Bug 1125422 - Read the force-dispatch-to-content flag from the layer tree and use it in the APZ code. r=botond

gfx/layers/LayerMetricsWrapper.h

@@ -338,6 +338,15 @@ public:
     return mLayer->GetClipRect();
   }
 
+  bool GetForceDispatchToContentRegion() const {
+    MOZ_ASSERT(IsValid());
+
+    if (mLayer->AsContainerLayer()) {
+      return mLayer->AsContainerLayer()->GetForceDispatchToContentRegion();
+    }
+    return false;
+  }
+
   // Expose an opaque pointer to the layer. Mostly used for printf
   // purposes. This is not intended to be a general-purpose accessor
   // for the underlying layer.

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -320,6 +320,20 @@ APZCTreeManager::RecycleOrCreateNode(TreeBuildingState& aState,
   return node.forget();
 }
 
+static bool
+ShouldForceDispatchToContent(HitTestingTreeNode* aParent,
+                             const LayerMetricsWrapper& aLayer)
+{
+  // Make it so that if the flag is set on the layer tree, it automatically
+  // propagates to all the nodes in the corresponding subtree rooted at that
+  // layer in the hit-test tree. This saves having to walk up the tree every
+  // we want to see if a hit-test node is affected by this flag.
+  if (aParent && aParent->GetForceDispatchToContent()) {
+    return true;
+  }
+  return aLayer.GetForceDispatchToContentRegion();
+}
+
 HitTestingTreeNode*
 APZCTreeManager::PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
                                      const FrameMetrics& aMetrics,
@@ -344,7 +358,8 @@ APZCTreeManager::PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
     node = RecycleOrCreateNode(aState, nullptr);
     AttachNodeToTree(node, aParent, aNextSibling);
     node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(),
-        aLayer.GetClipRect() ? Some(nsIntRegion(*aLayer.GetClipRect())) : Nothing());
+        aLayer.GetClipRect() ? Some(nsIntRegion(*aLayer.GetClipRect())) : Nothing(),
+        ShouldForceDispatchToContent(aParent, aLayer));
     return node;
   }
 
@@ -440,7 +455,8 @@ APZCTreeManager::PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
     MOZ_ASSERT(node->IsPrimaryHolder() && node->GetApzc() && node->GetApzc()->Matches(guid));
 
     nsIntRegion clipRegion = ComputeClipRegion(state->mController, aLayer);
-    node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(), Some(clipRegion));
+    node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(), Some(clipRegion),
+        ShouldForceDispatchToContent(aParent, aLayer));
     apzc->SetAncestorTransform(aAncestorTransform);
 
     PrintAPZCInfo(aLayer, apzc);
@@ -494,7 +510,8 @@ APZCTreeManager::PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
     MOZ_ASSERT(aAncestorTransform == apzc->GetAncestorTransform());
 
     nsIntRegion clipRegion = ComputeClipRegion(state->mController, aLayer);
-    node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(), Some(clipRegion));
+    node->SetHitTestData(GetEventRegions(aLayer), aLayer.GetTransform(), Some(clipRegion),
+        ShouldForceDispatchToContent(aParent, aLayer));
   }
 
   return node;

gfx/layers/apz/src/HitTestingTreeNode.cpp

@@ -21,6 +21,7 @@ HitTestingTreeNode::HitTestingTreeNode(AsyncPanZoomController* aApzc,
                                        bool aIsPrimaryHolder)
   : mApzc(aApzc)
   , mIsPrimaryApzcHolder(aIsPrimaryHolder)
+  , mForceDispatchToContent(false)
 {
   if (mIsPrimaryApzcHolder) {
     MOZ_ASSERT(mApzc);
@@ -155,11 +156,13 @@ HitTestingTreeNode::IsPrimaryHolder() const
 void
 HitTestingTreeNode::SetHitTestData(const EventRegions& aRegions,
                                    const gfx::Matrix4x4& aTransform,
-                                   const Maybe<nsIntRegion>& aClipRegion)
+                                   const Maybe<nsIntRegion>& aClipRegion,
+                                   bool aForceDispatchToContent)
 {
   mEventRegions = aRegions;
   mTransform = aTransform;
   mClipRegion = aClipRegion;
+  mForceDispatchToContent = aForceDispatchToContent;
 }
 
 bool
@@ -210,20 +213,29 @@ HitTestingTreeNode::HitTest(const ParentLayerPoint& aPoint) const
   if (!mEventRegions.mHitRegion.Contains(point.x, point.y)) {
     return HitTestResult::HitNothing;
   }
-  if (mEventRegions.mDispatchToContentHitRegion.Contains(point.x, point.y)) {
+  if (mForceDispatchToContent ||
+      mEventRegions.mDispatchToContentHitRegion.Contains(point.x, point.y))
+  {
     return HitTestResult::HitDispatchToContentRegion;
   }
   return HitTestResult::HitLayer;
 }
 
+bool
+HitTestingTreeNode::GetForceDispatchToContent() const
+{
+  return mForceDispatchToContent;
+}
+
 void
 HitTestingTreeNode::Dump(const char* aPrefix) const
 {
   if (mPrevSibling) {
     mPrevSibling->Dump(aPrefix);
   }
-  printf_stderr("%sHitTestingTreeNode (%p) APZC (%p) g=(%s) r=(%s) t=(%s) c=(%s)\n",
+  printf_stderr("%sHitTestingTreeNode (%p) APZC (%p) g=(%s) %sr=(%s) t=(%s) c=(%s)\n",
     aPrefix, this, mApzc.get(), mApzc ? Stringify(mApzc->GetGuid()).c_str() : "",
+    mForceDispatchToContent ? "fdtc " : "",
     Stringify(mEventRegions).c_str(), Stringify(mTransform).c_str(),
     mClipRegion ? Stringify(mClipRegion.ref()).c_str() : "none");
   if (mLastChild) {

gfx/layers/apz/src/HitTestingTreeNode.h

@@ -81,7 +81,8 @@ public:
 
   void SetHitTestData(const EventRegions& aRegions,
                       const gfx::Matrix4x4& aTransform,
-                      const Maybe<nsIntRegion>& aClipRegion);
+                      const Maybe<nsIntRegion>& aClipRegion,
+                      bool aForceDispatchToContent);
   bool IsOutsideClip(const ParentLayerPoint& aPoint) const;
   /* Convert aPoint into the LayerPixel space for the layer corresponding to
    * this node. */
@@ -89,6 +90,8 @@ public:
   /* Assuming aPoint is inside the clip region for this node, check which of the
    * event region spaces it falls inside. */
   HitTestResult HitTest(const ParentLayerPoint& aPoint) const;
+  /* Returns the mForceDispatchToContent flag. */
+  bool GetForceDispatchToContent() const;
 
   /* Debug helpers */
   void Dump(const char* aPrefix = "") const;
@@ -122,6 +125,11 @@ private:
    * because we may use the composition bounds of the layer if the clip is not
    * present. This value is in L's ParentLayerPixels. */
   Maybe<nsIntRegion> mClipRegion;
+
+  /* If this flag is set, then events to this node and the entire subtree under
+   * should always be treated as dispatch-to-content.
+   */
+  bool mForceDispatchToContent;
 };
 
 }