Fix painting of fixed background images in composited layers

Source/core/rendering/RenderBoxModelObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 678 matching lines @@
                 }
             } else if (bgColor.alpha()) {
                 context->fillRect(backgroundRect, bgColor, context->compositeOperation());
             }
         }
     }
 
     // no progressive loading of the background image
     if (shouldPaintBackgroundImage) {
         BackgroundImageGeometry geometry;
-        calculateBackgroundImageGeometry(bgLayer, scrolledPaintRect, geometry, backgroundObject);
+        calculateBackgroundImageGeometry(paintInfo.paintContainer(), bgLayer, scrolledPaintRect, geometry, backgroundObject);
         geometry.clip(paintInfo.rect);
         if (!geometry.destRect().isEmpty()) {
             CompositeOperator compositeOp = op == CompositeSourceOver ? bgLayer->composite() : op;
             RenderObject* clientForBackgroundImage = backgroundObject ? backgroundObject : this;
             RefPtr<Image> image = bgImage->image(clientForBackgroundImage, geometry.tileSize());
             InterpolationQuality interpolationQuality = chooseInterpolationQuality(context, image.get(), bgLayer, geometry.tileSize());
             if (bgLayer->maskSourceType() == MaskLuminance)
                 context->setColorFilter(ColorFilterLuminanceToAlpha);
             InterpolationQuality previousInterpolationQuality = context->imageInterpolationQuality();
             context->setImageInterpolationQuality(interpolationQuality);
@@ skipping 247 matching lines @@
 {
     int numberOfTiles = areaSize / tileSize;
     int space = -1;
 
     if (numberOfTiles > 1)
         space = lroundf((float)(areaSize - numberOfTiles * tileSize) / (numberOfTiles - 1));
 
     return space;
 }
 
-void RenderBoxModelObject::calculateBackgroundImageGeometry(const FillLayer* fillLayer, const LayoutRect& paintRect,
-    BackgroundImageGeometry& geometry, RenderObject* backgroundObject)
+void RenderBoxModelObject::calculateBackgroundImageGeometry(const RenderLayerModelObject* paintContainer, const FillLayer* fillLayer, const LayoutRect& paintRect,
+    BackgroundImageGeometry& geometry, RenderObject* backgroundObject) const
 {
     LayoutUnit left = 0;
     LayoutUnit top = 0;
     IntSize positioningAreaSize;
     IntRect snappedPaintRect = pixelSnappedIntRect(paintRect);
 
     // Determine the background positioning area and set destRect to the background painting area.
     // destRect will be adjusted later if the background is non-repeating.
+    // FIXME: transforms spec says that fixed backgrounds behave like scroll inside transforms.
     bool fixedAttachment = fillLayer->attachment() == FixedBackgroundAttachment;
 
 #if ENABLE(FAST_MOBILE_SCROLLING)
     if (view()->frameView() && view()->frameView()->shouldAttemptToScrollUsingFastPath()) {
         // As a side effect of an optimization to blit on scroll, we do not honor the CSS
         // property "background-attachment: fixed" because it may result in rendering
         // artifacts. Note, these artifacts only appear if we are blitting on scroll of
         // a page that has fixed background images.
         fixedAttachment = false;
     }
@@ skipping 21 matching lines @@
         // The background of the box generated by the root element covers the entire canvas including
         // its margins. Since those were added in already, we have to factor them out when computing
         // the background positioning area.
         if (isRoot()) {
             positioningAreaSize = pixelSnappedIntSize(toRenderBox(this)->size() - LayoutSize(left + right, top + bottom), toRenderBox(this)->location());
             left += marginLeft();
             top += marginTop();
         } else
             positioningAreaSize = pixelSnappedIntSize(paintRect.size() - LayoutSize(left + right, top + bottom), paintRect.location());
     } else {
+        geometry.setHasNonLocalGeometry();
+
         IntRect viewportRect = pixelSnappedIntRect(viewRect());
         if (fixedBackgroundPaintsInLocalCoordinates())
             viewportRect.setLocation(IntPoint());
         else if (FrameView* frameView = view()->frameView())
             viewportRect.setLocation(IntPoint(frameView->scrollOffsetForFixedPosition()));
 
+        if (paintContainer) {
+            IntPoint absoluteContainerOffset = roundedIntPoint(paintContainer->localToAbsolute(FloatPoint()));
+            viewportRect.moveBy(-absoluteContainerOffset);
+        }
+
         geometry.setDestRect(pixelSnappedIntRect(viewportRect));
         positioningAreaSize = geometry.destRect().size();
     }
 
-    RenderObject* clientForBackgroundImage = backgroundObject ? backgroundObject : this;
+    const RenderObject* clientForBackgroundImage = backgroundObject ? backgroundObject : this;
     IntSize fillTileSize = calculateFillTileSize(fillLayer, positioningAreaSize);
     fillLayer->image()->setContainerSizeForRenderer(clientForBackgroundImage, fillTileSize, style()->effectiveZoom());
     geometry.setTileSize(fillTileSize);
 
     EFillRepeat backgroundRepeatX = fillLayer->repeatX();
     EFillRepeat backgroundRepeatY = fillLayer->repeatY();
     int availableWidth = positioningAreaSize.width() - geometry.tileSize().width();
     int availableHeight = positioningAreaSize.height() - geometry.tileSize().height();
 
     LayoutUnit computedXPosition = roundedMinimumValueForLength(fillLayer->xPosition(), availableWidth);
@@ skipping 1770 matching lines @@
     ASSERT(!beforeChild || toBoxModelObject == beforeChild->parent());
     for (RenderObject* child = startChild; child && child != endChild; ) {
         // Save our next sibling as moveChildTo will clear it.
         RenderObject* nextSibling = child->nextSibling();
         moveChildTo(toBoxModelObject, child, beforeChild, fullRemoveInsert);
         child = nextSibling;
     }
 }
 
 } // namespace WebCore