Support subpixel layout for borders.

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights
  * reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@gmail.com>
@@ skipping 1025 matching lines @@
 }
 
 IntRect PaintLayerScrollableArea::rectForHorizontalScrollbar(
     const IntRect& borderBoxRect) const {
   if (!hasHorizontalScrollbar())
     return IntRect();
 
   const IntRect& scrollCorner = scrollCornerRect();
 
   return IntRect(horizontalScrollbarStart(borderBoxRect.x()),
-                 borderBoxRect.maxY() - box().borderBottom() -
+                 borderBoxRect.maxY() - box().borderBottom().toInt() -
                      horizontalScrollbar()->scrollbarThickness(),
                  borderBoxRect.width() -
-                     (box().borderLeft() + box().borderRight()) -
+                     (box().borderLeft() + box().borderRight()).toInt() -
                      scrollCorner.width(),
                  horizontalScrollbar()->scrollbarThickness());
 }
 
 IntRect PaintLayerScrollableArea::rectForVerticalScrollbar(
     const IntRect& borderBoxRect) const {
   if (!hasVerticalScrollbar())
     return IntRect();
 
   const IntRect& scrollCorner = scrollCornerRect();
 
   return IntRect(
       verticalScrollbarStart(borderBoxRect.x(), borderBoxRect.maxX()),
-      borderBoxRect.y() + box().borderTop(),
+      borderBoxRect.y() + box().borderTop().toInt(),
       verticalScrollbar()->scrollbarThickness(),
-      borderBoxRect.height() - (box().borderTop() + box().borderBottom()) -
+      borderBoxRect.height() -
+          (box().borderTop() + box().borderBottom()).toInt() -
           scrollCorner.height());
 }
 
 int PaintLayerScrollableArea::verticalScrollbarStart(int minX, int maxX) const {
   if (box().shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
-    return minX + box().borderLeft();
-  return maxX - box().borderRight() - verticalScrollbar()->scrollbarThickness();
+    return minX + box().borderLeft().toInt();
+  return maxX - box().borderRight().toInt() -
+         verticalScrollbar()->scrollbarThickness();
 }
 
 int PaintLayerScrollableArea::horizontalScrollbarStart(int minX) const {
-  int x = minX + box().borderLeft();
+  int x = minX + box().borderLeft().toInt();
   if (box().shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
     x += hasVerticalScrollbar()
              ? verticalScrollbar()->scrollbarThickness()
              : resizerCornerRect(box().pixelSnappedBorderBoxRect(),
                                  ResizerForPointer)
                    .width();
   return x;
 }
 
 IntSize PaintLayerScrollableArea::scrollbarOffset(
     const Scrollbar& scrollbar) const {
-  if (&scrollbar == verticalScrollbar())
+  if (&scrollbar == verticalScrollbar()) {
     return IntSize(verticalScrollbarStart(0, box().size().width().toInt()),
-                   box().borderTop());
+                   box().borderTop().toInt());
+  }
 
   if (&scrollbar == horizontalScrollbar())
     return IntSize(
         horizontalScrollbarStart(0),
         (box().size().height() - box().borderBottom() - scrollbar.height())
             .toInt());
 
   ASSERT_NOT_REACHED();
   return IntSize();
 }
@@ skipping 257 matching lines @@
     resizeControlRect =
         resizerCornerRect(box().pixelSnappedBorderBoxRect(), ResizerForPointer);
     if (resizeControlRect.contains(localPoint))
       return true;
   }
 
   int resizeControlSize = max(resizeControlRect.height(), 0);
   if (hasVerticalScrollbar() &&
       verticalScrollbar()->shouldParticipateInHitTesting()) {
     LayoutRect vBarRect(verticalScrollbarStart(0, box().size().width().toInt()),
-                        box().borderTop(),
+                        box().borderTop().toInt(),
                         verticalScrollbar()->scrollbarThickness(),
                         box().size().height().toInt() -
-                            (box().borderTop() + box().borderBottom()) -
+                            (box().borderTop() + box().borderBottom()).toInt() -
                             (hasHorizontalScrollbar()
                                  ? horizontalScrollbar()->scrollbarThickness()
                                  : resizeControlSize));
     if (vBarRect.contains(localPoint)) {
       result.setScrollbar(verticalScrollbar());
       return true;
     }
   }
 
   resizeControlSize = max(resizeControlRect.width(), 0);
@@ skipping 717 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollOffsetClampScope::
     clampScrollableAreas() {
   for (auto& scrollableArea : *s_needsClamp)
     scrollableArea->clampScrollOffsetAfterOverflowChange();
   delete s_needsClamp;
   s_needsClamp = nullptr;
 }
 
 }  // namespace blink