Implement Paint Containment

third_party/WebKit/Source/core/paint/PaintLayerClipper.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@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 51 matching lines @@
         clipRects.setFixed(true);
     } else if (position == RelativePosition) {
         clipRects.setPosClipRect(clipRects.overflowClipRect());
     } else if (position == AbsolutePosition) {
         clipRects.setOverflowClipRect(clipRects.posClipRect());
     }
 }
 
 static void applyClipRects(const ClipRectsContext& context, const LayoutObject& layoutObject, LayoutPoint offset, ClipRects& clipRects)
 {
-    ASSERT(layoutObject.hasOverflowClip() || layoutObject.hasClip());
+    ASSERT(layoutObject.hasOverflowClip() || layoutObject.hasClip() || layoutObject.style()->containsPaint());

[chrishtr, 2015/12/09 23:34:58]

hasClipRelatedProperty()

     LayoutView* view = layoutObject.view();
     ASSERT(view);
     if (clipRects.fixed() && context.rootLayer->layoutObject() == view)
         offset -= toIntSize(view->frameView()->scrollPosition());
-    if (layoutObject.hasOverflowClip()) {
+    if (layoutObject.hasOverflowClip() || layoutObject.style()->containsPaint()) {
         ClipRect newOverflowClip = toLayoutBox(layoutObject).overflowClipRect(offset, context.scrollbarRelevancy);
         newOverflowClip.setHasRadius(layoutObject.style()->hasBorderRadius());
         clipRects.setOverflowClipRect(intersection(newOverflowClip, clipRects.overflowClipRect()));
         if (layoutObject.isPositioned())
             clipRects.setPosClipRect(intersection(newOverflowClip, clipRects.posClipRect()));
         if (layoutObject.isLayoutView())
             clipRects.setFixedClipRect(intersection(newOverflowClip, clipRects.fixedClipRect()));
+        if (layoutObject.style()->containsPaint()) {
+            clipRects.setPosClipRect(intersection(newOverflowClip, clipRects.posClipRect()));
+            clipRects.setFixedClipRect(intersection(newOverflowClip, clipRects.fixedClipRect()));
+        }
     }
     if (layoutObject.hasClip()) {
         LayoutRect newClip = toLayoutBox(layoutObject).clipRect(offset);
         clipRects.setPosClipRect(intersection(newClip, clipRects.posClipRect()).setIsClippedByClipCss());
         clipRects.setOverflowClipRect(intersection(newClip, clipRects.overflowClipRect()).setIsClippedByClipCss());
         clipRects.setFixedClipRect(intersection(newClip, clipRects.fixedClipRect()).setIsClippedByClipCss());
 
     }
 }
 
@@ skipping 111 matching lines @@
     foregroundRect = backgroundRect;
 
     LayoutPoint offset;
     if (offsetFromRoot)
         offset = *offsetFromRoot;
     else
         m_layoutObject.layer()->convertToLayerCoords(context.rootLayer, offset);
     layerBounds = LayoutRect(offset, LayoutSize(m_layoutObject.layer()->size()));
 
     // Update the clip rects that will be passed to child layers.
-    if (m_layoutObject.hasOverflowClip() && shouldRespectOverflowClip(context)) {
+    if ((m_layoutObject.hasOverflowClip() && shouldRespectOverflowClip(context)) || m_layoutObject.style()->containsPaint()) {
         foregroundRect.intersect(toLayoutBox(m_layoutObject).overflowClipRect(offset, context.scrollbarRelevancy));
         if (m_layoutObject.style()->hasBorderRadius())
             foregroundRect.setHasRadius(true);
 
         // FIXME: Does not do the right thing with columns yet, since we don't yet factor in the
         // individual column boxes as overflow.
 
         // The LayoutView is special since its overflow clipping rect may be larger than its box rect (crbug.com/492871).
         LayoutRect layerBoundsWithVisualOverflow = m_layoutObject.isLayoutView() ? toLayoutView(m_layoutObject).viewRect() : toLayoutBox(m_layoutObject).visualOverflowRect();
         toLayoutBox(m_layoutObject).flipForWritingMode(layerBoundsWithVisualOverflow); // PaintLayer are in physical coordinates, so the overflow has to be flipped.
@@ skipping 33 matching lines @@
             clipRects = *parentLayer->clipper().cachedClipRects(context);
         } else {
             parentLayer->clipper().calculateClipRects(context, clipRects);
         }
     } else {
         clipRects.reset(LayoutRect(LayoutRect::infiniteIntRect()));
     }
 
     adjustClipRectsForChildren(m_layoutObject, clipRects);
 
-    if ((m_layoutObject.hasOverflowClip() && shouldRespectOverflowClip(context)) || m_layoutObject.hasClip()) {
+    if ((m_layoutObject.hasOverflowClip() && shouldRespectOverflowClip(context)) || m_layoutObject.hasClip() || m_layoutObject.style()->containsPaint()) {
         // This offset cannot use convertToLayerCoords, because sometimes our rootLayer may be across
         // some transformed layer boundary, for example, in the PaintLayerCompositor overlapMap, where
         // clipRects are needed in view space.
         applyClipRects(context, m_layoutObject, roundedLayoutPoint(m_layoutObject.localToContainerPoint(FloatPoint(), context.rootLayer->layoutObject())), clipRects);
     }
 }
 
 static ClipRect backgroundClipRectForPosition(const ClipRects& parentRects, EPosition position)
 {
     if (position == FixedPosition)
@@ skipping 50 matching lines @@
 
 ClipRects* PaintLayerClipper::paintingClipRects(const PaintLayer* rootLayer, ShouldRespectOverflowClip respectOverflowClip, const LayoutSize& subpixelAccumulation) const
 {
     ClipRectsContext context(rootLayer, PaintingClipRects, IgnoreOverlayScrollbarSize, subpixelAccumulation);
     if (respectOverflowClip == IgnoreOverflowClip)
         context.setIgnoreOverflowClip();
     return getClipRects(context);
 }
 
 } // namespace blink