Fix fixed-background offset issue

Source/core/paint/BackgroundImageGeometry.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 "config.h"
 #include "core/paint/BackgroundImageGeometry.h"
 
 #include "core/layout/LayoutBox.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutView.h"
@@ skipping 109 matching lines @@
             ? static_cast<float>(positioningAreaSize.height()) / imageIntrinsicSize.height() : 1;
         float scaleFactor = type == Contain ? std::min(horizontalScaleFactor, verticalScaleFactor) : std::max(horizontalScaleFactor, verticalScaleFactor);
         return IntSize(std::max(1l, lround(imageIntrinsicSize.width() * scaleFactor)), std::max(1l, lround(imageIntrinsicSize.height() * scaleFactor)));
     }
     }
 
     ASSERT_NOT_REACHED();
     return IntSize();
 }
 
+IntPoint accumulatedScrollOffset(const LayoutBoxModelObject& object, const LayoutBoxModelObject* container)
+{
+    const LayoutBlock* block = object.isLayoutBlock() ? toLayoutBlock(&object) : object.containingBlock();
+    IntPoint result;
+    while (block) {
+        if (block->hasOverflowClip())
+            result += block->scrolledContentOffset();
+        if (block == container)
+            break;
+        block = block->containingBlock();
+    }
+    return result;
+}
+
 } // anonymous namespace
 
 void BackgroundImageGeometry::setNoRepeatX(int xOffset)
 {
     m_destRect.move(std::max(xOffset, 0), 0);
     m_phase.setX(-std::min(xOffset, 0));
     m_destRect.setWidth(m_tileSize.width() + std::min(xOffset, 0));
 }
 
 void BackgroundImageGeometry::setNoRepeatY(int yOffset)
@@ skipping 76 matching lines @@
             // Since left/top is relative to the paint rect, we need to offset them back.
             left -= paintRect.x();
             top -= paintRect.y();
         } else {
             positioningAreaSize = pixelSnappedIntSize(paintRect.size() - LayoutSize(left + right, top + bottom), paintRect.location());
         }
     } else {
         setHasNonLocalGeometry();
 
         IntRect viewportRect = pixelSnappedIntRect(obj.viewRect());
-        if (fixedBackgroundPaintsInLocalCoordinates(obj, globalPaintFlags))
+        if (fixedBackgroundPaintsInLocalCoordinates(obj, globalPaintFlags)) {
             viewportRect.setLocation(IntPoint());
-        else if (FrameView* frameView = obj.view()->frameView())
-            viewportRect.setLocation(frameView->scrollPosition());
+        } else {
+            if (FrameView* frameView = obj.view()->frameView())
+                viewportRect.setLocation(frameView->scrollPosition());
+            // Compensate the translations created by ScrollRecorders.
+            // TODO(trchen): Fix this for SP phase 2. crbug.com/528226.

[chrishtr, 2015/09/09 22:46:33]

Wrong bug? I was thinking a tracking bug for this work in phase 2.

[Xianzhu, 2015/09/09 23:39:56]

Wanted to reuse the bug for phase 2.

Filed crbug.com/529963 and updated the above line.

+            viewportRect.moveBy(accumulatedScrollOffset(obj, paintContainer));
+        }
 
         if (paintContainer) {
             IntPoint absoluteContainerOffset = roundedIntPoint(paintContainer->localToAbsolute(FloatPoint()));
             viewportRect.moveBy(-absoluteContainerOffset);
         }
 
         setDestRect(viewportRect);
         positioningAreaSize = destRect().size();
     }
 
@@ skipping 85 matching lines @@
         setSpaceSize(IntSize(spaceSize().width(), 0));
     }
 
     if (fixedAttachment)
         useFixedAttachment(snappedPaintRect.location());
 
     clip(snappedPaintRect);
 }
 
 } // namespace blink