Recompute overflow after transform changes

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index 29e977f63c085cfb8145e8923a247e5e41b7918f..e7c523f599e2f1735dc5159d54780de018ca7faa 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -1797,24 +1797,16 @@ void RenderObject::handleDynamicFloatPositionChange()
 
 StyleDifference RenderObject::adjustStyleDifference(StyleDifference diff, unsigned contextSensitiveProperties) const
 {
-    // If transform changed, and the layer does not paint into its own separate backing, then we need to do a layout.
-    // FIXME: The comment above is what the code does, but it is technically not following spec. This means we will
-    // not to layout for 3d transforms, but we should be invoking a simplified relayout. Is it possible we are avoiding
-    // doing this for some performance reason at this time?
-    if (contextSensitiveProperties & ContextSensitivePropertyTransform) {
+    if (contextSensitiveProperties & ContextSensitivePropertyTransform && isSVG())
+        diff = StyleDifferenceLayout;

[esprehn, 2014/04/10 23:46:14]

Why the special case for SVG?

[trchen, 2014/04/11 22:04:55]

Because SVG is special. They do rely on layout to update transform correctly.
This behavior is the same as before. The logic was somehow obfuscated in the big
if-block we just removed.

+
+    // If transform changed, and the layer does not paint into its own separate backing, then we need to repaint.
+    if (contextSensitiveProperties & ContextSensitivePropertyTransform  && diff <= StyleDifferenceRepaintLayer) {
         // Text nodes share style with their parents but transforms don't apply to them,
         // hence the !isText() check.
-        // FIXME: when transforms are taken into account for overflow, we will need to do a layout.
-        if (!isText() && (!hasLayer() || !toRenderLayerModelObject(this)->layer()->hasDirectReasonsForCompositing())) {
-            // We need to set at least SimplifiedLayout, but if PositionedMovementOnly is already set
-            // then we actually need SimplifiedLayoutAndPositionedMovement.
-            if (!hasLayer())
-                diff = StyleDifferenceLayout; // FIXME: Do this for now since SimplifiedLayout cannot handle updating floating objects lists.
-            else if (diff < StyleDifferenceLayoutPositionedMovementOnly)
-                diff = StyleDifferenceSimplifiedLayout;
-            else if (diff < StyleDifferenceSimplifiedLayout)
-                diff = StyleDifferenceSimplifiedLayoutAndPositionedMovement;
-        } else if (diff < StyleDifferenceRecompositeLayer)
+        if (!isText() && (!hasLayer() || !toRenderLayerModelObject(this)->layer()->hasDirectReasonsForCompositing()))
+            diff = StyleDifferenceRepaintLayer;
+        else if (diff < StyleDifferenceRecompositeLayer)
             diff = StyleDifferenceRecompositeLayer;
     }
 
@@ -1892,6 +1884,18 @@ inline bool RenderObject::shouldRepaintForStyleDifference(StyleDifference diff)
     return diff == StyleDifferenceRepaint || (diff == StyleDifferenceRepaintIfTextOrColorChange && hasImmediateNonWhitespaceTextChildOrPropertiesDependentOnColor());
 }
 
+void RenderObject::markContainingBlocksForOverflowRecalc()
+{
+    for (RenderBlock* container = containingBlock(); container && !container->childNeedsOverflowRecalcAfterStyleChange(); container = container->containingBlock())
+        container->setChildNeedsOverflowRecalcAfterStyleChange(true);
+}
+
+void RenderObject::setNeedsOverflowRecalcAfterStyleChange()
+{
+    setSelfNeedsOverflowRecalcAfterStyleChange(true);
+    markContainingBlocksForOverflowRecalc();
+}
+
 void RenderObject::setStyle(PassRefPtr<RenderStyle> style)
 {
     if (m_style == style) {
@@ -1941,11 +1945,13 @@ void RenderObject::setStyle(PassRefPtr<RenderStyle> style)
             setNeedsLayoutAndPrefWidthsRecalc();
         else if (updatedDiff == StyleDifferenceLayoutPositionedMovementOnly)
             setNeedsPositionedMovementLayout();
-        else if (updatedDiff == StyleDifferenceSimplifiedLayoutAndPositionedMovement) {
-            setNeedsPositionedMovementLayout();
-            setNeedsSimplifiedNormalFlowLayout();
-        } else if (updatedDiff == StyleDifferenceSimplifiedLayout)
-            setNeedsSimplifiedNormalFlowLayout();
+    }
+
+    if (contextSensitiveProperties & ContextSensitivePropertyTransform && !needsLayout()) {
+        if (RenderBlock* container = containingBlock())
+            container->setNeedsOverflowRecalcAfterStyleChange();
+        if (isBox())
+            toRenderBox(this)->updateLayerTransform();
     }
 
     if (updatedDiff == StyleDifferenceRepaintLayer || shouldRepaintForStyleDifference(updatedDiff)) {
@@ -2080,7 +2086,7 @@ void RenderObject::styleDidChange(StyleDifference diff, const RenderStyle* oldSt
     if (!m_parent)
         return;
 
-    if (diff == StyleDifferenceLayout || diff == StyleDifferenceSimplifiedLayout) {
+    if (diff == StyleDifferenceLayout) {
         RenderCounter::rendererStyleChanged(*this, oldStyle, m_style.get());
 
         // If the object already needs layout, then setNeedsLayout won't do
@@ -2091,13 +2097,14 @@ void RenderObject::styleDidChange(StyleDifference diff, const RenderStyle* oldSt
         if (needsLayout() && oldStyle->position() != m_style->position())
             markContainingBlocksForLayout();
 
+        // Ditto.
+        if (needsOverflowRecalcAfterStyleChange() && oldStyle->position() != m_style->position()) {
+            if (RenderBlock* container = containingBlock())
+                container->markContainingBlocksForOverflowRecalc();

[esprehn, 2014/04/10 23:46:14]

This doesn't look right, you want to call
markContainingBlocksForOverflowRecalc() on yourself like we do above, not go up
one level from there.

[trchen, 2014/04/11 22:04:55]

Done.

+        }
+
         if (diff == StyleDifferenceLayout)
             setNeedsLayoutAndPrefWidthsRecalc();
-        else
-            setNeedsSimplifiedNormalFlowLayout();
-    } else if (diff == StyleDifferenceSimplifiedLayoutAndPositionedMovement) {
-        setNeedsPositionedMovementLayout();
-        setNeedsSimplifiedNormalFlowLayout();
     } else if (diff == StyleDifferenceLayoutPositionedMovementOnly)
         setNeedsPositionedMovementLayout();