1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef MINIKIN_LAYOUT_H 18 #define MINIKIN_LAYOUT_H 19 20 #include <hb.h> 21 22 #include <memory> 23 #include <vector> 24 25 #include <minikin/FontCollection.h> 26 27 namespace minikin { 28 29 struct LayoutGlyph { 30 // index into mFaces and mHbFonts vectors. We could imagine 31 // moving this into a run length representation, because it's 32 // more efficient for long strings, and we'll probably need 33 // something like that for paint attributes (color, underline, 34 // fake b/i, etc), as having those per-glyph is bloated. 35 int font_ix; 36 37 unsigned int glyph_id; 38 float x; 39 float y; 40 41 // libtxt extension: record the cluster (character index) that corresponds 42 // to this glyph 43 uint32_t cluster; 44 }; 45 46 // Internal state used during layout operation 47 struct LayoutContext; 48 49 enum { 50 kBidi_LTR = 0, 51 kBidi_RTL = 1, 52 kBidi_Default_LTR = 2, 53 kBidi_Default_RTL = 3, 54 kBidi_Force_LTR = 4, 55 kBidi_Force_RTL = 5, 56 57 kBidi_Mask = 0x7 58 }; 59 60 // Lifecycle and threading assumptions for Layout: 61 // The object is assumed to be owned by a single thread; multiple threads 62 // may not mutate it at the same time. 63 class Layout { 64 public: Layout()65 Layout() : mGlyphs(), mAdvances(), mFaces(), mAdvance(0), mBounds() { 66 mBounds.setEmpty(); 67 } 68 69 Layout(Layout&& layout) = default; 70 71 // Forbid copying and assignment. 72 Layout(const Layout&) = delete; 73 void operator=(const Layout&) = delete; 74 75 void dump() const; 76 77 void doLayout(const uint16_t* buf, 78 size_t start, 79 size_t count, 80 size_t bufSize, 81 bool isRtl, 82 const FontStyle& style, 83 const MinikinPaint& paint, 84 const std::shared_ptr<FontCollection>& collection); 85 86 static float measureText(const uint16_t* buf, 87 size_t start, 88 size_t count, 89 size_t bufSize, 90 bool isRtl, 91 const FontStyle& style, 92 const MinikinPaint& paint, 93 const std::shared_ptr<FontCollection>& collection, 94 float* advances); 95 96 // public accessors 97 size_t nGlyphs() const; 98 const MinikinFont* getFont(int i) const; 99 FontFakery getFakery(int i) const; 100 unsigned int getGlyphId(int i) const; 101 uint32_t getGlyphCluster(int i) const; // libtxt extension 102 float getX(int i) const; 103 float getY(int i) const; 104 105 float getAdvance() const; 106 107 // Get advances, copying into caller-provided buffer. The size of this 108 // buffer must match the length of the string (count arg to doLayout). 109 void getAdvances(float* advances); 110 111 // The i parameter is an offset within the buf relative to start, it is < 112 // count, where start and count are the parameters to doLayout getCharAdvance(size_t i)113 float getCharAdvance(size_t i) const { return mAdvances[i]; } 114 115 void getBounds(MinikinRect* rect) const; 116 117 // Purge all caches, useful in low memory conditions 118 static void purgeCaches(); 119 120 private: 121 friend class LayoutCacheKey; 122 123 // Find a face in the mFaces vector, or create a new entry 124 int findFace(const FakedFont& face, LayoutContext* ctx); 125 126 // Clears layout, ready to be used again 127 void reset(); 128 129 // Lay out a single bidi run 130 // When layout is not null, layout info will be stored in the object. 131 // When advances is not null, measurement results will be stored in the array. 132 static float doLayoutRunCached( 133 const uint16_t* buf, 134 size_t runStart, 135 size_t runLength, 136 size_t bufSize, 137 bool isRtl, 138 LayoutContext* ctx, 139 size_t dstStart, 140 const std::shared_ptr<FontCollection>& collection, 141 Layout* layout, 142 float* advances); 143 144 // Lay out a single word 145 static float doLayoutWord(const uint16_t* buf, 146 size_t start, 147 size_t count, 148 size_t bufSize, 149 bool isRtl, 150 LayoutContext* ctx, 151 size_t bufStart, 152 const std::shared_ptr<FontCollection>& collection, 153 Layout* layout, 154 float* advances); 155 156 // Lay out a single bidi run 157 void doLayoutRun(const uint16_t* buf, 158 size_t start, 159 size_t count, 160 size_t bufSize, 161 bool isRtl, 162 LayoutContext* ctx, 163 const std::shared_ptr<FontCollection>& collection); 164 165 // Append another layout (for example, cached value) into this one 166 void appendLayout(Layout* src, size_t start, float extraAdvance); 167 168 std::vector<LayoutGlyph> mGlyphs; 169 std::vector<float> mAdvances; 170 171 std::vector<FakedFont> mFaces; 172 float mAdvance; 173 MinikinRect mBounds; 174 }; 175 176 } // namespace minikin 177 178 #endif // MINIKIN_LAYOUT_H 179