Support subpixel layout for borders.

third_party/WebKit/Source/core/paint/ObjectPainter.cpp

 // Copyright 2014 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 "core/paint/ObjectPainter.h"
 
 #include "core/layout/LayoutBlock.h"
 #include "core/layout/LayoutInline.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/LayoutTheme.h"
@@ skipping 320 matching lines @@
                                       m_layoutObject.document().baseURL())) {
     String fragmentName = url.fragmentIdentifier();
     if (m_layoutObject.document().findAnchor(fragmentName))
       paintInfo.context.setURLFragmentForRect(fragmentName, rect);
     return;
   }
   paintInfo.context.setURLForRect(url, rect);
 }
 
 void ObjectPainter::drawLineForBoxSide(GraphicsContext& graphicsContext,
-                                       int x1,
-                                       int y1,
-                                       int x2,
-                                       int y2,
+                                       float x1,
+                                       float y1,
+                                       float x2,
+                                       float y2,
                                        BoxSide side,
                                        Color color,
                                        EBorderStyle style,
                                        int adjacentWidth1,
                                        int adjacentWidth2,
                                        bool antialias) {
-  int thickness;
-  int length;
+  float thickness;
+  float length;
   if (side == BSTop || side == BSBottom) {
     thickness = y2 - y1;
     length = x2 - x1;
   } else {
     thickness = x2 - x1;
     length = y2 - y1;
   }
 
   // We would like this check to be an ASSERT as we don't want to draw empty
   // borders. However nothing guarantees that the following recursive calls to
@@ skipping 79 matching lines @@
 }
 
 void ObjectPainter::drawDoubleBoxSide(GraphicsContext& graphicsContext,
                                       int x1,
                                       int y1,
                                       int x2,
                                       int y2,
                                       int length,
                                       BoxSide side,
                                       Color color,
-                                      int thickness,
+                                      float thickness,
                                       int adjacentWidth1,
                                       int adjacentWidth2,
                                       bool antialias) {
   int thirdOfThickness = (thickness + 1) / 3;
   DCHECK_GT(thirdOfThickness, 0);
 
   if (!adjacentWidth1 && !adjacentWidth2) {
     StrokeStyle oldStrokeStyle = graphicsContext.getStrokeStyle();
     graphicsContext.setStrokeStyle(NoStroke);
     graphicsContext.setFillColor(color);
@@ skipping 246 matching lines @@
     adjustedPaintOffset += toLayoutBox(m_layoutObject).location();
   DCHECK(m_layoutObject.paintOffset() == adjustedPaintOffset)
       << " Paint offset mismatch: " << m_layoutObject.debugName()
       << " from PaintPropertyTreeBuilder: "
       << m_layoutObject.paintOffset().toString()
       << " from painter: " << adjustedPaintOffset.toString();
 }
 #endif
 
 }  // namespace blink