Generate scroll/clip display item hierarchy for SPv2

Source/core/paint/DeprecatedPaintLayer.cpp

Index: Source/core/paint/DeprecatedPaintLayer.cpp
diff --git a/Source/core/paint/DeprecatedPaintLayer.cpp b/Source/core/paint/DeprecatedPaintLayer.cpp
index 7efcb1de19bc2510a2d8fdf498145e7b3b390274..cdb0de9b19bf351c5cfa08af8b3a26c41059cd1b 100644
--- a/Source/core/paint/DeprecatedPaintLayer.cpp
+++ b/Source/core/paint/DeprecatedPaintLayer.cpp
@@ -700,6 +700,19 @@ bool DeprecatedPaintLayer::update3DTransformedDescendantStatus()
     return has3DTransform();
 }
 
+LayoutPoint DeprecatedPaintLayer::locationSansOverflowScroll() const
+{
+    // Our m_location already has scroll offset baked-in. We have to revert it here.
+    IntSize scrollOffset;
+    if (DeprecatedPaintLayer* positionedParent = layoutObject()->isOutOfFlowPositioned() ? enclosingPositionedAncestor() : nullptr) {
+        if (positionedParent->layoutObject()->hasOverflowClip())
+            scrollOffset = positionedParent->layoutBox()->scrolledContentOffset();
+    } else if (parent() && parent()->layoutObject()->hasOverflowClip()) {
+        scrollOffset = parent()->layoutBox()->scrolledContentOffset();
+    }
+    return location() + LayoutSize(scrollOffset);

[pdr., 2015/08/25 20:47:55]

Shouldn't this be subtraction?

[trchen, 2015/08/26 07:39:04]

A layer moves up (subtraction) when it scrolls, so it is moving down (addition)
to revert scroll. ;)

+}
+
 bool DeprecatedPaintLayer::updateLayerPosition()
 {
     LayoutPoint localPoint;
@@ -1292,6 +1305,67 @@ void DeprecatedPaintLayer::convertToLayerCoords(const DeprecatedPaintLayer* ance
         currLayer = accumulateOffsetTowardsAncestor(currLayer, ancestorLayer, location);
 }
 
+// TODO(trchen): Deduplicate.
+static inline const DeprecatedPaintLayer* accumulateOffsetTowardsAncestorSansOverflowScroll(const DeprecatedPaintLayer* layer, const DeprecatedPaintLayer* ancestorLayer, LayoutPoint& location)
+{
+    ASSERT(ancestorLayer != layer);
+
+    const LayoutBoxModelObject* layoutObject = layer->layoutObject();
+    EPosition position = layoutObject->style()->position();
+
+    if (position == FixedPosition && (!ancestorLayer || ancestorLayer == layoutObject->view()->layer())) {
+        // If the fixed layer's container is the root, just add in the offset of the view. We can obtain this by calling
+        // localToAbsolute() on the LayoutView.
+        FloatPoint absPos = layoutObject->localToAbsolute(FloatPoint(), IsFixed);
+        location += LayoutSize(absPos.x(), absPos.y());
+        return ancestorLayer;
+    }
+
+    DeprecatedPaintLayer* parentLayer;
+    if (position == AbsolutePosition || position == FixedPosition) {
+        bool foundAncestorFirst;
+        parentLayer = layer->enclosingPositionedAncestor(ancestorLayer, &foundAncestorFirst);
+
+        if (foundAncestorFirst) {
+            // Found ancestorLayer before the container of the out-of-flow object, so compute offset
+            // of both relative to the container and subtract.
+
+            LayoutPoint thisCoords;
+            layer->convertToLayerCoordsSansOverflowScroll(parentLayer, thisCoords);
+
+            LayoutPoint ancestorCoords;
+            ancestorLayer->convertToLayerCoordsSansOverflowScroll(parentLayer, ancestorCoords);
+
+            location += (thisCoords - ancestorCoords);
+            return ancestorLayer;
+        }
+    } else if (layoutObject->isColumnSpanAll()) {
+        LayoutBlock* multicolContainer = layoutObject->containingBlock();
+        ASSERT(toLayoutBlockFlow(multicolContainer)->multiColumnFlowThread());
+        parentLayer = multicolContainer->layer();
+        ASSERT(parentLayer);
+    } else {
+        parentLayer = layer->parent();
+    }
+
+    if (!parentLayer)
+        return nullptr;
+
+    location += layer->locationSansOverflowScroll();
+    return parentLayer;
+}
+
+// TODO(trchen): Deduplicate.
+void DeprecatedPaintLayer::convertToLayerCoordsSansOverflowScroll(const DeprecatedPaintLayer* ancestorLayer, LayoutPoint& location) const
+{
+    if (ancestorLayer == this)
+        return;
+
+    const DeprecatedPaintLayer* currLayer = this;
+    while (currLayer && currLayer != ancestorLayer)
+        currLayer = accumulateOffsetTowardsAncestorSansOverflowScroll(currLayer, ancestorLayer, location);
+}
+
 void DeprecatedPaintLayer::convertToLayerCoords(const DeprecatedPaintLayer* ancestorLayer, LayoutRect& rect) const
 {
     LayoutPoint delta;
@@ -1405,7 +1479,7 @@ void DeprecatedPaintLayer::collectFragments(DeprecatedPaintLayerFragments& fragm
         outlineRectInFlowThread, &offsetWithinPaginatedLayer);
 
