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   // Creates a font from the specified native font.
  49   explicit Font(NativeFont native_font);
  50
  51   // Constructs a Font object with the specified PlatformFont object. The Font
  52   // object takes ownership of the PlatformFont object.
  53   explicit Font(PlatformFont* platform_font);
  54
  55   // Creates a font with the specified name in UTF-8 and size in pixels.
  56   Font(const std::string& font_name, int font_size);
  57
  58   ~Font();
  59
  60   // Returns a new Font derived from the existing font.
  61   // |size_delta| is the size in pixels to add to the current font. For example,
  62   // a value of 5 results in a font 5 pixels bigger than this font.
  63   // The style parameter specifies the new style for the font, and is a
  64   // bitmask of the values: BOLD, ITALIC and UNDERLINE.
  65   Font Derive(int size_delta, int style) const;
  66
  67   // Returns the number of vertical pixels needed to display characters from
  68   // the specified font.  This may include some leading, i.e. height may be
  69   // greater than just ascent + descent.  Specifically, the Windows and Mac
  70   // implementations include leading and the Linux one does not.  This may
  71   // need to be revisited in the future.
  72   int GetHeight() const;
  73
  74   // Returns the baseline, or ascent, of the font.
  75   int GetBaseline() const;
  76
  77   // Returns the cap height of the font.
  78   int GetCapHeight() const;
  79
  80   // Returns the expected number of horizontal pixels needed to display the
  81   // specified length of characters. Call gfx::GetStringWidth() to retrieve the
  82   // actual number.
  83   int GetExpectedTextWidth(int length) const;
  84
  85   // Returns the style of the font.
  86   int GetStyle() const;
  87
  88   // Returns the specified font name in UTF-8.
  89   std::string GetFontName() const;
  90
  91   // Returns the actually used font name in UTF-8.
  92   std::string GetActualFontNameForTesting() const;
  93
  94   // Returns the font size in pixels.
  95   int GetFontSize() const;
  96
  97   // Returns an object describing how the font should be rendered.
  98   const FontRenderParams& GetFontRenderParams() const;
  99
 100   // Returns the native font handle.
 101   // Lifetime lore:
 102   // Windows: This handle is owned by the Font object, and should not be
 103   //          destroyed by the caller.
 104   // Mac:     The object is owned by the system and should not be released.
 105   // Gtk:     This handle is created on demand, and must be freed by calling
 106   //          pango_font_description_free() when the caller is done using it or
 107   //          by using ScopedPangoFontDescription.
 108   NativeFont GetNativeFont() const;
 109
 110   // Raw access to the underlying platform font implementation. Can be
 111   // static_cast to a known implementation type if needed.
 112   PlatformFont* platform_font() const { return platform_font_.get(); }
 113
 114  private:
 115   // Wrapped platform font implementation.
 116   scoped_refptr<PlatformFont> platform_font_;
 117 };
 118
 119 }  // namespace gfx
 120
 121 #endif  // UI_GFX_FONT_H_