ui/gfx/render_text_harfbuzz.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ui/gfx/render_text_harfbuzz.h"
   6
   7 #include <limits>
   8 #include <map>
   9
  10 #include "base/i18n/bidi_line_iterator.h"
  11 #include "base/i18n/break_iterator.h"
  12 #include "base/i18n/char_iterator.h"
  13 #include "base/lazy_instance.h"
  14 #include "third_party/harfbuzz-ng/src/hb.h"
  15 #include "third_party/icu/source/common/unicode/ubidi.h"
  16 #include "third_party/skia/include/core/SkColor.h"
  17 #include "third_party/skia/include/core/SkTypeface.h"
  18 #include "ui/gfx/canvas.h"
  19 #include "ui/gfx/font_fallback.h"
  20 #include "ui/gfx/font_render_params.h"
  21 #include "ui/gfx/utf16_indexing.h"
  22
  23 #if defined(OS_WIN)
  24 #include "ui/gfx/font_fallback_win.h"
  25 #endif
  26
  27 namespace gfx {
  28
  29 namespace {
  30
  31 // The maximum number of scripts a Unicode character can belong to. This value
  32 // is arbitrarily chosen to be a good limit because it is unlikely for a single
  33 // character to belong to more scripts.
  34 const size_t kMaxScripts = 5;
  35
  36 // Maps from code points to glyph indices in a font.
  37 typedef std::map<uint32_t, uint16_t> GlyphCache;
  38
  39 // Font data provider for HarfBuzz using Skia. Copied from Blink.
  40 // TODO(ckocagil): Eliminate the duplication. http://crbug.com/368375
  41 struct FontData {
  42   FontData(GlyphCache* glyph_cache) : glyph_cache_(glyph_cache) {}
  43
  44   SkPaint paint_;
  45   GlyphCache* glyph_cache_;
  46 };
  47
  48 hb_position_t SkiaScalarToHarfBuzzPosition(SkScalar value) {
  49   return SkScalarToFixed(value);
  50 }
  51
  52 // Deletes the object at the given pointer after casting it to the given type.
  53 template<typename Type>
  54 void DeleteByType(void* data) {
  55   Type* typed_data = reinterpret_cast<Type*>(data);
  56   delete typed_data;
  57 }
  58
  59 template<typename Type>
  60 void DeleteArrayByType(void* data) {
  61   Type* typed_data = reinterpret_cast<Type*>(data);
  62   delete[] typed_data;
  63 }
  64
  65 // Outputs the |width| and |extents| of the glyph with index |codepoint| in
  66 // |paint|'s font.
  67 void GetGlyphWidthAndExtents(SkPaint* paint,
  68                              hb_codepoint_t codepoint,
  69                              hb_position_t* width,
  70                              hb_glyph_extents_t* extents) {
  71   DCHECK_LE(codepoint, 0xFFFFU);
  72   paint->setTextEncoding(SkPaint::kGlyphID_TextEncoding);
  73
  74   SkScalar sk_width;
  75   SkRect sk_bounds;
  76   uint16_t glyph = codepoint;
  77
  78   paint->getTextWidths(&glyph, sizeof(glyph), &sk_width, &sk_bounds);
  79   if (width)
  80     *width = SkiaScalarToHarfBuzzPosition(sk_width);
  81   if (extents) {
  82     // Invert y-axis because Skia is y-grows-down but we set up HarfBuzz to be
  83     // y-grows-up.
  84     extents->x_bearing = SkiaScalarToHarfBuzzPosition(sk_bounds.fLeft);
  85     extents->y_bearing = SkiaScalarToHarfBuzzPosition(-sk_bounds.fTop);
  86     extents->width = SkiaScalarToHarfBuzzPosition(sk_bounds.width());
  87     extents->height = SkiaScalarToHarfBuzzPosition(-sk_bounds.height());
  88   }
  89 }
  90
  91 // Writes the |glyph| index for the given |unicode| code point. Returns whether
  92 // the glyph exists, i.e. it is not a missing glyph.
  93 hb_bool_t GetGlyph(hb_font_t* font,
  94                    void* data,
  95                    hb_codepoint_t unicode,
  96                    hb_codepoint_t variation_selector,
  97                    hb_codepoint_t* glyph,
  98                    void* user_data) {
  99   FontData* font_data = reinterpret_cast<FontData*>(data);
 100   GlyphCache* cache = font_data->glyph_cache_;
 101
 102   bool exists = cache->count(unicode) != 0;
 103   if (!exists) {
 104     SkPaint* paint = &font_data->paint_;
 105     paint->setTextEncoding(SkPaint::kUTF32_TextEncoding);
 106     paint->textToGlyphs(&unicode, sizeof(hb_codepoint_t), &(*cache)[unicode]);
 107   }
 108   *glyph = (*cache)[unicode];
 109   return !!*glyph;
 110 }
 111
 112 // Returns the horizontal advance value of the |glyph|.
 113 hb_position_t GetGlyphHorizontalAdvance(hb_font_t* font,
 114                                         void* data,
 115                                         hb_codepoint_t glyph,
 116                                         void* user_data) {
 117   FontData* font_data = reinterpret_cast<FontData*>(data);
 118   hb_position_t advance = 0;
 119
 120   GetGlyphWidthAndExtents(&font_data->paint_, glyph, &advance, 0);
 121   return advance;
 122 }
 123
 124 hb_bool_t GetGlyphHorizontalOrigin(hb_font_t* font,
 125                                    void* data,
 126                                    hb_codepoint_t glyph,
 127                                    hb_position_t* x,
 128                                    hb_position_t* y,
 129                                    void* user_data) {
 130   // Just return true, like the HarfBuzz-FreeType implementation.
 131   return true;
 132 }
 133
 134 hb_position_t GetGlyphKerning(FontData* font_data,
 135                               hb_codepoint_t first_glyph,
 136                               hb_codepoint_t second_glyph) {
 137   SkTypeface* typeface = font_data->paint_.getTypeface();
 138   const uint16_t glyphs[2] = { static_cast<uint16_t>(first_glyph),
 139                                static_cast<uint16_t>(second_glyph) };
 140   int32_t kerning_adjustments[1] = { 0 };
 141
 142   if (!typeface->getKerningPairAdjustments(glyphs, 2, kerning_adjustments))
 143     return 0;
 144
 145   SkScalar upm = SkIntToScalar(typeface->getUnitsPerEm());
 146   SkScalar size = font_data->paint_.getTextSize();
 147   return SkiaScalarToHarfBuzzPosition(
 148       SkScalarMulDiv(SkIntToScalar(kerning_adjustments[0]), size, upm));
 149 }
 150
 151 hb_position_t GetGlyphHorizontalKerning(hb_font_t* font,
 152                                         void* data,
 153                                         hb_codepoint_t left_glyph,
 154                                         hb_codepoint_t right_glyph,
 155                                         void* user_data) {
 156   FontData* font_data = reinterpret_cast<FontData*>(data);
 157   if (font_data->paint_.isVerticalText()) {
 158     // We don't support cross-stream kerning.
