Enable subpixel positioning for UI

ui/gfx/render_text.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.h"
 
 #include <algorithm>
 #include <climits>
 
 #include "base/command_line.h"
@@ skipping 704 matching lines @@
 VisualCursorDirection RenderText::GetVisualDirectionOfLogicalEnd() {
   return GetTextDirection() == base::i18n::LEFT_TO_RIGHT ?
       CURSOR_RIGHT : CURSOR_LEFT;
 }
 
 SizeF RenderText::GetStringSizeF() {
   return GetStringSize();
 }
 
 float RenderText::GetContentWidth() {
-  return GetStringSizeF().width() + (cursor_enabled_ ? 1 : 0);
+  return cursor_enabled_ ?

[msw, 2014/11/24 21:51:00]

This change seems hinge on the cursor painting 1px beyond the int-enclosed text
bounds. Use std::ceil(GetStringSizeF.width()) instead of GetStringSize() to make
that behavior explicit and avoid GetStringSize(), which should probably be
deprecated. Also, perhaps add a comment about the behavior of the cursor here.

[ckocagil, 2014/11/25 01:39:47]

Correct.
Done and done.

+      GetStringSize().width() + 1 : GetStringSizeF().width();
 }
 
 int RenderText::GetBaseline() {
   if (baseline_ == kInvalidBaseline)
     baseline_ = DetermineBaselineCenteringText(display_rect(), font_list());
   DCHECK_NE(kInvalidBaseline, baseline_);
   return baseline_;
 }
 
 void RenderText::Draw(Canvas* canvas) {
@@ skipping 328 matching lines @@
 
 Vector2d RenderText::GetAlignmentOffset(size_t line_number) {
   // TODO(ckocagil): Enable |lines_| usage in other platforms.
 #if defined(OS_WIN)
   DCHECK_LT(line_number, lines_.size());
 #endif
   Vector2d offset;
   HorizontalAlignment horizontal_alignment = GetCurrentHorizontalAlignment();
   if (horizontal_alignment != ALIGN_LEFT) {
 #if defined(OS_WIN)
-    const int width = lines_[line_number].size.width() +
+    const int width = std::ceil(lines_[line_number].size.width()) +
         (cursor_enabled_ ? 1 : 0);
 #else
     const int width = GetContentWidth();
 #endif
     offset.set_x(display_rect().width() - width);
     // Put any extra margin pixel on the left to match legacy behavior.
     if (horizontal_alignment == ALIGN_CENTER)
       offset.set_x((offset.x() + 1) / 2);
   }
 
@@ skipping 318 matching lines @@
   SetDisplayOffset(display_offset_.x() + delta_x);
 }
 
 void RenderText::DrawSelection(Canvas* canvas) {
   const std::vector<Rect> sel = GetSubstringBounds(selection());
   for (std::vector<Rect>::const_iterator i = sel.begin(); i < sel.end(); ++i)
     canvas->FillRect(*i, selection_background_focused_color_);
 }
 
 }  // namespace gfx