From 3257622d4b3dfa28f33e6cea9dff78f0fa4cdc38 Mon Sep 17 00:00:00 2001
From: David Worsham <dworsham@google.com>
Date: Wed, 8 Jan 2020 12:15:12 -0800
Subject: [PATCH] Fix bad PhysicalShapeLayer performance when using
 system_composite

---
 flow/layers/physical_shape_layer.cc | 51 +++++------------------------
 flow/layers/physical_shape_layer.h  |  4 ---
 2 files changed, 9 insertions(+), 46 deletions(-)

diff --git a/flow/layers/physical_shape_layer.cc b/flow/layers/physical_shape_layer.cc
index 524c5a2ac939a..996fc1a3331f5 100644
--- a/flow/layers/physical_shape_layer.cc
+++ b/flow/layers/physical_shape_layer.cc
@@ -45,8 +45,6 @@ PhysicalShapeLayer::PhysicalShapeLayer(SkColor color,
     // an SkPath.
     frameRRect_ = SkRRect::MakeRect(path.getBounds());
   }
-
-  set_dimensions(frameRRect_);
 }
 
 void PhysicalShapeLayer::Preroll(PrerollContext* context,
@@ -61,57 +59,26 @@ void PhysicalShapeLayer::Preroll(PrerollContext* context,
     set_paint_bounds(path_.getBounds());
   } else {
     if (PhysicalShapeLayerBase::can_system_composite()) {
+      // always system composite these layers when possible and an elevation is
+      // present; we are doing it for the shadow effect and in order for
+      // elevation to be construed as height in Z
       set_needs_system_composite(true);
+
+      // paint_bounds should be explicitly empty when dimensions is set, or the
+      // layer's children could be drawn twice
+      set_dimensions(frameRRect_);
+      set_paint_bounds(SkRect::MakeEmpty());
+
       return;
     }
-    //#if defined(OS_FUCHSIA)
-    //    // Let the system compositor draw all shadows for us.
-    //    set_needs_system_composite(true);
-    //#else
     // We will draw the shadow in Paint(), so add some margin to the paint
     // bounds to leave space for the shadow. We fill this whole region and clip
     // children to it so we don't need to join the child paint bounds.
     set_paint_bounds(ComputeShadowBounds(path_.getBounds(), elevation(),
                                          context->frame_device_pixel_ratio));
-    //#endif  // defined(OS_FUCHSIA)
-  }
-}
-
-#if defined(OS_FUCHSIA)
-
-void PhysicalShapeLayer::UpdateScene(SceneUpdateContext& context) {
-  FML_DCHECK(needs_system_composite());
-  TRACE_EVENT0("flutter", "PhysicalShapeLayer::UpdateScene");
-
-  // Retained rendering: speedup by reusing a retained entity node if possible.
-  // When an entity node is reused, no paint layer is added to the frame so we
-  // won't call PhysicalShapeLayer::Paint.
-  LayerRasterCacheKey key(unique_id(), context.Matrix());
-  if (context.HasRetainedNode(key)) {
-    TRACE_EVENT_INSTANT0("flutter", "retained layer cache hit");
-    const scenic::EntityNode& retained_node = context.GetRetainedNode(key);
-    FML_DCHECK(context.top_entity());
-    FML_DCHECK(retained_node.session() == context.session());
-    context.top_entity()->entity_node().AddChild(retained_node);
-    return;
   }
-
-  TRACE_EVENT_INSTANT0("flutter", "cache miss, creating");
-  // If we can't find an existing retained surface, create one.
-  SceneUpdateContext::Frame frame(context, frameRRect_, color(), opacity(),
-                                  elevation(), this);
-
-  for (auto& layer : layers()) {
-    if (layer->needs_painting()) {
-      frame.AddPaintLayer(layer.get());
-    }
-  }
-
-  UpdateSceneChildren(context);
 }
 
-#endif  // defined(OS_FUCHSIA)
-
 void PhysicalShapeLayer::Paint(PaintContext& context) const {
   TRACE_EVENT0("flutter", "PhysicalShapeLayer::Paint");
   FML_DCHECK(needs_painting());
diff --git a/flow/layers/physical_shape_layer.h b/flow/layers/physical_shape_layer.h
index 34b3c59fe355b..b309da7fd5386 100644
--- a/flow/layers/physical_shape_layer.h
+++ b/flow/layers/physical_shape_layer.h
@@ -55,10 +55,6 @@ class PhysicalShapeLayer : public PhysicalShapeLayerBase {
     return clip_behavior_ == Clip::antiAliasWithSaveLayer;
   }
 
-#if defined(OS_FUCHSIA)
-  void UpdateScene(SceneUpdateContext& context) override;
-#endif  // defined(OS_FUCHSIA)
-
  private:
   SkColor shadow_color_;
   SkPath path_;