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_LIST_H_
6#define UI_GFX_FONT_LIST_H_
7
8#include <string>
9#include <vector>
10
11#include "base/memory/ref_counted.h"
12#include "ui/gfx/font.h"
13#include "ui/gfx/gfx_export.h"
14
15namespace gfx {
16
17class FontListImpl;
18
19// FontList represents a list of fonts and provides metrics which are common
20// in the fonts.  FontList is copyable and it's quite cheap to copy.
21//
22// The format of font description string complies with that of Pango detailed at
23// http://developer.gnome.org/pango/stable/pango-Fonts.html#pango-font-description-from-string
24// The format is "<FONT_FAMILY_LIST>,[STYLES] <SIZE>" where
25//     FONT_FAMILY_LIST is a comma-separated list of font family names,
26//     STYLES is a space-separated list of style names ("Bold" and "Italic"),
27//     SIZE is a font size in pixel with the suffix "px".
28// Here are examples of font description string:
29//     "Arial, Helvetica, Bold Italic 14px"
30//     "Arial, 14px"
31class GFX_EXPORT FontList {
32 public:
33  // Creates a font list with default font names, size and style, which are
34  // specified by SetDefaultFontDescription().
35  FontList();
36
37  // Creates a font list that is a clone of another font list.
38  FontList(const FontList& other);
39
40  // Creates a font list from a string representing font names, styles, and
41  // size.
42  explicit FontList(const std::string& font_description_string);
43
44  // Creates a font list from font names, styles and size.
45  FontList(const std::vector<std::string>& font_names,
46           int font_style,
47           int font_size);
48
49  // Creates a font list from a Font vector.
50  // All fonts in this vector should have the same style and size.
51  explicit FontList(const std::vector<Font>& fonts);
52
53  // Creates a font list from a Font.
54  explicit FontList(const Font& font);
55
56  ~FontList();
57
58  // Copies the given font list into this object.
59  FontList& operator=(const FontList& other);
60
61  // Sets the description string for default FontList construction. If it's
62  // empty, FontList will initialize using the default Font constructor.
63  //
64  // The client code must call this function before any call of the default
65  // constructor. This should be done on the UI thread.
66  //
67  // ui::ResourceBundle may call this function more than once when UI language
68  // is changed.
69  static void SetDefaultFontDescription(const std::string& font_description);
70
71  // Returns a new FontList with the same font names but resized and the given
72  // style. |size_delta| is the size in pixels to add to the current font size.
73  // |font_style| specifies the new style, which is a bitmask of the values:
74  // Font::BOLD, Font::ITALIC and Font::UNDERLINE.
75  FontList Derive(int size_delta, int font_style) const;
76
77  // Returns a new FontList with the same font names and style but resized.
78  // |size_delta| is the size in pixels to add to the current font size.
79  FontList DeriveWithSizeDelta(int size_delta) const;
80
81  // Returns a new FontList with the same font names and size but the given
82  // style. |font_style| specifies the new style, which is a bitmask of the
83  // values: Font::BOLD, Font::ITALIC and Font::UNDERLINE.
84  FontList DeriveWithStyle(int font_style) const;
85
86  // Shrinks the font size until the font list fits within |height| while
87  // having its cap height vertically centered. Returns a new FontList with
88  // the correct height.
89  //
90  // The expected layout:
91  //   +--------+-----------------------------------------------+------------+
92  //   |        | y offset                                      | space      |
93  //   |        +--------+-------------------+------------------+ above      |
94  //   |        |        |                   | internal leading | cap height |
95  //   | box    | font   | ascent (baseline) +------------------+------------+
96  //   | height | height |                   | cap height                    |
97  //   |        |        |-------------------+------------------+------------+
98  //   |        |        | descent (height - baseline)          | space      |
99  //   |        +--------+--------------------------------------+ below      |
100  //   |        | space at bottom                               | cap height |
101  //   +--------+-----------------------------------------------+------------+
102  // Goal:
103  //     center of box height == center of cap height
104  //     (i.e. space above cap height == space below cap height)
105  // Restrictions:
106  //     y offset >= 0
107  //     space at bottom >= 0
108  //     (i.e. Entire font must be visible inside the box.)
109  gfx::FontList DeriveWithHeightUpperBound(int height) const;
110
111  // Returns the height of this font list, which is max(ascent) + max(descent)
112  // for all the fonts in the font list.
113  int GetHeight() const;
114
115  // Returns the baseline of this font list, which is max(baseline) for all the
116  // fonts in the font list.
117  int GetBaseline() const;
118
119  // Returns the cap height of this font list.
120  // Currently returns the cap height of the primary font.
121  int GetCapHeight() const;
122
123  // Returns the expected number of horizontal pixels needed to display the
124  // specified length of characters. Call GetStringWidth() to retrieve the
125  // actual number.
126  int GetExpectedTextWidth(int length) const;
127
128  // Returns the |gfx::Font::FontStyle| style flags for this font list.
129  int GetFontStyle() const;
130
131  // Returns a string representing font names, styles, and size. If the FontList
132  // is initialized by a vector of Font, use the first font's style and size
133  // for the description.
134  const std::string& GetFontDescriptionString() const;
135
136  // Returns the font size in pixels.
137  int GetFontSize() const;
138
139  // Returns the Font vector.
140  const std::vector<Font>& GetFonts() const;
141
142  // Returns the first font in the list.
143  const Font& GetPrimaryFont() const;
144
145 private:
146  explicit FontList(FontListImpl* impl);
147
148  static const scoped_refptr<FontListImpl>& GetDefaultImpl();
149
150  scoped_refptr<FontListImpl> impl_;
151};
152
153}  // namespace gfx
154
155#endif  // UI_GFX_FONT_LIST_H_
156