ui/base/ime/composition_text_util_pango.cc

   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 #include "ui/base/ime/composition_text_util_pango.h"
   6
   7 #include <pango/pango-attributes.h>
   8
   9 #include "base/basictypes.h"
  10 #include "base/i18n/char_iterator.h"
  11 #include "base/strings/string16.h"
  12 #include "base/strings/utf_string_conversions.h"
  13 #include "ui/base/ime/composition_text.h"
  14
  15 namespace ui {
  16
  17 void ExtractCompositionTextFromGtkPreedit(const gchar* utf8_text,
  18                                           PangoAttrList* attrs,
  19                                           int cursor_position,
  20                                           CompositionText* composition) {
  21   composition->Clear();
  22   composition->text = base::UTF8ToUTF16(utf8_text);
  23
  24   if (composition->text.empty())
  25     return;
  26
  27   // Gtk/Pango uses character index for cursor position and byte index for
  28   // attribute range, but we use char16 offset for them. So we need to do
  29   // conversion here.
  30   std::vector<size_t> char16_offsets;
  31   size_t length = composition->text.length();
  32   base::i18n::UTF16CharIterator char_iterator(&composition->text);
  33   do {
  34     char16_offsets.push_back(char_iterator.array_pos());
  35   } while (char_iterator.Advance());
  36
  37   // The text length in Unicode characters.
  38   int char_length = static_cast<int>(char16_offsets.size());
  39   // Make sure we can convert the value of |char_length| as well.
  40   char16_offsets.push_back(length);
  41
  42   size_t cursor_offset =
  43       char16_offsets[std::max(0, std::min(char_length, cursor_position))];
  44
  45   composition->selection = gfx::Range(cursor_offset);
  46
  47   if (attrs) {
  48     int utf8_length = strlen(utf8_text);
  49     PangoAttrIterator* iter = pango_attr_list_get_iterator(attrs);
  50
  51     // We only care about underline and background attributes and convert
  52     // background attribute into selection if possible.
  53     do {
  54       gint start, end;
  55       pango_attr_iterator_range(iter, &start, &end);
  56
  57       start = std::min(start, utf8_length);
  58       end = std::min(end, utf8_length);
  59       if (start >= end)
  60         continue;
  61
  62       start = g_utf8_pointer_to_offset(utf8_text, utf8_text + start);
  63       end = g_utf8_pointer_to_offset(utf8_text, utf8_text + end);
  64
  65       // Double check, in case |utf8_text| is not a valid utf-8 string.
  66       start = std::min(start, char_length);
  67       end = std::min(end, char_length);
  68       if (start >= end)
  69         continue;
  70
  71       PangoAttribute* background_attr =
  72           pango_attr_iterator_get(iter, PANGO_ATTR_BACKGROUND);
  73       PangoAttribute* underline_attr =
  74           pango_attr_iterator_get(iter, PANGO_ATTR_UNDERLINE);
  75
  76       if (background_attr || underline_attr) {
  77         // Use a black thin underline by default.
  78         CompositionUnderline underline(char16_offsets[start],
  79                                        char16_offsets[end],
  80                                        SK_ColorBLACK,
  81                                        false,
  82                                        SK_ColorTRANSPARENT);
  83
  84         // Always use thick underline for a range with background color, which
  85         // is usually the selection range.
  86         if (background_attr) {
  87           underline.thick = true;
  88           // If the cursor is at start or end of this underline, then we treat
  89           // it as the selection range as well, but make sure to set the cursor
  90           // position to the selection end.
  91           if (underline.start_offset == cursor_offset) {
  92             composition->selection.set_start(underline.end_offset);
  93             composition->selection.set_end(cursor_offset);
  94           } else if (underline.end_offset == cursor_offset) {
  95             composition->selection.set_start(underline.start_offset);
  96             composition->selection.set_end(cursor_offset);
  97           }
  98         }
  99         if (underline_attr) {
 100           int type = reinterpret_cast<PangoAttrInt*>(underline_attr)->value;
 101           if (type == PANGO_UNDERLINE_DOUBLE)
 102             underline.thick = true;
 103           else if (type == PANGO_UNDERLINE_ERROR)
 104             underline.color = SK_ColorRED;
 105         }
 106         composition->underlines.push_back(underline);
 107       }
 108     } while (pango_attr_iterator_next(iter));
 109     pango_attr_iterator_destroy(iter);
 110   }
 111
 112   // Use a black thin underline by default.
 113   if (composition->underlines.empty()) {
 114     composition->underlines.push_back(CompositionUnderline(
 115         0, length, SK_ColorBLACK, false, SK_ColorTRANSPARENT));
 116   }
 117 }
 118
 119 }  // namespace ui