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
15namespace ui {
16
17void 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
120