Uses and returns the fractional width in text eliding

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() {
 }
 
 Size RenderTextMac::GetStringSize() {
   EnsureLayout();

[sky, 2013/10/08 02:12:56]

How about
return ToCeiledSize(GetStringSizeF())
?

[jianli, 2013/10/08 18:29:48]

Returning both ceiled width and height will cause test
RenderTextTest.StringSizeRespectsFontListMetrics to fail. This is because
[NSLayoutManager defaultLineHeightForFont] (called by Font::GetHeight) returns
the non-fractional height while CTLineGetTypographicBounds (used by
RenderTextMac in height computation) returns the fractional height.

+  return Size(std::ceil(string_size_.width()), string_size_.height());
+}
+
+SizeF RenderTextMac::GetStringSizeF() {
+  EnsureLayout();
   return string_size_;
 }
 
 int RenderTextMac::GetBaseline() {
   EnsureLayout();
   return common_baseline_;
 }
 
 SelectionModel RenderTextMac::FindCursorPosition(const Point& point) {
   // TODO(asvitkine): Implement this. http://crbug.com/131618
@@ skipping 104 matching lines @@
   double width = CTLineGetTypographicBounds(line_, &ascent, &descent, &leading);
   // Ensure ascent and descent are not smaller than ones of the font list.
   // Keep them tall enough to draw often-used characters.
   // For example, if a text field contains a Japanese character, which is
   // smaller than Latin ones, and then later a Latin one is inserted, this
   // ensures that the text baseline does not shift.
   CGFloat font_list_height = font_list().GetHeight();
   CGFloat font_list_baseline = font_list().GetBaseline();
   ascent = std::max(ascent, font_list_baseline);
   descent = std::max(descent, font_list_height - font_list_baseline);
-  string_size_ = Size(std::ceil(width), ascent + descent + leading);
+  string_size_ = SizeF(width, ascent + descent + leading);
   common_baseline_ = ascent;
 }
 
 void RenderTextMac::DrawVisualText(Canvas* canvas) {
   DCHECK(line_);
   if (!runs_valid_)
     ComputeRuns();
 
   internal::SkiaTextRenderer renderer(canvas);
   ApplyFadeEffects(&renderer);
@@ skipping 170 matching lines @@
     run_origin.offset(run_width, 0);
   }
   runs_valid_ = true;
 }
 
 RenderText* RenderText::CreateInstance() {
   return new RenderTextMac;
 }
 
 }  // namespace gfx