ui/gfx/platform_font_pango.h

   1 // Copyright (c) 2012 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 #ifndef UI_GFX_PLATFORM_FONT_PANGO_H_
   6 #define UI_GFX_PLATFORM_FONT_PANGO_H_
   7
   8 #include "base/compiler_specific.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "skia/ext/refptr.h"
  11 #include "third_party/skia/include/core/SkRefCnt.h"
  12 #include "ui/gfx/platform_font.h"
  13
  14 class SkTypeface;
  15 class SkPaint;
  16
  17 namespace gfx {
  18
  19 class UI_EXPORT PlatformFontPango : public PlatformFont {
  20  public:
  21   PlatformFontPango();
  22   explicit PlatformFontPango(NativeFont native_font);
  23   PlatformFontPango(const std::string& font_name, int font_size);
  24
  25   // Converts |gfx_font| to a new pango font. Free the returned font with
  26   // pango_font_description_free().
  27   static PangoFontDescription* PangoFontFromGfxFont(const gfx::Font& gfx_font);
  28
  29   // Resets and reloads the cached system font used by the default constructor.
  30   // This function is useful when the system font has changed, for example, when
  31   // the locale has changed.
  32   static void ReloadDefaultFont();
  33
  34   // Position as an offset from the height of the drawn text, used to draw
  35   // an underline. This is a negative number, so the underline would be
  36   // drawn at y + height + underline_position.
  37   double underline_position() const;
  38   // The thickness to draw the underline.
  39   double underline_thickness() const;
  40
  41   // Overridden from PlatformFont:
  42   virtual Font DeriveFont(int size_delta, int style) const OVERRIDE;
  43   virtual int GetHeight() const OVERRIDE;
  44   virtual int GetBaseline() const OVERRIDE;
  45   virtual int GetAverageCharacterWidth() const OVERRIDE;
  46   virtual int GetStringWidth(const base::string16& text) const OVERRIDE;
  47   virtual int GetExpectedTextWidth(int length) const OVERRIDE;
  48   virtual int GetStyle() const OVERRIDE;
  49   virtual std::string GetFontName() const OVERRIDE;
  50   virtual int GetFontSize() const OVERRIDE;
  51   virtual NativeFont GetNativeFont() const OVERRIDE;
  52
  53  private:
  54   // Create a new instance of this object with the specified properties. Called
  55   // from DeriveFont.
  56   PlatformFontPango(const skia::RefPtr<SkTypeface>& typeface,
  57                     const std::string& name,
  58                     int size,
  59                     int style);
  60   virtual ~PlatformFontPango();
  61
  62   // Initialize this object.
  63   void InitWithNameAndSize(const std::string& font_name, int font_size);
  64   void InitWithTypefaceNameSizeAndStyle(
  65       const skia::RefPtr<SkTypeface>& typeface,
  66       const std::string& name,
  67       int size,
  68       int style);
  69   void InitFromPlatformFont(const PlatformFontPango* other);
  70
  71   // Potentially slow call to get pango metrics (average width, underline info).
  72   void InitPangoMetrics();
  73
  74   // Setup a Skia context to use the current typeface.
  75   void PaintSetup(SkPaint* paint) const;
  76
  77   // Make |this| a copy of |other|.
  78   void CopyFont(const Font& other);
  79
  80   // The average width of a character, initialized and cached if needed.
  81   double GetAverageWidth() const;
  82
  83   skia::RefPtr<SkTypeface> typeface_;
  84
  85   // Additional information about the face
  86   // Skia actually expects a family name and not a font name.
  87   std::string font_family_;
  88   int font_size_pixels_;
  89   int style_;
  90
  91   // Cached metrics, generated at construction.
  92   int height_pixels_;
  93   int ascent_pixels_;
  94
  95   // The pango metrics are much more expensive so we wait until we need them
  96   // to compute them.
  97   bool pango_metrics_inited_;
  98   double average_width_pixels_;
  99   double underline_position_pixels_;
 100   double underline_thickness_pixels_;
 101
 102   // The default font, used for the default constructor.
 103   static Font* default_font_;
 104
 105   DISALLOW_COPY_AND_ASSIGN(PlatformFontPango);
 106 };
 107
 108 }  // namespace gfx
 109
 110 #endif  // UI_GFX_PLATFORM_FONT_PANGO_H_