ui/gfx/font_list.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_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
  15 namespace gfx {
  16
  17 class 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"
  31 class 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_