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      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 <map>
      9 #include <queue>
     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/range/range.h"
     15 #include "ui/gfx/size.h"
     16 #include "ui/views/controls/link_listener.h"
     17 #include "ui/views/view.h"
     18 
     19 namespace views {
     20 
     21 class Link;
     22 class StyledLabelListener;
     23 
     24 // A class which can apply mixed styles to a block of text. Currently, text is
     25 // always multiline. Trailing whitespace in the styled label text is not
     26 // supported and will be trimmed on StyledLabel construction. Leading
     27 // whitespace is respected, provided not only whitespace fits in the first line.
     28 // In this case, leading whitespace is ignored.
     29 class VIEWS_EXPORT StyledLabel : public View, public LinkListener {
     30  public:
     31   // Parameters that define label style for a styled label's text range.
     32   struct VIEWS_EXPORT RangeStyleInfo {
     33     RangeStyleInfo();
     34     ~RangeStyleInfo();
     35 
     36     // Creates a range style info with default values for link.
     37     static RangeStyleInfo CreateForLink();
     38 
     39     // The font style that will be applied to the range. Should be a bitmask of
     40     // values defined in gfx::Font::FontStyle (BOLD, ITALIC, UNDERLINE).
     41     int font_style;
     42 
     43     // The text color for the range.
     44     SkColor color;
     45 
     46     // Tooltip for the range.
     47     string16 tooltip;
     48 
     49     // If set, the whole range will be put on a single line.
     50     bool disable_line_wrapping;
     51 
     52     // If set, the range will be created as a link.
     53     bool is_link;
     54   };
     55 
     56   // Note that any trailing whitespace in |text| will be trimmed.
     57   StyledLabel(const string16& text, StyledLabelListener* listener);
     58   virtual ~StyledLabel();
     59 
     60   // Sets the text to be displayed, and clears any previous styling.
     61   void SetText(const string16& text);
     62 
     63   // Marks the given range within |text_| with style defined by |style_info|.
     64   // |range| must be contained in |text_|.
     65   void AddStyleRange(const gfx::Range& range, const RangeStyleInfo& style_info);
     66 
     67   // Sets the default style to use for any part of the text that isn't within
     68   // a range set by AddStyleRange.
     69   void SetDefaultStyle(const RangeStyleInfo& style_info);
     70 
     71   // Sets the color of the background on which the label is drawn. This won't
     72   // be explicitly drawn, but the label will force the text color to be
     73   // readable over it.
     74   void SetDisplayedOnBackgroundColor(SkColor color);
     75   SkColor displayed_on_background_color() const {
     76     return displayed_on_background_color_;
     77   }
     78 
     79   void set_auto_color_readability_enabled(bool auto_color_readability) {
     80     auto_color_readability_enabled_ = auto_color_readability;
     81   }
     82 
     83   // View implementation:
     84   virtual gfx::Insets GetInsets() const OVERRIDE;
     85   virtual int GetHeightForWidth(int w) OVERRIDE;
     86   virtual void Layout() OVERRIDE;
     87   virtual void PreferredSizeChanged() OVERRIDE;
     88 
     89   // LinkListener implementation:
     90   virtual void LinkClicked(Link* source, int event_flags) OVERRIDE;
     91 
     92  private:
     93   struct StyleRange {
     94     StyleRange(const gfx::Range& range,
     95                const RangeStyleInfo& style_info)
     96         : range(range),
     97           style_info(style_info) {
     98     }
     99     ~StyleRange() {}
    100 
    101     bool operator<(const StyleRange& other) const;
    102 
    103     gfx::Range range;
    104     RangeStyleInfo style_info;
    105   };
    106 
    107   // Calculates how to layout child views, creates them and sets their size
    108   // and position. |width| is the horizontal space, in pixels, that the view
    109   // has to work with. If |dry_run| is true, the view hierarchy is not touched.
    110   // The return value is the height in pixels.
    111   int CalculateAndDoLayout(int width, bool dry_run);
    112 
    113   // The text to display.
    114   string16 text_;
    115 
    116   // The default style to use for any part of the text that isn't within
    117   // a range in |style_ranges_|.
    118   RangeStyleInfo default_style_info_;
    119 
    120   // The listener that will be informed of link clicks.
    121   StyledLabelListener* listener_;
    122 
    123   // The ranges that should be linkified, sorted by start position.
    124   std::priority_queue<StyleRange> style_ranges_;
    125 
    126   // A mapping from a view to the range it corresponds to in |text_|. Only views
    127   // that correspond to ranges with is_link style set will be added to the map.
    128   std::map<View*, gfx::Range> link_targets_;
    129 
    130   // This variable saves the result of the last GetHeightForWidth call in order
    131   // to avoid repeated calculation.
    132   gfx::Size calculated_size_;
    133 
    134   // Background color on which the label is drawn, for auto color readability.
    135   SkColor displayed_on_background_color_;
    136   bool displayed_on_background_color_set_;
    137 
    138   // Controls whether the text is automatically re-colored to be readable on the
    139   // background.
    140   bool auto_color_readability_enabled_;
    141 
    142   DISALLOW_COPY_AND_ASSIGN(StyledLabel);
    143 };
    144 
    145 }  // namespace views
    146 
    147 #endif  // UI_VIEWS_CONTROLS_STYLED_LABEL_H_
    148