Make compositingState explicit

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index e6c157de1bd0c9325ca1d0d1520cf63d82f9c532..e52ca654748c87be0d38470fe0f1df81ab8434ba 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -217,11 +217,10 @@ bool RenderLayer::canRender3DTransforms() const
 
 bool RenderLayer::paintsWithFilters() const
 {
-    // FIXME: Eventually there will be more factors than isComposited() to decide whether or not to render the filter
     if (!renderer()->hasFilter())
         return false;
 
-    if (!isComposited())
+    if (compositingState() != PaintsIntoOwnBacking)
         return true;
 
     if (!m_backing || !m_backing->canCompositeFilters())
@@ -308,7 +307,7 @@ void RenderLayer::updateLayerPositions(RenderGeometryMap* geometryMap, UpdateLay
 
     // Clear the IsCompositingUpdateRoot flag once we've found the first compositing layer in this update.
     bool isUpdateRoot = (flags & IsCompositingUpdateRoot);
-    if (isComposited())
+    if (backing())
         flags &= ~IsCompositingUpdateRoot;
 
     if (useRegionBasedColumns() && renderer()->isInFlowRenderFlowThread()) {
@@ -322,7 +321,7 @@ void RenderLayer::updateLayerPositions(RenderGeometryMap* geometryMap, UpdateLay
     for (RenderLayer* child = firstChild(); child; child = child->nextSibling())
         child->updateLayerPositions(geometryMap, flags);
 
-    if ((flags & UpdateCompositingLayers) && isComposited()) {
+    if ((flags & UpdateCompositingLayers) && backing()) {
         RenderLayerBacking::UpdateAfterLayoutFlags updateFlags = RenderLayerBacking::CompositingChildrenOnly;
         if (flags & NeedsFullRepaintInBacking)
             updateFlags |= RenderLayerBacking::NeedsFullRepaint;
@@ -835,7 +834,7 @@ void RenderLayer::updatePagination()
     m_isPaginated = false;
     m_enclosingPaginationLayer = 0;
 
-    if (isComposited() || !parent())
+    if (backing() || !parent())
         return; // FIXME: We will have to deal with paginated compositing layers someday.
                 // FIXME: For now the RenderView can't be paginated.  Eventually printing will move to a model where it is though.
 
@@ -1145,7 +1144,7 @@ bool RenderLayer::updateLayerPosition()
             localPoint += offset;
         }
     } else if (parent()) {
-        if (isComposited()) {
+        if (backing()) {
             // FIXME: Composited layers ignore pagination, so about the best we can do is make sure they're offset into the appropriate column.
             // They won't split across columns properly.
             LayoutSize columnOffset;
@@ -1277,13 +1276,16 @@ static inline const RenderLayer* compositingContainer(const RenderLayer* layer)
     return layer->isNormalFlowOnly() ? layer->parent() : layer->ancestorStackingContainer();
 }
 
+// FIXME: having two different functions named enclosingCompositingLayer and enclosingCompositingLayerForRepaint
+//        is error-prone and misleading for reading code that uses these functions - especially compounded with
+//        the includeSelf option.

[Julien - ping for review, 2013/10/03 20:08:36]

Nit: We usually don't align FIXMEs in Blink.

[shawnsingh, 2013/10/07 11:45:04]

Done

 RenderLayer* RenderLayer::enclosingCompositingLayer(bool includeSelf) const
 {
-    if (includeSelf && isComposited())
+    if (includeSelf && backing())
         return const_cast<RenderLayer*>(this);
 
     for (const RenderLayer* curr = compositingContainer(this); curr; curr = compositingContainer(curr)) {
-        if (curr->isComposited())
+        if (curr->backing())
             return const_cast<RenderLayer*>(curr);
     }
 
@@ -1292,11 +1294,11 @@ RenderLayer* RenderLayer::enclosingCompositingLayer(bool includeSelf) const
 
