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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ui/gfx/harfbuzz_font_skia.h"
#include <limits>
#include <map>
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "third_party/skia/include/core/SkPaint.h"
#include "third_party/skia/include/core/SkTypeface.h"
#include "ui/gfx/render_text.h"
namespace gfx {
namespace {
class HarfBuzzFace;
// Maps from code points to glyph indices in a font.
typedef std::map<uint32_t, uint16_t> GlyphCache;
typedef std::pair<HarfBuzzFace, GlyphCache> FaceCache;
// Font data provider for HarfBuzz using Skia. Copied from Blink.
// TODO(ckocagil): Eliminate the duplication.
struct FontData {
FontData(GlyphCache* glyph_cache) : glyph_cache_(glyph_cache) {}
SkPaint paint_;
GlyphCache* glyph_cache_;
// Deletes the object at the given pointer after casting it to the given type.
template<typename Type>
void DeleteByType(void* data) {
Type* typed_data = reinterpret_cast<Type*>(data);
delete typed_data;
template<typename Type>
void DeleteArrayByType(void* data) {
Type* typed_data = reinterpret_cast<Type*>(data);
delete[] typed_data;
// Outputs the |width| and |extents| of the glyph with index |codepoint| in
// |paint|'s font.
void GetGlyphWidthAndExtents(SkPaint* paint,
hb_codepoint_t codepoint,
hb_position_t* width,
hb_glyph_extents_t* extents) {
DCHECK_LE(codepoint, std::numeric_limits<uint16_t>::max());
SkScalar sk_width;
SkRect sk_bounds;
uint16_t glyph = static_cast<uint16_t>(codepoint);
paint->getTextWidths(&glyph, sizeof(glyph), &sk_width, &sk_bounds);
if (width)
*width = SkScalarToFixed(sk_width);
if (extents) {
// Invert y-axis because Skia is y-grows-down but we set up HarfBuzz to be
// y-grows-up.
extents->x_bearing = SkScalarToFixed(sk_bounds.fLeft);
extents->y_bearing = SkScalarToFixed(-sk_bounds.fTop);
extents->width = SkScalarToFixed(sk_bounds.width());
extents->height = SkScalarToFixed(-sk_bounds.height());
// Writes the |glyph| index for the given |unicode| code point. Returns whether
// the glyph exists, i.e. it is not a missing glyph.
hb_bool_t GetGlyph(hb_font_t* font,
void* data,
hb_codepoint_t unicode,
hb_codepoint_t variation_selector,
hb_codepoint_t* glyph,
void* user_data) {
FontData* font_data = reinterpret_cast<FontData*>(data);
GlyphCache* cache = font_data->glyph_cache_;
bool exists = cache->count(unicode) != 0;
if (!exists) {
SkPaint* paint = &font_data->paint_;
paint->textToGlyphs(&unicode, sizeof(hb_codepoint_t), &(*cache)[unicode]);
*glyph = (*cache)[unicode];
return !!*glyph;
// Returns the horizontal advance value of the |glyph|.
hb_position_t GetGlyphHorizontalAdvance(hb_font_t* font,
void* data,
hb_codepoint_t glyph,
void* user_data) {
FontData* font_data = reinterpret_cast<FontData*>(data);
hb_position_t advance = 0;
GetGlyphWidthAndExtents(&font_data->paint_, glyph, &advance, 0);
return advance;
hb_bool_t GetGlyphHorizontalOrigin(hb_font_t* font,
void* data,
hb_codepoint_t glyph,
hb_position_t* x,
hb_position_t* y,
void* user_data) {
// Just return true, like the HarfBuzz-FreeType implementation.
return true;
hb_position_t GetGlyphKerning(FontData* font_data,
hb_codepoint_t first_glyph,
hb_codepoint_t second_glyph) {
SkTypeface* typeface = font_data->paint_.getTypeface();
const uint16_t glyphs[2] = { static_cast<uint16_t>(first_glyph),
static_cast<uint16_t>(second_glyph) };
int32_t kerning_adjustments[1] = { 0 };
if (!typeface->getKerningPairAdjustments(glyphs, 2, kerning_adjustments))
return 0;
SkScalar upm = SkIntToScalar(typeface->getUnitsPerEm());
SkScalar size = font_data->paint_.getTextSize();
return SkScalarToFixed(
SkScalarMulDiv(SkIntToScalar(kerning_adjustments[0]), size, upm));
hb_position_t GetGlyphHorizontalKerning(hb_font_t* font,
void* data,
hb_codepoint_t left_glyph,
hb_codepoint_t right_glyph,
void* user_data) {
FontData* font_data = reinterpret_cast<FontData*>(data);
if (font_data->paint_.isVerticalText()) {
// We don't support cross-stream kerning.
