ui/gfx/platform_font_pango.h

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_GFX_PLATFORM_FONT_PANGO_H_
#define UI_GFX_PLATFORM_FONT_PANGO_H_

#include <string>

#include "base/compiler_specific.h"
#include "base/memory/scoped_ptr.h"
#include "skia/ext/refptr.h"
#include "third_party/skia/include/core/SkRefCnt.h"
#include "ui/gfx/font_render_params.h"
#include "ui/gfx/platform_font.h"

class SkTypeface;
class SkPaint;

namespace gfx {

class GFX_EXPORT PlatformFontPango : public PlatformFont {
 public:
  PlatformFontPango();
  explicit PlatformFontPango(NativeFont native_font);
  PlatformFontPango(const std::string& font_name, int font_size_pixels);

  // Converts |gfx_font| to a new pango font. Free the returned font with
  // pango_font_description_free().
  static PangoFontDescription* PangoFontFromGfxFont(const gfx::Font& gfx_font);

  // Resets and reloads the cached system font used by the default constructor.
  // This function is useful when the system font has changed, for example, when
  // the locale has changed.
  static void ReloadDefaultFont();

#if defined(OS_CHROMEOS)
  // Sets the default font. |font_description| is a Pango font description that
  // will be passed to pango_font_description_from_string().
  static void SetDefaultFontDescription(const std::string& font_description);
#endif

  // Overridden from PlatformFont:
  virtual Font DeriveFont(int size_delta, int style) const override;
  virtual int GetHeight() const override;
  virtual int GetBaseline() const override;
  virtual int GetCapHeight() const override;
  virtual int GetExpectedTextWidth(int length) const override;
  virtual int GetStyle() const override;
  virtual std::string GetFontName() const override;
  virtual std::string GetActualFontNameForTesting() const override;
  virtual int GetFontSize() const override;
  virtual const FontRenderParams& GetFontRenderParams() const override;
  virtual NativeFont GetNativeFont() const override;

 private:
  // Create a new instance of this object with the specified properties. Called
  // from DeriveFont.
  PlatformFontPango(const skia::RefPtr<SkTypeface>& typeface,
                    const std::string& name,
                    int size_pixels,
                    int style,
                    const FontRenderParams& params);
  virtual ~PlatformFontPango();

  // Initializes this object based on the passed-in details. If |typeface| is
  // empty, a new typeface will be loaded.
  void InitFromDetails(
      const skia::RefPtr<SkTypeface>& typeface,
      const std::string& font_family,
      int font_size_pixels,
      int style,
      const FontRenderParams& params);

  // Initializes this object as a copy of another PlatformFontPango.
  void InitFromPlatformFont(const PlatformFontPango* other);

  // Potentially slow call to get pango metrics (average width).
  void InitPangoMetrics();

  // Setup a Skia context to use the current typeface.
  void PaintSetup(SkPaint* paint) const;

  // Make |this| a copy of |other|.
  void CopyFont(const Font& other);

  // The average width of a character, initialized and cached if needed.
  double GetAverageWidth() const;

  skia::RefPtr<SkTypeface> typeface_;

  // Additional information about the face.
  // Skia actually expects a family name and not a font name.
  std::string font_family_;
  int font_size_pixels_;
  int style_;

  // Information describing how the font should be rendered.
  FontRenderParams font_render_params_;

  // Cached metrics, generated at construction.
  int ascent_pixels_;
  int height_pixels_;
  int cap_height_pixels_;

  // The pango metrics are much more expensive so we wait until we need them
  // to compute them.
  bool pango_metrics_inited_;
  double average_width_pixels_;

  // The default font, used for the default constructor.
  static Font* default_font_;

#if defined(OS_CHROMEOS)
  // A Pango font description.
  static std::string* default_font_description_;
#endif

  DISALLOW_COPY_AND_ASSIGN(PlatformFontPango);
};

}  // namespace gfx

#endif  // UI_GFX_PLATFORM_FONT_PANGO_H_