cc: Make visible rect computation aware of pixel-moving filters

cc/trees/draw_property_utils.cc

Index: cc/trees/draw_property_utils.cc
diff --git a/cc/trees/draw_property_utils.cc b/cc/trees/draw_property_utils.cc
index 7a216f0e10445e920cfc9068653f7ef00efe7439..84b3e8f4bece627682b93d9fb8ac024bb609e746 100644
--- a/cc/trees/draw_property_utils.cc
+++ b/cc/trees/draw_property_utils.cc
@@ -137,6 +137,29 @@ static ConditionalClip ComputeTargetRectInLocalSpace(
                          MathUtil::ProjectClippedRect(target_to_local, rect)};
 }
 
+static ConditionalClip ConvertRectBetweenSurfaceSpaces(
+    gfx::RectF rect,
+    const PropertyTrees* property_trees,
+    int source_transform_id,
+    int source_effect_id,
+    int dest_transform_id,
+    int dest_effect_id) {
+  gfx::Transform source_to_dest;
+  bool success = property_trees->GetToTarget(source_transform_id,
+                                             dest_effect_id, &source_to_dest);
+  if (!success)
+    return ConditionalClip{false, gfx::RectF()};
+  const EffectTree& effect_tree = property_trees->effect_tree;
+  const EffectNode* source_effect_node = effect_tree.Node(source_effect_id);
+  ConcatInverseSurfaceContentsScale(source_effect_node, &source_to_dest);
+  if (source_transform_id > dest_transform_id) {
+    return ConditionalClip{true,  // is_clipped
+                           MathUtil::MapClippedRect(source_to_dest, rect)};
+  }
+  return ConditionalClip{true,  // is_clipped
+                         MathUtil::ProjectClippedRect(source_to_dest, rect)};
+}
+
 static ConditionalClip ComputeLocalRectInTargetSpace(
     gfx::RectF rect,
     const PropertyTrees* property_trees,
@@ -178,9 +201,71 @@ static ConditionalClip ComputeCurrentClip(const ClipNode* clip_node,
   return ConditionalClip{true /* is_clipped */, current_clip};
 }
 
+static bool ApplyClipNodeToAccumulatedClip(const PropertyTrees* property_trees,
+                                           bool include_expanding_clips,
+                                           int target_id,
+                                           int target_transform_id,
+                                           const ClipNode* clip_node,
+                                           gfx::RectF* accumulated_clip) {
+  switch (clip_node->clip_type) {
+    case ClipNode::ClipType::APPLIES_LOCAL_CLIP: {
+      ConditionalClip current_clip = ComputeCurrentClip(
+          clip_node, property_trees, target_transform_id, target_id);
+
+      // If transform is not invertible, no clip will be applied.
+      if (!current_clip.is_clipped)
+        return false;
+
+      *accumulated_clip =
+          gfx::IntersectRects(*accumulated_clip, current_clip.clip_rect);
+      return true;
+    }
+    case ClipNode::ClipType::EXPANDS_CLIP: {
+      if (!include_expanding_clips)
+        return true;
+
+      // Bring the accumulated clip to the space of the expanding effect.
+      const EffectNode* expanding_effect_node =
+          property_trees->effect_tree.Node(
+              clip_node->clip_expander->target_effect_id());
+      ConditionalClip accumulated_clip_in_expanding_space =
+          ConvertRectBetweenSurfaceSpaces(
+              *accumulated_clip, property_trees, target_transform_id, target_id,
+              expanding_effect_node->transform_id, expanding_effect_node->id);
+      // If transform is not invertible, no clip will be applied.
+      if (!accumulated_clip_in_expanding_space.is_clipped)
+        return false;
+
+      // Do the expansion.
+      gfx::RectF expanded_clip_in_expanding_space =
+          gfx::RectF(clip_node->clip_expander->MapRectReverse(
+              gfx::ToEnclosingRect(
+                  accumulated_clip_in_expanding_space.clip_rect),
+              property_trees));
+
+      // Put the expanded clip back into the original target space.
+      ConditionalClip expanded_clip_in_target_space =
+          ConvertRectBetweenSurfaceSpaces(
+              expanded_clip_in_expanding_space, property_trees,
+              expanding_effect_node->transform_id, expanding_effect_node->id,
+              target_transform_id, target_id);
+      // If transform is not invertible, no clip will be applied.
+      if (!expanded_clip_in_target_space.is_clipped)
+        return false;
+      *accumulated_clip = expanded_clip_in_target_space.clip_rect;
+      return true;
+    }
+    case ClipNode::ClipType::NONE:
+      return true;
+  }
+  NOTREACHED();
+  return true;
+}
+
 static ConditionalClip ComputeAccumulatedClip(
     const PropertyTrees* property_trees,
     bool include_viewport_clip,
+    bool include_expanding_clips,
     int local_clip_id,
     int target_id) {
   DCHECK(!include_viewport_clip ||
@@ -191,7 +276,6 @@ static ConditionalClip ComputeAccumulatedClip(
   const ClipNode* clip_node = clip_tree.Node(local_clip_id);
   const EffectNode* target_node = effect_tree.Node(target_id);
   int target_transform_id = target_node->transform_id;
-  bool is_clipped = false;
 
