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