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 <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "skia/ext/refptr.h"
  13 #include "third_party/skia/include/core/SkRefCnt.h"
  14 #include "ui/gfx/platform_font.h"
  15
  16 class SkTypeface;
  17 class SkPaint;
  18
  19 namespace gfx {
  20
  21 class GFX_EXPORT PlatformFontPango : public PlatformFont {
  22  public:
  23   PlatformFontPango();
  24   explicit PlatformFontPango(NativeFont native_font);
  25   PlatformFontPango(const std::string& font_name, int font_size);
  26
  27   // Converts |gfx_font| to a new pango font. Free the returned font with
  28   // pango_font_description_free().
  29   static PangoFontDescription* PangoFontFromGfxFont(const gfx::Font& gfx_font);
  30
  31   // Resets and reloads the cached system font used by the default constructor.
  32   // This function is useful when the system font has changed, for example, when
  33   // the locale has changed.
  34   static void ReloadDefaultFont();
  35
  36 #if defined(OS_CHROMEOS)
  37   // Sets the default font.
  38   static void SetDefaultFontDescription(const std::string& font_description);
  39 #endif
  40
  41   // Position as an offset from the height of the drawn text, used to draw
  42   // an underline. This is a negative number, so the underline would be
  43   // drawn at y + height + underline_position.
  44   double underline_position() const;
  45   // The thickness to draw the underline.
  46   double underline_thickness() const;
  47
  48   // Overridden from PlatformFont:
  49   virtual Font DeriveFont(int size_delta, int style) const OVERRIDE;
  50   virtual int GetHeight() const OVERRIDE;
  51   virtual int GetBaseline() const OVERRIDE;
  52   virtual int GetCapHeight() const OVERRIDE;
  53   virtual int GetExpectedTextWidth(int length) const OVERRIDE;
  54   virtual int GetStyle() const OVERRIDE;
  55   virtual std::string GetFontName() const OVERRIDE;
  56   virtual std::string GetActualFontNameForTesting() const OVERRIDE;
  57   virtual int GetFontSize() const OVERRIDE;
  58   virtual NativeFont GetNativeFont() const OVERRIDE;
  59
  60  private:
  61   // Create a new instance of this object with the specified properties. Called
  62   // from DeriveFont.
  63   PlatformFontPango(const skia::RefPtr<SkTypeface>& typeface,
  64                     const std::string& name,
  65                     int size,
  66                     int style);
  67   virtual ~PlatformFontPango();
  68
  69   // Returns a Pango font description (suitable for parsing by
  70   // pango_font_description_from_string()) for the default UI font.
  71   static std::string GetDefaultFont();
  72
  73   // Initialize this object.
  74   void InitWithNameAndSize(const std::string& font_name, int font_size);
  75   void InitWithTypefaceNameSizeAndStyle(
  76       const skia::RefPtr<SkTypeface>& typeface,
  77       const std::string& font_family,
  78       int font_size,
  79       int style);
  80   void InitFromPlatformFont(const PlatformFontPango* other);
  81
  82   // Potentially slow call to get pango metrics (average width, underline info).
  83   void InitPangoMetrics();
  84
  85   // Setup a Skia context to use the current typeface.
  86   void PaintSetup(SkPaint* paint) const;
  87
  88   // Make |this| a copy of |other|.
  89   void CopyFont(const Font& other);
  90
  91   // The average width of a character, initialized and cached if needed.
  92   double GetAverageWidth() const;
  93
  94   skia::RefPtr<SkTypeface> typeface_;
  95
  96   // Additional information about the face
  97   // Skia actually expects a family name and not a font name.
  98   std::string font_family_;
  99   int font_size_pixels_;
 100   int style_;
 101
 102   // Cached metrics, generated at construction.
 103   int height_pixels_;
 104   int ascent_pixels_;
 105   int cap_height_pixels_;
 106
 107   // The pango metrics are much more expensive so we wait until we need them
 108   // to compute them.
 109   bool pango_metrics_inited_;
 110   double average_width_pixels_;
 111   double underline_position_pixels_;
 112   double underline_thickness_pixels_;
 113
 114   // The default font, used for the default constructor.
 115   static Font* default_font_;
 116
 117 #if defined(OS_CHROMEOS)
 118   static std::string* default_font_description_;
 119 #endif
 120
 121   DISALLOW_COPY_AND_ASSIGN(PlatformFontPango);
 122 };
 123
 124 }  // namespace gfx
 125
 126 #endif  // UI_GFX_PLATFORM_FONT_PANGO_H_