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.
+            viewportRect.moveBy(accumulatedScrollOffset(obj, paintContainer));

[chrishtr, 2015/09/09 22:07:05]

Add a TODO(trchen) to fix this for SP phase 2, and note in the appropriate bug.

[Xianzhu, 2015/09/09 22:40:47]

Done.

+        }
 
-        if (paintContainer) {
+        if (paintContainer && paintContainer->view() == obj.view()) {

[chrishtr, 2015/09/09 22:07:05]

Why this change?

[Xianzhu, 2015/09/09 22:40:47]

Thought paintContainer could be in ancestor view of the current view. Debugged
and found that paintContainer will be the view even if the view is not
composited.

Removed the change.

             IntPoint absoluteContainerOffset = roundedIntPoint(paintContainer->localToAbsolute(FloatPoint()));
             viewportRect.moveBy(-absoluteContainerOffset);
         }
 
         setDestRect(viewportRect);
         positioningAreaSize = destRect().size();
     }
 
     const LayoutObject* clientForBackgroundImage = backgroundObject ? backgroundObject : &obj;
     IntSize fillTileSize = calculateFillTileSize(positioningBox, fillLayer, positioningAreaSize);
@@ skipping 83 matching lines @@
         setSpaceSize(IntSize(spaceSize().width(), 0));
     }
 
     if (fixedAttachment)
         useFixedAttachment(snappedPaintRect.location());
 
     clip(snappedPaintRect);
 }
 
 } // namespace blink