gecko-dev/gfx/thebes/gfxSVGGlyphs.h

/* 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 GFX_SVG_GLYPHS_WRAPPER_H
#define GFX_SVG_GLYPHS_WRAPPER_H

#include "gfxFontUtils.h"
#include "mozilla/gfx/2D.h"
#include "nsString.h"
#include "nsClassHashtable.h"
#include "nsBaseHashtable.h"
#include "nsHashKeys.h"
#include "gfxPattern.h"
#include "mozilla/gfx/UserData.h"
#include "mozilla/SVGContextPaint.h"
#include "nsRefreshDriver.h"

class nsIDocument;
class nsIContentViewer;
class nsIPresShell;
class gfxSVGGlyphs;

namespace mozilla {
class SVGContextPaint;
namespace dom {
class Element;
} // namespace dom
} // namespace mozilla

/**
 * Wraps an SVG document contained in the SVG table of an OpenType font.
 * There may be multiple SVG documents in an SVG table which we lazily parse
 *   so we have an instance of this class for every document in the SVG table
 *   which contains a glyph ID which has been used
 * Finds and looks up elements contained in the SVG document which have glyph
 *   mappings to be drawn by gfxSVGGlyphs
 */
class gfxSVGGlyphsDocument final : public nsAPostRefreshObserver
{
    typedef mozilla::dom::Element Element;

public:
    gfxSVGGlyphsDocument(const uint8_t *aBuffer, uint32_t aBufLen,
                         gfxSVGGlyphs *aSVGGlyphs);

    Element *GetGlyphElement(uint32_t aGlyphId);

    ~gfxSVGGlyphsDocument();

    virtual void DidRefresh() override;

    size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

private:
    nsresult ParseDocument(const uint8_t *aBuffer, uint32_t aBufLen);

    nsresult SetupPresentation();

    void FindGlyphElements(Element *aElement);

    void InsertGlyphId(Element *aGlyphElement);

    // Weak so as not to create a cycle. mOwner owns us so this can't dangle.
    gfxSVGGlyphs* mOwner;
    nsCOMPtr<nsIDocument> mDocument;
    nsCOMPtr<nsIContentViewer> mViewer;
    nsCOMPtr<nsIPresShell> mPresShell;

    nsBaseHashtable<nsUint32HashKey, Element*, Element*> mGlyphIdMap;

    nsCString mSVGGlyphsDocumentURI;
};

/**
 * Used by |gfxFontEntry| to represent the SVG table of an OpenType font.
 * Handles lazy parsing of the SVG documents in the table, looking up SVG glyphs
 *   and rendering SVG glyphs.
 * Each |gfxFontEntry| owns at most one |gfxSVGGlyphs| instance.
 */
class gfxSVGGlyphs
{
private:
    typedef mozilla::dom::Element Element;

public:
    /**
     * @param aSVGTable The SVG table from the OpenType font
     *
     * The gfxSVGGlyphs object takes over ownership of the blob references
     * that are passed in, and will hb_blob_destroy() them when finished;
     * the caller should -not- destroy these references.
     */
    gfxSVGGlyphs(hb_blob_t *aSVGTable, gfxFontEntry *aFontEntry);

    /**
     * Releases our references to the SVG table and cleans up everything else.
     */
    ~gfxSVGGlyphs();

    /**
     * This is called when the refresh driver has ticked.
     */
    void DidRefresh();

    /**
     * Find the |gfxSVGGlyphsDocument| containing an SVG glyph for |aGlyphId|.
     * If |aGlyphId| does not map to an SVG document, return null.
     * If a |gfxSVGGlyphsDocument| has not been created for the document, create one.
     */
    gfxSVGGlyphsDocument *FindOrCreateGlyphsDocument(uint32_t aGlyphId);

    /**
     * Return true iff there is an SVG glyph for |aGlyphId|
     */
    bool HasSVGGlyph(uint32_t aGlyphId);

    /**
     * Render the SVG glyph for |aGlyphId|
     * @param aContextPaint Information on text context paints.
     *   See |SVGContextPaint|.
     */
    bool RenderGlyph(gfxContext *aContext, uint32_t aGlyphId,
                     mozilla::SVGContextPaint* aContextPaint);

