views::Textfield: Implement transpose editing command.

ui/views/controls/textfield/textfield_model.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/controls/textfield/textfield_model.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 509 matching lines @@
 
   base::string16 actual_text = base::CollapseWhitespace(text, false);
   // If the clipboard contains all whitespaces then paste a single space.
   if (actual_text.empty())
     actual_text = base::ASCIIToUTF16(" ");
 
   InsertTextInternal(actual_text, false);
   return true;
 }
 
+bool TextfieldModel::Transpose() {
+  if (HasCompositionText() || HasSelection())
+    return false;
+
+  size_t cur = GetCursorPosition();
+  size_t next = render_text_->IndexOfAdjacentGrapheme(cur, gfx::CURSOR_FORWARD);
+  size_t prev =
+      render_text_->IndexOfAdjacentGrapheme(cur, gfx::CURSOR_BACKWARD);
+
+  // At the end of the line, the last two characters should be transposed.
+  if (cur == text().length()) {
+    DCHECK_EQ(cur, next);
+    cur = prev;
+    prev = render_text_->IndexOfAdjacentGrapheme(prev, gfx::CURSOR_BACKWARD);
+  }
+
+  // This happens at the beginning of the line or when the line has less than
+  // two graphemes.
+  if (gfx::UTF16IndexToOffset(text(), prev, next) != 2)
+    return false;
+
+  SelectRange(gfx::Range(prev, next));
+  base::string16 text = GetSelectedText();
+  base::string16 transposed_text =
+      text.substr(cur - prev) + text.substr(0, cur - prev);
+
+  InsertTextInternal(transposed_text, false);
+  return true;
+}
+
 bool TextfieldModel::HasSelection() const {
   return !render_text_->selection().is_empty();
 }
 
 void TextfieldModel::DeleteSelection() {
   DCHECK(!HasCompositionText());
   DCHECK(HasSelection());
   ExecuteAndRecordDelete(render_text_->selection(), false);
 }
 
@@ skipping 234 matching lines @@
   ClearComposition();
   if (delete_from != delete_to)
     render_text_->SetText(old_text.erase(delete_from, delete_to - delete_from));
   if (!new_text.empty())
     render_text_->SetText(old_text.insert(new_text_insert_at, new_text));
   render_text_->SetCursorPosition(new_cursor_pos);
   // TODO(oshima): Select text that was just undone, like Mac (but not GTK).
 }
 
 }  // namespace views