Implement Pango RenderText for Linux.

views/controls/textfield/textfield_views_model.cc

 // Copyright (c) 2011 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 "views/controls/textfield/textfield_views_model.h"
 
 #include <algorithm>
 
 #include "base/i18n/break_iterator.h"
 #include "base/logging.h"
@@ skipping 593 matching lines @@
   AddOrMergeEditHistory(new InsertEdit(false, text, range.start()));
   render_text_->SetCursorPosition(range.end());
   ClearComposition();
   if (delegate_)
     delegate_->OnCompositionTextConfirmedOrCleared();
 }
 
 void TextfieldViewsModel::CancelCompositionText() {
   DCHECK(HasCompositionText());
   ui::Range range = render_text_->GetCompositionRange();
+  ClearComposition();

[msw, 2011/08/29 20:38:05]

Why did you make this change?
I have a vague feeling that I tried this before and it caused problems, but I
don't remember exactly what. Perhaps oshima can take a look.

[xji, 2011/08/30 00:39:41]

Inside SetCursorPosition(), we will need to get the previous grapheme of the
last index, which depends on pango layout is set up. During set up layout, pango
attribute is set up, including styles of composition text.  
Without ClearComposition(), we will be accessing the Composition range of
previous text during the setup of current text.

BTW, should not we reset composition_range_ inside SetText()?

[msw, 2011/08/30 01:17:07]

OK.
Perhaps, I'm not an expert with the IME code.

[xji, 2011/08/31 19:01:06]

From suzhe
"The caller should make sure that the composition text has been committed or
cancelled before calling RenderText::SetText(), so it's probably reasonable to
do a DCHECK in RenderText::SetText() to make sure the composition range has been
cleared."

   string16 new_text = GetText();
   render_text_->SetText(new_text.erase(range.start(), range.length()));
   render_text_->SetCursorPosition(range.start());
-  ClearComposition();
   if (delegate_)
     delegate_->OnCompositionTextConfirmedOrCleared();
 }
 
 void TextfieldViewsModel::ClearComposition() {
   render_text_->SetCompositionRange(ui::Range::InvalidRange());
 }
 
 void TextfieldViewsModel::GetCompositionTextRange(ui::Range* range) const {
   *range = ui::Range(render_text_->GetCompositionRange());
@@ skipping 147 matching lines @@
   if (delete_from != delete_to)
     render_text_->SetText(text.erase(delete_from, delete_to - delete_from));
   if (!new_text.empty())
     render_text_->SetText(text.insert(new_text_insert_at, new_text));
   render_text_->SetCursorPosition(new_cursor_pos);
   // TODO(oshima): mac selects the text that is just undone (but gtk doesn't).
   // This looks fine feature and we may want to do the same.
 }
 
 }  // namespace views