    /**
     * Get the extents for the SVG glyph associated with |aGlyphId|
     * @param aSVGToAppSpace The matrix mapping the SVG glyph space to the
     *   target context space
     */
    bool GetGlyphExtents(uint32_t aGlyphId, const gfxMatrix& aSVGToAppSpace,
                         gfxRect *aResult);

    size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;

private:
    Element *GetGlyphElement(uint32_t aGlyphId);

    nsClassHashtable<nsUint32HashKey, gfxSVGGlyphsDocument> mGlyphDocs;
    nsBaseHashtable<nsUint32HashKey, Element*, Element*> mGlyphIdMap;

    hb_blob_t *mSVGData;
    gfxFontEntry *mFontEntry;

    const struct Header {
        mozilla::AutoSwap_PRUint16 mVersion;
        mozilla::AutoSwap_PRUint32 mDocIndexOffset;
        mozilla::AutoSwap_PRUint32 mColorPalettesOffset;
    } *mHeader;

    struct IndexEntry {
        mozilla::AutoSwap_PRUint16 mStartGlyph;
        mozilla::AutoSwap_PRUint16 mEndGlyph;
        mozilla::AutoSwap_PRUint32 mDocOffset;
        mozilla::AutoSwap_PRUint32 mDocLength;
    };

    const struct DocIndex {
      mozilla::AutoSwap_PRUint16 mNumEntries;
      IndexEntry mEntries[1]; /* actual length = mNumEntries */
    } *mDocIndex;

    static int CompareIndexEntries(const void *_a, const void *_b);
};

/**
 * XXX This is a complete hack and should die (see bug 1291494).
 *
 * This class is used when code fails to pass through an SVGContextPaint from
 * the context in which we are painting.  In that case we create one of these
 * as a fallback and have it wrap the gfxContext's current gfxPattern and
 * pretend that that is the paint context's fill pattern.  In some contexts
 * that will be the case, in others it will not.  As we convert more code to
 * Moz2D the less likely it is that this hack will work.  It will also make
 * converting to Moz2D harder.
 */
class SimpleTextContextPaint : public mozilla::SVGContextPaint
{
private:
    static const mozilla::gfx::Color sZero;

    static gfxMatrix SetupDeviceToPatternMatrix(gfxPattern *aPattern,
                                                const gfxMatrix& aCTM)
    {
        if (!aPattern) {
            return gfxMatrix();
        }
        gfxMatrix deviceToUser = aCTM;
        if (!deviceToUser.Invert()) {
            return gfxMatrix(0, 0, 0, 0, 0, 0); // singular
        }
        return deviceToUser * aPattern->GetMatrix();
    }

public:
    SimpleTextContextPaint(gfxPattern *aFillPattern, gfxPattern *aStrokePattern,
                          const gfxMatrix& aCTM) :
        mFillPattern(aFillPattern ? aFillPattern : new gfxPattern(sZero)),
        mStrokePattern(aStrokePattern ? aStrokePattern : new gfxPattern(sZero))
    {
        mFillMatrix = SetupDeviceToPatternMatrix(aFillPattern, aCTM);
        mStrokeMatrix = SetupDeviceToPatternMatrix(aStrokePattern, aCTM);
    }

    mozilla::Pair<DrawResult, RefPtr<gfxPattern>>
    GetFillPattern(const DrawTarget* aDrawTarget,
                   float aOpacity,
                   const gfxMatrix& aCTM,
                   uint32_t aFlags) {
        if (mFillPattern) {
            mFillPattern->SetMatrix(aCTM * mFillMatrix);
        }
        RefPtr<gfxPattern> fillPattern = mFillPattern;
        return MakePair(DrawResult::SUCCESS, Move(fillPattern));
    }

    mozilla::Pair<DrawResult, RefPtr<gfxPattern>>
    GetStrokePattern(const DrawTarget* aDrawTarget,
                     float aOpacity,
                     const gfxMatrix& aCTM,
                     uint32_t aFlags) {
        if (mStrokePattern) {
            mStrokePattern->SetMatrix(aCTM * mStrokeMatrix);
        }
        RefPtr<gfxPattern> strokePattern = mStrokePattern;
        return MakePair(DrawResult::SUCCESS, Move(strokePattern));
    }

    float GetFillOpacity() const {
        return mFillPattern ? 1.0f : 0.0f;
    }

    float GetStrokeOpacity() const {
        return mStrokePattern ? 1.0f : 0.0f;
    }

private:
    RefPtr<gfxPattern> mFillPattern;
    RefPtr<gfxPattern> mStrokePattern;

    // Device space to pattern space transforms
    gfxMatrix mFillMatrix;
    gfxMatrix mStrokeMatrix;
};

#endif