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Diffstat (limited to 'src/ports/SkHarfBuzzFont.cpp')
| -rw-r--r-- | src/ports/SkHarfBuzzFont.cpp | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/src/ports/SkHarfBuzzFont.cpp b/src/ports/SkHarfBuzzFont.cpp new file mode 100644 index 0000000..bb229a1 --- /dev/null +++ b/src/ports/SkHarfBuzzFont.cpp @@ -0,0 +1,195 @@ +/* + * Copyright (C) 2009 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include "SkHarfBuzzFont.h" +#include "SkFontHost.h" +#include "SkPaint.h" +#include "SkPath.h" + +// HB_Fixed is a 26.6 fixed point format. +static inline HB_Fixed SkScalarToHarfbuzzFixed(SkScalar value) { +#ifdef SK_SCALAR_IS_FLOAT + return static_cast<HB_Fixed>(value * 64); +#else + // convert .16 to .6 + return value >> (16 - 6); +#endif +} + +static HB_Bool stringToGlyphs(HB_Font hbFont, const HB_UChar16* characters, + hb_uint32 length, HB_Glyph* glyphs, + hb_uint32* glyphsSize, HB_Bool isRTL) { + SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); + SkPaint paint; + + paint.setTypeface(font->getTypeface()); + paint.setTextEncoding(SkPaint::kUTF16_TextEncoding); + int numGlyphs = paint.textToGlyphs(characters, length * sizeof(uint16_t), + reinterpret_cast<uint16_t*>(glyphs)); + + // HB_Glyph is 32-bit, but Skia outputs only 16-bit numbers. So our + // |glyphs| array needs to be converted. + for (int i = numGlyphs - 1; i >= 0; --i) { + uint16_t value; + // We use a memcpy to avoid breaking strict aliasing rules. + memcpy(&value, reinterpret_cast<char*>(glyphs) + sizeof(uint16_t) * i, sizeof(uint16_t)); + glyphs[i] = value; + } + + *glyphsSize = numGlyphs; + return 1; +} + +static void glyphsToAdvances(HB_Font hbFont, const HB_Glyph* glyphs, + hb_uint32 numGlyphs, HB_Fixed* advances, int flags) { + SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); + SkPaint paint; + + font->setupPaint(&paint); + paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); + + SkAutoMalloc storage(numGlyphs * (sizeof(SkScalar) + sizeof(uint16_t))); + SkScalar* scalarWidths = reinterpret_cast<SkScalar*>(storage.get()); + uint16_t* glyphs16 = reinterpret_cast<uint16_t*>(scalarWidths + numGlyphs); + + // convert HB 32bit glyphs to skia's 16bit + for (hb_uint32 i = 0; i < numGlyphs; ++i) { + glyphs16[i] = SkToU16(glyphs[i]); + } + paint.getTextWidths(glyphs16, numGlyphs * sizeof(uint16_t), scalarWidths); + + for (hb_uint32 i = 0; i < numGlyphs; ++i) { + advances[i] = SkScalarToHarfbuzzFixed(scalarWidths[i]); + } +} + +static HB_Bool canRender(HB_Font hbFont, const HB_UChar16* characters, + hb_uint32 length) { + SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); + SkPaint paint; + + paint.setTypeface(font->getTypeface()); + paint.setTextEncoding(SkPaint::kUTF16_TextEncoding); + return paint.containsText(characters, length * sizeof(uint16_t)); +} + +static HB_Error getOutlinePoint(HB_Font hbFont, HB_Glyph glyph, int flags, + hb_uint32 index, HB_Fixed* xPos, HB_Fixed* yPos, + hb_uint32* resultingNumPoints) { + SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); + SkPaint paint; + + font->setupPaint(&paint); + paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); + if (flags & HB_ShaperFlag_UseDesignMetrics) { + paint.setHinting(SkPaint::kNo_Hinting); + } + + SkPath path; + uint16_t glyph16 = SkToU16(glyph); + paint.getTextPath(&glyph16, sizeof(glyph16), 0, 0, &path); + int numPoints = path.countPoints(); + if (index >= numPoints) { + return HB_Err_Invalid_SubTable; + } + + SkPoint pt = path.getPoint(index); + *xPos = SkScalarToHarfbuzzFixed(pt.fX); + *yPos = SkScalarToHarfbuzzFixed(pt.fY); + *resultingNumPoints = numPoints; + + return HB_Err_Ok; +} + +static void getGlyphMetrics(HB_Font hbFont, HB_Glyph glyph, + HB_GlyphMetrics* metrics) { + SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); + SkPaint paint; + + font->setupPaint(&paint); + paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding); + + SkScalar width; + SkRect bounds; + uint16_t glyph16 = SkToU16(glyph); + paint.getTextWidths(&glyph16, sizeof(glyph16), &width, &bounds); + + metrics->x = SkScalarToHarfbuzzFixed(bounds.fLeft); + metrics->y = SkScalarToHarfbuzzFixed(bounds.fTop); + metrics->width = SkScalarToHarfbuzzFixed(bounds.width()); + metrics->height = SkScalarToHarfbuzzFixed(bounds.height()); + + metrics->xOffset = SkScalarToHarfbuzzFixed(width); + // We can't actually get the |y| correct because Skia doesn't export + // the vertical advance. However, nor we do ever render vertical text at + // the moment so it's unimportant. + metrics->yOffset = 0; +} + +static HB_Fixed getFontMetric(HB_Font hbFont, HB_FontMetric metric) +{ + SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData); + SkPaint paint; + SkPaint::FontMetrics skiaMetrics; + + font->setupPaint(&paint); + paint.getFontMetrics(&skiaMetrics); + + switch (metric) { + case HB_FontAscent: + return SkScalarToHarfbuzzFixed(-skiaMetrics.fAscent); + default: + SkDebugf("--- unknown harfbuzz metric enum %d\n", metric); + return 0; + } +} + +static HB_FontClass gSkHarfBuzzFontClass = { + stringToGlyphs, + glyphsToAdvances, + canRender, + getOutlinePoint, + getGlyphMetrics, + getFontMetric, +}; + +const HB_FontClass& SkHarfBuzzFont::GetFontClass() { + return gSkHarfBuzzFontClass; +} + +HB_Error SkHarfBuzzFont::GetFontTableFunc(void* voidface, const HB_Tag tag, + HB_Byte* buffer, HB_UInt* len) { + SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(voidface); + uint32_t uniqueID = SkTypeface::UniqueID(font->getTypeface()); + + const size_t tableSize = SkFontHost::GetTableSize(uniqueID, tag); + if (!tableSize) { + return HB_Err_Invalid_Argument; + } + // If Harfbuzz specified a NULL buffer then it's asking for the size. + if (!buffer) { + *len = tableSize; + return HB_Err_Ok; + } + + if (*len < tableSize) { + // is this right, or should we just copy less than the full table? + return HB_Err_Invalid_Argument; + } + SkFontHost::GetTableData(uniqueID, tag, 0, tableSize, buffer); + return HB_Err_Ok; +} + |