 159     return 0;
 160   }
 161
 162   return GetGlyphKerning(font_data, left_glyph, right_glyph);
 163 }
 164
 165 hb_position_t GetGlyphVerticalKerning(hb_font_t* font,
 166                                       void* data,
 167                                       hb_codepoint_t top_glyph,
 168                                       hb_codepoint_t bottom_glyph,
 169                                       void* user_data) {
 170   FontData* font_data = reinterpret_cast<FontData*>(data);
 171   if (!font_data->paint_.isVerticalText()) {
 172     // We don't support cross-stream kerning.
 173     return 0;
 174   }
 175
 176   return GetGlyphKerning(font_data, top_glyph, bottom_glyph);
 177 }
 178
 179 // Writes the |extents| of |glyph|.
 180 hb_bool_t GetGlyphExtents(hb_font_t* font,
 181                           void* data,
 182                           hb_codepoint_t glyph,
 183                           hb_glyph_extents_t* extents,
 184                           void* user_data) {
 185   FontData* font_data = reinterpret_cast<FontData*>(data);
 186
 187   GetGlyphWidthAndExtents(&font_data->paint_, glyph, 0, extents);
 188   return true;
 189 }
 190
 191 class FontFuncs {
 192  public:
 193   FontFuncs() : font_funcs_(hb_font_funcs_create()) {
 194     hb_font_funcs_set_glyph_func(font_funcs_, GetGlyph, 0, 0);
 195     hb_font_funcs_set_glyph_h_advance_func(
 196         font_funcs_, GetGlyphHorizontalAdvance, 0, 0);
 197     hb_font_funcs_set_glyph_h_kerning_func(
 198         font_funcs_, GetGlyphHorizontalKerning, 0, 0);
 199     hb_font_funcs_set_glyph_h_origin_func(
 200         font_funcs_, GetGlyphHorizontalOrigin, 0, 0);
 201     hb_font_funcs_set_glyph_v_kerning_func(
 202         font_funcs_, GetGlyphVerticalKerning, 0, 0);
 203     hb_font_funcs_set_glyph_extents_func(
 204         font_funcs_, GetGlyphExtents, 0, 0);
 205     hb_font_funcs_make_immutable(font_funcs_);
 206   }
 207
 208   ~FontFuncs() {
 209     hb_font_funcs_destroy(font_funcs_);
 210   }
 211
 212   hb_font_funcs_t* get() { return font_funcs_; }
 213
 214  private:
 215   hb_font_funcs_t* font_funcs_;
 216
 217   DISALLOW_COPY_AND_ASSIGN(FontFuncs);
 218 };
 219
 220 base::LazyInstance<FontFuncs>::Leaky g_font_funcs = LAZY_INSTANCE_INITIALIZER;
 221
 222 // Returns the raw data of the font table |tag|.
 223 hb_blob_t* GetFontTable(hb_face_t* face, hb_tag_t tag, void* user_data) {
 224   SkTypeface* typeface = reinterpret_cast<SkTypeface*>(user_data);
 225
 226   const size_t table_size = typeface->getTableSize(tag);
 227   if (!table_size)
 228     return 0;
 229
 230   scoped_ptr<char[]> buffer(new char[table_size]);
 231   if (!buffer)
 232     return 0;
 233   size_t actual_size = typeface->getTableData(tag, 0, table_size, buffer.get());
 234   if (table_size != actual_size)
 235     return 0;
 236
 237   char* buffer_raw = buffer.release();
 238   return hb_blob_create(buffer_raw, table_size, HB_MEMORY_MODE_WRITABLE,
 239                         buffer_raw, DeleteArrayByType<char>);
 240 }
 241
 242 void UnrefSkTypeface(void* data) {
 243   SkTypeface* skia_face = reinterpret_cast<SkTypeface*>(data);
 244   SkSafeUnref(skia_face);
 245 }
 246
 247 // Wrapper class for a HarfBuzz face created from a given Skia face.
 248 class HarfBuzzFace {
 249  public:
 250   HarfBuzzFace() : face_(NULL) {}
 251
 252   ~HarfBuzzFace() {
 253     if (face_)
 254       hb_face_destroy(face_);
 255   }
 256
 257   void Init(SkTypeface* skia_face) {
 258     SkSafeRef(skia_face);
 259     face_ = hb_face_create_for_tables(GetFontTable, skia_face, UnrefSkTypeface);
 260     DCHECK(face_);
 261   }
 262
 263   hb_face_t* get() {
 264     return face_;
 265   }
 266
 267  private:
 268   hb_face_t* face_;
 269 };
 270
 271 // Creates a HarfBuzz font from the given Skia face and text size.
 272 hb_font_t* CreateHarfBuzzFont(SkTypeface* skia_face, int text_size) {
 273   typedef std::pair<HarfBuzzFace, GlyphCache> FaceCache;
 274
 275   // TODO(ckocagil): This shouldn't grow indefinitely. Maybe use base::MRUCache?
 276   static std::map<SkFontID, FaceCache> face_caches;
 277
 278   FaceCache* face_cache = &face_caches[skia_face->uniqueID()];
 279   if (face_cache->first.get() == NULL)
 280     face_cache->first.Init(skia_face);
 281
 282   hb_font_t* harfbuzz_font = hb_font_create(face_cache->first.get());
 283   const int scale = SkScalarToFixed(text_size);
 284   hb_font_set_scale(harfbuzz_font, scale, scale);
 285   FontData* hb_font_data = new FontData(&face_cache->second);
 286   hb_font_data->paint_.setTypeface(skia_face);
 287   hb_font_data->paint_.setTextSize(text_size);
 288   hb_font_set_funcs(harfbuzz_font, g_font_funcs.Get().get(), hb_font_data,
 289                     DeleteByType<FontData>);
 290   hb_font_make_immutable(harfbuzz_font);
 291   return harfbuzz_font;
 292 }
 293
 294 // Returns true if characters of |block_code| may trigger font fallback.
