1 /* 2 * Copyright (c) 2010 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 ComplexTextControllerLinux_h 32 #define ComplexTextControllerLinux_h 33 34 #include "HarfbuzzSkia.h" 35 #include "SkScalar.h" 36 #include "TextRun.h" 37 38 #include <unicode/uchar.h> 39 #include <wtf/OwnArrayPtr.h> 40 #include <wtf/OwnPtr.h> 41 42 namespace WebCore { 43 44 class Font; 45 class FontPlatformData; 46 class SimpleFontData; 47 48 // ComplexTextController walks a TextRun and presents each script run in sequence. A 49 // TextRun is a sequence of code-points with the same embedding level (i.e. they 50 // are all left-to-right or right-to-left). A script run is a subsequence where 51 // all the characters have the same script (e.g. Arabic, Thai etc). Shaping is 52 // only ever done with script runs since the shapers only know how to deal with 53 // a single script. 54 // 55 // Iteration is always in logical (aka reading) order. For RTL text that means 56 // the rightmost part of the text will be first. 57 // 58 // Once you have setup the object, call |nextScriptRun| to get the first script 59 // run. This will return false when the iteration is complete. At any time you 60 // can call |reset| to start over again. 61 class ComplexTextController { 62 public: 63 ComplexTextController(const TextRun&, unsigned, const Font*); 64 ~ComplexTextController(); 65 66 bool isWordBreak(unsigned); 67 int determineWordBreakSpacing(unsigned); 68 // setPadding sets a number of pixels to be distributed across the TextRun. 69 // WebKit uses this to justify text. 70 void setPadding(int); 71 void reset(unsigned offset); 72 // Advance to the next script run, returning false when the end of the 73 // TextRun has been reached. 74 bool nextScriptRun(); 75 float widthOfFullRun(); 76 77 // setWordSpacingAdjustment sets a delta (in pixels) which is applied at 78 // each word break in the TextRun. 79 void setWordSpacingAdjustment(int wordSpacingAdjustment) { m_wordSpacingAdjustment = wordSpacingAdjustment; } 80 81 // setLetterSpacingAdjustment sets an additional number of pixels that is 82 // added to the advance after each output cluster. This matches the behaviour 83 // of WidthIterator::advance. 84 void setLetterSpacingAdjustment(int letterSpacingAdjustment) { m_letterSpacing = letterSpacingAdjustment; } 85 int letterSpacing() const { return m_letterSpacing; } 86 87 // Set the x offset for the next script run. This affects the values in 88 // |xPositions| 89 bool rtl() const { return m_run.rtl(); } 90 const uint16_t* glyphs() const { return m_glyphs16; } 91 92 // Return the length of the array returned by |glyphs| 93 const unsigned length() const { return m_item.num_glyphs; } 94 95 // Return the x offset for each of the glyphs. Note that this is translated 96 // by the current x offset and that the x offset is updated for each script 97 // run. 98 const SkScalar* xPositions() const { return m_xPositions; } 99 100 // Get the advances (widths) for each glyph. 101 const HB_Fixed* advances() const { return m_item.advances; } 102 103 // Return the width (in px) of the current script run. 104 const unsigned width() const { return m_pixelWidth; } 105 106 // Return the cluster log for the current script run. For example: 107 // script run: f i a n c (fi gets ligatured) 108 // log clutrs: 0 0 1 2 3 4 109 // So, for each input code point, the log tells you which output glyph was 110 // generated for it. 111 const unsigned short* logClusters() const { return m_item.log_clusters; } 112 113 // return the number of code points in the current script run 114 const unsigned numCodePoints() const { return m_item.item.length; } 115 116 // Return the current pixel position of the controller. 117 const unsigned offsetX() const { return m_offsetX; } 118 119 const FontPlatformData* fontPlatformDataForScriptRun() { return reinterpret_cast<FontPlatformData*>(m_item.font->userData); } 120 121 private: 122 void setupFontForScriptRun(); 123 HB_FontRec* allocHarfbuzzFont(); 124 void deleteGlyphArrays(); 125 void createGlyphArrays(int); 126 void resetGlyphArrays(); 127 void shapeGlyphs(); 128 void setGlyphXPositions(bool); 129 130 static void normalizeSpacesAndMirrorChars(const UChar* source, bool rtl, UChar* destination, int length); 131 static const TextRun& getNormalizedTextRun(const TextRun& originalRun, OwnPtr<TextRun>& normalizedRun, OwnArrayPtr<UChar>& normalizedBuffer); 132 133 // This matches the logic in RenderBlock::findNextLineBreak 134 static bool isCodepointSpace(HB_UChar16 c) { return c == ' ' || c == '\t'; } 135 136 const Font* const m_font; 137 const SimpleFontData* m_currentFontData; 138 HB_ShaperItem m_item; 139 uint16_t* m_glyphs16; // A vector of 16-bit glyph ids. 140 SkScalar* m_xPositions; // A vector of x positions for each glyph. 141 ssize_t m_indexOfNextScriptRun; // Indexes the script run in |m_run|. 142 unsigned m_offsetX; // Offset in pixels to the start of the next script run. 143 unsigned m_pixelWidth; // Width (in px) of the current script run. 144 unsigned m_glyphsArrayCapacity; // Current size of all the Harfbuzz arrays. 145 146 OwnPtr<TextRun> m_normalizedRun; 147 OwnArrayPtr<UChar> m_normalizedBuffer; // A buffer for normalized run. 148 const TextRun& m_run; 149 int m_wordSpacingAdjustment; // delta adjustment (pixels) for each word break. 150 float m_padding; // pixels to be distributed over the line at word breaks. 151 float m_padPerWordBreak; // pixels to be added to each word break. 152 float m_padError; // |m_padPerWordBreak| might have a fractional component. 153 // Since we only add a whole number of padding pixels at 154 // each word break we accumulate error. This is the 155 // number of pixels that we are behind so far. 156 int m_letterSpacing; // pixels to be added after each glyph. 157 String m_smallCapsString; // substring of m_run converted to small caps. 158 }; 159 160 } // namespace WebCore 161 162 #endif // ComplexTextControllerLinux_h 163
