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 // across the fonts.  FontList is copyable and quite cheap to copy.
  21 //
  22 // The format of font description strings is a subset of that used by Pango, as
  23 // described at
  24 // http://developer.gnome.org/pango/stable/pango-Fonts.html#pango-font-description-from-string
  25 //
  26 // Pango font description strings should not be passed directly into FontLists.
  27 //
  28 // The format is "<FONT_FAMILY_LIST>,[STYLES] <SIZE>", where:
  29 // - FONT_FAMILY_LIST is a comma-separated list of font family names,
  30 // - STYLES is an optional space-separated list of style names (case-sensitive
  31 //   "Bold" and "Italic" are supported), and
  32 // - SIZE is an integer font size in pixels with the suffix "px".
  33 //
  34 // Here are examples of valid font description strings:
  35 // - "Arial, Helvetica, Bold Italic 14px"
  36 // - "Arial, 14px"
  37 class GFX_EXPORT FontList {
  38  public:
  39   // Parses a FontList description string into |families_out|, |style_out| (a
  40   // bitfield of gfx::Font::Style values), and |size_pixels_out|. Returns true
  41   // if the string is properly-formed.
  42   static bool ParseDescription(const std::string& description,
  43                                std::vector<std::string>* families_out,
  44                                int* style_out,
  45                                int* size_pixels_out);
  46
  47   // Creates a font list with default font names, size and style, which are
  48   // specified by SetDefaultFontDescription().
  49   FontList();
  50
  51   // Creates a font list that is a clone of another font list.
  52   FontList(const FontList& other);
  53
  54   // Creates a font list from a string representing font names, styles, and
  55   // size.
  56   explicit FontList(const std::string& font_description_string);
  57
  58   // Creates a font list from font names, styles and size.
  59   FontList(const std::vector<std::string>& font_names,
  60            int font_style,
  61            int font_size);
  62
  63   // Creates a font list from a Font vector.
  64   // All fonts in this vector should have the same style and size.
  65   explicit FontList(const std::vector<Font>& fonts);
  66
  67   // Creates a font list from a Font.
  68   explicit FontList(const Font& font);
  69
  70   ~FontList();
  71
  72   // Copies the given font list into this object.
  73   FontList& operator=(const FontList& other);
  74
  75   // Sets the description string for default FontList construction. If it's
  76   // empty, FontList will initialize using the default Font constructor.
  77   //
  78   // The client code must call this function before any call of the default
  79   // constructor. This should be done on the UI thread.
  80   //
  81   // ui::ResourceBundle may call this function more than once when UI language
  82   // is changed.
  83   static void SetDefaultFontDescription(const std::string& font_description);
  84
  85   // Returns a new FontList with the same font names but resized and the given
  86   // style. |size_delta| is the size in pixels to add to the current font size.
  87   // |font_style| specifies the new style, which is a bitmask of the values:
  88   // Font::BOLD, Font::ITALIC and Font::UNDERLINE.
  89   FontList Derive(int size_delta, int font_style) const;
  90
  91   // Returns a new FontList with the same font names and style but resized.
  92   // |size_delta| is the size in pixels to add to the current font size.
  93   FontList DeriveWithSizeDelta(int size_delta) const;
  94
  95   // Returns a new FontList with the same font names and size but the given
  96   // style. |font_style| specifies the new style, which is a bitmask of the
  97   // values: Font::BOLD, Font::ITALIC and Font::UNDERLINE.
  98   FontList DeriveWithStyle(int font_style) const;
  99
 100   // Shrinks the font size until the font list fits within |height| while
 101   // having its cap height vertically centered. Returns a new FontList with
 102   // the correct height.
 103   //
 104   // The expected layout:
 105   //   +--------+-----------------------------------------------+------------+
 106   //   |        | y offset                                      | space      |
 107   //   |        +--------+-------------------+------------------+ above      |
 108   //   |        |        |                   | internal leading | cap height |
 109   //   | box    | font   | ascent (baseline) +------------------+------------+
 110   //   | height | height |                   | cap height                    |
 111   //   |        |        |-------------------+------------------+------------+
 112   //   |        |        | descent (height - baseline)          | space      |
 113   //   |        +--------+--------------------------------------+ below      |
 114   //   |        | space at bottom                               | cap height |
 115   //   +--------+-----------------------------------------------+------------+
 116   // Goal:
 117   //     center of box height == center of cap height
 118   //     (i.e. space above cap height == space below cap height)
 119   // Restrictions:
 120   //     y offset >= 0
 121   //     space at bottom >= 0
 122   //     (i.e. Entire font must be visible inside the box.)
 123   gfx::FontList DeriveWithHeightUpperBound(int height) const;
 124
 125   // Returns the height of this font list, which is max(ascent) + max(descent)
 126   // for all the fonts in the font list.
 127   int GetHeight() const;
 128
 129   // Returns the baseline of this font list, which is max(baseline) for all the
 130   // fonts in the font list.
 131   int GetBaseline() const;
 132
 133   // Returns the cap height of this font list.
 134   // Currently returns the cap height of the primary font.
 135   int GetCapHeight() const;
 136
 137   // Returns the expected number of horizontal pixels needed to display the
 138   // specified length of characters. Call GetStringWidth() to retrieve the
 139   // actual number.
 140   int GetExpectedTextWidth(int length) const;
 141
 142   // Returns the |gfx::Font::FontStyle| style flags for this font list.
 143   int GetFontStyle() const;
 144
 145   // Returns the font size in pixels.
 146   int GetFontSize() const;
 147
 148   // Returns the Font vector.
 149   const std::vector<Font>& GetFonts() const;
 150
 151   // Returns the first font in the list.
 152   const Font& GetPrimaryFont() const;
 153
 154  private:
 155   explicit FontList(FontListImpl* impl);
 156
 157   static const scoped_refptr<FontListImpl>& GetDefaultImpl();
 158
 159   scoped_refptr<FontListImpl> impl_;
 160 };
 161
 162 }  // namespace gfx
 163
 164 #endif  // UI_GFX_FONT_LIST_H_