 295 bool IsUnusualBlockCode(UBlockCode block_code) {
 296   return block_code == UBLOCK_GEOMETRIC_SHAPES ||
 297          block_code == UBLOCK_MISCELLANEOUS_SYMBOLS;
 298 }
 299
 300 // Returns the index of the first unusual character after a usual character or
 301 // vice versa. Unusual characters are defined by |IsUnusualBlockCode|.
 302 size_t FindUnusualCharacter(const base::string16& text,
 303                             size_t run_start,
 304                             size_t run_break) {
 305   const int32 run_length = static_cast<int32>(run_break - run_start);
 306   base::i18n::UTF16CharIterator iter(text.c_str() + run_start,
 307                                      run_length);
 308   const UBlockCode first_block_code = ublock_getCode(iter.get());
 309   const bool first_block_unusual = IsUnusualBlockCode(first_block_code);
 310   while (iter.Advance() && iter.array_pos() < run_length) {
 311     const UBlockCode current_block_code = ublock_getCode(iter.get());
 312     if (current_block_code != first_block_code &&
 313         (first_block_unusual || IsUnusualBlockCode(current_block_code))) {
 314       return run_start + iter.array_pos();
 315     }
 316   }
 317   return run_break;
 318 }
 319
 320 // If the given scripts match, returns the one that isn't USCRIPT_COMMON or
 321 // USCRIPT_INHERITED, i.e. the more specific one. Otherwise returns
 322 // USCRIPT_INVALID_CODE.
 323 UScriptCode ScriptIntersect(UScriptCode first, UScriptCode second) {
 324   if (first == second ||
 325       (second > USCRIPT_INVALID_CODE && second <= USCRIPT_INHERITED)) {
 326     return first;
 327   }
 328   if (first > USCRIPT_INVALID_CODE && first <= USCRIPT_INHERITED)
 329     return second;
 330   return USCRIPT_INVALID_CODE;
 331 }
 332
 333 // Writes the script and the script extensions of the character with the
 334 // Unicode |codepoint|. Returns the number of written scripts.
 335 int GetScriptExtensions(UChar32 codepoint, UScriptCode* scripts) {
 336   UErrorCode icu_error = U_ZERO_ERROR;
 337   // ICU documentation incorrectly states that the result of
 338   // |uscript_getScriptExtensions| will contain the regular script property.
 339   // Write the character's script property to the first element.
 340   scripts[0] = uscript_getScript(codepoint, &icu_error);
 341   if (U_FAILURE(icu_error))
 342     return 0;
 343   // Fill the rest of |scripts| with the extensions.
 344   int count = uscript_getScriptExtensions(codepoint, scripts + 1,
 345                                           kMaxScripts - 1, &icu_error);
 346   if (U_FAILURE(icu_error))
 347     count = 0;
 348   return count + 1;
 349 }
 350
 351 // Intersects the script extensions set of |codepoint| with |result| and writes
 352 // to |result|, reading and updating |result_size|.
 353 void ScriptSetIntersect(UChar32 codepoint,
 354                         UScriptCode* result,
 355                         size_t* result_size) {
 356   UScriptCode scripts[kMaxScripts] = { USCRIPT_INVALID_CODE };
 357   int count = GetScriptExtensions(codepoint, scripts);
 358
 359   size_t out_size = 0;
 360
 361   for (size_t i = 0; i < *result_size; ++i) {
 362     for (int j = 0; j < count; ++j) {
 363       UScriptCode intersection = ScriptIntersect(result[i], scripts[j]);
 364       if (intersection != USCRIPT_INVALID_CODE) {
 365         result[out_size++] = intersection;
 366         break;
 367       }
 368     }
 369   }
 370
 371   *result_size = out_size;
 372 }
 373
 374 // Find the longest sequence of characters from 0 and up to |length| that
 375 // have at least one common UScriptCode value. Writes the common script value to
 376 // |script| and returns the length of the sequence. Takes the characters' script
 377 // extensions into account. http://www.unicode.org/reports/tr24/#ScriptX
 378 //
 379 // Consider 3 characters with the script values {Kana}, {Hira, Kana}, {Kana}.
 380 // Without script extensions only the first script in each set would be taken
 381 // into account, resulting in 3 runs where 1 would be enough.
 382 // TODO(ckocagil): Write a unit test for the case above.
 383 int ScriptInterval(const base::string16& text,
 384                    size_t start,
 385                    size_t length,
 386                    UScriptCode* script) {
 387   DCHECK_GT(length, 0U);
 388
 389   UScriptCode scripts[kMaxScripts] = { USCRIPT_INVALID_CODE };
 390
 391   base::i18n::UTF16CharIterator char_iterator(text.c_str() + start, length);
 392   size_t scripts_size = GetScriptExtensions(char_iterator.get(), scripts);
 393   *script = scripts[0];
 394
 395   while (char_iterator.Advance()) {
 396     ScriptSetIntersect(char_iterator.get(), scripts, &scripts_size);
 397     if (scripts_size == 0U)
 398       return char_iterator.array_pos();
 399     *script = scripts[0];
 400   }
 401
 402   return length;
 403 }
 404
 405 // A port of hb_icu_script_to_script because harfbuzz on CrOS is built without
 406 // hb-icu. See http://crbug.com/356929
 407 inline hb_script_t ICUScriptToHBScript(UScriptCode script) {
 408   if (script == USCRIPT_INVALID_CODE)
 409     return HB_SCRIPT_INVALID;
 410   return hb_script_from_string(uscript_getShortName(script), -1);
 411 }
 412
 413 // Helper template function for |TextRunHarfBuzz::GetClusterAt()|. |Iterator|
 414 // can be a forward or reverse iterator type depending on the text direction.
