ui/accessibility/ax_text_utils.cc

   1 // Copyright (c) 2011 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 #include "ui/accessibility/ax_text_utils.h"
   6
   7 #include "base/logging.h"
   8 #include "base/strings/string_util.h"
   9
  10 namespace ui {
  11
  12 size_t FindAccessibleTextBoundary(const base::string16& text,
  13                                   const std::vector<int>& line_breaks,
  14                                   TextBoundaryType boundary,
  15                                   size_t start_offset,
  16                                   TextBoundaryDirection direction) {
  17   size_t text_size = text.size();
  18   DCHECK(start_offset <= text_size);
  19
  20   if (boundary == CHAR_BOUNDARY) {
  21     if (direction == FORWARDS_DIRECTION && start_offset < text_size)
  22       return start_offset + 1;
  23     else
  24       return start_offset;
  25   } else if (boundary == LINE_BOUNDARY) {
  26     if (direction == FORWARDS_DIRECTION) {
  27       for (size_t j = 0; j < line_breaks.size(); ++j) {
  28           size_t line_break = line_breaks[j] >= 0 ? line_breaks[j] : 0;
  29         if (line_break > start_offset)
  30           return line_break;
  31       }
  32       return text_size;
  33     } else {
  34       for (size_t j = line_breaks.size(); j != 0; --j) {
  35         size_t line_break = line_breaks[j - 1] >= 0 ? line_breaks[j - 1] : 0;
  36         if (line_break < start_offset)
  37           return line_break;
  38       }
  39       return 0;
  40     }
  41   }
  42
  43   size_t result = start_offset;
  44   for (;;) {
  45     size_t pos;
  46     if (direction == FORWARDS_DIRECTION) {
  47       if (result >= text_size)
  48         return text_size;
  49       pos = result;
  50     } else {
  51       if (result == 0)
  52         return 0;
  53       pos = result - 1;
  54     }
  55
  56     switch (boundary) {
  57       case CHAR_BOUNDARY:
  58       case LINE_BOUNDARY:
  59         NOTREACHED();  // These are handled above.
  60         break;
  61       case WORD_BOUNDARY:
  62         if (IsWhitespace(text[pos]))
  63           return result;
  64         break;
  65       case PARAGRAPH_BOUNDARY:
  66         if (text[pos] == '\n')
  67           return result;
  68         break;
  69       case SENTENCE_BOUNDARY:
  70         if ((text[pos] == '.' || text[pos] == '!' || text[pos] == '?') &&
  71             (pos == text_size - 1 || IsWhitespace(text[pos + 1]))) {
  72           return result;
  73         }
  74         break;
  75       case ALL_BOUNDARY:
  76       default:
  77         break;
  78     }
  79
  80     if (direction == FORWARDS_DIRECTION) {
  81       result++;
  82     } else {
  83       result--;
  84     }
  85   }
  86 }
  87
  88 }  // Namespace ui