More or less implement RenderTextHarfBuzz

ui/gfx/render_text_harfbuzz.h

Index: ui/gfx/render_text_harfbuzz.h
diff --git a/ui/gfx/render_text_harfbuzz.h b/ui/gfx/render_text_harfbuzz.h
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+++ b/ui/gfx/render_text_harfbuzz.h
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+// Copyright (c) 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 "third_party/harfbuzz-ng/src/hb.h"
+#include "third_party/icu/source/common/unicode/ubidi.h"
+#include "ui/gfx/render_text.h"
+
+namespace gfx {
+
+namespace internal {
+
+struct TextRunHarfBuzz {
+  TextRunHarfBuzz();
+  ~TextRunHarfBuzz();
+
+  UBiDiDirection direction;
+  Range range;
+  scoped_ptr<uint16[]> glyphs;
+  scoped_ptr<SkPoint[]> positions;
+  scoped_ptr<uint32[]> glyph_to_char;
+  size_t glyph_count;
+  int width;
+  SkTypeface* skia_face;
+  int font_size;
+};
+
+}  // namespace internal
+
+class RenderTextHarfBuzz : public RenderText {
+ public:
+  RenderTextHarfBuzz();
+  virtual ~RenderTextHarfBuzz();
+
+  // Overridden from RenderText.
+  virtual Size GetStringSize() OVERRIDE;
+  virtual SelectionModel FindCursorPosition(const Point& point) OVERRIDE;
+  virtual bool IsCursorablePosition(size_t position) OVERRIDE;
+  virtual std::vector<FontSpan> GetFontSpansForTesting() OVERRIDE;
+
+ protected:
+  // Overridden from RenderText.
+  virtual int GetLayoutTextBaseline() OVERRIDE;
+  virtual SelectionModel AdjacentCharSelectionModel(
+      const SelectionModel& selection,
+      VisualCursorDirection direction) OVERRIDE;
+  virtual SelectionModel AdjacentWordSelectionModel(
+      const SelectionModel& selection,
+      VisualCursorDirection direction) OVERRIDE;
+  virtual Range GetGlyphBounds(size_t index) OVERRIDE;
+  virtual std::vector<Rect> GetSubstringBounds(const Range& range) OVERRIDE;
+  virtual size_t TextIndexToLayoutIndex(size_t index) const OVERRIDE;
+  virtual size_t LayoutIndexToTextIndex(size_t index) const OVERRIDE;
+  virtual void ResetLayout() OVERRIDE;
+  virtual void EnsureLayout() OVERRIDE;
+  virtual void DrawVisualText(Canvas* canvas) OVERRIDE;
+
+  void ShapeRun(Range range,
+                UBiDiDirection direction,
+                internal::TextRunHarfBuzz* run);
+
+  size_t GetRunContainingCaret(const SelectionModel& caret) const;
+
+  // Returns the X coordinate of the leading or |trailing| edge of the glyph
+  // starting at |index|, relative to the left of the text (not the view).
+  int GetGlyphXBoundary(size_t run_index, size_t text_index, bool trailing);
+
+  SelectionModel RenderTextHarfBuzz::FirstSelectionModelInsideRun(
+      const internal::TextRunHarfBuzz* run);
+
+  SelectionModel RenderTextHarfBuzz::LastSelectionModelInsideRun(
+      const internal::TextRunHarfBuzz* run);
+
+  size_t GetRunContainingXCoord(int x, int* offset) const;
+
+ private:
+  // Text runs in visual order.
+  scoped_ptr<internal::TextRunHarfBuzz[]> runs_;
+  size_t num_runs_;
+
+  bool needs_layout_;
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_RENDER_TEXT_HARFBUZZ_H_