 415 template <class Iterator>
 416 void GetClusterAtImpl(size_t pos,
 417                       Range range,
 418                       Iterator elements_begin,
 419                       Iterator elements_end,
 420                       bool reversed,
 421                       Range* chars,
 422                       Range* glyphs) {
 423   Iterator element = std::upper_bound(elements_begin, elements_end, pos);
 424   chars->set_end(element == elements_end ? range.end() : *element);
 425   glyphs->set_end(reversed ? elements_end - element : element - elements_begin);
 426
 427   DCHECK(element != elements_begin);
 428   while (--element != elements_begin && *element == *(element - 1));
 429   chars->set_start(*element);
 430   glyphs->set_start(
 431       reversed ? elements_end - element : element - elements_begin);
 432   if (reversed)
 433     *glyphs = Range(glyphs->end(), glyphs->start());
 434
 435   DCHECK(!chars->is_reversed());
 436   DCHECK(!chars->is_empty());
 437   DCHECK(!glyphs->is_reversed());
 438   DCHECK(!glyphs->is_empty());
 439 }
 440
 441 }  // namespace
 442
 443 namespace internal {
 444
 445 TextRunHarfBuzz::TextRunHarfBuzz()
 446     : width(0.0f),
 447       preceding_run_widths(0.0f),
 448       is_rtl(false),
 449       level(0),
 450       script(USCRIPT_INVALID_CODE),
 451       glyph_count(static_cast<size_t>(-1)),
 452       font_size(0),
 453       font_style(0),
 454       strike(false),
 455       diagonal_strike(false),
 456       underline(false) {}
 457
 458 TextRunHarfBuzz::~TextRunHarfBuzz() {}
 459
 460 void TextRunHarfBuzz::GetClusterAt(size_t pos,
 461                                    Range* chars,
 462                                    Range* glyphs) const {
 463   DCHECK(range.Contains(Range(pos, pos + 1)));
 464   DCHECK(chars);
 465   DCHECK(glyphs);
 466
 467   if (glyph_count == 0) {
 468     *chars = range;
 469     *glyphs = Range();
 470     return;
 471   }
 472
 473   if (is_rtl) {
 474     GetClusterAtImpl(pos, range, glyph_to_char.rbegin(), glyph_to_char.rend(),
 475         true, chars, glyphs);
 476     return;
 477   }
 478
 479   GetClusterAtImpl(pos, range, glyph_to_char.begin(), glyph_to_char.end(),
 480       false, chars, glyphs);
 481 }
 482
 483 Range TextRunHarfBuzz::CharRangeToGlyphRange(const Range& char_range) const {
 484   DCHECK(range.Contains(char_range));
 485   DCHECK(!char_range.is_reversed());
 486   DCHECK(!char_range.is_empty());
 487
 488   Range start_glyphs;
 489   Range end_glyphs;
 490   Range temp_range;
 491   GetClusterAt(char_range.start(), &temp_range, &start_glyphs);
 492   GetClusterAt(char_range.end() - 1, &temp_range, &end_glyphs);
 493
 494   return is_rtl ? Range(end_glyphs.start(), start_glyphs.end()) :
 495       Range(start_glyphs.start(), end_glyphs.end());
 496 }
 497
 498 size_t TextRunHarfBuzz::CountMissingGlyphs() const {
 499   static const int kMissingGlyphId = 0;
 500   size_t missing = 0;
 501   for (size_t i = 0; i < glyph_count; ++i)
 502     missing += (glyphs[i] == kMissingGlyphId) ? 1 : 0;
 503   return missing;
 504 }
 505
 506 Range TextRunHarfBuzz::GetGraphemeBounds(
 507     base::i18n::BreakIterator* grapheme_iterator,
 508     size_t text_index) {
 509   DCHECK_LT(text_index, range.end());
 510   // TODO(msw): Support floating point grapheme bounds.
 511   const int preceding_run_widths_int = SkScalarRoundToInt(preceding_run_widths);
 512   if (glyph_count == 0)
 513     return Range(preceding_run_widths_int, preceding_run_widths_int + width);
 514
 515   Range chars;
 516   Range glyphs;
 517   GetClusterAt(text_index, &chars, &glyphs);
 518   const int cluster_begin_x = SkScalarRoundToInt(positions[glyphs.start()].x());
 519   const int cluster_end_x = glyphs.end() < glyph_count ?
 520       SkScalarRoundToInt(positions[glyphs.end()].x()) : width;
 521
 522   // A cluster consists of a number of code points and corresponds to a number
 523   // of glyphs that should be drawn together. A cluster can contain multiple
 524   // graphemes. In order to place the cursor at a grapheme boundary inside the
 525   // cluster, we simply divide the cluster width by the number of graphemes.
 526   if (chars.length() > 1 && grapheme_iterator) {
 527     int before = 0;
 528     int total = 0;
 529     for (size_t i = chars.start(); i < chars.end(); ++i) {
 530       if (grapheme_iterator->IsGraphemeBoundary(i)) {
 531         if (i < text_index)
 532           ++before;
 533         ++total;
 534       }
 535     }
 536     DCHECK_GT(total, 0);
 537     if (total > 1) {
 538       if (is_rtl)
 539         before = total - before - 1;
 540       DCHECK_GE(before, 0);
 541       DCHECK_LT(before, total);
 542       const int cluster_width = cluster_end_x - cluster_begin_x;
 543       const int grapheme_begin_x = cluster_begin_x + static_cast<int>(0.5f +
 544           cluster_width * before / static_cast<float>(total));
 545       const int grapheme_end_x = cluster_begin_x + static_cast<int>(0.5f +
 546           cluster_width * (before + 1) / static_cast<float>(total));
 547       return Range(preceding_run_widths_int + grapheme_begin_x,
 548                    preceding_run_widths_int + grapheme_end_x);
 549     }
 550   }
 551
 552   return Range(preceding_run_widths_int + cluster_begin_x,
 553                preceding_run_widths_int + cluster_end_x);
 554 }
 555
 556 }  // namespace internal
 557
 558 RenderTextHarfBuzz::RenderTextHarfBuzz()
 559     : RenderText(),
 560       needs_layout_(false) {}
 561
 562 RenderTextHarfBuzz::~RenderTextHarfBuzz() {}
 563
 564 Size RenderTextHarfBuzz::GetStringSize() {
 565   const SizeF size_f = GetStringSizeF();
 566   return Size(std::ceil(size_f.width()), size_f.height());
 567 }
 568
 569 SizeF RenderTextHarfBuzz::GetStringSizeF() {
 570   EnsureLayout();
 571   return lines()[0].size;
 572 }
 573
 574 SelectionModel RenderTextHarfBuzz::FindCursorPosition(const Point& point) {
 575   EnsureLayout();
 576
 577   int x = ToTextPoint(point).x();
 578   int offset = 0;
 579   size_t run_index = GetRunContainingXCoord(x, &offset);
 580   if (run_index >= runs_.size())
 581     return EdgeSelectionModel((x < 0) ? CURSOR_LEFT : CURSOR_RIGHT);
 582   const internal::TextRunHarfBuzz& run = *runs_[run_index];
 583
 584   for (size_t i = 0; i < run.glyph_count; ++i) {
 585     const SkScalar end =
 586         i + 1 == run.glyph_count ? run.width : run.positions[i + 1].x();
 587     const SkScalar middle = (end + run.positions[i].x()) / 2;
 588
 589     if (offset < middle) {
 590       return SelectionModel(LayoutIndexToTextIndex(
 591           run.glyph_to_char[i] + (run.is_rtl ? 1 : 0)),
 592           (run.is_rtl ? CURSOR_BACKWARD : CURSOR_FORWARD));
 593     }
 594     if (offset < end) {
 595       return SelectionModel(LayoutIndexToTextIndex(
 596           run.glyph_to_char[i] + (run.is_rtl ? 0 : 1)),
 597           (run.is_rtl ? CURSOR_FORWARD : CURSOR_BACKWARD));
 598     }
 599   }
 600   return EdgeSelectionModel(CURSOR_RIGHT);
 601 }
 602
 603 std::vector<RenderText::FontSpan> RenderTextHarfBuzz::GetFontSpansForTesting() {
 604   NOTIMPLEMENTED();
 605   return std::vector<RenderText::FontSpan>();
 606 }
 607
 608 Range RenderTextHarfBuzz::GetGlyphBounds(size_t index) {
 609   EnsureLayout();
 610   const size_t run_index =
 611       GetRunContainingCaret(SelectionModel(index, CURSOR_FORWARD));
 612   // Return edge bounds if the index is invalid or beyond the layout text size.
