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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 "core/platform/graphics/FloatPoint.h"
     35 #include "core/platform/graphics/GlyphBuffer.h"
     36 #include "core/platform/graphics/TextRun.h"
     37 #include "hb.h"
     38 #include "wtf/HashSet.h"
     39 #include "wtf/OwnArrayPtr.h"
     40 #include "wtf/OwnPtr.h"
     41 #include "wtf/PassOwnPtr.h"
     42 #include "wtf/unicode/CharacterNames.h"
     43 #include "wtf/Vector.h"
     44 
     45 namespace WebCore {
     46 
     47 class Font;
     48 class SimpleFontData;
     49 
     50 class HarfBuzzShaper {
     51 public:
     52     enum NormalizeMode {
     53         DoNotNormalizeMirrorChars,
     54         NormalizeMirrorChars
     55     };
     56 
     57     HarfBuzzShaper(const Font*, const TextRun&);
     58     virtual ~HarfBuzzShaper();
     59 
     60     void setDrawRange(int from, int to);
     61     bool shape(GlyphBuffer* = 0);
     62     FloatPoint adjustStartPoint(const FloatPoint&);
     63     float totalWidth() { return m_totalWidth; }
     64     int offsetForPosition(float targetX);
     65     FloatRect selectionRect(const FloatPoint&, int height, int from, int to);
     66 
     67 private:
     68     class HarfBuzzRun {
     69     public:
     70         static PassOwnPtr<HarfBuzzRun> create(const SimpleFontData* fontData, unsigned startIndex, unsigned numCharacters, TextDirection direction, hb_script_t script)
     71         {
     72             return adoptPtr(new HarfBuzzRun(fontData, startIndex, numCharacters, direction, script));
     73         }
     74 
     75         void applyShapeResult(hb_buffer_t*);
     76         void setGlyphAndPositions(unsigned index, uint16_t glyphId, float advance, float offsetX, float offsetY);
     77         void setWidth(float width) { m_width = width; }
     78 
     79         int characterIndexForXPosition(float targetX);
     80         float xPositionForOffset(unsigned offset);
     81 
     82         const SimpleFontData* fontData() { return m_fontData; }
     83         unsigned startIndex() const { return m_startIndex; }
     84         unsigned numCharacters() const { return m_numCharacters; }
     85         unsigned numGlyphs() const { return m_numGlyphs; }
     86         uint16_t* glyphs() { return &m_glyphs[0]; }
     87         float* advances() { return &m_advances[0]; }
     88         FloatPoint* offsets() { return &m_offsets[0]; }
     89         uint16_t* glyphToCharacterIndexes() { return &m_glyphToCharacterIndexes[0]; }
     90         float width() { return m_width; }
     91         bool rtl() { return m_direction == RTL; }
     92         hb_script_t script() { return m_script; }
     93 
     94     private:
     95         HarfBuzzRun(const SimpleFontData*, unsigned startIndex, unsigned numCharacters, TextDirection, hb_script_t);
     96 
     97         const SimpleFontData* m_fontData;
     98         unsigned m_startIndex;
     99         size_t m_numCharacters;
    100         unsigned m_numGlyphs;
    101         TextDirection m_direction;
    102         hb_script_t m_script;
    103         Vector<uint16_t, 256> m_glyphs;
    104         Vector<float, 256> m_advances;
    105         Vector<uint16_t, 256> m_glyphToCharacterIndexes;
    106         Vector<FloatPoint, 256> m_offsets;
    107         float m_width;
    108     };
    109 
    110     void setNormalizedBuffer(NormalizeMode = DoNotNormalizeMirrorChars);
    111 
    112     bool isWordEnd(unsigned);
    113     int determineWordBreakSpacing();
    114     // setPadding sets a number of pixels to be distributed across the TextRun.
    115     // WebKit uses this to justify text.
    116     void setPadding(int);
    117 
    118     // In complex text word-spacing affects each line-break, space (U+0020) and non-breaking space (U+00A0).
    119     static bool isCodepointSpace(UChar c) { return c == ' ' || c == noBreakSpace || c == '\n'; }
    120 
    121     void setFontFeatures();
    122 
    123     bool collectHarfBuzzRuns();
    124     bool shapeHarfBuzzRuns(bool shouldSetDirection);
    125     bool fillGlyphBuffer(GlyphBuffer*);
    126     void fillGlyphBufferFromHarfBuzzRun(GlyphBuffer*, HarfBuzzRun*, FloatPoint& firstOffsetOfNextRun);
    127     void setGlyphPositionsForHarfBuzzRun(HarfBuzzRun*, hb_buffer_t*);
    128 
    129     GlyphBufferAdvance createGlyphBufferAdvance(float, float);
    130 
    131     const Font* m_font;
    132     OwnArrayPtr<UChar> m_normalizedBuffer;
    133     unsigned m_normalizedBufferLength;
    134     const TextRun& m_run;
    135 
    136     int m_wordSpacingAdjustment; // Delta adjustment (pixels) for each word break.
    137     float m_padding; // Pixels to be distributed over the line at word breaks.
    138     float m_padPerWordBreak; // Pixels to be added to each word break.
    139     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.
    140     int m_letterSpacing; // Pixels to be added after each glyph.
    141 
    142     Vector<hb_feature_t, 4> m_features;
    143     Vector<OwnPtr<HarfBuzzRun>, 16> m_harfBuzzRuns;
    144 
    145     FloatPoint m_startOffset;
    146 
    147     int m_fromIndex;
    148     int m_toIndex;
    149 
    150     float m_totalWidth;
    151 };
    152 
    153 } // namespace WebCore
    154 
    155 #endif // HarfBuzzShaper_h
    156