return 0;
return GetGlyphKerning(font_data, left_glyph, right_glyph);
hb_position_t GetGlyphVerticalKerning(hb_font_t* font,
void* data,
hb_codepoint_t top_glyph,
hb_codepoint_t bottom_glyph,
void* user_data) {
FontData* font_data = reinterpret_cast<FontData*>(data);
if (!font_data->paint_.isVerticalText()) {
// We don't support cross-stream kerning.
return 0;
return GetGlyphKerning(font_data, top_glyph, bottom_glyph);
// Writes the |extents| of |glyph|.
hb_bool_t GetGlyphExtents(hb_font_t* font,
void* data,
hb_codepoint_t glyph,
hb_glyph_extents_t* extents,
void* user_data) {
FontData* font_data = reinterpret_cast<FontData*>(data);
GetGlyphWidthAndExtents(&font_data->paint_, glyph, 0, extents);
return true;
class FontFuncs {
FontFuncs() : font_funcs_(hb_font_funcs_create()) {
hb_font_funcs_set_glyph_func(font_funcs_, GetGlyph, 0, 0);
font_funcs_, GetGlyphHorizontalAdvance, 0, 0);
font_funcs_, GetGlyphHorizontalKerning, 0, 0);
font_funcs_, GetGlyphHorizontalOrigin, 0, 0);
font_funcs_, GetGlyphVerticalKerning, 0, 0);
font_funcs_, GetGlyphExtents, 0, 0);
~FontFuncs() {
hb_font_funcs_t* get() { return font_funcs_; }
hb_font_funcs_t* font_funcs_;
base::LazyInstance<FontFuncs>::Leaky g_font_funcs = LAZY_INSTANCE_INITIALIZER;
// Returns the raw data of the font table |tag|.
hb_blob_t* GetFontTable(hb_face_t* face, hb_tag_t tag, void* user_data) {
SkTypeface* typeface = reinterpret_cast<SkTypeface*>(user_data);
const size_t table_size = typeface->getTableSize(tag);
if (!table_size)
return 0;
scoped_ptr<char[]> buffer(new char[table_size]);
if (!buffer)
return 0;
size_t actual_size = typeface->getTableData(tag, 0, table_size, buffer.get());
if (table_size != actual_size)
return 0;
char* buffer_raw = buffer.release();
return hb_blob_create(buffer_raw, table_size, HB_MEMORY_MODE_WRITABLE,
buffer_raw, DeleteArrayByType<char>);
void UnrefSkTypeface(void* data) {
SkTypeface* skia_face = reinterpret_cast<SkTypeface*>(data);
// Wrapper class for a HarfBuzz face created from a given Skia face.
class HarfBuzzFace {
HarfBuzzFace() : face_(NULL) {}
~HarfBuzzFace() {
if (face_)
void Init(SkTypeface* skia_face) {
face_ = hb_face_create_for_tables(GetFontTable, skia_face, UnrefSkTypeface);
hb_face_t* get() {
return face_;
hb_face_t* face_;
} // namespace
// Creates a HarfBuzz font from the given Skia face and text size.
hb_font_t* CreateHarfBuzzFont(SkTypeface* skia_face,
SkScalar text_size,
const FontRenderParams& params,
bool subpixel_rendering_suppressed) {
// TODO(ckocagil): This shouldn't grow indefinitely. Maybe use base::MRUCache?
static std::map<SkFontID, FaceCache> face_caches;
FaceCache* face_cache = &face_caches[skia_face->uniqueID()];
if (face_cache->first.get() == NULL)
hb_font_t* harfbuzz_font = hb_font_create(face_cache->first.get());
const int scale = SkScalarToFixed(text_size);
hb_font_set_scale(harfbuzz_font, scale, scale);
FontData* hb_font_data = new FontData(&face_cache->second);
// TODO(ckocagil): Do we need to update these params later?
internal::ApplyRenderParams(params, subpixel_rendering_suppressed,
hb_font_set_funcs(harfbuzz_font, g_font_funcs.Get().get(), hb_font_data,
return harfbuzz_font;
} // namespace gfx