 613   if (run_index >= runs_.size())
 614     return Range(GetStringSize().width());
 615   const size_t layout_index = TextIndexToLayoutIndex(index);
 616   internal::TextRunHarfBuzz* run = runs_[run_index];
 617   Range bounds = run->GetGraphemeBounds(grapheme_iterator_.get(), layout_index);
 618   return run->is_rtl ? Range(bounds.end(), bounds.start()) : bounds;
 619 }
 620
 621 int RenderTextHarfBuzz::GetLayoutTextBaseline() {
 622   EnsureLayout();
 623   return lines()[0].baseline;
 624 }
 625
 626 SelectionModel RenderTextHarfBuzz::AdjacentCharSelectionModel(
 627     const SelectionModel& selection,
 628     VisualCursorDirection direction) {
 629   DCHECK(!needs_layout_);
 630   internal::TextRunHarfBuzz* run;
 631   size_t run_index = GetRunContainingCaret(selection);
 632   if (run_index >= runs_.size()) {
 633     // The cursor is not in any run: we're at the visual and logical edge.
 634     SelectionModel edge = EdgeSelectionModel(direction);
 635     if (edge.caret_pos() == selection.caret_pos())
 636       return edge;
 637     int visual_index = (direction == CURSOR_RIGHT) ? 0 : runs_.size() - 1;
 638     run = runs_[visual_to_logical_[visual_index]];
 639   } else {
 640     // If the cursor is moving within the current run, just move it by one
 641     // grapheme in the appropriate direction.
 642     run = runs_[run_index];
 643     size_t caret = selection.caret_pos();
 644     bool forward_motion = run->is_rtl == (direction == CURSOR_LEFT);
 645     if (forward_motion) {
 646       if (caret < LayoutIndexToTextIndex(run->range.end())) {
 647         caret = IndexOfAdjacentGrapheme(caret, CURSOR_FORWARD);
 648         return SelectionModel(caret, CURSOR_BACKWARD);
 649       }
 650     } else {
 651       if (caret > LayoutIndexToTextIndex(run->range.start())) {
 652         caret = IndexOfAdjacentGrapheme(caret, CURSOR_BACKWARD);
 653         return SelectionModel(caret, CURSOR_FORWARD);
 654       }
 655     }
 656     // The cursor is at the edge of a run; move to the visually adjacent run.
 657     int visual_index = logical_to_visual_[run_index];
 658     visual_index += (direction == CURSOR_LEFT) ? -1 : 1;
 659     if (visual_index < 0 || visual_index >= static_cast<int>(runs_.size()))
 660       return EdgeSelectionModel(direction);
 661     run = runs_[visual_to_logical_[visual_index]];
 662   }
 663   bool forward_motion = run->is_rtl == (direction == CURSOR_LEFT);
 664   return forward_motion ? FirstSelectionModelInsideRun(run) :
 665                           LastSelectionModelInsideRun(run);
 666 }
 667
 668 SelectionModel RenderTextHarfBuzz::AdjacentWordSelectionModel(
 669     const SelectionModel& selection,
 670     VisualCursorDirection direction) {
 671   if (obscured())
 672     return EdgeSelectionModel(direction);
 673
 674   base::i18n::BreakIterator iter(text(), base::i18n::BreakIterator::BREAK_WORD);
 675   bool success = iter.Init();
 676   DCHECK(success);
 677   if (!success)
 678     return selection;
 679
 680   // Match OS specific word break behavior.
 681 #if defined(OS_WIN)
 682   size_t pos;
 683   if (direction == CURSOR_RIGHT) {
 684     pos = std::min(selection.caret_pos() + 1, text().length());
 685     while (iter.Advance()) {
 686       pos = iter.pos();
 687       if (iter.IsWord() && pos > selection.caret_pos())
 688         break;
 689     }
 690   } else {  // direction == CURSOR_LEFT
 691     // Notes: We always iterate words from the beginning.
 692     // This is probably fast enough for our usage, but we may
 693     // want to modify WordIterator so that it can start from the
 694     // middle of string and advance backwards.
 695     pos = std::max<int>(selection.caret_pos() - 1, 0);
 696     while (iter.Advance()) {
 697       if (iter.IsWord()) {
 698         size_t begin = iter.pos() - iter.GetString().length();
 699         if (begin == selection.caret_pos()) {
 700           // The cursor is at the beginning of a word.
 701           // Move to previous word.
 702           break;
 703         } else if (iter.pos() >= selection.caret_pos()) {
 704           // The cursor is in the middle or at the end of a word.
 705           // Move to the top of current word.
 706           pos = begin;
 707           break;
 708         }
 709         pos = iter.pos() - iter.GetString().length();
 710       }
 711     }
 712   }
 713   return SelectionModel(pos, CURSOR_FORWARD);
 714 #else
 715   SelectionModel cur(selection);
 716   for (;;) {
 717     cur = AdjacentCharSelectionModel(cur, direction);
 718     size_t run = GetRunContainingCaret(cur);
 719     if (run == runs_.size())
 720       break;
 721     const bool is_forward = runs_[run]->is_rtl == (direction == CURSOR_LEFT);
 722     size_t cursor = cur.caret_pos();
 723     if (is_forward ? iter.IsEndOfWord(cursor) : iter.IsStartOfWord(cursor))
 724       break;
 725   }
 726   return cur;
 727 #endif
 728 }
 729
 730 std::vector<Rect> RenderTextHarfBuzz::GetSubstringBounds(const Range& range) {
 731   DCHECK(!needs_layout_);
 732   DCHECK(Range(0, text().length()).Contains(range));
 733   Range layout_range(TextIndexToLayoutIndex(range.start()),
 734                      TextIndexToLayoutIndex(range.end()));
 735   DCHECK(Range(0, GetLayoutText().length()).Contains(layout_range));
 736
 737   std::vector<Rect> rects;
 738   if (layout_range.is_empty())
 739     return rects;
 740   std::vector<Range> bounds;
 741
 742   // Add a Range for each run/selection intersection.
