Extract the Skia implementation of HarfBuzz font to its own file

ui/gfx/render_text_harfbuzz.cc

Index: ui/gfx/render_text_harfbuzz.cc
diff --git a/ui/gfx/render_text_harfbuzz.cc b/ui/gfx/render_text_harfbuzz.cc
index 82580b3961f5d475e71b407b70839cc35b8cc6be..ddc9d6f7b5f0d290a57d861deb7adf77d6a5d1dd 100644
--- a/ui/gfx/render_text_harfbuzz.cc
+++ b/ui/gfx/render_text_harfbuzz.cc
@@ -5,12 +5,10 @@
 #include "ui/gfx/render_text_harfbuzz.h"
 
 #include <limits>
-#include <map>
 
 #include "base/i18n/bidi_line_iterator.h"
 #include "base/i18n/break_iterator.h"
 #include "base/i18n/char_iterator.h"
-#include "base/lazy_instance.h"
 #include "base/profiler/scoped_tracker.h"
 #include "third_party/harfbuzz-ng/src/hb.h"
 #include "third_party/icu/source/common/unicode/ubidi.h"
@@ -19,6 +17,7 @@
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/font_fallback.h"
 #include "ui/gfx/font_render_params.h"
+#include "ui/gfx/harfbuzz_font_skia.h"
 #include "ui/gfx/utf16_indexing.h"
 
 #if defined(OS_WIN)
@@ -40,270 +39,6 @@ const size_t kMaxTextLength = 10000;
 // character to belong to more scripts.
 const size_t kMaxScripts = 5;
 
-// Maps from code points to glyph indices in a font.
-typedef std::map<uint32_t, uint16_t> GlyphCache;
-
-// Font data provider for HarfBuzz using Skia. Copied from Blink.
-// TODO(ckocagil): Eliminate the duplication. http://crbug.com/368375
-struct FontData {
-  FontData(GlyphCache* glyph_cache) : glyph_cache_(glyph_cache) {}
-
-  SkPaint paint_;
-  GlyphCache* glyph_cache_;
-};
-
-hb_position_t SkiaScalarToHarfBuzzPosition(SkScalar value) {
-  return SkScalarToFixed(value);
-}
-
-// 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>::max());
-  paint->setTextEncoding(SkPaint::kGlyphID_TextEncoding);
-
-  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 = SkiaScalarToHarfBuzzPosition(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 = SkiaScalarToHarfBuzzPosition(sk_bounds.fLeft);
-    extents->y_bearing = SkiaScalarToHarfBuzzPosition(-sk_bounds.fTop);
-    extents->width = SkiaScalarToHarfBuzzPosition(sk_bounds.width());
-    extents->height = SkiaScalarToHarfBuzzPosition(-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->setTextEncoding(SkPaint::kUTF32_TextEncoding);
-    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 SkiaScalarToHarfBuzzPosition(
-      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 {
- public:
-  FontFuncs() : font_funcs_(hb_font_funcs_create()) {
-    hb_font_funcs_set_glyph_func(font_funcs_, GetGlyph, 0, 0);
-    hb_font_funcs_set_glyph_h_advance_func(
-        font_funcs_, GetGlyphHorizontalAdvance, 0, 0);
-    hb_font_funcs_set_glyph_h_kerning_func(
-        font_funcs_, GetGlyphHorizontalKerning, 0, 0);
-    hb_font_funcs_set_glyph_h_origin_func(
-        font_funcs_, GetGlyphHorizontalOrigin, 0, 0);
-    hb_font_funcs_set_glyph_v_kerning_func(
-        font_funcs_, GetGlyphVerticalKerning, 0, 0);
-    hb_font_funcs_set_glyph_extents_func(
-        font_funcs_, GetGlyphExtents, 0, 0);
-    hb_font_funcs_make_immutable(font_funcs_);
-  }
-
-  ~FontFuncs() {
-    hb_font_funcs_destroy(font_funcs_);
-  }
-
-  hb_font_funcs_t* get() { return font_funcs_; }
-
- private:
-  hb_font_funcs_t* font_funcs_;
-
-  DISALLOW_COPY_AND_ASSIGN(FontFuncs);
-};
-
-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);
-  SkSafeUnref(skia_face);
-}
-
-// Wrapper class for a HarfBuzz face created from a given Skia face.
-class HarfBuzzFace {
- public:
-  HarfBuzzFace() : face_(NULL) {}
-
-  ~HarfBuzzFace() {
-    if (face_)
-      hb_face_destroy(face_);
-  }
-
-  void Init(SkTypeface* skia_face) {
-    SkSafeRef(skia_face);
-    face_ = hb_face_create_for_tables(GetFontTable, skia_face, UnrefSkTypeface);
-    DCHECK(face_);
-  }
-
-  hb_face_t* get() {
-    return face_;
-  }
-
- private:
-  hb_face_t* face_;
-};
-
-// 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 background_is_transparent) {
-  typedef std::pair<HarfBuzzFace, GlyphCache> FaceCache;
-
-  // 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)
-    face_cache->first.Init(skia_face);
-
-  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);
-  hb_font_data->paint_.setTypeface(skia_face);
-  hb_font_data->paint_.setTextSize(text_size);
-  // TODO(ckocagil): Do we need to update these params later?
-  internal::ApplyRenderParams(params, background_is_transparent,
-                              &hb_font_data->paint_);
-  hb_font_set_funcs(harfbuzz_font, g_font_funcs.Get().get(), hb_font_data,
-                    DeleteByType<FontData>);
-  hb_font_make_immutable(harfbuzz_font);
-  return harfbuzz_font;
-}
-
 // Returns true if characters of |block_code| may trigger font fallback.
 // Dingbats and emoticons can be rendered through the color emoji font file,
 // therefore it needs to be trigerred as fallbacks. See crbug.com/448909