michael@0: 
michael@0: /*
michael@0:  * Copyright 2009 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: #include "SkHarfBuzzFont.h"
michael@0: #include "SkFontHost.h"
michael@0: #include "SkPaint.h"
michael@0: #include "SkPath.h"
michael@0: 
michael@0: // HB_Fixed is a 26.6 fixed point format.
michael@0: static inline HB_Fixed SkScalarToHarfbuzzFixed(SkScalar value) {
michael@0:     return static_cast<HB_Fixed>(value * 64);
michael@0: }
michael@0: 
michael@0: static HB_Bool stringToGlyphs(HB_Font hbFont, const HB_UChar16* characters,
michael@0:                               hb_uint32 length, HB_Glyph* glyphs,
michael@0:                               hb_uint32* glyphsSize, HB_Bool isRTL) {
michael@0:     SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
michael@0:     SkPaint paint;
michael@0: 
michael@0:     paint.setTypeface(font->getTypeface());
michael@0:     paint.setTextEncoding(SkPaint::kUTF16_TextEncoding);
michael@0:     int numGlyphs = paint.textToGlyphs(characters, length * sizeof(uint16_t),
michael@0:                                        reinterpret_cast<uint16_t*>(glyphs));
michael@0: 
michael@0:     // HB_Glyph is 32-bit, but Skia outputs only 16-bit numbers. So our
michael@0:     // |glyphs| array needs to be converted.
michael@0:     for (int i = numGlyphs - 1; i >= 0; --i) {
michael@0:         uint16_t value;
michael@0:         // We use a memcpy to avoid breaking strict aliasing rules.
michael@0:         memcpy(&value, reinterpret_cast<char*>(glyphs) + sizeof(uint16_t) * i, sizeof(uint16_t));
michael@0:         glyphs[i] = value;
michael@0:     }
michael@0: 
michael@0:     *glyphsSize = numGlyphs;
michael@0:     return 1;
michael@0: }
michael@0: 
michael@0: static void glyphsToAdvances(HB_Font hbFont, const HB_Glyph* glyphs,
michael@0:                          hb_uint32 numGlyphs, HB_Fixed* advances, int flags) {
michael@0:     SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
michael@0:     SkPaint paint;
michael@0: 
michael@0:     font->setupPaint(&paint);
michael@0:     paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
michael@0: 
michael@0:     SkAutoMalloc storage(numGlyphs * (sizeof(SkScalar) + sizeof(uint16_t)));
michael@0:     SkScalar* scalarWidths = reinterpret_cast<SkScalar*>(storage.get());
michael@0:     uint16_t* glyphs16 = reinterpret_cast<uint16_t*>(scalarWidths + numGlyphs);
michael@0: 
michael@0:     // convert HB 32bit glyphs to skia's 16bit
michael@0:     for (hb_uint32 i = 0; i < numGlyphs; ++i) {
michael@0:         glyphs16[i] = SkToU16(glyphs[i]);
michael@0:     }
michael@0:     paint.getTextWidths(glyphs16, numGlyphs * sizeof(uint16_t), scalarWidths);
michael@0: 
michael@0:     for (hb_uint32 i = 0; i < numGlyphs; ++i) {
michael@0:         advances[i] = SkScalarToHarfbuzzFixed(scalarWidths[i]);
michael@0:     }
michael@0: }
michael@0: 
michael@0: static HB_Bool canRender(HB_Font hbFont, const HB_UChar16* characters,
michael@0:                          hb_uint32 length) {
michael@0:     SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
michael@0:     SkPaint paint;
michael@0: 
michael@0:     paint.setTypeface(font->getTypeface());
michael@0:     paint.setTextEncoding(SkPaint::kUTF16_TextEncoding);
michael@0:     return paint.containsText(characters, length * sizeof(uint16_t));
michael@0: }
michael@0: 
michael@0: static HB_Error getOutlinePoint(HB_Font hbFont, HB_Glyph glyph, int flags,
michael@0:                                 hb_uint32 index, HB_Fixed* xPos, HB_Fixed* yPos,
michael@0:                                 hb_uint32* resultingNumPoints) {
michael@0:     SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
michael@0:     SkPaint paint;
michael@0: 
michael@0:     font->setupPaint(&paint);
michael@0:     paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
michael@0:     if (flags & HB_ShaperFlag_UseDesignMetrics) {
michael@0:         paint.setHinting(SkPaint::kNo_Hinting);
michael@0:     }