 743   for (size_t i = 0; i < runs_.size(); ++i) {
 744     internal::TextRunHarfBuzz* run = runs_[visual_to_logical_[i]];
 745     Range intersection = run->range.Intersect(layout_range);
 746     if (!intersection.IsValid())
 747       continue;
 748     DCHECK(!intersection.is_reversed());
 749     const Range leftmost_character_x = run->GetGraphemeBounds(
 750         grapheme_iterator_.get(),
 751         run->is_rtl ? intersection.end() - 1 : intersection.start());
 752     const Range rightmost_character_x = run->GetGraphemeBounds(
 753         grapheme_iterator_.get(),
 754         run->is_rtl ? intersection.start() : intersection.end() - 1);
 755     Range range_x(leftmost_character_x.start(), rightmost_character_x.end());
 756     DCHECK(!range_x.is_reversed());
 757     if (range_x.is_empty())
 758       continue;
 759
 760     // Union this with the last range if they're adjacent.
 761     DCHECK(bounds.empty() || bounds.back().GetMax() <= range_x.GetMin());
 762     if (!bounds.empty() && bounds.back().GetMax() == range_x.GetMin()) {
 763       range_x = Range(bounds.back().GetMin(), range_x.GetMax());
 764       bounds.pop_back();
 765     }
 766     bounds.push_back(range_x);
 767   }
 768   for (size_t i = 0; i < bounds.size(); ++i) {
 769     std::vector<Rect> current_rects = TextBoundsToViewBounds(bounds[i]);
 770     rects.insert(rects.end(), current_rects.begin(), current_rects.end());
 771   }
 772   return rects;
 773 }
 774
 775 size_t RenderTextHarfBuzz::TextIndexToLayoutIndex(size_t index) const {
 776   DCHECK_LE(index, text().length());
 777   ptrdiff_t i = obscured() ? UTF16IndexToOffset(text(), 0, index) : index;
 778   CHECK_GE(i, 0);
 779   // Clamp layout indices to the length of the text actually used for layout.
 780   return std::min<size_t>(GetLayoutText().length(), i);
 781 }
 782
 783 size_t RenderTextHarfBuzz::LayoutIndexToTextIndex(size_t index) const {
 784   if (!obscured())
 785     return index;
 786
 787   DCHECK_LE(index, GetLayoutText().length());
 788   const size_t text_index = UTF16OffsetToIndex(text(), 0, index);
 789   DCHECK_LE(text_index, text().length());
 790   return text_index;
 791 }
 792
 793 bool RenderTextHarfBuzz::IsValidCursorIndex(size_t index) {
 794   if (index == 0 || index == text().length())
 795     return true;
 796   if (!IsValidLogicalIndex(index))
 797     return false;
 798   EnsureLayout();
 799   return !grapheme_iterator_ || grapheme_iterator_->IsGraphemeBoundary(index);
 800 }
 801
 802 void RenderTextHarfBuzz::ResetLayout() {
 803   needs_layout_ = true;
 804 }
 805
 806 void RenderTextHarfBuzz::EnsureLayout() {
 807   if (needs_layout_) {
 808     runs_.clear();
 809     grapheme_iterator_.reset();
 810
 811     if (!GetLayoutText().empty()) {
 812       grapheme_iterator_.reset(new base::i18n::BreakIterator(GetLayoutText(),
 813           base::i18n::BreakIterator::BREAK_CHARACTER));
 814       if (!grapheme_iterator_->Init())
 815         grapheme_iterator_.reset();
 816
 817       ItemizeText();
 818
 819       for (size_t i = 0; i < runs_.size(); ++i)
 820         ShapeRun(runs_[i]);
 821
 822       // Precalculate run width information.
 823       float preceding_run_widths = 0.0f;
 824       for (size_t i = 0; i < runs_.size(); ++i) {
 825         internal::TextRunHarfBuzz* run = runs_[visual_to_logical_[i]];
 826         run->preceding_run_widths = preceding_run_widths;
 827         preceding_run_widths += run->width;
 828       }
 829     }
 830
 831     needs_layout_ = false;
 832     std::vector<internal::Line> empty_lines;
 833     set_lines(&empty_lines);
 834   }
 835
 836   if (lines().empty()) {
 837     std::vector<internal::Line> lines;
 838     lines.push_back(internal::Line());
 839     lines[0].baseline = font_list().GetBaseline();
 840     lines[0].size.set_height(font_list().GetHeight());
 841
 842     int current_x = 0;
 843     SkPaint paint;
 844
 845     for (size_t i = 0; i < runs_.size(); ++i) {
 846       const internal::TextRunHarfBuzz& run = *runs_[visual_to_logical_[i]];
 847       internal::LineSegment segment;
 848       segment.x_range = Range(current_x, current_x + run.width);
 849       segment.char_range = run.range;
 850       segment.run = i;
 851       lines[0].segments.push_back(segment);
 852
 853       paint.setTypeface(run.skia_face.get());
 854       paint.setTextSize(run.font_size);
 855       SkPaint::FontMetrics metrics;
 856       paint.getFontMetrics(&metrics);
 857
 858       lines[0].size.set_width(lines[0].size.width() + run.width);
 859       lines[0].size.set_height(std::max(lines[0].size.height(),
 860                                         metrics.fDescent - metrics.fAscent));
 861       lines[0].baseline = std::max(lines[0].baseline,
 862                                    SkScalarRoundToInt(-metrics.fAscent));
 863     }
 864
 865     set_lines(&lines);
 866   }
 867 }
 868
 869 void RenderTextHarfBuzz::DrawVisualText(Canvas* canvas) {
 870   DCHECK(!needs_layout_);
 871   internal::SkiaTextRenderer renderer(canvas);
 872   ApplyFadeEffects(&renderer);
 873   ApplyTextShadows(&renderer);
 874
 875 #if defined(OS_WIN) || defined(OS_LINUX)
 876   renderer.SetFontRenderParams(
 877       font_list().GetPrimaryFont().GetFontRenderParams(),
 878       background_is_transparent());
 879 #endif
 880
 881   ApplyCompositionAndSelectionStyles();
 882
 883   int current_x = 0;
 884   const Vector2d line_offset = GetLineOffset(0);
 885   for (size_t i = 0; i < runs_.size(); ++i) {
 886     const internal::TextRunHarfBuzz& run = *runs_[visual_to_logical_[i]];
 887     renderer.SetTypeface(run.skia_face.get());
 888     renderer.SetTextSize(run.font_size);
 889
 890     Vector2d origin = line_offset + Vector2d(current_x, lines()[0].baseline);