   // Collect all the clips that need to be accumulated.
   std::stack<const ClipNode*> parent_chain;
@@ -220,43 +304,42 @@ static ConditionalClip ComputeAccumulatedClip(
     parent_chain.pop();
   }
 
-  // TODO(weiliangc): If we don't create clip for render surface, we don't need
-  // to check applies_local_clip.
+  // Find the first clip in the chain that we need to apply.
   while (clip_node->clip_type != ClipNode::ClipType::APPLIES_LOCAL_CLIP &&
          parent_chain.size() > 0) {
     clip_node = parent_chain.top();
     parent_chain.pop();
   }
 
-  if (clip_node->clip_type != ClipNode::ClipType::APPLIES_LOCAL_CLIP)
+  if (clip_node->clip_type != ClipNode::ClipType::APPLIES_LOCAL_CLIP) {
     // No clip node applying clip in between.
     return ConditionalClip{false, gfx::RectF()};
+  }
 
   ConditionalClip current_clip = ComputeCurrentClip(
       clip_node, property_trees, target_transform_id, target_id);
-  is_clipped = current_clip.is_clipped;
+
+  // If transform is not invertible, no clip will be applied.
+  if (!current_clip.is_clipped)
+    return ConditionalClip{false, gfx::RectF()};
   gfx::RectF accumulated_clip = current_clip.clip_rect;
 
   while (parent_chain.size() > 0) {
     clip_node = parent_chain.top();
     parent_chain.pop();
-    if (clip_node->clip_type != ClipNode::ClipType::APPLIES_LOCAL_CLIP) {
-      continue;
-    }
-    ConditionalClip current_clip = ComputeCurrentClip(
-        clip_node, property_trees, target_transform_id, target_id);
-
-    // If transform is not invertible, no clip will be applied.
-    if (!current_clip.is_clipped)
-      return ConditionalClip{false, gfx::RectF()};
-
-    is_clipped = true;
-    accumulated_clip =
-        gfx::IntersectRects(accumulated_clip, current_clip.clip_rect);
+    bool success = ApplyClipNodeToAccumulatedClip(
+        property_trees, include_expanding_clips, target_id, target_transform_id,
+        clip_node, &accumulated_clip);
+
+    // Failure to apply the clip means we encountered an uninvertible transform,
+    // so no clip will be applied.
+    if (!success)
+      return ConditionalClip{false /* is_clipped */, gfx::RectF()};
   }
 
-  return ConditionalClip{
-      is_clipped, accumulated_clip.IsEmpty() ? gfx::RectF() : accumulated_clip};
+  return ConditionalClip{true /* is_clipped */, accumulated_clip.IsEmpty()
+                                                    ? gfx::RectF()
+                                                    : accumulated_clip};
 }
 
