RenderTextHarfBuzz: Implement font fallback for Win and Linux

ui/gfx/render_text_harfbuzz.cc

 // Copyright 2014 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/render_text_harfbuzz.h"
 
 #include <map>
 
 #include "base/debug/leak_annotations.h"
 #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 "third_party/harfbuzz-ng/src/hb.h"
 #include "third_party/icu/source/common/unicode/ubidi.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkTypeface.h"
 #include "ui/gfx/canvas.h"
+#include "ui/gfx/font_fallback.h"
 #include "ui/gfx/utf16_indexing.h"
 
 #if defined(OS_WIN)
 #include "ui/gfx/font_smoothing_win.h"
 #endif
 
 namespace gfx {
 
 namespace {
 
@@ skipping 924 matching lines @@
   visual_to_logical_.resize(num_runs);
   ubidi_reorderVisual(&levels[0], num_runs, &visual_to_logical_[0]);
   logical_to_visual_.resize(num_runs);
   ubidi_reorderLogical(&levels[0], num_runs, &logical_to_visual_[0]);
 }
 
 void RenderTextHarfBuzz::ShapeRun(internal::TextRunHarfBuzz* run) {
   const base::string16& text = GetLayoutText();
   // TODO(ckocagil|yukishiino): Implement font fallback.
   const Font& primary_font = font_list().GetPrimaryFont();
-  run->skia_face = internal::CreateSkiaTypeface(primary_font.GetFontName(),
-                                                run->font_style);
   run->font_size = primary_font.GetFontSize();
+  std::vector<std::string> fonts =
+      GetFallbackFontFamilies(primary_font.GetFontName());
 
-  hb_font_t* harfbuzz_font = CreateHarfBuzzFont(run->skia_face.get(),
-                                                run->font_size);
+  for (size_t i = 0; !shaped && i < fonts.size(); ++i) {
+    run->skia_face = internal::CreateSkiaTypeface(fonts[i], run->font_style);
 
-  // Create a HarfBuzz buffer and add the string to be shaped. The HarfBuzz
-  // buffer holds our text, run information to be used by the shaping engine,
-  // and the resulting glyph data.
-  hb_buffer_t* buffer = hb_buffer_create();
-  hb_buffer_add_utf16(buffer, reinterpret_cast<const uint16*>(text.c_str()),
-                      text.length(), run->range.start(), run->range.length());
-  hb_buffer_set_script(buffer, ICUScriptToHBScript(run->script));
-  hb_buffer_set_direction(buffer,
-      run->is_rtl ? HB_DIRECTION_RTL : HB_DIRECTION_LTR);
-  // TODO(ckocagil): Should we determine the actual language?
-  hb_buffer_set_language(buffer, hb_language_get_default());
+    hb_font_t* harfbuzz_font = CreateHarfBuzzFont(run->skia_face.get(),
+                                                  run->font_size);
 
-  // Shape the text.
-  hb_shape(harfbuzz_font, buffer, NULL, 0);
+    // Create a HarfBuzz buffer and add the string to be shaped. The HarfBuzz
+    // buffer holds our text, run information to be used by the shaping engine,
+    // and the resulting glyph data.
+    hb_buffer_t* buffer = hb_buffer_create();
+    hb_buffer_add_utf16(buffer, reinterpret_cast<const uint16*>(text.c_str()),
+                        text.length(), run->range.start(), run->range.length());
+    hb_buffer_set_script(buffer, ICUScriptToHBScript(run->script));
+    hb_buffer_set_direction(buffer,
+        run->is_rtl ? HB_DIRECTION_RTL : HB_DIRECTION_LTR);
+    // TODO(ckocagil): Should we determine the actual language?
+    hb_buffer_set_language(buffer, hb_language_get_default());
 
-  // Populate the run fields with the resulting glyph data in the buffer.
-  unsigned int glyph_count = 0;
-  hb_glyph_info_t* infos = hb_buffer_get_glyph_infos(buffer, &glyph_count);
-  hb_glyph_position_t* hb_positions = hb_buffer_get_glyph_positions(buffer,
-                                                                    NULL);
-  run->glyph_count = glyph_count;
-  run->glyphs.reset(new uint16[run->glyph_count]);
-  run->glyph_to_char.reset(new uint32[run->glyph_count]);
-  run->positions.reset(new SkPoint[run->glyph_count]);
-  for (size_t i = 0; i < run->glyph_count; ++i) {
-    run->glyphs[i] = infos[i].codepoint;
-    run->glyph_to_char[i] = infos[i].cluster;
-    const int x_offset =
-        SkScalarRoundToInt(SkFixedToScalar(hb_positions[i].x_offset));
-    const int y_offset =
-        SkScalarRoundToInt(SkFixedToScalar(hb_positions[i].y_offset));
-    run->positions[i].set(run->width + x_offset, y_offset);
-    run->width +=
-        SkScalarRoundToInt(SkFixedToScalar(hb_positions[i].x_advance));
+    // Shape the text.
+    hb_shape(harfbuzz_font, buffer, NULL, 0);
+
+    // Populate the run fields with the resulting glyph data in the buffer.
+    unsigned int glyph_count = 0;
+    hb_glyph_info_t* infos = hb_buffer_get_glyph_infos(buffer, &glyph_count);
+    hb_glyph_position_t* hb_positions = hb_buffer_get_glyph_positions(buffer,
+                                                                      NULL);
+    run->glyph_count = glyph_count;
+    run->glyphs.reset(new uint16[run->glyph_count]);
+    run->glyph_to_char.reset(new uint32[run->glyph_count]);
+    run->positions.reset(new SkPoint[run->glyph_count]);
+    run->width = 0;
+    for (size_t i = 0; i < run->glyph_count; ++i) {
+      run->glyphs[i] = infos[i].codepoint;
+      run->glyph_to_char[i] = infos[i].cluster;
+      const int x_offset =
+          SkScalarRoundToInt(SkFixedToScalar(hb_positions[i].x_offset));
+      const int y_offset =
+          SkScalarRoundToInt(SkFixedToScalar(hb_positions[i].y_offset));
+      run->positions[i].set(run->width + x_offset, y_offset);
+      run->width +=
+          SkScalarRoundToInt(SkFixedToScalar(hb_positions[i].x_advance));
+    }
+
+    hb_buffer_destroy(buffer);
+    hb_font_destroy(harfbuzz_font);
+
+    if (!run->HasMissingGlyphs())

[msw, 2014/06/30 17:35:54]

Do we want something like RenderTextWin's best_partial_font? Otherwise it seems
like we'll return the last fallback font's results, which may be worse than the
original font.
https://code.google.com/p/chromium/codesearch#chromium/src/ui/gfx/render_text...

[ckocagil, 2014/07/04 15:30:16]

Done.

+      return;
   }
-
-  hb_buffer_destroy(buffer);
-  hb_font_destroy(harfbuzz_font);
 }
 
 }  // namespace gfx