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 // line_breaks is a Misnomer. Blink provides the start offsets of each line
  13 // not the line breaks.
  14 // TODO(nektar): Rename line_breaks a11y attribute and variable references.
  15 size_t FindAccessibleTextBoundary(const base::string16& text,
  16                                   const std::vector<int>& line_breaks,
  17                                   TextBoundaryType boundary,
  18                                   size_t start_offset,
  19                                   TextBoundaryDirection direction) {
  20   size_t text_size = text.size();
  21   DCHECK_LE(start_offset, text_size);
  22
  23   if (boundary == CHAR_BOUNDARY) {
  24     if (direction == FORWARDS_DIRECTION && start_offset < text_size)
  25       return start_offset + 1;
  26     else
  27       return start_offset;
  28   } else if (boundary == LINE_BOUNDARY) {
  29     if (direction == FORWARDS_DIRECTION) {
  30       for (size_t j = 0; j < line_breaks.size(); ++j) {
  31           size_t line_break = line_breaks[j] >= 0 ? line_breaks[j] : 0;
  32         if (line_break > start_offset)
  33           return line_break;
  34       }
  35       return text_size;
  36     } else {
  37       for (size_t j = line_breaks.size(); j != 0; --j) {
  38         size_t line_break = line_breaks[j - 1] >= 0 ? line_breaks[j - 1] : 0;
  39         if (line_break <= start_offset)
  40           return line_break;
  41       }
  42       return 0;
  43     }
  44   }
  45
  46   size_t result = start_offset;
  47   for (;;) {
  48     size_t pos;
  49     if (direction == FORWARDS_DIRECTION) {
  50       if (result >= text_size)
  51         return text_size;
  52       pos = result;
  53     } else {
  54       if (result == 0)
  55         return 0;
  56       pos = result - 1;
  57     }
  58
  59     switch (boundary) {
  60       case CHAR_BOUNDARY:
  61       case LINE_BOUNDARY:
  62         NOTREACHED();  // These are handled above.
  63         break;
  64       case WORD_BOUNDARY:
  65         if (base::IsUnicodeWhitespace(text[pos]))
  66           return result;
  67         break;
  68       case PARAGRAPH_BOUNDARY:
  69         if (text[pos] == '\n')
  70           return result;
  71         break;
  72       case SENTENCE_BOUNDARY:
  73         if ((text[pos] == '.' || text[pos] == '!' || text[pos] == '?') &&
  74             (pos == text_size - 1 ||
  75              base::IsUnicodeWhitespace(text[pos + 1]))) {
  76           return result;
  77         }
  78         break;
  79       case ALL_BOUNDARY:
  80       default:
  81         break;
  82     }
  83
  84     if (direction == FORWARDS_DIRECTION) {
  85       result++;
  86     } else {
  87       result--;
  88     }
  89   }
  90 }
  91
  92 }  // Namespace ui