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   // The text to be sliced.
  55   const base::string16& text_;
  56
  57   // Ellipsis string to use.
  58   const base::string16& ellipsis_;
  59
  60   // If true, the middle of the string will be elided.
  61   bool elide_in_middle_;
  62
  63   // If true, the beginning of the string will be elided.
  64   bool elide_at_beginning_;
  65
  66   DISALLOW_COPY_AND_ASSIGN(StringSlicer);
  67 };
  68
  69 // Elides |text| to fit the |available_pixel_width| with the specified behavior.
  70 GFX_EXPORT base::string16 ElideText(const base::string16& text,
  71                                     const gfx::FontList& font_list,
  72                                     float available_pixel_width,
  73                                     ElideBehavior elide_behavior);
  74
  75 // Elide a filename to fit a given pixel width, with an emphasis on not hiding
  76 // the extension unless we have to. If filename contains a path, the path will
  77 // be removed if filename doesn't fit into available_pixel_width. The elided
  78 // filename is forced to have LTR directionality, which means that in RTL UI
  79 // the elided filename is wrapped with LRE (Left-To-Right Embedding) mark and
  80 // PDF (Pop Directional Formatting) mark.
  81 GFX_EXPORT base::string16 ElideFilename(const base::FilePath& filename,
  82                                         const gfx::FontList& font_list,
  83                                         float available_pixel_width);
  84
  85 // Functions to elide strings when the font information is unknown. As opposed
  86 // to the above functions, ElideString() and ElideRectangleString() operate in
  87 // terms of character units, not pixels.
  88
  89 // If the size of |input| is more than |max_len|, this function returns
  90 // true and |input| is shortened into |output| by removing chars in the
  91 // middle (they are replaced with up to 3 dots, as size permits).
  92 // Ex: ElideString(ASCIIToUTF16("Hello"), 10, &str) puts Hello in str and
  93 // returns false.  ElideString(ASCIIToUTF16("Hello my name is Tom"), 10, &str)
  94 // puts "Hell...Tom" in str and returns true.
  95 // TODO(tsepez): Doesn't handle UTF-16 surrogate pairs properly.
  96 // TODO(tsepez): Doesn't handle bidi properly.
  97 GFX_EXPORT bool ElideString(const base::string16& input, int max_len,
  98                             base::string16* output);
  99
 100 // Reformat |input| into |output| so that it fits into a |max_rows| by
 101 // |max_cols| rectangle of characters.  Input newlines are respected, but
 102 // lines that are too long are broken into pieces.  If |strict| is true,
 103 // we break first at naturally occuring whitespace boundaries, otherwise
 104 // we assume some other mechanism will do this in approximately the same
 105 // spot after the fact.  If the word itself is too long, we always break
 106 // intra-word (respecting UTF-16 surrogate pairs) as necssary. Truncation
 107 // (indicated by an added 3 dots) occurs if the result is still too long.
 108 //  Returns true if the input had to be truncated (and not just reformatted).
 109 GFX_EXPORT bool ElideRectangleString(const base::string16& input,
 110                                      size_t max_rows,
 111                                      size_t max_cols,
 112                                      bool strict,
 113                                      base::string16* output);
 114
 115 // Indicates whether the |available_pixel_width| by |available_pixel_height|
 116 // rectangle passed to |ElideRectangleText()| had insufficient space to
 117 // accommodate the given |text|, leading to elision or truncation.
 118 enum ReformattingResultFlags {
 119   INSUFFICIENT_SPACE_HORIZONTAL = 1 << 0,
 120   INSUFFICIENT_SPACE_VERTICAL = 1 << 1,
 121 };
 122
 123 // Reformats |text| into output vector |lines| so that the resulting text fits
 124 // into an |available_pixel_width| by |available_pixel_height| rectangle with
 125 // the specified |font_list|. Input newlines are respected, but lines that are
 126 // too long are broken into pieces. For words that are too wide to fit on a
 127 // single line, the wrapping behavior can be specified with the |wrap_behavior|
 128 // param. Returns a combination of |ReformattingResultFlags| that indicate
 129 // whether the given rectangle had insufficient space to accommodate |text|,
 130 // leading to elision or truncation (and not just reformatting).
 131 GFX_EXPORT int ElideRectangleText(const base::string16& text,
 132                                   const gfx::FontList& font_list,
 133                                   float available_pixel_width,
 134                                   int available_pixel_height,
 135                                   WordWrapBehavior wrap_behavior,
 136                                   std::vector<base::string16>* lines);
 137
 138 // Truncates |string| to |length| characters. This breaks the string according
 139 // to the specified |break_type|, which must be either WORD_BREAK or
 140 // CHARACTER_BREAK, and adds the horizontal ellipsis character (unicode
 141 // character 0x2026) to render "...". The supplied string is returned if the
 142 // string has |length| characters or less.
 143 GFX_EXPORT base::string16 TruncateString(const base::string16& string,
 144                                          size_t length,
 145                                          BreakType break_type);
 146
 147 }  // namespace gfx
 148
 149 #endif  // UI_GFX_TEXT_ELIDER_H_