[SPv2] Add filter support in PaintArtifactCompositor

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index 7809718197662d42c7d098da2a81de3594935373..5b68b74d74f7d9cc5d7b134999dae473b9218da3 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -26,6 +26,7 @@ PaintPropertyTreeBuilder::setupInitialContext() {
   context.current.clip = context.absolutePosition.clip =
       context.fixedPosition.clip = ClipPaintPropertyNode::root();
   context.currentEffect = EffectPaintPropertyNode::root();
+  context.inputClipOfCurrentEffect = ClipPaintPropertyNode::root();
   context.current.transform = context.absolutePosition.transform =
       context.fixedPosition.transform = TransformPaintPropertyNode::root();
   context.current.scroll = context.absolutePosition.scroll =
@@ -356,7 +357,8 @@ void PaintPropertyTreeBuilder::updateEffect(
     filter = layer->createCompositorFilterOperationsForFilter(style);
   }
 
-  const ClipPaintPropertyNode* outputClip = ClipPaintPropertyNode::root();
+  const ClipPaintPropertyNode* outputClip = context.inputClipOfCurrentEffect;
+  const ClipPaintPropertyNode* expansionHint = nullptr;
   // The CSS filter spec didn't specify how filters interact with overflow
   // clips. The implementation here mimics the old Blink/WebKit behavior for
   // backward compatibility.
@@ -382,6 +384,7 @@ void PaintPropertyTreeBuilder::updateEffect(
     // TODO(trchen): A filter may contain spatial operations such that an
     // output pixel may depend on an input pixel outside of the output clip.
     // We should generate a special clip node to represent this expansion.
+    expansionHint = outputClip;

[chrishtr, 2016/11/14 19:45:10]

Why is it called expansionHint? It's not a hint is it?

[trchen, 2016/11/23 04:47:18]

We haven't implemented one yet. The output clip is used as an approximation.

   }
 
   if (effectNodeNeeded) {
@@ -396,11 +399,11 @@ void PaintPropertyTreeBuilder::updateEffect(
   const auto* properties = object.paintProperties();
   if (properties && properties->effect()) {
     context.currentEffect = properties->effect();
-    // TODO(pdr): Once the expansion clip node is created above, it should be
-    // used here to update all current clip nodes;
-    const ClipPaintPropertyNode* expansionHint = context.current.clip;
-    context.current.clip = context.absolutePosition.clip =
-        context.fixedPosition.clip = expansionHint;
+    if (expansionHint) {
+      context.inputClipOfCurrentEffect = context.current.clip =
+          context.absolutePosition.clip = context.fixedPosition.clip =
+              expansionHint;
+    }
   }
 }