 RenderLayer* RenderLayer::enclosingCompositingLayerForRepaint(bool includeSelf) const
 {
-    if (includeSelf && isComposited() && !backing()->paintsIntoCompositedAncestor())
+    if (includeSelf && compositingState() == PaintsIntoOwnBacking)
         return const_cast<RenderLayer*>(this);
 
     for (const RenderLayer* curr = compositingContainer(this); curr; curr = compositingContainer(curr)) {
-        if (curr->isComposited() && !curr->backing()->paintsIntoCompositedAncestor())
+        if (curr->compositingState() == PaintsIntoOwnBacking)
             return const_cast<RenderLayer*>(curr);
     }
 
@@ -1334,7 +1336,7 @@ RenderLayer* RenderLayer::enclosingFilterLayer(bool includeSelf) const
 RenderLayer* RenderLayer::enclosingFilterRepaintLayer() const
 {
     for (const RenderLayer* curr = this; curr; curr = curr->parent()) {
-        if ((curr != this && curr->requiresFullLayerImageForFilters()) || curr->isComposited() || curr->isRootLayer())
+        if ((curr != this && curr->requiresFullLayerImageForFilters()) || curr->compositingState() == PaintsIntoOwnBacking || curr->isRootLayer())
             return const_cast<RenderLayer*>(curr);
     }
     return 0;
@@ -1365,7 +1367,7 @@ void RenderLayer::setFilterBackendNeedsRepaintingInRect(const LayoutRect& rect)
     FloatQuad repaintQuad(rectForRepaint);
     LayoutRect parentLayerRect = renderer()->localToContainerQuad(repaintQuad, parentLayer->renderer()).enclosingBoundingBox();
 
-    if (parentLayer->isComposited()) {
+    if (parentLayer->backing()) {
         parentLayer->setBackingNeedsRepaintInRect(parentLayerRect);
         return;
     }
@@ -1396,7 +1398,7 @@ bool RenderLayer::hasAncestorWithFilterOutsets() const
 
 RenderLayer* RenderLayer::clippingRootForPainting() const
 {
-    if (isComposited())
+    if (backing())
         return const_cast<RenderLayer*>(this);
 
     const RenderLayer* current = this;
@@ -1407,7 +1409,7 @@ RenderLayer* RenderLayer::clippingRootForPainting() const
         current = compositingContainer(current);
         ASSERT(current);
         if (current->transform()
-            || (current->isComposited() && !current->backing()->paintsIntoCompositedAncestor())
+            || (current->backing() && !current->backing()->paintsIntoCompositedAncestor())
         )
             return const_cast<RenderLayer*>(current);
     }
@@ -1442,11 +1444,11 @@ bool RenderLayer::isTransparent() const
 
 RenderLayer* RenderLayer::transparentPaintingAncestor()
 {
-    if (isComposited())
+    if (backing())

[Julien - ping for review, 2013/10/03 20:08:36]

This gets called from RenderLayer::beginTransparencyLayers, which filters
through paintsWithTransparency (ie !PaintsIntoOwnBacking) so wouldn't the only
condition where this triggers is HasOwnBackingButPaintsIntoAncestor? In this
case, it's probably better to state it explicitly (but I don't feel too strongly
about this).

[shawnsingh, 2013/10/07 11:45:04]

This is a confusing one, and for the sake of moving forward I would like to
defer it to a follow-up patch... is that OK with you?

         return 0;
 
     for (RenderLayer* curr = parent(); curr; curr = curr->parent()) {
-        if (curr->isComposited())
+        if (curr->backing())
             return 0;
         if (curr->isTransparent())
             return curr;
@@ -1885,7 +1887,7 @@ bool RenderLayer::usesCompositedScrolling() const
     if (box && (box->isIntristicallyScrollable(VerticalScrollbar) || box->isIntristicallyScrollable(HorizontalScrollbar)))
         return false;
 
