Reduce the number of text reshaping in RenderText

ui/gfx/render_text_mac.cc

 // Copyright (c) 2012 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/gfx/render_text_mac.h"
 
 #include <ApplicationServices/ApplicationServices.h>
 
 #include <algorithm>
 #include <cmath>
 #include <utility>
 
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/strings/sys_string_conversions.h"
 #include "skia/ext/skia_utils_mac.h"
 
 namespace gfx {
 
-RenderTextMac::RenderTextMac() : common_baseline_(0), runs_valid_(false) {
+RenderTextMac::RenderTextMac()
+    : common_baseline_(0), runs_valid_(false) {
 }
 
 RenderTextMac::~RenderTextMac() {
 }
 
 scoped_ptr<RenderText> RenderTextMac::CreateInstanceOfSameType() const {
   return scoped_ptr<RenderTextMac>(new RenderTextMac);
 }
 
+const base::string16& RenderTextMac::GetLayoutText() {
+  if (elide_behavior() == NO_ELIDE ||
+      elide_behavior() == FADE_TAIL) {
+    return layout_text();
+  }
+  return text_elided() ? elided_text() : layout_text();
+}
+
 Size RenderTextMac::GetStringSize() {
   EnsureLayout();
   return Size(std::ceil(string_size_.width()), string_size_.height());
 }
 
 SizeF RenderTextMac::GetStringSizeF() {
   EnsureLayout();
   return string_size_;
 }
 
@@ skipping 40 matching lines @@
 Range RenderTextMac::GetGlyphBounds(size_t index) {
   // TODO(asvitkine): Implement this. http://crbug.com/131618
   return Range();
 }
 
 std::vector<Rect> RenderTextMac::GetSubstringBounds(const Range& range) {
   // TODO(asvitkine): Implement this. http://crbug.com/131618
   return std::vector<Rect>();
 }
 
-size_t RenderTextMac::TextIndexToLayoutIndex(size_t index) const {
+size_t RenderTextMac::TextIndexToLayoutIndex(size_t index) {
   // TODO(asvitkine): Implement this. http://crbug.com/131618
   return index;
 }
 
-size_t RenderTextMac::LayoutIndexToTextIndex(size_t index) const {
+size_t RenderTextMac::LayoutIndexToTextIndex(size_t index) {
   // TODO(asvitkine): Implement this. http://crbug.com/131618
   return index;
 }
 
 bool RenderTextMac::IsValidCursorIndex(size_t index) {
   // TODO(asvitkine): Implement this. http://crbug.com/131618
   return IsValidLogicalIndex(index);
 }
 
-void RenderTextMac::ResetLayout() {
+void RenderTextMac::OnLayoutTextShapeChanged(bool text_changed) {
+  if (text_changed &&
+      elide_behavior() != NO_ELIDE &&
+      elide_behavior() != FADE_TAIL &&
+      !layout_text().empty()) {
+    UpdateElidedText(GetContentWidth());
+  }
   line_.reset();
   attributes_.reset();
   runs_.clear();
   runs_valid_ = false;
 }
 
+void RenderTextMac::OnElidedTextShapeChanged() {
+  OnLayoutTextShapeChanged(true);
+}
+
 void RenderTextMac::EnsureLayout() {
   if (line_.get())
     return;
   runs_.clear();
   runs_valid_ = false;
 
   CTFontRef ct_font = base::mac::NSToCFCast(
       font_list().GetPrimaryFont().GetNativeFont());
 
   const void* keys[] = { kCTFontAttributeName };
@@ skipping 217 matching lines @@
     CTUnderlineStyle value = kCTUnderlineStyleNone;
     if (underline && CFNumberGetValue(underline, kCFNumberSInt32Type, &value))
       run->underline = (value == kCTUnderlineStyleSingle);
 
     run_origin.offset(run_width, 0);
   }
   runs_valid_ = true;
 }
 
 }  // namespace gfx