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