[NOT FOR REVIEW] calc visible rect dynamically

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 a9b6f3d9114204ddd4e546070a07f6bb0dba34f0..3faf8e7676f90ac19fd3eca4cecdef11a49d9868 100644
--- a/cc/trees/draw_property_utils.cc
+++ b/cc/trees/draw_property_utils.cc
@@ -350,189 +350,47 @@ void CalculateClipRects(
   }
 }
 
-bool GetLayerClipRect(const LayerImpl* layer,
-                      const ClipNode* clip_node,
-                      const PropertyTrees* property_trees,
-                      int target_node_id,
-                      gfx::RectF* clip_rect_in_target_space) {
-  // This is equivalent of calling ComputeClipRectInTargetSpace.
-  *clip_rect_in_target_space = gfx::RectF(layer->clip_rect());
-  return property_trees->transform_tree.Node(target_node_id)
-      ->ancestors_are_invertible;
-}
-
 void CalculateVisibleRects(const LayerImplList& visible_layer_list,
                            const PropertyTrees* property_trees,
                            bool non_root_surfaces_enabled) {
   const EffectTree& effect_tree = property_trees->effect_tree;
-  const TransformTree& transform_tree = property_trees->transform_tree;
-  const ClipTree& clip_tree = property_trees->clip_tree;
   for (auto& layer : visible_layer_list) {
     gfx::Size layer_bounds = layer->bounds();
 
+    int root_effect_space = EffectTree::kContentsRootNodeId;
+
     int effect_ancestor_with_copy_request =
         effect_tree.ClosestAncestorWithCopyRequest(layer->effect_tree_index());
-    if (effect_ancestor_with_copy_request > 1) {
-      // Non root copy request.
-      ConditionalClip accumulated_clip_rect =
-          ComputeAccumulatedClip(property_trees, 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;
-      }
-
-      gfx::RectF accumulated_clip_in_copy_request_space =
-          accumulated_clip_rect.clip_rect;
-
-      const EffectNode* copy_request_effect_node =
-          effect_tree.Node(effect_ancestor_with_copy_request);
-      ConditionalClip clip_in_layer_space = ComputeTargetRectInLocalSpace(
-          accumulated_clip_in_copy_request_space, property_trees,
-          copy_request_effect_node->transform_id, layer->transform_tree_index(),
-          copy_request_effect_node->id);
-
-      if (clip_in_layer_space.is_clipped) {
-        gfx::RectF clip_rect = clip_in_layer_space.clip_rect;
-        clip_rect.Offset(-layer->offset_to_transform_parent());
-        gfx::Rect visible_rect = gfx::ToEnclosingRect(clip_rect);
-        visible_rect.Intersect(gfx::Rect(layer_bounds));
-        layer->set_visible_layer_rect(visible_rect);
-      } else {
-        layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
-      }
-      continue;
-    }
-
-    const ClipNode* clip_node = clip_tree.Node(layer->clip_tree_index());
-    const TransformNode* transform_node =
-        transform_tree.Node(layer->transform_tree_index());
-    if (!non_root_surfaces_enabled) {
-      // When we only have a root surface, the clip node and the layer must
-      // necessarily have the same target (the root).
-      if (transform_node->ancestors_are_invertible) {
-        gfx::RectF combined_clip_rect_in_target_space =
-            clip_node->combined_clip_in_target_space;
-        gfx::Transform target_to_content;
-        target_to_content.Translate(-layer->offset_to_transform_parent().x(),
-                                    -layer->offset_to_transform_parent().y());
-        target_to_content.PreconcatTransform(
-            transform_tree.FromScreen(transform_node->id));
-
-        gfx::Rect visible_rect =
-            gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
-                target_to_content, combined_clip_rect_in_target_space));
-        visible_rect.Intersect(gfx::Rect(layer_bounds));
-        layer->set_visible_layer_rect(visible_rect);
-      } else {
-        layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
-      }
-      continue;
-    }
-
-    // When both the layer and the target are unclipped, the entire layer
-    // content rect is visible.
-    const bool fully_visible =
-        !clip_node->layers_are_clipped && !clip_node->target_is_clipped;
-
-    if (fully_visible) {
+    // If there is copy request, regard copy request as the "root space".
+    if (effect_ancestor_with_copy_request > 0)
+      root_effect_space = effect_ancestor_with_copy_request;
+
+    // Accumulates all clips appied to layer in "root space".
+    ConditionalClip accumulated_clip_rect = ComputeAccumulatedClip(
+        property_trees, layer->clip_tree_index(), root_effect_space);
+    if (!accumulated_clip_rect.is_clipped) {
       layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
       continue;
     }
 
