Fix sub-pixel handling of transparency boxes in DPL

Source/core/paint/DeprecatedPaintLayer.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 985 matching lines @@
 static void expandClipRectForDescendantsAndReflection(LayoutRect& clipRect, const DeprecatedPaintLayer* layer, const DeprecatedPaintLayer* rootLayer,
     DeprecatedPaintLayer::TransparencyClipBoxBehavior transparencyBehavior, const LayoutSize& subPixelAccumulation, GlobalPaintFlags globalPaintFlags)
 {
     // If we have a mask, then the clip is limited to the border box area (and there is
     // no need to examine child layers).
     if (!layer->layoutObject()->hasMask()) {
         // Note: we don't have to walk z-order lists since transparent elements always establish
         // a stacking container. This means we can just walk the layer tree directly.
         for (DeprecatedPaintLayer* curr = layer->firstChild(); curr; curr = curr->nextSibling()) {
             if (!layer->reflectionInfo() || layer->reflectionInfo()->reflectionLayer() != curr)
-                clipRect.unite(DeprecatedPaintLayer::transparencyClipBox(curr, rootLayer, transparencyBehavior, DeprecatedPaintLayer::DescendantsOfTransparencyClipBox, subPixelAccumulation, globalPaintFlags));
+                clipRect.unite(DeprecatedPaintLayer::transparencyClipBox(curr, rootLayer, transparencyBehavior, DeprecatedPaintLayer::DescendantsOfTransparencyClipBox, globalPaintFlags));
         }
     }
 
     // If we have a reflection, then we need to account for that when we push the clip.  Reflect our entire
     // current transparencyClipBox to catch all child layers.
     // FIXME: Accelerated compositing will eventually want to do something smart here to avoid incorporating this
     // size into the parent layer.
     if (layer->layoutObject()->hasReflection()) {
         LayoutPoint delta;
         layer->convertToLayerCoords(rootLayer, delta);
         clipRect.move(-delta.x(), -delta.y());
         clipRect.unite(layer->layoutBox()->reflectedRect(clipRect));
         clipRect.moveBy(delta);
     }
 }
 
 LayoutRect DeprecatedPaintLayer::transparencyClipBox(const DeprecatedPaintLayer* layer, const DeprecatedPaintLayer* rootLayer, TransparencyClipBoxBehavior transparencyBehavior,
-    TransparencyClipBoxMode transparencyMode, const LayoutSize& subPixelAccumulation, GlobalPaintFlags globalPaintFlags)
+    TransparencyClipBoxMode transparencyMode, GlobalPaintFlags globalPaintFlags)
 {
     // FIXME: Although this function completely ignores CSS-imposed clipping, we did already intersect with the
     // paintDirtyRect, and that should cut down on the amount we have to paint.  Still it
     // would be better to respect clips.
 
     if (rootLayer != layer && ((transparencyBehavior == PaintingTransparencyClipBox && layer->paintsWithTransform(globalPaintFlags))
         || (transparencyBehavior == HitTestingTransparencyClipBox && layer->hasTransformRelatedProperty()))) {
         // The best we can do here is to use enclosed bounding boxes to establish a "fuzzy" enough clip to encompass
         // the transformed layer and all of its children.
         const DeprecatedPaintLayer* paginationLayer = transparencyMode == DescendantsOfTransparencyClipBox ? layer->enclosingPaginationLayer() : 0;
         const DeprecatedPaintLayer* rootLayerForTransform = paginationLayer ? paginationLayer : rootLayer;
         LayoutPoint delta;
         layer->convertToLayerCoords(rootLayerForTransform, delta);
 
-        delta.move(subPixelAccumulation);
+        delta.move(layer->subpixelAccumulation());
         IntPoint pixelSnappedDelta = roundedIntPoint(delta);
         TransformationMatrix transform;
         transform.translate(pixelSnappedDelta.x(), pixelSnappedDelta.y());
         if (layer->transform())
             transform = transform * *layer->transform();
 
         // We don't use fragment boxes when collecting a transformed layer's bounding box, since it always
         // paints unfragmented.
         LayoutRect clipRect = layer->physicalBoundingBox(layer);
-        expandClipRectForDescendantsAndReflection(clipRect, layer, layer, transparencyBehavior, subPixelAccumulation, globalPaintFlags);
+        expandClipRectForDescendantsAndReflection(clipRect, layer, layer, transparencyBehavior, layer->subpixelAccumulation(), globalPaintFlags);
         clipRect.expand(layer->layoutObject()->style()->filterOutsets());
         LayoutRect result = transform.mapRect(clipRect);
         if (!paginationLayer)
             return result;
 
