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      1 /*
      2  * Copyright (C) 2012 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef HarfBuzzShaper_h
     32 #define HarfBuzzShaper_h
     33 
     34 #include "hb.h"
     35 #include "platform/geometry/FloatBoxExtent.h"
     36 #include "platform/geometry/FloatPoint.h"
     37 #include "platform/text/TextRun.h"
     38 #include "wtf/HashSet.h"
     39 #include "wtf/OwnPtr.h"
     40 #include "wtf/PassOwnPtr.h"
     41 #include "wtf/unicode/CharacterNames.h"
     42 #include "wtf/Vector.h"
     43 
     44 #include <unicode/uscript.h>
     45 
     46 namespace WebCore {
     47 
     48 class Font;
     49 class GlyphBuffer;
     50 class SimpleFontData;
     51 
     52 class HarfBuzzShaper FINAL {
     53 public:
     54     enum ForTextEmphasisOrNot {
     55         NotForTextEmphasis,
     56         ForTextEmphasis
     57     };
     58 
     59     HarfBuzzShaper(const Font*, const TextRun&, ForTextEmphasisOrNot = NotForTextEmphasis);
     60 
     61     void setDrawRange(int from, int to);
     62     bool shape(GlyphBuffer* = 0);
     63     FloatPoint adjustStartPoint(const FloatPoint&);
     64     float totalWidth() { return m_totalWidth; }
     65     int offsetForPosition(float targetX);
     66     FloatRect selectionRect(const FloatPoint&, int height, int from, int to);
     67     FloatBoxExtent glyphBoundingBox() const { return m_glyphBoundingBox; }
     68 
     69 private:
     70     class HarfBuzzRun {
     71     public:
     72         HarfBuzzRun(const HarfBuzzRun&);
     73         ~HarfBuzzRun();
     74 
     75         static PassOwnPtr<HarfBuzzRun> create(const SimpleFontData* fontData, unsigned startIndex, unsigned numCharacters, TextDirection direction, hb_script_t script)
     76         {
     77             return adoptPtr(new HarfBuzzRun(fontData, startIndex, numCharacters, direction, script));
     78         }
     79 
     80         void applyShapeResult(hb_buffer_t*);
     81         void copyShapeResultAndGlyphPositions(const HarfBuzzRun&);
     82         void setGlyphAndPositions(unsigned index, uint16_t glyphId, float advance, float offsetX, float offsetY);
     83         void setWidth(float width) { m_width = width; }
     84 
     85         int characterIndexForXPosition(float targetX);
     86         float xPositionForOffset(unsigned offset);
     87 
     88         const SimpleFontData* fontData() { return m_fontData; }
     89         unsigned startIndex() const { return m_startIndex; }
     90         unsigned numCharacters() const { return m_numCharacters; }
     91         unsigned numGlyphs() const { return m_numGlyphs; }
     92         uint16_t* glyphs() { return &m_glyphs[0]; }
     93         float* advances() { return &m_advances[0]; }
     94         FloatPoint* offsets() { return &m_offsets[0]; }
     95         bool hasGlyphToCharacterIndexes() const
     96         {
     97             return m_glyphToCharacterIndexes.size() > 0;
     98         }
     99         uint16_t* glyphToCharacterIndexes()
    100         {
    101             return &m_glyphToCharacterIndexes[0];
    102         }
    103         float width() { return m_width; }
    104         bool rtl() { return m_direction == RTL; }
    105         hb_script_t script() { return m_script; }
    106 
    107     private:
    108         HarfBuzzRun(const SimpleFontData*, unsigned startIndex, unsigned numCharacters, TextDirection, hb_script_t);
    109 
    110         const SimpleFontData* m_fontData;
    111         unsigned m_startIndex;
    112         size_t m_numCharacters;
    113         unsigned m_numGlyphs;
    114         TextDirection m_direction;
    115         hb_script_t m_script;
    116         Vector<uint16_t, 256> m_glyphs;
    117         Vector<float, 256> m_advances;
    118         Vector<uint16_t, 256> m_glyphToCharacterIndexes;
    119         Vector<FloatPoint, 256> m_offsets;
    120         float m_width;
    121     };
    122 
    123     bool isWordEnd(unsigned);
    124     int determineWordBreakSpacing();
    125     // setPadding sets a number of pixels to be distributed across the TextRun.
    126     // WebKit uses this to justify text.
    127     void setPadding(int);
    128 
    129     // In complex text word-spacing affects each line-break, space (U+0020) and non-breaking space (U+00A0).
    130     static bool isCodepointSpace(UChar c) { return c == ' ' || c == noBreakSpace || c == '\n'; }
    131 
    132     void setFontFeatures();
    133 
    134     bool createHarfBuzzRuns();
    135     bool shapeHarfBuzzRuns();
    136     bool fillGlyphBuffer(GlyphBuffer*);
    137     void fillGlyphBufferFromHarfBuzzRun(GlyphBuffer*, HarfBuzzRun*, FloatPoint& firstOffsetOfNextRun);
    138     void fillGlyphBufferForTextEmphasis(GlyphBuffer*, HarfBuzzRun* currentRun);
    139     void setGlyphPositionsForHarfBuzzRun(HarfBuzzRun*, hb_buffer_t*);
    140     void addHarfBuzzRun(unsigned startCharacter, unsigned endCharacter, const SimpleFontData*, UScriptCode);
    141 
    142     const Font* m_font;
    143     OwnPtr<UChar[]> m_normalizedBuffer;
    144     unsigned m_normalizedBufferLength;
    145     const TextRun& m_run;
    146 
    147     float m_wordSpacingAdjustment; // Delta adjustment (pixels) for each word break.
    148     float m_padding; // Pixels to be distributed over the line at word breaks.
    149     float m_padPerWordBreak; // Pixels to be added to each word break.
    150     float m_padError; // m_padPerWordBreak might have a fractional component. Since we only add a whole number of padding pixels at each word break we accumulate error. This is the number of pixels that we are behind so far.
    151     float m_letterSpacing; // Pixels to be added after each glyph.
    152 
    153     Vector<hb_feature_t, 4> m_features;
    154     Vector<OwnPtr<HarfBuzzRun>, 16> m_harfBuzzRuns;
    155 
    156     FloatPoint m_startOffset;
    157 
    158     int m_fromIndex;
    159     int m_toIndex;
    160 
    161     ForTextEmphasisOrNot m_forTextEmphasis;
    162 
    163     float m_totalWidth;
    164     FloatBoxExtent m_glyphBoundingBox;
    165 
    166     friend struct CachedShapingResults;
    167 };
    168 
    169 } // namespace WebCore
    170 
    171 #endif // HarfBuzzShaper_h
    172