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
15namespace gfx {
16
17struct FontRenderParams;
18class 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//   +--------+--------------------------------------+
31class 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_
122