     // Take our bounding box within the flow thread and clip it.
-    LayoutRect layerBoundingBoxInFlowThread = layerBoundingBox ? *layerBoundingBox : physicalBoundingBox(enclosingPaginationLayer(), &offsetWithinPaginatedLayer);
+    LayoutRect layerBoundingBoxInFlowThread = layerBoundingBox ? *layerBoundingBox : physicalBoundingBox(nullptr, &offsetWithinPaginatedLayer);
     layerBoundingBoxInFlowThread.intersect(backgroundRectInFlowThread.rect());
 
     // Make the dirty rect relative to the fragmentation context (multicol container, etc.).
@@ -2014,6 +2088,7 @@ bool DeprecatedPaintLayer::hasBlockSelectionGapBounds() const
 
 bool DeprecatedPaintLayer::intersectsDamageRect(const LayoutRect& layerBounds, const LayoutRect& damageRect, const DeprecatedPaintLayer* rootLayer, const LayoutPoint* offsetFromRoot) const
 {
+    ASSERT(!(rootLayer && offsetFromRoot));
     // Always examine the canvas and the root.
     // FIXME: Could eliminate the isDocumentElement() check if we fix background painting so that the LayoutView
     // paints the root's background.
@@ -2082,6 +2157,7 @@ static inline LayoutRect flippedLogicalBoundingBox(LayoutRect boundingBox, Layou
 
 LayoutRect DeprecatedPaintLayer::physicalBoundingBox(const DeprecatedPaintLayer* ancestorLayer, const LayoutPoint* offsetFromRoot) const
 {
+    ASSERT(!(ancestorLayer && offsetFromRoot));
     LayoutRect result = flippedLogicalBoundingBox(logicalBoundingBox(), layoutObject());
     if (offsetFromRoot)
         result.moveBy(*offsetFromRoot);
@@ -2129,10 +2205,10 @@ static void expandRectForReflectionAndStackingChildren(const DeprecatedPaintLaye
     }
 }
 
-LayoutRect DeprecatedPaintLayer::physicalBoundingBoxIncludingReflectionAndStackingChildren(const DeprecatedPaintLayer* ancestorLayer, const LayoutPoint& offsetFromRoot) const
+LayoutRect DeprecatedPaintLayer::physicalBoundingBoxIncludingReflectionAndStackingChildren(const LayoutPoint& offsetFromRoot) const
 {
     LayoutPoint origin;
-    LayoutRect result = physicalBoundingBox(ancestorLayer, &origin);
+    LayoutRect result = physicalBoundingBox(nullptr, &origin);
 
     const_cast<DeprecatedPaintLayer*>(this)->stackingNode()->updateLayerListsIfNeeded();
 
@@ -2167,7 +2243,7 @@ LayoutRect DeprecatedPaintLayer::boundingBoxForCompositing(const DeprecatedPaint
     LayoutRect result = clipper().localClipRect();
     if (result == LayoutRect::infiniteIntRect()) {
         LayoutPoint origin;
-        result = physicalBoundingBox(ancestorLayer, &origin);
+        result = physicalBoundingBox(nullptr, &origin);
 
         const_cast<DeprecatedPaintLayer*>(this)->stackingNode()->updateLayerListsIfNeeded();