directly painting + * the text frames. + * + * @param aShouldPaintSVGGlyphs (out) Whether SVG glyphs in the text + * should be painted. + */ + bool ShouldRenderAsPath(nsTextFrame* aFrame, bool& aShouldPaintSVGGlyphs); + + // Methods to get information for a <textPath> frame. + already_AddRefed<Path> GetTextPath(nsIFrame* aTextPathFrame); + gfxFloat GetOffsetScale(nsIFrame* aTextPathFrame); + gfxFloat GetStartOffset(nsIFrame* aTextPathFrame); + + /** + * The MutationObserver we have registered for the <text> element subtree. + */ + RefPtr<MutationObserver> mMutationObserver; + + /** + * The number of characters in the DOM after the final nsTextFrame. For + * example, with + * + * <text>abcd<tspan display="none">ef</tspan></text> + * + * mTrailingUndisplayedCharacters would be 2. + */ + uint32_t mTrailingUndisplayedCharacters; + + /** + * Computed position information for each DOM character within the <text>. + */ + nsTArray<CharPosition> mPositions; + + /** + * mFontSizeScaleFactor is used to cause the nsTextFrames to create text + * runs with a font size different from the actual font-size property value. + * This is used so that, for example with: + * + * <svg> + * <g transform="scale(2)"> + * <text font-size="10">abc</text> + * </g> + * </svg> + * + * a font size of 20 would be used. It's preferable to use a font size that + * is identical or close to the size that the text will appear on the screen, + * because at very small or large font sizes, text metrics will be computed + * differently due to the limited precision that text runs have. + * + * mFontSizeScaleFactor is the amount the actual font-size property value + * should be multiplied by to cause the text run font size to (a) be within a + * "reasonable" range, and (b) be close to the actual size to be painted on + * screen. (The "reasonable" range as determined by some #defines in + * SVGTextFrame.cpp is 8..200.) + */ + float mFontSizeScaleFactor; + + /** + * The scale of the context that we last used to compute mFontSizeScaleFactor. + * We record this so that we can tell when our scale transform has changed + * enough to warrant reflowing the text. + */ + float mLastContextScale; + + /** + * The amount that we need to scale each rendered run to account for + * lengthAdjust="spacingAndGlyphs". + */ + float mLengthAdjustScaleFactor; +}; + +} // namespace mozilla + +#endif // LAYOUT_SVG_SVGTEXTFRAME_H_ |