 891     scoped_ptr<SkPoint[]> positions(new SkPoint[run.glyph_count]);
 892     for (size_t j = 0; j < run.glyph_count; ++j) {
 893       positions[j] = run.positions[j];
 894       positions[j].offset(SkIntToScalar(origin.x()), SkIntToScalar(origin.y()));
 895     }
 896
 897     for (BreakList<SkColor>::const_iterator it =
 898              colors().GetBreak(run.range.start());
 899          it != colors().breaks().end() && it->first < run.range.end();
 900          ++it) {
 901       const Range intersection = colors().GetRange(it).Intersect(run.range);
 902       const Range colored_glyphs = run.CharRangeToGlyphRange(intersection);
 903       // The range may be empty if a portion of a multi-character grapheme is
 904       // selected, yielding two colors for a single glyph. For now, this just
 905       // paints the glyph with a single style, but it should paint it twice,
 906       // clipped according to selection bounds. See http://crbug.com/366786
 907       if (colored_glyphs.is_empty())
 908         continue;
 909
 910       renderer.SetForegroundColor(it->second);
 911       renderer.DrawPosText(&positions[colored_glyphs.start()],
 912                            &run.glyphs[colored_glyphs.start()],
 913                            colored_glyphs.length());
 914       int width = (colored_glyphs.end() == run.glyph_count ? run.width :
 915               run.positions[colored_glyphs.end()].x()) -
 916           run.positions[colored_glyphs.start()].x();
 917       renderer.DrawDecorations(origin.x(), origin.y(), width, run.underline,
 918                                run.strike, run.diagonal_strike);
 919     }
 920
 921     current_x += run.width;
 922   }
 923
 924   renderer.EndDiagonalStrike();
 925
 926   UndoCompositionAndSelectionStyles();
 927 }
 928
 929 size_t RenderTextHarfBuzz::GetRunContainingCaret(
 930     const SelectionModel& caret) const {
 931   DCHECK(!needs_layout_);
 932   size_t layout_position = TextIndexToLayoutIndex(caret.caret_pos());
 933   LogicalCursorDirection affinity = caret.caret_affinity();
 934   for (size_t run = 0; run < runs_.size(); ++run) {
 935     if (RangeContainsCaret(runs_[run]->range, layout_position, affinity))
 936       return run;
 937   }
 938   return runs_.size();
 939 }
 940
 941 size_t RenderTextHarfBuzz::GetRunContainingXCoord(int x, int* offset) const {
 942   DCHECK(!needs_layout_);
 943   if (x < 0)
 944     return runs_.size();
 945   // Find the text run containing the argument point (assumed already offset).
 946   int current_x = 0;
 947   for (size_t i = 0; i < runs_.size(); ++i) {
 948     size_t run = visual_to_logical_[i];
 949     current_x += runs_[run]->width;
 950     if (x < current_x) {
 951       *offset = x - (current_x - runs_[run]->width);
 952       return run;
 953     }
 954   }
 955   return runs_.size();
 956 }
 957
 958 SelectionModel RenderTextHarfBuzz::FirstSelectionModelInsideRun(
 959     const internal::TextRunHarfBuzz* run) {
 960   size_t position = LayoutIndexToTextIndex(run->range.start());
 961   position = IndexOfAdjacentGrapheme(position, CURSOR_FORWARD);
 962   return SelectionModel(position, CURSOR_BACKWARD);
 963 }
 964
 965 SelectionModel RenderTextHarfBuzz::LastSelectionModelInsideRun(
 966     const internal::TextRunHarfBuzz* run) {
 967   size_t position = LayoutIndexToTextIndex(run->range.end());
 968   position = IndexOfAdjacentGrapheme(position, CURSOR_BACKWARD);
 969   return SelectionModel(position, CURSOR_FORWARD);
 970 }
 971
 972 void RenderTextHarfBuzz::ItemizeText() {
 973   const base::string16& text = GetLayoutText();
 974   const bool is_text_rtl = GetTextDirection() == base::i18n::RIGHT_TO_LEFT;
 975   DCHECK_NE(0U, text.length());
 976
 977   // If ICU fails to itemize the text, we create a run that spans the entire
 978   // text. This is needed because leaving the runs set empty causes some clients
 979   // to misbehave since they expect non-zero text metrics from a non-empty text.
 980   base::i18n::BiDiLineIterator bidi_iterator;
 981   if (!bidi_iterator.Open(text, is_text_rtl, false)) {
 982     internal::TextRunHarfBuzz* run = new internal::TextRunHarfBuzz;
 983     run->range = Range(0, text.length());
 984     runs_.push_back(run);
 985     visual_to_logical_ = logical_to_visual_ = std::vector<int32_t>(1, 0);
 986     return;
 987   }
 988
 989   // Temporarily apply composition underlines and selection colors.
 990   ApplyCompositionAndSelectionStyles();
 991
 992   // Build the list of runs from the script items and ranged styles. Use an
 993   // empty color BreakList to avoid breaking runs at color boundaries.
 994   BreakList<SkColor> empty_colors;
 995   empty_colors.SetMax(text.length());
 996   internal::StyleIterator style(empty_colors, styles());
 997
 998   for (size_t run_break = 0; run_break < text.length();) {
 999     internal::TextRunHarfBuzz* run = new internal::TextRunHarfBuzz;
1000     run->range.set_start(run_break);
1001     run->font_style = (style.style(BOLD) ? Font::BOLD : 0) |
1002                       (style.style(ITALIC) ? Font::ITALIC : 0);
1003     run->strike = style.style(STRIKE);
1004     run->diagonal_strike = style.style(DIAGONAL_STRIKE);
1005     run->underline = style.style(UNDERLINE);
1006
1007     int32 script_item_break = 0;
1008     bidi_iterator.GetLogicalRun(run_break, &script_item_break, &run->level);
1009     // Odd BiDi embedding levels correspond to RTL runs.
1010     run->is_rtl = (run->level % 2) == 1;
1011     // Find the length and script of this script run.
1012     script_item_break = ScriptInterval(text, run_break,
1013         script_item_break - run_break, &run->script) + run_break;
1014
1015     // Find the next break and advance the iterators as needed.
