ui/gfx/text_elider.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 // This file defines utility functions for eliding and formatting UI text.
   6
   7 #ifndef UI_GFX_TEXT_ELIDER_H_
   8 #define UI_GFX_TEXT_ELIDER_H_
   9
  10 #include <string>
  11 #include <vector>
  12
  13 #include "base/basictypes.h"
  14 #include "base/strings/string16.h"
  15 #include "ui/gfx/gfx_export.h"
  16 #include "ui/gfx/text_constants.h"
  17
  18 class GURL;
  19
  20 namespace base {
  21 class FilePath;
  22 }
  23
  24 namespace gfx {
  25 class FontList;
  26
  27 GFX_EXPORT extern const char kEllipsis[];
  28 GFX_EXPORT extern const base::char16 kEllipsisUTF16[];
  29 GFX_EXPORT extern const base::char16 kForwardSlash;
  30
  31 // Helper class to split + elide text, while respecting UTF-16 surrogate pairs
  32 // and combining character sequences.
  33 class GFX_EXPORT StringSlicer {
  34  public:
  35   // Warning: Retains a reference to |text| and |ellipsis|. They must have a
  36   // longer lifetime than the StringSlicer.
  37   StringSlicer(const base::string16& text,
  38                const base::string16& ellipsis,
  39                bool elide_in_middle,
  40                bool elide_at_beginning);
  41
  42   // Cuts |text_| to be at most |length| UTF-16 code units long. If
  43   // |elide_in_middle_| is true, the middle of the string is removed to leave
  44   // equal-length pieces from the beginning and end of the string; otherwise,
  45   // the end of the string is removed and only the beginning remains. If
  46   // |insert_ellipsis| is true, then an ellipsis character will be inserted at
  47   // the cut point (note that the ellipsis will does not count towards the
  48   // |length| limit).
  49   // Note: Characters may still be omitted even if |length| is the full string
  50   // length, if surrogate pairs fall on the split boundary.
  51   base::string16 CutString(size_t length, bool insert_ellipsis) const;
  52
  53  private:
  54   // Returns a valid cut boundary at or before/after |index|.
  55   size_t FindValidBoundaryBefore(size_t index) const;
  56   size_t FindValidBoundaryAfter(size_t index) const;
  57
  58   // The text to be sliced.
  59   const base::string16& text_;
  60
  61   // Ellipsis string to use.
  62   const base::string16& ellipsis_;
  63
  64   // If true, the middle of the string will be elided.
  65   bool elide_in_middle_;
  66
  67   // If true, the beginning of the string will be elided.
  68   bool elide_at_beginning_;
  69
  70   DISALLOW_COPY_AND_ASSIGN(StringSlicer);
  71 };
  72
  73 // Elides |text| to fit the |available_pixel_width| with the specified behavior.
  74 GFX_EXPORT base::string16 ElideText(const base::string16& text,
  75                                     const gfx::FontList& font_list,
  76                                     float available_pixel_width,
  77                                     ElideBehavior elide_behavior);
  78
  79 // Elide a filename to fit a given pixel width, with an emphasis on not hiding
  80 // the extension unless we have to. If filename contains a path, the path will
  81 // be removed if filename doesn't fit into available_pixel_width. The elided
  82 // filename is forced to have LTR directionality, which means that in RTL UI
  83 // the elided filename is wrapped with LRE (Left-To-Right Embedding) mark and
  84 // PDF (Pop Directional Formatting) mark.
  85 GFX_EXPORT base::string16 ElideFilename(const base::FilePath& filename,
  86                                         const gfx::FontList& font_list,
  87                                         float available_pixel_width);
  88
  89 // Functions to elide strings when the font information is unknown. As opposed
  90 // to the above functions, ElideString() and ElideRectangleString() operate in
  91 // terms of character units, not pixels.
  92
  93 // If the size of |input| is more than |max_len|, this function returns
  94 // true and |input| is shortened into |output| by removing chars in the
  95 // middle (they are replaced with up to 3 dots, as size permits).
  96 // Ex: ElideString(ASCIIToUTF16("Hello"), 10, &str) puts Hello in str and
  97 // returns false.  ElideString(ASCIIToUTF16("Hello my name is Tom"), 10, &str)
  98 // puts "Hell...Tom" in str and returns true.
  99 // TODO(tsepez): Doesn't handle UTF-16 surrogate pairs properly.
 100 // TODO(tsepez): Doesn't handle bidi properly.
 101 GFX_EXPORT bool ElideString(const base::string16& input, int max_len,
 102                             base::string16* output);
 103
 104 // Reformat |input| into |output| so that it fits into a |max_rows| by
 105 // |max_cols| rectangle of characters.  Input newlines are respected, but
 106 // lines that are too long are broken into pieces.  If |strict| is true,
 107 // we break first at naturally occuring whitespace boundaries, otherwise
 108 // we assume some other mechanism will do this in approximately the same
 109 // spot after the fact.  If the word itself is too long, we always break
 110 // intra-word (respecting UTF-16 surrogate pairs) as necssary. Truncation
 111 // (indicated by an added 3 dots) occurs if the result is still too long.
 112 //  Returns true if the input had to be truncated (and not just reformatted).
 113 GFX_EXPORT bool ElideRectangleString(const base::string16& input,
 114                                      size_t max_rows,
 115                                      size_t max_cols,
 116                                      bool strict,
 117                                      base::string16* output);
 118
 119 // Indicates whether the |available_pixel_width| by |available_pixel_height|
 120 // rectangle passed to |ElideRectangleText()| had insufficient space to
 121 // accommodate the given |text|, leading to elision or truncation.
 122 enum ReformattingResultFlags {
 123   INSUFFICIENT_SPACE_HORIZONTAL = 1 << 0,
 124   INSUFFICIENT_SPACE_VERTICAL = 1 << 1,
 125 };
 126
 127 // Reformats |text| into output vector |lines| so that the resulting text fits
 128 // into an |available_pixel_width| by |available_pixel_height| rectangle with
 129 // the specified |font_list|. Input newlines are respected, but lines that are
 130 // too long are broken into pieces. For words that are too wide to fit on a
 131 // single line, the wrapping behavior can be specified with the |wrap_behavior|
 132 // param. Returns a combination of |ReformattingResultFlags| that indicate
 133 // whether the given rectangle had insufficient space to accommodate |text|,
 134 // leading to elision or truncation (and not just reformatting).
 135 GFX_EXPORT int ElideRectangleText(const base::string16& text,
 136                                   const gfx::FontList& font_list,
 137                                   float available_pixel_width,
 138                                   int available_pixel_height,
 139                                   WordWrapBehavior wrap_behavior,
 140                                   std::vector<base::string16>* lines);
 141
 142 // Truncates |string| to |length| characters. This breaks the string according
 143 // to the specified |break_type|, which must be either WORD_BREAK or
 144 // CHARACTER_BREAK, and adds the horizontal ellipsis character (unicode
 145 // character 0x2026) to render "...". The supplied string is returned if the
 146 // string has |length| characters or less.
 147 GFX_EXPORT base::string16 TruncateString(const base::string16& string,
 148                                          size_t length,
 149                                          BreakType break_type);
 150
 151 }  // namespace gfx
 152
 153 #endif  // UI_GFX_TEXT_ELIDER_H_