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 struct FontRenderParams;
  18 class PlatformFont;
  19
  20 // Font provides a wrapper around an underlying font. Copy and assignment
  21 // operators are explicitly allowed, and cheap.
  22 //
  23 // Figure of font metrics:
  24 //   +--------+-------------------+------------------+
  25 //   |        |                   | internal leading |
  26 //   |        | ascent (baseline) +------------------+
  27 //   | height |                   | cap height       |
  28 //   |        |-------------------+------------------+
  29 //   |        | descent (height - baseline)          |
  30 //   +--------+--------------------------------------+
  31 class GFX_EXPORT Font {
  32  public:
  33   // The following constants indicate the font style.
  34   enum FontStyle {
  35     NORMAL = 0,
  36     BOLD = 1,
  37     ITALIC = 2,
  38     UNDERLINE = 4,
  39   };
  40
  41   // Creates a font with the default name and style.
  42   Font();
  43
  44   // Creates a font that is a clone of another font object.
  45   Font(const Font& other);
  46   Font& operator=(const Font& other);
  47
  48 #if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_IOS)
  49   // Creates a font from the specified native font.
  50   explicit Font(NativeFont native_font);
  51 #endif
  52
  53   // Constructs a Font object with the specified PlatformFont object. The Font
  54   // object takes ownership of the PlatformFont object.
  55   explicit Font(PlatformFont* platform_font);
  56
  57   // Creates a font with the specified name in UTF-8 and size in pixels.
  58   Font(const std::string& font_name, int font_size);
  59
  60   ~Font();
  61
  62   // Returns a new Font derived from the existing font.
  63   // |size_delta| is the size in pixels to add to the current font. For example,
  64   // a value of 5 results in a font 5 pixels bigger than this font.
  65   // The style parameter specifies the new style for the font, and is a
  66   // bitmask of the values: BOLD, ITALIC and UNDERLINE.
  67   Font Derive(int size_delta, int style) const;
  68
  69   // Returns the number of vertical pixels needed to display characters from
  70   // the specified font.  This may include some leading, i.e. height may be
  71   // greater than just ascent + descent.  Specifically, the Windows and Mac
  72   // implementations include leading and the Linux one does not.  This may
  73   // need to be revisited in the future.
  74   int GetHeight() const;
  75
  76   // Returns the baseline, or ascent, of the font.
  77   int GetBaseline() const;
  78
  79   // Returns the cap height of the font.
  80   int GetCapHeight() const;
  81
  82   // Returns the expected number of horizontal pixels needed to display the
  83   // specified length of characters. Call gfx::GetStringWidth() to retrieve the
  84   // actual number.
  85   int GetExpectedTextWidth(int length) const;
  86
  87   // Returns the style of the font.
  88   int GetStyle() const;
  89
  90   // Returns the specified font name in UTF-8.
  91   std::string GetFontName() const;
  92
  93   // Returns the actually used font name in UTF-8.
  94   std::string GetActualFontNameForTesting() const;
  95
  96   // Returns the font size in pixels.
  97   int GetFontSize() const;
  98
  99   // Returns an object describing how the font should be rendered.
 100   const FontRenderParams& GetFontRenderParams() const;
 101
 102 #if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_IOS)
 103   // Returns the native font handle.
 104   // Lifetime lore:
 105   // Windows: This handle is owned by the Font object, and should not be
 106   //          destroyed by the caller.
 107   // Mac:     The object is owned by the system and should not be released.
 108   NativeFont GetNativeFont() const;
 109 #endif
 110
 111   // Raw access to the underlying platform font implementation. Can be
 112   // static_cast to a known implementation type if needed.
 113   PlatformFont* platform_font() const { return platform_font_.get(); }
 114
 115  private:
 116   // Wrapped platform font implementation.
 117   scoped_refptr<PlatformFont> platform_font_;
 118 };
 119
 120 }  // namespace gfx
 121
 122 #endif  // UI_GFX_FONT_H_