Enable subpixel positioning for UI

ui/gfx/render_text_harfbuzz.h

 // 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.
 
 #ifndef UI_GFX_RENDER_TEXT_HARFBUZZ_H_
 #define UI_GFX_RENDER_TEXT_HARFBUZZ_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "third_party/harfbuzz-ng/src/hb.h"
 #include "third_party/icu/source/common/unicode/ubidi.h"
 #include "third_party/icu/source/common/unicode/uscript.h"
 #include "ui/gfx/render_text.h"
 
 namespace base {
 namespace i18n {
 class BreakIterator;
 }
 }
 
 namespace gfx {
 
 namespace internal {
 
+// TODO(ckocagil): Make Range a template class and RangeF an instance of it.
+typedef std::pair<float, float> RangeF;
+
+// Applies std::round to the start and end values of the given RangeF.
+Range GFX_EXPORT RoundRangeF(const RangeF& range_f);
+
 struct GFX_EXPORT TextRunHarfBuzz {
   TextRunHarfBuzz();
   ~TextRunHarfBuzz();
 
   // Returns the index of the first glyph that corresponds to the character at
   // |pos|.
   size_t CharToGlyph(size_t pos) const;
 
   // Returns the corresponding glyph range of the given character range.
   // |range| is in text-space (0 corresponds to |GetLayoutText()[0]|). Returned
   // value is in run-space (0 corresponds to the first glyph in the run).
   Range CharRangeToGlyphRange(const Range& range) const;
 
   // Returns the number of missing glyphs in the shaped text run.
   size_t CountMissingGlyphs() const;
 
   // Writes the character and glyph ranges of the cluster containing |pos|.
   void GetClusterAt(size_t pos, Range* chars, Range* glyphs) const;
 
   // Returns the grapheme bounds at |text_index|. Handles multi-grapheme glyphs.
-  Range GetGraphemeBounds(base::i18n::BreakIterator* grapheme_iterator,
-                          size_t text_index);
+  RangeF GetGraphemeBounds(base::i18n::BreakIterator* grapheme_iterator,
+                           size_t text_index);
 
   // Returns whether the given shaped run contains any missing glyphs.
   bool HasMissingGlyphs() const;
 
   float width;
   float preceding_run_widths;
   Range range;
   bool is_rtl;
   UBiDiLevel level;
   UScriptCode script;
@@ skipping 52 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_RunDirection);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_BreakRunsByUnicodeBlocks);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_SubglyphGraphemeCases);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_SubglyphGraphemePartition);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_NonExistentFont);
   FRIEND_TEST_ALL_PREFIXES(RenderTextTest, HarfBuzz_UniscribeFallback);
 
   // Return the run index that contains the argument; or the length of the
   // |runs_| vector if argument exceeds the text length or width.
   size_t GetRunContainingCaret(const SelectionModel& caret) const;
-  size_t GetRunContainingXCoord(int x, int* offset) const;
+  size_t GetRunContainingXCoord(float x, float* offset) const;
 
   // Given a |run|, returns the SelectionModel that contains the logical first
   // or last caret position inside (not at a boundary of) the run.
   // The returned value represents a cursor/caret position without a selection.
   SelectionModel FirstSelectionModelInsideRun(
       const internal::TextRunHarfBuzz* run);
   SelectionModel LastSelectionModelInsideRun(
       const internal::TextRunHarfBuzz* run);
 
   // Break the text into logical runs and populate the visual <-> logical maps.
@@ skipping 29 matching lines @@
   // ICU grapheme iterator for the layout text. Valid when |!needs_layout_|. Can
   // be NULL in case of an error.
   scoped_ptr<base::i18n::BreakIterator> grapheme_iterator_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderTextHarfBuzz);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_RENDER_TEXT_HARFBUZZ_H_