         // We have to break up the transformed extent across our columns.
         // Split our box up into the actual fragment boxes that layout in the columns/pages and unite those together to
         // get our true bounding box.
         LayoutFlowThread* enclosingFlowThread = toLayoutFlowThread(paginationLayer->layoutObject());
         result = enclosingFlowThread->fragmentsBoundingBox(result);
 
         LayoutPoint rootLayerDelta;
         paginationLayer->convertToLayerCoords(rootLayer, rootLayerDelta);
         result.moveBy(rootLayerDelta);
         return result;
     }
 
     LayoutRect clipRect = layer->fragmentsBoundingBox(rootLayer);
-    expandClipRectForDescendantsAndReflection(clipRect, layer, rootLayer, transparencyBehavior, subPixelAccumulation, globalPaintFlags);
+    expandClipRectForDescendantsAndReflection(clipRect, layer, rootLayer, transparencyBehavior, layer->subpixelAccumulation(), globalPaintFlags);
     clipRect.expand(layer->layoutObject()->style()->filterOutsets());
-    clipRect.move(subPixelAccumulation);
+    clipRect.move(layer->subpixelAccumulation());
     return clipRect;
 }
 
-LayoutRect DeprecatedPaintLayer::paintingExtent(const DeprecatedPaintLayer* rootLayer, const LayoutRect& paintDirtyRect, const LayoutSize& subPixelAccumulation, GlobalPaintFlags globalPaintFlags)
+LayoutRect DeprecatedPaintLayer::paintingExtent(const DeprecatedPaintLayer* rootLayer, const LayoutRect& paintDirtyRect, GlobalPaintFlags globalPaintFlags)
 {
-    return intersection(transparencyClipBox(this, rootLayer, PaintingTransparencyClipBox, RootOfTransparencyClipBox, subPixelAccumulation, globalPaintFlags), paintDirtyRect);
+    return intersection(transparencyClipBox(this, rootLayer, PaintingTransparencyClipBox, RootOfTransparencyClipBox, globalPaintFlags), paintDirtyRect);
 }
 
 void* DeprecatedPaintLayer::operator new(size_t sz)
 {
     return partitionAlloc(WTF::Partitions::layoutPartition(), sz);
 }
 
 void DeprecatedPaintLayer::operator delete(void* ptr)
 {
     partitionFree(ptr);
@@ skipping 703 matching lines @@
 
     return false;
 }
 
 DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestTransformedLayerInFragments(DeprecatedPaintLayer* rootLayer, DeprecatedPaintLayer* containerLayer, HitTestResult& result,
     const LayoutRect& hitTestRect, const HitTestLocation& hitTestLocation, const HitTestingTransformState* transformState, double* zOffset, ClipRectsCacheSlot clipRectsCacheSlot)
 {
     DeprecatedPaintLayerFragments enclosingPaginationFragments;
     LayoutPoint offsetOfPaginationLayerFromRoot;
     // FIXME: We're missing a sub-pixel offset here crbug.com/348728
-    LayoutRect transformedExtent = transparencyClipBox(this, enclosingPaginationLayer(), HitTestingTransparencyClipBox, DeprecatedPaintLayer::RootOfTransparencyClipBox, LayoutSize());
+    LayoutRect transformedExtent = transparencyClipBox(this, enclosingPaginationLayer(), HitTestingTransparencyClipBox, DeprecatedPaintLayer::RootOfTransparencyClipBox);
     enclosingPaginationLayer()->collectFragments(enclosingPaginationFragments, rootLayer, hitTestRect,
         clipRectsCacheSlot, IncludeOverlayScrollbarSize, RespectOverflowClip, &offsetOfPaginationLayerFromRoot, LayoutSize(), &transformedExtent);
 
     for (int i = enclosingPaginationFragments.size() - 1; i >= 0; --i) {
         const DeprecatedPaintLayerFragment& fragment = enclosingPaginationFragments.at(i);
 
         // Apply the page/column clip for this fragment, as well as any clips established by layers in between us and
         // the enclosing pagination layer.
         LayoutRect clipRect = fragment.backgroundRect.rect();
 
@@ skipping 860 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif