third_party/WebKit/Source/platform/fonts/GlyphBuffer.h

   1 /*
   2  * Copyright (C) 2006, 2009, 2011 Apple Inc. All rights reserved.
   3  * Copyright (C) 2007-2008 Torch Mobile Inc.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1.  Redistributions of source code must retain the above copyright
  10  *     notice, this list of conditions and the following disclaimer.
  11  * 2.  Redistributions in binary form must reproduce the above copyright
  12  *     notice, this list of conditions and the following disclaimer in the
  13  *     documentation and/or other materials provided with the distribution.
  14  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  15  *     its contributors may be used to endorse or promote products derived
  16  *     from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  21  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  22  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  25  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #ifndef GlyphBuffer_h
  31 #define GlyphBuffer_h
  32
  33 #include "platform/fonts/Glyph.h"
  34 #include "platform/geometry/FloatPoint.h"
  35 #include "platform/heap/Heap.h"
  36 #include "wtf/Vector.h"
  37
  38 namespace blink {
  39
  40 class SimpleFontData;
  41
  42 class GlyphBuffer {
  43     STACK_ALLOCATED();
  44 public:
  45     bool isEmpty() const { return m_fontData.isEmpty(); }
  46     unsigned size() const
  47     {
  48         ASSERT(m_fontData.size() == m_glyphs.size());
  49         ASSERT(m_fontData.size() == m_offsets.size() || 2 * m_fontData.size() == m_offsets.size());
  50         return m_fontData.size();
  51     }
  52
  53     bool hasVerticalOffsets() const
  54     {
  55         // We exclusively store either horizontal/x-only ofssets -- in which case m_offsets.size == size,
  56         // or vertical/xy offsets -- in which case m_offsets.size == size * 2.
  57         return size() != m_offsets.size();
  58     }
  59
  60     const Glyph* glyphs(unsigned from) const
  61     {
  62         ASSERT(from < size());
  63         return m_glyphs.data() + from;
  64     }
  65
  66     // Depending on the GlyphBuffer-wide positioning mode, this either points to an array of
  67     // x-only offsets for horizontal positioning ([x1, x2, ... xn]), or interleaved x,y offsets
  68     // for full positioning ([x1, y1, x2, y2, ... xn, yn]).
  69     const float* offsets(unsigned from) const
  70     {
  71         ASSERT(from < size());
  72         return m_offsets.data() + (hasVerticalOffsets() ? from * 2 : from);
  73     }
  74
  75     const SimpleFontData* fontDataAt(unsigned index) const
  76     {
  77         ASSERT(index < size());
  78         return m_fontData[index];
  79     }
  80
  81     Glyph glyphAt(unsigned index) const
  82     {
  83         ASSERT(index < size());
  84         return m_glyphs[index];
  85     }
  86
  87     float xOffsetAt(unsigned index) const
  88     {
  89         ASSERT(index < size());
  90         return hasVerticalOffsets() ? m_offsets[index * 2] : m_offsets[index];
  91
  92     }
  93
  94     float yOffsetAt(unsigned index) const
  95     {
  96         ASSERT(index < size());
  97         ASSERT(hasVerticalOffsets());
  98         return m_offsets[index * 2 + 1];
  99     }
 100
 101     void add(Glyph glyph, const SimpleFontData* font, float x)
 102     {
 103         // cannot mix x-only/xy offsets
 104         ASSERT(!hasVerticalOffsets());
 105
 106         m_fontData.append(font);
 107         m_glyphs.append(glyph);
 108         m_offsets.append(x);
 109     }
 110
 111     void add(Glyph glyph, const SimpleFontData* font, const FloatPoint& offset)
 112     {
 113         // cannot mix x-only/xy offsets
 114         ASSERT(isEmpty() || hasVerticalOffsets());
 115
 116         m_fontData.append(font);
 117         m_glyphs.append(glyph);
 118         m_offsets.append(offset.x());
 119         m_offsets.append(offset.y());
 120     }
 121
 122     void reverseForSimpleRTL(float afterOffset, float totalWidth)
 123     {
 124         ASSERT(!hasVerticalOffsets());
 125
 126         if (isEmpty())
 127             return;
 128
 129         m_fontData.reverse();
 130         m_glyphs.reverse();
 131
 132         // | .. [X0 X1 ..   Xn]     ..   |
 133         // ^                   ^         ^
 134         // 0             afterOffset totalWidth
 135         //
 136         // The input buffer is shaped using RTL advances, but since the right edge is unknown at
 137         // that time, offsets are computed as if the advances were LTR. This method performs the
 138         // required adjustments by reconstructing advances and positioning offsets in an RTL
 139         // progression.
 140
 141         // FIXME: we should get rid of this (idea: store negative offsets while shaping,
 142         //        and adjust the initial advance accordingly -> should yield correctly positioned
 143         //        RTL glyphs without any post-shape munging).
 144         ASSERT_WITH_SECURITY_IMPLICATION(!m_offsets.isEmpty());
 145         for (unsigned i = 0; i + 1 < m_offsets.size(); ++i)
 146             m_offsets[i] = totalWidth - m_offsets[i + 1];
 147         m_offsets.last() = totalWidth - afterOffset;
 148
 149         m_offsets.reverse();
 150     }
 151
 152 protected:
 153     Vector<const SimpleFontData*, 2048> m_fontData;
 154     Vector<Glyph, 2048> m_glyphs;
 155
 156     // Glyph positioning: either x-only offsets, or interleaved x,y offsets
 157     // (depending on the buffer-wide positioning mode). This matches the
 158     // glyph positioning format used by Skia.
 159     Vector<float, 2048> m_offsets;
 160 };
 161
 162 } // namespace blink
 163
 164 #endif