-    int target_node_id = transform_tree.ContentTargetId(transform_node->id);
-
-    // The clip node stores clip rect in its target space. If required,
-    // this clip rect should be mapped to the current layer's target space.
-    gfx::RectF combined_clip_rect_in_target_space;
-
-    if (clip_node->target_transform_id != target_node_id) {
-      // In this case, layer has a clip parent or scroll parent (or shares the
-      // target with an ancestor layer that has clip parent) and the clip
-      // parent's target is different from the layer's target. As the layer's
-      // target has unclippped descendants, it is unclippped.
-      if (!clip_node->layers_are_clipped) {
-        layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
-        continue;
-      }
-
-      // We use the clip node's clip_in_target_space (and not
-      // combined_clip_in_target_space) here because we want to clip
-      // with respect to clip parent's local clip and not its combined clip as
-      // the combined clip has even the clip parent's target's clip baked into
-      // it and as our target is different, we don't want to use it in our
-      // visible rect computation.
-      if (!GetLayerClipRect(layer, clip_node, property_trees, target_node_id,
-                            &combined_clip_rect_in_target_space)) {
-        layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
-        continue;
-      }
+    gfx::RectF accumulated_clip_in_root_space = accumulated_clip_rect.clip_rect;
+
+    // Convert accumulated clip into layer space.
+    const EffectNode* root_effect_node = effect_tree.Node(root_effect_space);
+    ConditionalClip clip_in_layer_space = ComputeTargetRectInLocalSpace(
+        accumulated_clip_in_root_space, property_trees,
+        root_effect_node->transform_id, layer->transform_tree_index(),
+        root_effect_node->id);
+
+    if (clip_in_layer_space.is_clipped) {
+      gfx::RectF clip_rect = clip_in_layer_space.clip_rect;
+      clip_rect.Offset(-layer->offset_to_transform_parent());
+      gfx::Rect visible_rect = gfx::ToEnclosingRect(clip_rect);
+      visible_rect.Intersect(gfx::Rect(layer_bounds));
+      layer->set_visible_layer_rect(visible_rect);
     } else {
-      if (clip_node->target_is_clipped) {
-        combined_clip_rect_in_target_space =
-            clip_node->combined_clip_in_target_space;
-      } else {
-        combined_clip_rect_in_target_space = clip_node->clip_in_target_space;
-      }
-    }
-
-    // The clip rect should be intersected with layer rect in target space.
-    gfx::Transform content_to_target = transform_tree.ToTarget(
-        transform_node->id, layer->render_target_effect_tree_index());
-    content_to_target.Translate(layer->offset_to_transform_parent().x(),
-                                layer->offset_to_transform_parent().y());
-    gfx::Rect layer_content_rect = gfx::Rect(layer_bounds);
-    gfx::RectF layer_content_bounds_in_target_space = MathUtil::MapClippedRect(
-        content_to_target, gfx::RectF(layer_content_rect));
-    // If the layer is fully contained within the clip, treat it as fully
-    // visible.
-    if (!layer_content_bounds_in_target_space.IsEmpty() &&
-        combined_clip_rect_in_target_space.Contains(
-            layer_content_bounds_in_target_space)) {
       layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
-      continue;
-    }
-
-    combined_clip_rect_in_target_space.Intersect(
-        layer_content_bounds_in_target_space);
-    if (combined_clip_rect_in_target_space.IsEmpty()) {
-      layer->set_visible_layer_rect(gfx::Rect());
-      continue;
-    }
-
-    gfx::Transform target_to_layer;
-    if (transform_node->ancestors_are_invertible) {
-      target_to_layer = transform_tree.FromTarget(
-          transform_node->id, layer->render_target_effect_tree_index());
-    } else {
-      const EffectNode* target_effect_node =
-          ContentsTargetEffectNode(layer->effect_tree_index(), effect_tree);
-      bool success = property_trees->ComputeTransformFromTarget(
-          transform_node->id, target_effect_node->id, &target_to_layer);
-      if (!success) {
-        // An animated singular transform may become non-singular during the
-        // animation, so we still need to compute a visible rect. In this
-        // situation, we treat the entire layer as visible.
-        layer->set_visible_layer_rect(gfx::Rect(layer_bounds));
-        continue;
-      }
-      if (target_effect_node->id > EffectTree::kContentsRootNodeId) {
-        ConcatInverseSurfaceContentsScale(target_effect_node, &target_to_layer);
-#if DCHECK_IS_ON()
-        VerifySurfaceContentsScalesMatch(target_effect_node->id, target_node_id,
-                                         effect_tree, transform_tree);
-#endif
-      }
     }
-    gfx::Transform target_to_content;
-    target_to_content.Translate(-layer->offset_to_transform_parent().x(),
-                                -layer->offset_to_transform_parent().y());
-    target_to_content.PreconcatTransform(target_to_layer);
-
-    gfx::Rect visible_rect = gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
-        target_to_content, combined_clip_rect_in_target_space));
-    visible_rect.Intersect(gfx::Rect(layer_bounds));
-    layer->set_visible_layer_rect(visible_rect);
   }
 }