michael@0: 
michael@0:     SkPath path;
michael@0:     uint16_t glyph16 = SkToU16(glyph);
michael@0:     paint.getTextPath(&glyph16, sizeof(glyph16), 0, 0, &path);
michael@0:     int numPoints = path.countPoints();
michael@0:     if (index >= numPoints) {
michael@0:         return HB_Err_Invalid_SubTable;
michael@0:     }
michael@0: 
michael@0:     SkPoint pt = path.getPoint(index);
michael@0:     *xPos = SkScalarToHarfbuzzFixed(pt.fX);
michael@0:     *yPos = SkScalarToHarfbuzzFixed(pt.fY);
michael@0:     *resultingNumPoints = numPoints;
michael@0: 
michael@0:     return HB_Err_Ok;
michael@0: }
michael@0: 
michael@0: static void getGlyphMetrics(HB_Font hbFont, HB_Glyph glyph,
michael@0:                             HB_GlyphMetrics* metrics) {
michael@0:     SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
michael@0:     SkPaint paint;
michael@0: 
michael@0:     font->setupPaint(&paint);
michael@0:     paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
michael@0: 
michael@0:     SkScalar width;
michael@0:     SkRect bounds;
michael@0:     uint16_t glyph16 = SkToU16(glyph);
michael@0:     paint.getTextWidths(&glyph16, sizeof(glyph16), &width, &bounds);
michael@0: 
michael@0:     metrics->x = SkScalarToHarfbuzzFixed(bounds.fLeft);
michael@0:     metrics->y = SkScalarToHarfbuzzFixed(bounds.fTop);
michael@0:     metrics->width = SkScalarToHarfbuzzFixed(bounds.width());
michael@0:     metrics->height = SkScalarToHarfbuzzFixed(bounds.height());
michael@0: 
michael@0:     metrics->xOffset = SkScalarToHarfbuzzFixed(width);
michael@0:     // We can't actually get the |y| correct because Skia doesn't export
michael@0:     // the vertical advance. However, nor we do ever render vertical text at
michael@0:     // the moment so it's unimportant.
michael@0:     metrics->yOffset = 0;
michael@0: }
michael@0: 
michael@0: static HB_Fixed getFontMetric(HB_Font hbFont, HB_FontMetric metric)
michael@0: {
michael@0:     SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(hbFont->userData);
michael@0:     SkPaint paint;
michael@0:     SkPaint::FontMetrics skiaMetrics;
michael@0: 
michael@0:     font->setupPaint(&paint);
michael@0:     paint.getFontMetrics(&skiaMetrics);
michael@0: 
michael@0:     switch (metric) {
michael@0:     case HB_FontAscent:
michael@0:         return SkScalarToHarfbuzzFixed(-skiaMetrics.fAscent);
michael@0:     default:
michael@0:         SkDebugf("--- unknown harfbuzz metric enum %d\n", metric);
michael@0:         return 0;
michael@0:     }
michael@0: }
michael@0: 
michael@0: static HB_FontClass gSkHarfBuzzFontClass = {
michael@0:     stringToGlyphs,
michael@0:     glyphsToAdvances,
michael@0:     canRender,
michael@0:     getOutlinePoint,
michael@0:     getGlyphMetrics,
michael@0:     getFontMetric,
michael@0: };
michael@0: 
michael@0: const HB_FontClass& SkHarfBuzzFont::GetFontClass() {
michael@0:     return gSkHarfBuzzFontClass;
michael@0: }
michael@0: 
michael@0: HB_Error SkHarfBuzzFont::GetFontTableFunc(void* voidface, const HB_Tag tag,
michael@0:                                           HB_Byte* buffer, HB_UInt* len) {
michael@0:     SkHarfBuzzFont* font = reinterpret_cast<SkHarfBuzzFont*>(voidface);
michael@0:     SkTypeface* typeface = font->getTypeface();
michael@0: 
michael@0:     const size_t tableSize = typeface->getTableSize(tag);
michael@0:     if (!tableSize) {
michael@0:         return HB_Err_Invalid_Argument;
michael@0:     }
michael@0:     // If Harfbuzz specified a NULL buffer then it's asking for the size.
michael@0:     if (!buffer) {
michael@0:         *len = tableSize;
michael@0:         return HB_Err_Ok;
michael@0:     }
michael@0: 
michael@0:     if (*len < tableSize) {
michael@0:         // is this right, or should we just copy less than the full table?
michael@0:         return HB_Err_Invalid_Argument;
michael@0:     }
michael@0:     typeface->getTableData(tag, 0, tableSize, buffer);
michael@0:     return HB_Err_Ok;
michael@0: }