1 2 /* 3 * Copyright 2009 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #include "SkHarfBuzzFont.h" 11 #include "SkFontHost.h" 12 #include "SkPaint.h" 13 #include "SkPath.h" 14 15 // HB_Fixed is a 26.6 fixed point format. 16 static inline HB_Fixed SkScalarToHarfbuzzFixed(SkScalar value) { 17 #ifdef SK_SCALAR_IS_FLOAT 18 return static_cast<HB_Fixed>(value * 64); 19 #else 20 // convert .16 to .6 21 return value >> (16 - 6); 22 #endif 23 } 24 25 static HB_Bool stringToGlyphs(HB_Font hbFont, const HB_UChar16* characters, 26 hb_uint32 length, HB_Glyph* glyphs, 27 hb_uint32* glyphsSize, HB_Bool isRTL) { 28 SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); 29 SkPaint paint; 30 31 paint.setTypeface(font->getTypeface()); 32 paint.setTextEncoding(SkPaint::kUTF16_TextEncoding); 33 int numGlyphs = paint.textToGlyphs(characters, length * sizeof(uint16_t), 34 reinterpret_cast<uint16_t*>(glyphs)); 35 36 // HB_Glyph is 32-bit, but Skia outputs only 16-bit numbers. So our 37 // |glyphs| array needs to be converted. 38 for (int i = numGlyphs - 1; i >= 0; --i) { 39 uint16_t value; 40 // We use a memcpy to avoid breaking strict aliasing rules. 41 memcpy(&value, reinterpret_cast<char*>(glyphs) + sizeof(uint16_t) * i, sizeof(uint16_t)); 42 glyphs[i] = value; 43 } 44 45 *glyphsSize = numGlyphs; 46 return 1; 47 } 48 49 static void glyphsToAdvances(HB_Font hbFont, const HB_Glyph* glyphs, 50 hb_uint32 numGlyphs, HB_Fixed* advances, int flags) { 51 SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); 52 SkPaint paint; 53 54 font->setupPaint(&paint); 55 paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); 56 57 SkAutoMalloc storage(numGlyphs * (sizeof(SkScalar) + sizeof(uint16_t))); 58 SkScalar* scalarWidths = reinterpret_cast<SkScalar*>(storage.get()); 59 uint16_t* glyphs16 = reinterpret_cast<uint16_t*>(scalarWidths + numGlyphs); 60 61 // convert HB 32bit glyphs to skia's 16bit 62 for (hb_uint32 i = 0; i < numGlyphs; ++i) { 63 glyphs16[i] = SkToU16(glyphs[i]); 64 } 65 paint.getTextWidths(glyphs16, numGlyphs * sizeof(uint16_t), scalarWidths); 66 67 for (hb_uint32 i = 0; i < numGlyphs; ++i) { 68 advances[i] = SkScalarToHarfbuzzFixed(scalarWidths[i]); 69 } 70 } 71 72 static HB_Bool canRender(HB_Font hbFont, const HB_UChar16* characters, 73 hb_uint32 length) { 74 SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); 75 SkPaint paint; 76 77 paint.setTypeface(font->getTypeface()); 78 paint.setTextEncoding(SkPaint::kUTF16_TextEncoding); 79 return paint.containsText(characters, length * sizeof(uint16_t)); 80 } 81 82 static HB_Error getOutlinePoint(HB_Font hbFont, HB_Glyph glyph, int flags, 83 hb_uint32 index, HB_Fixed* xPos, HB_Fixed* yPos, 84 hb_uint32* resultingNumPoints) { 85 SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); 86 SkPaint paint; 87 88 font->setupPaint(&paint); 89 paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); 90 if (flags & HB_ShaperFlag_UseDesignMetrics) { 91 paint.setHinting(SkPaint::kNo_Hinting); 92 } 93 94 SkPath path; 95 uint16_t glyph16 = SkToU16(glyph); 96 paint.getTextPath(&glyph16, sizeof(glyph16), 0, 0, &path); 97 int numPoints = path.countPoints(); 98 if (index >= numPoints) { 99 return HB_Err_Invalid_SubTable; 100 } 101 102 SkPoint pt = path.getPoint(index); 103 *xPos = SkScalarToHarfbuzzFixed(pt.fX); 104 *yPos = SkScalarToHarfbuzzFixed(pt.fY); 105 *resultingNumPoints = numPoints; 106 107 return HB_Err_Ok; 108 } 109 110 static void getGlyphMetrics(HB_Font hbFont, HB_Glyph glyph, 111 HB_GlyphMetrics* metrics) { 112 SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); 113 SkPaint paint; 114 115 font->setupPaint(&paint); 116 paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); 117 118 SkScalar width; 119 SkRect bounds; 120 uint16_t glyph16 = SkToU16(glyph); 121 paint.getTextWidths(&glyph16, sizeof(glyph16), &width, &bounds); 122 123 metrics->x = SkScalarToHarfbuzzFixed(bounds.fLeft); 124 metrics->y = SkScalarToHarfbuzzFixed(bounds.fTop); 125 metrics->width = SkScalarToHarfbuzzFixed(bounds.width()); 126 metrics->height = SkScalarToHarfbuzzFixed(bounds.height()); 127 128 metrics->xOffset = SkScalarToHarfbuzzFixed(width); 129 // We can't actually get the |y| correct because Skia doesn't export 130 // the vertical advance. However, nor we do ever render vertical text at 131 // the moment so it's unimportant. 132 metrics->yOffset = 0; 133 } 134 135 static HB_Fixed getFontMetric(HB_Font hbFont, HB_FontMetric metric) 136 { 137 SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); 138 SkPaint paint; 139 SkPaint::FontMetrics skiaMetrics; 140 141 font->setupPaint(&paint); 142 paint.getFontMetrics(&skiaMetrics); 143 144 switch (metric) { 145 case HB_FontAscent: 146 return SkScalarToHarfbuzzFixed(-skiaMetrics.fAscent); 147 default: 148 SkDebugf("--- unknown harfbuzz metric enum %d\n", metric); 149 return 0; 150 } 151 } 152 153 static HB_FontClass gSkHarfBuzzFontClass = { 154 stringToGlyphs, 155 glyphsToAdvances, 156 canRender, 157 getOutlinePoint, 158 getGlyphMetrics, 159 getFontMetric, 160 }; 161 162 const HB_FontClass& SkHarfBuzzFont::GetFontClass() { 163 return gSkHarfBuzzFontClass; 164 } 165 166 HB_Error SkHarfBuzzFont::GetFontTableFunc(void* voidface, const HB_Tag tag, 167 HB_Byte* buffer, HB_UInt* len) { 168 SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(voidface); 169 SkTypeface* typeface = font->getTypeface(); 170 171 const size_t tableSize = typeface->getTableSize(tag); 172 if (!tableSize) { 173 return HB_Err_Invalid_Argument; 174 } 175 // If Harfbuzz specified a NULL buffer then it's asking for the size. 176 if (!buffer) { 177 *len = tableSize; 178 return HB_Err_Ok; 179 } 180 181 if (*len < tableSize) { 182 // is this right, or should we just copy less than the full table? 183 return HB_Err_Invalid_Argument; 184 } 185 typeface->getTableData(tag, 0, tableSize, buffer); 186 return HB_Err_Ok; 187 } 188