-    return isComposited() && backing()->scrollingLayer();
+    return backing() && backing()->scrollingLayer();
 }
 
 bool RenderLayer::needsCompositedScrolling() const
@@ -2514,7 +2516,7 @@ static bool paintForFixedRootBackground(const RenderLayer* layer, RenderLayer::P
 
 void RenderLayer::paintLayer(GraphicsContext* context, const LayerPaintingInfo& paintingInfo, PaintLayerFlags paintFlags)
 {
-    if (isComposited()) {
+    if (backing()) {
         // The updatingControlTints() painting pass goes through compositing layers,
         // but we need to ensure that we don't cache clip rects computed with the wrong root in this case.
         if (context->updatingControlTints() || (paintingInfo.paintBehavior & PaintBehaviorFlattenCompositingLayers)) {
@@ -4312,7 +4314,7 @@ IntRect RenderLayer::calculateLayerBounds(const RenderLayer* ancestorLayer, cons
     const_cast<RenderLayer*>(this)->updateLayerListsIfNeeded();
 
     if (RenderLayer* reflection = reflectionLayer()) {
-        if (!reflection->isComposited()) {
+        if (!reflection->backing()) {
             IntRect childUnionBounds = reflection->calculateLayerBounds(this, 0, descendantFlags);
             unionBounds.unite(childUnionBounds);
         }
@@ -4328,7 +4330,7 @@ IntRect RenderLayer::calculateLayerBounds(const RenderLayer* ancestorLayer, cons
         size_t listSize = negZOrderList->size();
         for (size_t i = 0; i < listSize; ++i) {
             RenderLayer* curLayer = negZOrderList->at(i);
-            if (flags & IncludeCompositedDescendants || !curLayer->isComposited()) {
+            if (flags & IncludeCompositedDescendants || !curLayer->backing()) {
                 IntRect childUnionBounds = curLayer->calculateLayerBounds(this, 0, descendantFlags);
                 unionBounds.unite(childUnionBounds);
             }
@@ -4339,7 +4341,7 @@ IntRect RenderLayer::calculateLayerBounds(const RenderLayer* ancestorLayer, cons
         size_t listSize = posZOrderList->size();
         for (size_t i = 0; i < listSize; ++i) {
             RenderLayer* curLayer = posZOrderList->at(i);
-            if (flags & IncludeCompositedDescendants || !curLayer->isComposited()) {
+            if (flags & IncludeCompositedDescendants || !curLayer->backing()) {
                 IntRect childUnionBounds = curLayer->calculateLayerBounds(this, 0, descendantFlags);
                 unionBounds.unite(childUnionBounds);
             }
@@ -4350,7 +4352,7 @@ IntRect RenderLayer::calculateLayerBounds(const RenderLayer* ancestorLayer, cons
         size_t listSize = normalFlowList->size();
         for (size_t i = 0; i < listSize; ++i) {
             RenderLayer* curLayer = normalFlowList->at(i);
-            if (flags & IncludeCompositedDescendants || !curLayer->isComposited()) {
+            if (flags & IncludeCompositedDescendants || !curLayer->backing()) {
                 IntRect curAbsBounds = curLayer->calculateLayerBounds(this, 0, descendantFlags);
                 unionBounds.unite(curAbsBounds);
             }
@@ -4403,6 +4405,21 @@ void RenderLayer::clearClipRects(ClipRectsType typeToClear)
     }
 }
 
+CompositingState RenderLayer::compositingState() const
+{
+    // This is computed procedurally so there is no redundant state variable that
+    // can get out of sync from the real actual compositing state.
+
+    if (!m_backing)
+        return NotComposited;
+
+    if (m_backing && backing()->paintsIntoCompositedAncestor())
+        return HasOwnBackingButPaintsIntoAncestor;
+
+    ASSERT(m_backing);
+    return PaintsIntoOwnBacking;
+}

[Julien - ping for review, 2013/10/03 20:08:36]

The PaintsIntoGroupBacking state is never reached so could we postpone adding
it?

[shawnsingh, 2013/10/07 11:45:04]

OK, removed for now.

