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/strings/string16.h"
  12 #include "ui/gfx/gfx_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 //
  22 // Figure of font metrics:
  23 //   +--------+-------------------+------------------+
  24 //   |        |                   | internal leading |
  25 //   |        | ascent (baseline) +------------------+
  26 //   | height |                   | cap height       |
  27 //   |        |-------------------+------------------+
  28 //   |        | descent (height - baseline)          |
  29 //   +--------+--------------------------------------+
  30 class GFX_EXPORT Font {
  31  public:
  32   // The following constants indicate the font style.
  33   enum FontStyle {
  34     NORMAL = 0,
  35     BOLD = 1,
  36     ITALIC = 2,
  37     UNDERLINE = 4,
  38   };
  39
  40   // Creates a font with the default name and style.
  41   Font();
  42
  43   // Creates a font that is a clone of another font object.
  44   Font(const Font& other);
  45   Font& operator=(const Font& other);
  46
  47   // Creates a font from the specified native font.
  48   explicit Font(NativeFont native_font);
  49
  50   // Constructs a Font object with the specified PlatformFont object. The Font
  51   // object takes ownership of the PlatformFont object.
  52   explicit Font(PlatformFont* platform_font);
  53
  54   // Creates a font with the specified name in UTF-8 and size in pixels.
  55   Font(const std::string& font_name, int font_size);
  56
  57   ~Font();
  58
  59   // Returns a new Font derived from the existing font.
  60   // |size_delta| is the size in pixels to add to the current font. For example,
  61   // a value of 5 results in a font 5 pixels bigger than this font.
  62   // The style parameter specifies the new style for the font, and is a
  63   // bitmask of the values: BOLD, ITALIC and UNDERLINE.
  64   Font Derive(int size_delta, int style) const;
  65
  66   // Returns the number of vertical pixels needed to display characters from
  67   // the specified font.  This may include some leading, i.e. height may be
  68   // greater than just ascent + descent.  Specifically, the Windows and Mac
  69   // implementations include leading and the Linux one does not.  This may
  70   // need to be revisited in the future.
  71   int GetHeight() const;
  72
  73   // Returns the baseline, or ascent, of the font.
  74   int GetBaseline() const;
  75
  76   // Returns the cap height of the font.
  77   int GetCapHeight() const;
  78
  79   // Returns the expected number of horizontal pixels needed to display the
  80   // specified length of characters. Call gfx::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 specified font name in UTF-8.
  88   std::string GetFontName() const;
  89
  90   // Returns the actually used font name in UTF-8.
  91   std::string GetActualFontNameForTesting() const;
  92
  93   // Returns the font size in pixels.
  94   int GetFontSize() const;
  95
  96   // Returns the native font handle.
  97   // Lifetime lore:
  98   // Windows: This handle is owned by the Font object, and should not be
  99   //          destroyed by the caller.
 100   // Mac:     The object is owned by the system and should not be released.
 101   // Gtk:     This handle is created on demand, and must be freed by calling
 102   //          pango_font_description_free() when the caller is done using it or
 103   //          by using ScopedPangoFontDescription.
 104   NativeFont GetNativeFont() const;
 105
 106   // Raw access to the underlying platform font implementation. Can be
 107   // static_cast to a known implementation type if needed.
 108   PlatformFont* platform_font() const { return platform_font_.get(); }
 109
 110  private:
 111   // Wrapped platform font implementation.
 112   scoped_refptr<PlatformFont> platform_font_;
 113 };
 114
 115 }  // namespace gfx
 116
 117 #endif  // UI_GFX_FONT_H_