[AiS] for desktop, two lines and font sytles

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index 2b51d8aa8c75156871e18fda188ba726cad0c33a..64872c3ccc0001671b1c386271945898ee467bac 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -445,21 +445,15 @@ void RenderText::SetText(const base::string16& text) {
   DCHECK(!composition_range_.IsValid());
   if (text_ == text)
     return;
-  text_ = text;
+  text_.clear();
+  DoAppendText(text);
 
-  // Adjust ranged styles, baselines, and colors to accommodate a new text
-  // length. Clear style ranges as they might break new text graphemes and apply
+  // Clear style ranges as they might break new text graphemes and apply
   // the first style to the whole text instead.
-  const size_t text_length = text_.length();
-  colors_.SetMax(text_length);
+  colors_.SetValue(colors_.breaks().begin()->second);
   baselines_.SetValue(baselines_.breaks().begin()->second);
-  baselines_.SetMax(text_length);
-  for (size_t style = 0; style < NUM_TEXT_STYLES; ++style) {
-    BreakList<bool>& break_list = styles_[style];
-    break_list.SetValue(break_list.breaks().begin()->second);
-    break_list.SetMax(text_length);
-  }
-  cached_bounds_and_offset_valid_ = false;
+  for (size_t style = 0; style < NUM_TEXT_STYLES; ++style)
+    styles_[style].SetValue(styles_[style].breaks().begin()->second);
 
   // Reset selection model. SetText should always followed by SetSelectionModel
   // or SetCursorPosition in upper layer.
@@ -469,7 +463,11 @@ void RenderText::SetText(const base::string16& text) {
   if (directionality_mode_ == DIRECTIONALITY_FROM_TEXT)
     text_direction_ = base::i18n::UNKNOWN_DIRECTION;
 
-  obscured_reveal_index_ = -1;
+  OnTextAttributeChanged();
+}
+
+void RenderText::AppendText(const base::string16& text) {
+  DoAppendText(text);
   OnTextAttributeChanged();
 }
 
@@ -1241,6 +1239,18 @@ size_t RenderText::TextIndexToGivenTextIndex(const base::string16& given_text,
   return std::min<size_t>(given_text.length(), i);
 }
 
+void RenderText::DoAppendText(const base::string16& text) {
+  text_ += text;
+  // Adjust ranged styles and colors to accommodate a new text length.
+  const size_t text_length = text_.length();
+  colors_.SetMax(text_length);
+  baselines_.SetMax(text_length);
+  for (size_t style = 0; style < NUM_TEXT_STYLES; ++style)
+    styles_[style].SetMax(text_length);
+  cached_bounds_and_offset_valid_ = false;

[msw, 2015/03/18 20:20:16]

Sorry, I changed my mind here a bit. I think it'd be more appropriate if this
function limited its behavior to just extending the breaklists, and call it
something like "UpdateStyleLengths". The callers should either assign or append
to |text_|, set |cached_bounds_and_offset_valid_| and |obscured_reveal_index_|,
and call OnTextAttributeChanged()... Otherwise, I fear that this function might
be misconstrued as a sufficient and self-contained mechanism to extend the text
content and leave the RenderText in a good state; it isn't.

+  obscured_reveal_index_ = -1;
+}
+
 // static
 bool RenderText::RangeContainsCaret(const Range& range,
                                     size_t caret_pos,