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/font_render_params.h"
  15 #include "ui/gfx/platform_font.h"
  16
  17 class SkTypeface;
  18 class SkPaint;
  19
  20 namespace gfx {
  21
  22 class GFX_EXPORT PlatformFontPango : public PlatformFont {
  23  public:
  24   PlatformFontPango();
  25   explicit PlatformFontPango(NativeFont native_font);
  26   PlatformFontPango(const std::string& font_name, int font_size_pixels);
  27
  28   // Converts |gfx_font| to a new pango font. Free the returned font with
  29   // pango_font_description_free().
  30   static PangoFontDescription* PangoFontFromGfxFont(const gfx::Font& gfx_font);
  31
  32   // Resets and reloads the cached system font used by the default constructor.
  33   // This function is useful when the system font has changed, for example, when
  34   // the locale has changed.
  35   static void ReloadDefaultFont();
  36
  37 #if defined(OS_CHROMEOS)
  38   // Sets the default font. |font_description| is a Pango font description that
  39   // will be passed to pango_font_description_from_string().
  40   static void SetDefaultFontDescription(const std::string& font_description);
  41 #endif
  42
  43   // Position as an offset from the height of the drawn text, used to draw
  44   // an underline. This is a negative number, so the underline would be
  45   // drawn at y + height + underline_position.
  46   double underline_position() const;
  47   // The thickness to draw the underline.
  48   double underline_thickness() const;
  49
  50   // Overridden from PlatformFont:
  51   virtual Font DeriveFont(int size_delta, int style) const OVERRIDE;
  52   virtual int GetHeight() const OVERRIDE;
  53   virtual int GetBaseline() const OVERRIDE;
  54   virtual int GetCapHeight() const OVERRIDE;
  55   virtual int GetExpectedTextWidth(int length) const OVERRIDE;
  56   virtual int GetStyle() const OVERRIDE;
  57   virtual std::string GetFontName() const OVERRIDE;
  58   virtual std::string GetActualFontNameForTesting() const OVERRIDE;
  59   virtual int GetFontSize() const OVERRIDE;
  60   virtual const FontRenderParams& GetFontRenderParams() const OVERRIDE;
  61   virtual NativeFont GetNativeFont() const OVERRIDE;
  62
  63  private:
  64   // Create a new instance of this object with the specified properties. Called
  65   // from DeriveFont.
  66   PlatformFontPango(const skia::RefPtr<SkTypeface>& typeface,
  67                     const std::string& name,
  68                     int size_pixels,
  69                     int style,
  70                     const FontRenderParams& params);
  71   virtual ~PlatformFontPango();
  72
  73   // Initializes this object based on the passed-in details. If |typeface| is
  74   // empty, a new typeface will be loaded.
  75   void InitFromDetails(
  76       const skia::RefPtr<SkTypeface>& typeface,
  77       const std::string& font_family,
  78       int font_size_pixels,
  79       int style,
  80       const FontRenderParams& params);
  81
  82   // Initializes this object as a copy of another PlatformFontPango.
  83   void InitFromPlatformFont(const PlatformFontPango* other);
  84
  85   // Potentially slow call to get pango metrics (average width, underline info).
  86   void InitPangoMetrics();
  87
  88   // Setup a Skia context to use the current typeface.
  89   void PaintSetup(SkPaint* paint) const;
  90
  91   // Make |this| a copy of |other|.
  92   void CopyFont(const Font& other);
  93
  94   // The average width of a character, initialized and cached if needed.
  95   double GetAverageWidth() const;
  96
  97   skia::RefPtr<SkTypeface> typeface_;
  98
  99   // Additional information about the face.
 100   // Skia actually expects a family name and not a font name.
 101   std::string font_family_;
 102   int font_size_pixels_;
 103   int style_;
 104
 105   // Information describing how the font should be rendered.
 106   FontRenderParams font_render_params_;
 107
 108   // Cached metrics, generated at construction.
 109   int ascent_pixels_;
 110   int height_pixels_;
 111   int cap_height_pixels_;
 112
 113   // The pango metrics are much more expensive so we wait until we need them
 114   // to compute them.
 115   bool pango_metrics_inited_;
 116   double average_width_pixels_;
 117   double underline_position_pixels_;
 118   double underline_thickness_pixels_;
 119
 120   // The default font, used for the default constructor.
 121   static Font* default_font_;
 122
 123 #if defined(OS_CHROMEOS)
 124   // A Pango font description.
 125   static std::string* default_font_description_;
 126 #endif
 127
 128   DISALLOW_COPY_AND_ASSIGN(PlatformFontPango);
 129 };
 130
 131 }  // namespace gfx
 132
 133 #endif  // UI_GFX_PLATFORM_FONT_PANGO_H_