+
 RenderLayerBacking* RenderLayer::ensureBacking()
 {
     if (!m_backing) {
@@ -4464,7 +4481,7 @@ GraphicsLayer* RenderLayer::layerForScrollCorner() const
 
 bool RenderLayer::paintsWithTransform(PaintBehavior paintBehavior) const
 {
-    return transform() && ((paintBehavior & PaintBehaviorFlattenCompositingLayers) || !isComposited());
+    return transform() && ((paintBehavior & PaintBehaviorFlattenCompositingLayers) || compositingState() != PaintsIntoOwnBacking);
 }
 
 bool RenderLayer::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const
@@ -4515,7 +4532,7 @@ bool RenderLayer::listBackgroundIsKnownToBeOpaqueInRect(const Vector<RenderLayer
 
     for (Vector<RenderLayer*>::const_reverse_iterator iter = list->rbegin(); iter != list->rend(); ++iter) {
         const RenderLayer* childLayer = *iter;
-        if (childLayer->isComposited())
+        if (childLayer->backing())
             continue;
 
         if (!childLayer->canUseConvertToLayerCoords())
@@ -4772,7 +4789,7 @@ void RenderLayer::repaintIncludingDescendants()
 
 void RenderLayer::setBackingNeedsRepaint()
 {
-    ASSERT(isComposited());
+    ASSERT(backing());
     backing()->setContentsNeedDisplay();
 }
 
@@ -4780,8 +4797,8 @@ void RenderLayer::setBackingNeedsRepaintInRect(const LayoutRect& r)
 {
     // https://bugs.webkit.org/show_bug.cgi?id=61159 describes an unreproducible crash here,
     // so assert but check that the layer is composited.
-    ASSERT(isComposited());
-    if (!isComposited()) {
+    ASSERT(backing());
+    if (!backing()) {
         // If we're trying to repaint the placeholder document layer, propagate the
         // repaint to the native view system.
         LayoutRect absRect(r);
@@ -4997,7 +5014,7 @@ inline bool RenderLayer::needsCompositingLayersRebuiltForClip(const RenderStyle*
 inline bool RenderLayer::needsCompositingLayersRebuiltForOverflow(const RenderStyle* oldStyle, const RenderStyle* newStyle) const
 {
     ASSERT(newStyle);
-    return !isComposited() && oldStyle && (oldStyle->overflowX() != newStyle->overflowX()) && ancestorStackingContainer()->hasCompositingDescendant();
+    return !backing() && oldStyle && (oldStyle->overflowX() != newStyle->overflowX()) && ancestorStackingContainer()->hasCompositingDescendant();
 }
 
 inline bool RenderLayer::needsCompositingLayersRebuiltForFilters(const RenderStyle* oldStyle, const RenderStyle* newStyle, bool didPaintWithFilters) const
@@ -5041,7 +5058,7 @@ void RenderLayer::updateFilters(const RenderStyle* oldStyle, const RenderStyle*
     updateOrRemoveFilterClients();
     // During an accelerated animation, both WebKit and the compositor animate properties.
     // However, WebKit shouldn't ask the compositor to update its filters if the compositor is performing the animation.
-    bool shouldUpdateFilters = isComposited() && !renderer()->animation()->isRunningAcceleratedAnimationOnRenderer(renderer(), CSSPropertyWebkitFilter);
+    bool shouldUpdateFilters = backing() && !renderer()->animation()->isRunningAcceleratedAnimationOnRenderer(renderer(), CSSPropertyWebkitFilter);
     if (shouldUpdateFilters)
         backing()->updateFilters(renderer()->style());
     updateOrRemoveFilterEffectRenderer();
@@ -5087,7 +5104,7 @@ void RenderLayer::styleChanged(StyleDifference, const RenderStyle* oldStyle)
         || needsCompositingLayersRebuiltForOverflow(oldStyle, newStyle)
         || needsCompositingLayersRebuiltForFilters(oldStyle, newStyle, didPaintWithFilters))
         compositor()->setCompositingLayersNeedRebuild();
-    else if (isComposited())
+    else if (backing())
         backing()->updateGraphicsLayerGeometry();
 }