Flutter iOS Embedder
text_input_model.cc
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1 // Copyright 2013 The Flutter 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 
6 
7 #include <algorithm>
8 #include <string>
9 
10 #include "flutter/fml/string_conversion.h"
11 
12 namespace flutter {
13 
14 namespace {
15 
16 // Returns true if |code_point| is a leading surrogate of a surrogate pair.
17 bool IsLeadingSurrogate(char32_t code_point) {
18  return (code_point & 0xFFFFFC00) == 0xD800;
19 }
20 // Returns true if |code_point| is a trailing surrogate of a surrogate pair.
21 bool IsTrailingSurrogate(char32_t code_point) {
22  return (code_point & 0xFFFFFC00) == 0xDC00;
23 }
24 
25 } // namespace
26 
28 
30 
31 bool TextInputModel::SetText(const std::string& text,
32  const TextRange& selection,
33  const TextRange& composing_range) {
34  text_ = fml::Utf8ToUtf16(text);
35  if (!text_range().Contains(selection) ||
36  !text_range().Contains(composing_range)) {
37  return false;
38  }
39 
40  selection_ = selection;
41  composing_range_ = composing_range;
42  composing_ = !composing_range.collapsed();
43  return true;
44 }
45 
47  if (composing_ && !range.collapsed()) {
48  return false;
49  }
50  if (!editable_range().Contains(range)) {
51  return false;
52  }
53  selection_ = range;
54  return true;
55 }
56 
58  size_t cursor_offset) {
59  if (!composing_ || !text_range().Contains(range)) {
60  return false;
61  }
62  composing_range_ = range;
63  selection_ = TextRange(range.start() + cursor_offset);
64  return true;
65 }
66 
68  composing_ = true;
69  composing_range_ = TextRange(selection_.start());
70 }
71 
72 void TextInputModel::UpdateComposingText(const std::u16string& text,
73  const TextRange& selection) {
74  // Preserve selection if we get a no-op update to the composing region.
75  if (text.length() == 0 && composing_range_.collapsed()) {
76  return;
77  }
78  const TextRange& rangeToDelete =
79  composing_range_.collapsed() ? selection_ : composing_range_;
80  text_.replace(rangeToDelete.start(), rangeToDelete.length(), text);
81  composing_range_.set_end(composing_range_.start() + text.length());
82  selection_ = TextRange(selection.start() + composing_range_.start(),
83  selection.extent() + composing_range_.start());
84 }
85 
86 void TextInputModel::UpdateComposingText(const std::u16string& text) {
87  UpdateComposingText(text, TextRange(text.length()));
88 }
89 
90 void TextInputModel::UpdateComposingText(const std::string& text) {
91  UpdateComposingText(fml::Utf8ToUtf16(text));
92 }
93 
95  // Preserve selection if no composing text was entered.
96  if (composing_range_.collapsed()) {
97  return;
98  }
99  composing_range_ = TextRange(composing_range_.end());
100  selection_ = composing_range_;
101 }
102 
104  composing_ = false;
105  composing_range_ = TextRange(0);
106 }
107 
108 bool TextInputModel::DeleteSelected() {
109  if (selection_.collapsed()) {
110  return false;
111  }
112  size_t start = selection_.start();
113  text_.erase(start, selection_.length());
114  selection_ = TextRange(start);
115  if (composing_) {
116  // This occurs only immediately after composing has begun with a selection.
117  composing_range_ = selection_;
118  }
119  return true;
120 }
121 
123  if (c <= 0xFFFF) {
124  AddText(std::u16string({static_cast<char16_t>(c)}));
125  } else {
126  char32_t to_decompose = c - 0x10000;
127  AddText(std::u16string({
128  // High surrogate.
129  static_cast<char16_t>((to_decompose >> 10) + 0xd800),
130  // Low surrogate.
131  static_cast<char16_t>((to_decompose % 0x400) + 0xdc00),
132  }));
133  }
134 }
135 
136 void TextInputModel::AddText(const std::u16string& text) {
137  DeleteSelected();
138  if (composing_) {
139  // Delete the current composing text, set the cursor to composing start.
140  text_.erase(composing_range_.start(), composing_range_.length());
141  selection_ = TextRange(composing_range_.start());
142  composing_range_.set_end(composing_range_.start() + text.length());
143  }
144  size_t position = selection_.position();
145  text_.insert(position, text);
146  selection_ = TextRange(position + text.length());
147 }
148 
149 void TextInputModel::AddText(const std::string& text) {
150  AddText(fml::Utf8ToUtf16(text));
151 }
152 
154  if (DeleteSelected()) {
155  return true;
156  }
157  // There is no selection. Delete the preceding codepoint.
158  size_t position = selection_.position();
159  if (position != editable_range().start()) {
160  int count = IsTrailingSurrogate(text_.at(position - 1)) ? 2 : 1;
161  text_.erase(position - count, count);
162  selection_ = TextRange(position - count);
163  if (composing_) {
164  composing_range_.set_end(composing_range_.end() - count);
165  }
166  return true;
167  }
168  return false;
169 }
170 
172  if (DeleteSelected()) {
173  return true;
174  }
175  // There is no selection. Delete the preceding codepoint.
176  size_t position = selection_.position();
177  if (position < editable_range().end()) {
178  int count = IsLeadingSurrogate(text_.at(position)) ? 2 : 1;
179  text_.erase(position, count);
180  if (composing_) {
181  composing_range_.set_end(composing_range_.end() - count);
182  }
183  return true;
184  }
185  return false;
186 }
187 
188 bool TextInputModel::DeleteSurrounding(int offset_from_cursor, int count) {
189  size_t max_pos = editable_range().end();
190  size_t start = selection_.extent();
191  if (offset_from_cursor < 0) {
192  for (int i = 0; i < -offset_from_cursor; i++) {
193  // If requested start is before the available text then reduce the
194  // number of characters to delete.
