ui/gfx/font.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_FONT_H_
   6 #define UI_GFX_FONT_H_
   7
   8 #include <string>
   9
  10 #include "base/memory/ref_counted.h"
  11 #include "base/string16.h"
  12 #include "ui/base/ui_export.h"
  13 #include "ui/gfx/native_widget_types.h"
  14
  15 namespace gfx {
  16
  17 class PlatformFont;
  18
  19 // Font provides a wrapper around an underlying font. Copy and assignment
  20 // operators are explicitly allowed, and cheap.
  21 class UI_EXPORT Font {
  22  public:
  23   // The following constants indicate the font style.
  24   enum FontStyle {
  25     NORMAL = 0,
  26     BOLD = 1,
  27     ITALIC = 2,
  28     UNDERLINE = 4,
  29   };
  30
  31   // Creates a font with the default name and style.
  32   Font();
  33
  34   // Creates a font that is a clone of another font object.
  35   Font(const Font& other);
  36   gfx::Font& operator=(const Font& other);
  37
  38   // Creates a font from the specified native font.
  39   explicit Font(NativeFont native_font);
  40
  41   // Constructs a Font object with the specified PlatformFont object. The Font
  42   // object takes ownership of the PlatformFont object.
  43   explicit Font(PlatformFont* platform_font);
  44
  45   // Creates a font with the specified name in UTF-8 and size in pixels.
  46   Font(const std::string& font_name, int font_size);
  47
  48   ~Font();
  49
  50   // Returns a new Font derived from the existing font.
  51   // |size_deta| is the size in pixels to add to the current font. For example,
  52   // a value of 5 results in a font 5 pixels bigger than this font.
  53   Font DeriveFont(int size_delta) const;
  54
  55   // Returns a new Font derived from the existing font.
  56   // |size_delta| is the size in pixels to add to the current font. See the
  57   // single argument version of this method for an example.
  58   // The style parameter specifies the new style for the font, and is a
  59   // bitmask of the values: BOLD, ITALIC and UNDERLINE.
  60   Font DeriveFont(int size_delta, int style) const;
  61
  62   // Returns the number of vertical pixels needed to display characters from
  63   // the specified font.  This may include some leading, i.e. height may be
  64   // greater than just ascent + descent.  Specifically, the Windows and Mac
  65   // implementations include leading and the Linux one does not.  This may
  66   // need to be revisited in the future.
  67   int GetHeight() const;
  68
  69   // Returns the baseline, or ascent, of the font.
  70   int GetBaseline() const;
  71
  72   // Returns the average character width for the font.
  73   int GetAverageCharacterWidth() const;
  74
  75   // Returns the number of horizontal pixels needed to display the specified
  76   // string.
  77   int GetStringWidth(const string16& text) const;
  78
  79   // Returns the expected number of horizontal pixels needed to display the
  80   // specified length of characters. Call GetStringWidth() to retrieve the
  81   // actual number.
  82   int GetExpectedTextWidth(int length) const;
  83
  84   // Returns the style of the font.
  85   int GetStyle() const;
  86
  87   // Returns the font name in UTF-8.
  88   std::string GetFontName() const;
  89
  90   // Returns the font size in pixels.
  91   int GetFontSize() const;
  92
  93   // Returns the native font handle.
  94   // Lifetime lore:
  95   // Windows: This handle is owned by the Font object, and should not be
  96   //          destroyed by the caller.
  97   // Mac:     The object is owned by the system and should not be released.
  98   // Gtk:     This handle is created on demand, and must be freed by calling
  99   //          pango_font_description_free() when the caller is done using it or
 100   //          by using ScopedPangoFontDescription.
 101   NativeFont GetNativeFont() const;
 102
 103   // Raw access to the underlying platform font implementation. Can be
 104   // static_cast to a known implementation type if needed.
 105   PlatformFont* platform_font() const { return platform_font_.get(); }
 106
 107  private:
 108   // Wrapped platform font implementation.
 109   scoped_refptr<PlatformFont> platform_font_;
 110 };
 111
 112 }  // namespace gfx
 113
 114 #endif  // UI_GFX_FONT_H_