ui/views/controls/styled_label.h

   1 // Copyright 2013 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_VIEWS_CONTROLS_STYLED_LABEL_H_
   6 #define UI_VIEWS_CONTROLS_STYLED_LABEL_H_
   7
   8 #include <list>
   9 #include <map>
  10
  11 #include "base/basictypes.h"
  12 #include "base/strings/string16.h"
  13 #include "third_party/skia/include/core/SkColor.h"
  14 #include "ui/gfx/font_list.h"
  15 #include "ui/gfx/geometry/size.h"
  16 #include "ui/gfx/range/range.h"
  17 #include "ui/views/controls/link_listener.h"
  18 #include "ui/views/view.h"
  19
  20 namespace views {
  21
  22 class Link;
  23 class StyledLabelListener;
  24
  25 // A class which can apply mixed styles to a block of text. Currently, text is
  26 // always multiline. Trailing whitespace in the styled label text is not
  27 // supported and will be trimmed on StyledLabel construction. Leading
  28 // whitespace is respected, provided not only whitespace fits in the first line.
  29 // In this case, leading whitespace is ignored.
  30 class VIEWS_EXPORT StyledLabel : public View, public LinkListener {
  31  public:
  32   // Internal class name.
  33   static const char kViewClassName[];
  34
  35   // Parameters that define label style for a styled label's text range.
  36   struct VIEWS_EXPORT RangeStyleInfo {
  37     RangeStyleInfo();
  38     ~RangeStyleInfo();
  39
  40     // Creates a range style info with default values for link.
  41     static RangeStyleInfo CreateForLink();
  42
  43     // The font style that will be applied to the range. Should be a bitmask of
  44     // values defined in gfx::Font::FontStyle (BOLD, ITALIC, UNDERLINE).
  45     int font_style;
  46
  47     // The text color for the range.
  48     SkColor color;
  49
  50     // Tooltip for the range.
  51     base::string16 tooltip;
  52
  53     // If set, the whole range will be put on a single line.
  54     bool disable_line_wrapping;
  55
  56     // If set, the range will be created as a link.
  57     bool is_link;
  58   };
  59
  60   // Note that any trailing whitespace in |text| will be trimmed.
  61   StyledLabel(const base::string16& text, StyledLabelListener* listener);
  62   ~StyledLabel() override;
  63
  64   // Sets the text to be displayed, and clears any previous styling.
  65   void SetText(const base::string16& text);
  66
  67   // Sets the fonts used by all labels. Can be augemented by styling set by
  68   // AddStyleRange and SetDefaultStyle.
  69   void SetBaseFontList(const gfx::FontList& font_list);
  70
  71   // Marks the given range within |text_| with style defined by |style_info|.
  72   // |range| must be contained in |text_|.
  73   void AddStyleRange(const gfx::Range& range, const RangeStyleInfo& style_info);
  74
  75   // Sets the default style to use for any part of the text that isn't within
  76   // a range set by AddStyleRange.
  77   void SetDefaultStyle(const RangeStyleInfo& style_info);
  78
  79   // Get or set the distance in pixels between baselines of multi-line text.
  80   // Default is 0, indicating the distance between lines should be the standard
  81   // one for the label's text, font list, and platform.
  82   void SetLineHeight(int height);
  83
  84   // Sets the color of the background on which the label is drawn. This won't
  85   // be explicitly drawn, but the label will force the text color to be
  86   // readable over it.
  87   void SetDisplayedOnBackgroundColor(SkColor color);
  88   SkColor displayed_on_background_color() const {
  89     return displayed_on_background_color_;
  90   }
  91
  92   void set_auto_color_readability_enabled(bool auto_color_readability) {
  93     auto_color_readability_enabled_ = auto_color_readability;
  94   }
  95
  96   // Resizes the label so its width is set to the width of the longest line and
  97   // its height deduced accordingly.
  98   // This is only intended for multi-line labels and is useful when the label's
  99   // text contains several lines separated with \n.
 100   // |max_width| is the maximum width that will be used (longer lines will be
 101   // wrapped). If 0, no maximum width is enforced.
 102   void SizeToFit(int max_width);
 103
 104   // View:
 105   const char* GetClassName() const override;
 106   gfx::Insets GetInsets() const override;
 107   gfx::Size GetPreferredSize() const override;
 108   int GetHeightForWidth(int w) const override;
 109   void Layout() override;
 110   void PreferredSizeChanged() override;
 111
 112   // LinkListener implementation:
 113   void LinkClicked(Link* source, int event_flags) override;
 114
 115  private:
 116   struct StyleRange {
 117     StyleRange(const gfx::Range& range,
 118                const RangeStyleInfo& style_info)
 119         : range(range),
 120           style_info(style_info) {
 121     }
 122     ~StyleRange() {}
 123
 124     bool operator<(const StyleRange& other) const;
 125
 126     gfx::Range range;
 127     RangeStyleInfo style_info;
 128   };
 129   typedef std::list<StyleRange> StyleRanges;
 130
 131   // Calculates how to layout child views, creates them and sets their size and
 132   // position. |width| is the horizontal space, in pixels, that the view has to
 133   // work with. If |dry_run| is true, the view hierarchy is not touched. Caches
 134   // the results in |calculated_size_|, |width_at_last_layout_|, and
 135   // |width_at_last_size_calculation_|. Returns the needed size.
 136   gfx::Size CalculateAndDoLayout(int width, bool dry_run);
 137
 138   // The text to display.
 139   base::string16 text_;
 140
 141   // Fonts used to display text. Can be augmented by RangeStyleInfo.
 142   gfx::FontList font_list_;
 143
 144   // Line height.
 145   int specified_line_height_;
 146
 147   // The default style to use for any part of the text that isn't within
 148   // a range in |style_ranges_|.
 149   RangeStyleInfo default_style_info_;
 150
 151   // The listener that will be informed of link clicks.
 152   StyledLabelListener* listener_;
 153
 154   // The ranges that should be linkified, sorted by start position.
 155   StyleRanges style_ranges_;
 156
 157   // A mapping from a view to the range it corresponds to in |text_|. Only views
 158   // that correspond to ranges with is_link style set will be added to the map.
 159   std::map<View*, gfx::Range> link_targets_;
 160
 161   // This variable saves the result of the last GetHeightForWidth call in order
 162   // to avoid repeated calculation.
 163   mutable gfx::Size calculated_size_;
 164   mutable int width_at_last_size_calculation_;
 165   int width_at_last_layout_;
 166
 167   // Background color on which the label is drawn, for auto color readability.
 168   SkColor displayed_on_background_color_;
 169   bool displayed_on_background_color_set_;
 170
 171   // Controls whether the text is automatically re-colored to be readable on the
 172   // background.
 173   bool auto_color_readability_enabled_;
 174
 175   DISALLOW_COPY_AND_ASSIGN(StyledLabel);
 176 };
 177
 178 }  // namespace views
 179
 180 #endif  // UI_VIEWS_CONTROLS_STYLED_LABEL_H_