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 "ui/gfx/font.h"
  12 #include "ui/gfx/gfx_export.h"
  13
  14 namespace gfx {
  15
  16 // FontList represents a list of fonts either in the form of Font vector or in
  17 // the form of a string representing font names, styles, and size.
  18 //
  19 // The string representation is in the form "FAMILY_LIST [STYLE_OPTIONS] SIZE",
  20 // where FAMILY_LIST is a comma separated list of families terminated by a
  21 // comma, STYLE_OPTIONS is a whitespace separated list of words where each word
  22 // describes one of style, variant, weight, stretch, or gravity, and SIZE is
  23 // a decimal number followed by "px" for absolute size. STYLE_OPTIONS may be
  24 // absent.
  25 //
  26 // The string format complies with that of Pango detailed at
  27 // http://developer.gnome.org/pango/stable/pango-Fonts.html#pango-font-description-from-string
  28 //
  29 // FontList could be initialized either way without conversion to the other
  30 // form. The conversion to the other form is done only when asked to get the
  31 // other form.
  32 //
  33 // FontList allows operator= since FontList is a data member type in RenderText,
  34 // and operator= is used in RenderText::SetFontList().
  35 class GFX_EXPORT FontList {
  36  public:
  37   // Creates a font list with a Font with default name and style.
  38   FontList();
  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   // Returns a new FontList with the given |font_style| flags.
  59   FontList DeriveFontList(int font_style) const;
  60
  61   // Returns a new FontList with the same font names and style but with the
  62   // given font |size| in pixels.
  63   FontList DeriveFontListWithSize(int size) const;
  64
  65   // Returns a new FontList with the same font names and style but resized.
  66   // |size_delta| is the size in pixels to add to the current font size.
  67   FontList DeriveFontListWithSizeDelta(int size_delta) const;
  68
  69   // Returns a new FontList with the same font names but resized and the given
  70   // style. |size_delta| is the size in pixels to add to the current font size.
  71   // |font_style| specifies the new style, which is a bitmask of the values:
  72   // Font::BOLD, Font::ITALIC and Font::UNDERLINE.
  73   FontList DeriveFontListWithSizeDeltaAndStyle(int size_delta,
  74                                                int font_style) const;
  75
  76   // Returns the height of this font list, which is max(ascent) + max(descent)
  77   // for all the fonts in the font list.
  78   int GetHeight() const;
  79
  80   // Returns the baseline of this font list, which is max(baseline) for all the
  81   // fonts in the font list.
  82   int GetBaseline() const;
  83
  84   // Returns the cap height of this font list.
  85   // Currently returns the cap height of the primary font.
  86   int GetCapHeight() const;
  87
  88   // Returns the number of horizontal pixels needed to display |text|.
  89   int GetStringWidth(const base::string16& text) const;
  90
  91   // Returns the expected number of horizontal pixels needed to display the
  92   // specified length of characters. Call GetStringWidth() to retrieve the
  93   // actual number.
  94   int GetExpectedTextWidth(int length) const;
  95
  96   // Returns the |gfx::Font::FontStyle| style flags for this font list.
  97   int GetFontStyle() const;
  98
  99   // Returns a string representing font names, styles, and size. If the FontList
 100   // is initialized by a vector of Font, use the first font's style and size
 101   // for the description.
 102   const std::string& GetFontDescriptionString() const;
 103
 104   // Returns the font size in pixels.
 105   int GetFontSize() const;
 106
 107   // Returns the Font vector.
 108   const std::vector<Font>& GetFonts() const;
 109
 110   // Returns the first font in the list.
 111   const Font& GetPrimaryFont() const;
 112
 113  private:
 114   // Extracts common font height and baseline into |common_height_| and
 115   // |common_baseline_|.
 116   void CacheCommonFontHeightAndBaseline() const;
 117
 118   // Extracts font style and size into |font_style_| and |font_size_|.
 119   void CacheFontStyleAndSize() const;
 120
 121   // A vector of Font. If FontList is constructed with font description string,
 122   // |fonts_| is not initialized during construction. Instead, it is computed
 123   // lazily when user asked to get the font vector.
 124   mutable std::vector<Font> fonts_;
 125
 126   // A string representing font names, styles, and sizes.
 127   // Please refer to the comments before class declaration for details on string
 128   // format.
 129   // If FontList is constructed with a vector of font,
 130   // |font_description_string_| is not initialized during construction. Instead,
 131   // it is computed lazily when user asked to get the font description string.
 132   mutable std::string font_description_string_;
 133
 134   // The cached common height and baseline of the fonts in the font list.
 135   mutable int common_height_;
 136   mutable int common_baseline_;
 137
 138   // Cached font style and size.
 139   mutable int font_style_;
 140   mutable int font_size_;
 141 };
 142
 143 }  // namespace gfx
 144
 145 #endif  // UI_GFX_FONT_LIST_H_