1016     run_break = std::min(static_cast<size_t>(script_item_break),
1017                          TextIndexToLayoutIndex(style.GetRange().end()));
1018
1019     // Break runs adjacent to character substrings in certain code blocks.
1020     // This avoids using their fallback fonts for more characters than needed,
1021     // in cases like "\x25B6 Media Title", etc. http://crbug.com/278913
1022     if (run_break > run->range.start())
1023       run_break = FindUnusualCharacter(text, run->range.start(), run_break);
1024
1025     DCHECK(IsValidCodePointIndex(text, run_break));
1026     style.UpdatePosition(LayoutIndexToTextIndex(run_break));
1027     run->range.set_end(run_break);
1028
1029     runs_.push_back(run);
1030   }
1031
1032   // Undo the temporarily applied composition underlines and selection colors.
1033   UndoCompositionAndSelectionStyles();
1034
1035   const size_t num_runs = runs_.size();
1036   std::vector<UBiDiLevel> levels(num_runs);
1037   for (size_t i = 0; i < num_runs; ++i)
1038     levels[i] = runs_[i]->level;
1039   visual_to_logical_.resize(num_runs);
1040   ubidi_reorderVisual(&levels[0], num_runs, &visual_to_logical_[0]);
1041   logical_to_visual_.resize(num_runs);
1042   ubidi_reorderLogical(&levels[0], num_runs, &logical_to_visual_[0]);
1043 }
1044
1045 void RenderTextHarfBuzz::ShapeRun(internal::TextRunHarfBuzz* run) {
1046   const Font& primary_font = font_list().GetPrimaryFont();
1047   const std::string primary_font_name = primary_font.GetFontName();
1048   run->font_size = primary_font.GetFontSize();
1049
1050   size_t best_font_missing = std::numeric_limits<size_t>::max();
1051   std::string best_font;
1052   std::string current_font;
1053
1054   // Try shaping with |primary_font|.
1055   if (ShapeRunWithFont(run, primary_font_name)) {
1056     current_font = primary_font_name;
1057     size_t current_missing = run->CountMissingGlyphs();
1058     if (current_missing == 0)
1059       return;
1060     if (current_missing < best_font_missing) {
1061       best_font_missing = current_missing;
1062       best_font = current_font;
1063     }
1064   }
1065
1066 #if defined(OS_WIN)
1067   Font uniscribe_font;
1068   const base::char16* run_text = &(GetLayoutText()[run->range.start()]);
1069   if (GetUniscribeFallbackFont(primary_font, run_text, run->range.length(),
1070                                &uniscribe_font) &&
1071       ShapeRunWithFont(run, uniscribe_font.GetFontName())) {
1072     current_font = uniscribe_font.GetFontName();
1073     size_t current_missing = run->CountMissingGlyphs();
1074     if (current_missing == 0)
1075       return;
1076     if (current_missing < best_font_missing) {
1077       best_font_missing = current_missing;
1078       best_font = current_font;
1079     }
1080   }
1081 #endif
1082
1083   // Try shaping with the fonts in the fallback list except the first, which is
1084   // |primary_font|.
1085   std::vector<std::string> fonts = GetFallbackFontFamilies(primary_font_name);
1086   for (size_t i = 1; i < fonts.size(); ++i) {
1087     if (!ShapeRunWithFont(run, fonts[i]))
1088       continue;
1089     current_font = fonts[i];
1090     size_t current_missing = run->CountMissingGlyphs();
1091     if (current_missing == 0)
1092       return;
1093     if (current_missing < best_font_missing) {
1094       best_font_missing = current_missing;
1095       best_font = current_font;
1096     }
1097   }
1098
1099   if (!best_font.empty() &&
1100       (best_font == current_font || ShapeRunWithFont(run, best_font))) {
1101     return;
1102   }
1103
1104   run->glyph_count = 0;
1105   run->width = 0.0f;
1106 }
1107
1108 bool RenderTextHarfBuzz::ShapeRunWithFont(internal::TextRunHarfBuzz* run,
1109                                           const std::string& font_family) {
1110   const base::string16& text = GetLayoutText();
1111   skia::RefPtr<SkTypeface> skia_face =
1112       internal::CreateSkiaTypeface(font_family, run->font_style);
1113   if (skia_face == NULL)
1114     return false;
1115   run->skia_face = skia_face;
1116   hb_font_t* harfbuzz_font = CreateHarfBuzzFont(run->skia_face.get(),
1117                                                 run->font_size);
1118
1119   // Create a HarfBuzz buffer and add the string to be shaped. The HarfBuzz
1120   // buffer holds our text, run information to be used by the shaping engine,
1121   // and the resulting glyph data.
1122   hb_buffer_t* buffer = hb_buffer_create();
1123   hb_buffer_add_utf16(buffer, reinterpret_cast<const uint16*>(text.c_str()),
1124                       text.length(), run->range.start(), run->range.length());
1125   hb_buffer_set_script(buffer, ICUScriptToHBScript(run->script));
1126   hb_buffer_set_direction(buffer,
1127       run->is_rtl ? HB_DIRECTION_RTL : HB_DIRECTION_LTR);
1128   // TODO(ckocagil): Should we determine the actual language?
1129   hb_buffer_set_language(buffer, hb_language_get_default());
1130
1131   // Shape the text.
1132   hb_shape(harfbuzz_font, buffer, NULL, 0);
1133
1134   // Populate the run fields with the resulting glyph data in the buffer.
1135   unsigned int glyph_count = 0;
1136   hb_glyph_info_t* infos = hb_buffer_get_glyph_infos(buffer, &glyph_count);
1137   run->glyph_count = glyph_count;
1138   hb_glyph_position_t* hb_positions =
1139       hb_buffer_get_glyph_positions(buffer, NULL);
1140   run->glyphs.reset(new uint16[run->glyph_count]);
1141   run->glyph_to_char.resize(run->glyph_count);
1142   run->positions.reset(new SkPoint[run->glyph_count]);
1143   run->width = 0.0f;
1144   for (size_t i = 0; i < run->glyph_count; ++i) {
1145     run->glyphs[i] = infos[i].codepoint;
1146     run->glyph_to_char[i] = infos[i].cluster;
1147     const int x_offset = SkFixedToScalar(hb_positions[i].x_offset);
1148     const int y_offset = SkFixedToScalar(hb_positions[i].y_offset);
1149     run->positions[i].set(run->width + x_offset, -y_offset);
1150     run->width += SkFixedToScalar(hb_positions[i].x_advance);
1151   }
1152
1153   hb_buffer_destroy(buffer);
1154   hb_font_destroy(harfbuzz_font);
1155   return true;
1156 }
1157
1158 }  // namespace gfx