195  if (start == editable_range().start()) {
196  count = i;
197  break;
198  }
199  start -= IsTrailingSurrogate(text_.at(start - 1)) ? 2 : 1;
200  }
201  } else {
202  for (int i = 0; i < offset_from_cursor && start != max_pos; i++) {
203  start += IsLeadingSurrogate(text_.at(start)) ? 2 : 1;
204  }
205  }
206 
207  auto end = start;
208  for (int i = 0; i < count && end != max_pos; i++) {
209  end += IsLeadingSurrogate(text_.at(start)) ? 2 : 1;
210  }
211 
212  if (start == end) {
213  return false;
214  }
215 
216  auto deleted_length = end - start;
217  text_.erase(start, deleted_length);
218 
219  // Cursor moves only if deleted area is before it.
220  selection_ = TextRange(offset_from_cursor <= 0 ? start : selection_.start());
221 
222  // Adjust composing range.
223  if (composing_) {
224  composing_range_.set_end(composing_range_.end() - deleted_length);
225  }
226  return true;
227 }
228 
230  size_t min_pos = editable_range().start();
231  if (selection_.collapsed() && selection_.position() == min_pos) {
232  return false;
233  }
234  selection_ = TextRange(min_pos);
235  return true;
236 }
237 
239  size_t max_pos = editable_range().end();
240  if (selection_.collapsed() && selection_.position() == max_pos) {
241  return false;
242  }
243  selection_ = TextRange(max_pos);
244  return true;
245 }
246 
248  size_t min_pos = editable_range().start();
249  if (selection_.collapsed() && selection_.position() == min_pos) {
250  return false;
251  }
252  selection_ = TextRange(selection_.base(), min_pos);
253  return true;
254 }
255 
257  size_t max_pos = editable_range().end();
258  if (selection_.collapsed() && selection_.position() == max_pos) {
259  return false;
260  }
261  selection_ = TextRange(selection_.base(), max_pos);
262  return true;
263 }
264 
266  // If there's a selection, move to the end of the selection.
267  if (!selection_.collapsed()) {
268  selection_ = TextRange(selection_.end());
269  return true;
270  }
271  // Otherwise, move the cursor forward.
272  size_t position = selection_.position();
273  if (position != editable_range().end()) {
274  int count = IsLeadingSurrogate(text_.at(position)) ? 2 : 1;
275  selection_ = TextRange(position + count);
276  return true;
277  }
278  return false;
279 }
280 
282  // If there's a selection, move to the beginning of the selection.
283  if (!selection_.collapsed()) {
284  selection_ = TextRange(selection_.start());
285  return true;
286  }
287  // Otherwise, move the cursor backward.
288  size_t position = selection_.position();
289  if (position != editable_range().start()) {
290  int count = IsTrailingSurrogate(text_.at(position - 1)) ? 2 : 1;
291  selection_ = TextRange(position - count);
292  return true;
293  }
294  return false;
295 }
296 
297 std::string TextInputModel::GetText() const {
298  return fml::Utf16ToUtf8(text_);
299 }
300 
302  // Measure the length of the current text up to the selection extent.
303  // There is probably a much more efficient way of doing this.
304  auto leading_text = text_.substr(0, selection_.extent());
305  return fml::Utf16ToUtf8(leading_text).size();
306 }
307 
308 } // namespace flutter
flutter::TextInputModel::MoveCursorToBeginning
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Definition: text_input_model.cc:229
flutter::TextInputModel::SetText
bool SetText(const std::string &text, const TextRange &selection=TextRange(0), const TextRange &composing_range=TextRange(0))
Definition: text_input_model.cc:31
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size_t end() const
Definition: text_range.h:54
flutter::TextInputModel::text_range
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Definition: text_input_model.h:198
flutter::TextInputModel::SelectToEnd
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Definition: text_input_model.cc:256
flutter::TextInputModel::composing_range
TextRange composing_range() const
Definition: text_input_model.h:206
flutter::TextRange::position
size_t position() const
Definition: text_range.h:68
flutter::TextInputModel::selection
TextRange selection() const
Definition: text_input_model.h:201
flutter::TextInputModel::BeginComposing
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Definition: text_input_model.cc:67
flutter::TextInputModel::~TextInputModel
virtual ~TextInputModel()
flutter::TextInputModel::DeleteSurrounding
bool DeleteSurrounding(int offset_from_cursor, int count)
Definition: text_input_model.cc:188
text_input_model.h
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Definition: text_range.h:19
flutter::TextRange::base
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Definition: text_range.h:30
flutter::TextInputModel::TextInputModel
TextInputModel()
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Definition: text_input_model.cc:153
flutter::TextInputModel::GetText
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Definition: text_input_model.cc:297
flutter::TextInputModel::SetSelection
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Definition: text_input_model.cc:46
flutter::TextInputModel::SelectToBeginning
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Definition: text_input_model.cc:247
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Definition: text_range.h:77
flutter::TextInputModel::UpdateComposingText
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Definition: text_input_model.cc:72
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Definition: text_input_model.cc:57
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Definition: text_input_model.cc:265
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Definition: text_input_model.cc:301
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Definition: text_input_model.cc:94
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Definition: text_range.h:36
flutter::TextInputModel::EndComposing
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Definition: text_input_model.cc:103
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Definition: text_input_model.cc:238
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Definition: text_range.h:42
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Definition: text_range.h:74
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Definition: text_input_model.cc:281
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Definition: text_input_model.cc:136
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Definition: text_input_model.cc:171
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Definition: text_input_model.cc:122