 static gfx::RectF ComputeAccumulatedClipInRootSpaceForVisibleRect(
@@ -264,8 +347,10 @@ static gfx::RectF ComputeAccumulatedClipInRootSpaceForVisibleRect(
     int local_clip_id) {
   const int root_effect_id = EffectTree::kContentsRootNodeId;
   bool include_viewport_clip = true;
+  bool include_expanding_clips = true;
   ConditionalClip accumulated_clip = ComputeAccumulatedClip(
-      property_trees, include_viewport_clip, local_clip_id, root_effect_id);
+      property_trees, include_viewport_clip, include_expanding_clips,
+      local_clip_id, root_effect_id);
   DCHECK(accumulated_clip.is_clipped);
   return accumulated_clip.clip_rect;
 }
@@ -338,9 +423,10 @@ void CalculateVisibleRects(const LayerImplList& visible_layer_list,
     if (effect_ancestor_with_copy_request > 1) {
       // Non root copy request.
       bool include_viewport_clip = false;
+      bool include_expanding_clips = true;
       ConditionalClip accumulated_clip_rect = ComputeAccumulatedClip(
-          property_trees, include_viewport_clip, layer->clip_tree_index(),
-          effect_ancestor_with_copy_request);
+          property_trees, include_viewport_clip, include_expanding_clips,
+          layer->clip_tree_index(), effect_ancestor_with_copy_request);
       if (!accumulated_clip_rect.is_clipped) {
         layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
         continue;
@@ -792,6 +878,12 @@ void ComputeClips(PropertyTrees* property_trees,
         continue;
       parent_combined_clip_in_target_space = MathUtil::ProjectClippedRect(
           parent_to_current, parent_clip_node->combined_clip_in_target_space);
+      if (clip_node->clip_type == ClipNode::ClipType::EXPANDS_CLIP) {
+        parent_combined_clip_in_target_space =
+            gfx::RectF(clip_node->clip_expander->MapRectReverse(
+                gfx::ToEnclosingRect(parent_combined_clip_in_target_space),
+                property_trees));
+      }
       parent_clip_in_target_space = MathUtil::ProjectClippedRect(
           parent_to_current, parent_clip_node->clip_in_target_space);
     }
@@ -930,9 +1022,10 @@ static void ComputeClipsWithEffectTree(PropertyTrees* property_trees) {
     EffectNode* effect_node = effect_tree->Node(i);
     const EffectNode* target_node = effect_tree->Node(effect_node->target_id);
     bool include_viewport_clip = false;
-    ConditionalClip accumulated_clip_rect =
-        ComputeAccumulatedClip(property_trees, include_viewport_clip,
-                               effect_node->clip_id, target_node->id);
+    bool include_expanding_clips = false;
+    ConditionalClip accumulated_clip_rect = ComputeAccumulatedClip(
+        property_trees, include_viewport_clip, include_expanding_clips,
+        effect_node->clip_id, target_node->id);
     gfx::RectF accumulated_clip = accumulated_clip_rect.clip_rect;
     const RenderSurfaceImpl* render_surface = effect_node->render_surface;
     if (render_surface && render_surface->is_clipped()) {
@@ -963,9 +1056,10 @@ static void ComputeLayerClipRect(const PropertyTrees* property_trees,
   }
 
   bool include_viewport_clip = false;
-  ConditionalClip accumulated_clip_rect =
-      ComputeAccumulatedClip(property_trees, include_viewport_clip,
-                             layer->clip_tree_index(), target_node->id);
+  bool include_expanding_clips = false;
+  ConditionalClip accumulated_clip_rect = ComputeAccumulatedClip(
+      property_trees, include_viewport_clip, include_expanding_clips,
+      layer->clip_tree_index(), target_node->id);
 
   bool is_clipped_from_clip_tree =
       property_trees->non_root_surfaces_enabled
@@ -1098,9 +1192,10 @@ gfx::Rect ComputeLayerVisibleRectDynamic(const PropertyTrees* property_trees,
   gfx::RectF accumulated_clip_in_root_space;
   if (non_root_copy_request) {
     bool include_viewport_clip = false;
+    bool include_expanding_clips = true;
     ConditionalClip accumulated_clip = ComputeAccumulatedClip(
-        property_trees, include_viewport_clip, layer->clip_tree_index(),
-        effect_ancestor_with_copy_request);
+        property_trees, include_viewport_clip, include_expanding_clips,
+        layer->clip_tree_index(), effect_ancestor_with_copy_request);
     if (!accumulated_clip.is_clipped)
       return layer_content_rect;
     accumulated_clip_in_root_space = accumulated_clip.clip_rect;