Rework gfx::Font by moving platform-specific code into inner classes....

gfx/platform_font_gtk.h

+// Copyright (c) 2010 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 GFX_PLATFORM_FONT_GTK_
+#define GFX_PLATFORM_FONT_GTK_
+#pragma once
+
+#include "base/scoped_ptr.h"
+#include "gfx/platform_font.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
+
+class SkTypeface;
+class SkPaint;
+
+namespace gfx {
+
+class PlatformFontGtk : public PlatformFont {
+ public:
+  PlatformFontGtk();
+  explicit PlatformFontGtk(const Font& other);
+  explicit PlatformFontGtk(NativeFont native_font);
+  PlatformFontGtk(const std::wstring& font_name,
+                  int font_size);
+
+  // Converts |gfx_font| to a new pango font. Free the returned font with
+  // pango_font_description_free().
+  static PangoFontDescription* PangoFontFromGfxFont(const gfx::Font& gfx_font);
+
+  // Position as an offset from the height of the drawn text, used to draw
+  // an underline. This is a negative number, so the underline would be
+  // drawn at y + height + underline_position;
+  double underline_position() const;
+  // The thickness to draw the underline.
+  double underline_thickness() const;
+
+  // Overridden from PlatformFont:
+  virtual Font DeriveFont(int size_delta, int style) const;
+  virtual int GetHeight() const;
+  virtual int GetBaseline() const;
+  virtual int GetAverageCharacterWidth() const;
+  virtual int GetStringWidth(const std::wstring& text) const;
+  virtual int GetExpectedTextWidth(int length) const;
+  virtual int GetStyle() const;
+  virtual const std::wstring& GetFontName() const;
+  virtual int GetFontSize() const;
+  virtual NativeFont GetNativeFont() const;
+
+ private:
+  // Create a new instance of this object with the specified properties. Called
+  // from DeriveFont.
+  PlatformFontGtk(SkTypeface* typeface,
+                  const std::wstring& name,
+                  int size,
+                  int style);
+  virtual ~PlatformFontGtk() {}
+
+  // Initialize this object.
+  void InitWithNameAndSize(const std::wstring& font_name, int font_size);
+  void InitWithTypefaceNameSizeAndStyle(SkTypeface* typeface,
+                                        const std::wstring& name,
+                                        int size,
+                                        int style);
+  void InitFromPlatformFont(const PlatformFontGtk* other);
+
+  // Potentially slow call to get pango metrics (average width, underline info).
+  void InitPangoMetrics();
+
+  // Setup a Skia context to use the current typeface
+  void PaintSetup(SkPaint* paint) const;
+
+  // Make |this| a copy of |other|.
+  void CopyFont(const Font& other);
+
+  // Return the scale factor for fonts that account for DPI.
+  static float GetPangoScaleFactor();
+
+  // The average width of a character, initialized and cached if needed.
+  double GetAverageWidth() const;
+
+  // These two both point to the same SkTypeface. We use the SkAutoUnref to
+  // handle the reference counting, but without @typeface_ we would have to
+  // cast the SkRefCnt from @typeface_helper_ every time.
+  scoped_ptr<SkAutoUnref> typeface_helper_;
+  SkTypeface *typeface_;
+
+  // Additional information about the face
+  // Skia actually expects a family name and not a font name.
+  std::wstring font_family_;
+  int font_size_;
+  int style_;
+
+  // Cached metrics, generated at construction
+  int height_;
+  int ascent_;
+
+  // The pango metrics are much more expensive so we wait until we need them
+  // to compute them.
+  bool pango_metrics_inited_;
+  double average_width_;
+  double underline_position_;
+  double underline_thickness_;
+
+  // The default font, used for the default constructor.
+  static Font* default_font_;
+};
+
+}  // namespace gfx
+
+#endif  // GFX_PLATFORM_FONT_GTK_
+