cc/blimp: Set up the framework for state serialization.

cc/blimp/compositor_state_deserializer.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "cc/blimp/compositor_state_deserializer.h"
+
+#include "base/bind.h"
+#include "base/memory/ptr_util.h"
+#include "cc/blimp/compositor_state_deserializer_client.h"
+#include "cc/blimp/layer_factory.h"
+#include "cc/input/layer_selection_bound.h"
+#include "cc/layers/layer.h"
+#include "cc/proto/cc_conversions.h"
+#include "cc/proto/gfx_conversions.h"
+#include "cc/proto/layer_tree_host.pb.h"
+#include "cc/proto/skia_conversions.h"
+#include "cc/trees/layer_tree_host.h"
+
+namespace cc {
+namespace {
+
+class DefaultLayerFactory : public LayerFactory {
+ public:
+  DefaultLayerFactory() = default;
+  ~DefaultLayerFactory() override = default;
+
+  // LayerFactory implementation.
+  scoped_refptr<Layer> CreateLayer(int engine_layer_id) override {
+    return Layer::Create();
+  }
+};
+
+}  // namespace
+
+CompositorStateDeserializer::CompositorStateDeserializer(
+    LayerTreeHost* layer_tree_host,
+    ScrollCallback scroll_callback,
+    CompositorStateDeserializerClient* client)
+    : layer_factory_(base::MakeUnique<DefaultLayerFactory>()),
+      layer_tree_host_(layer_tree_host),
+      scroll_callback_(scroll_callback),
+      client_(client) {
+  DCHECK(layer_tree_host_);
+  DCHECK(client_);
+}
+
+CompositorStateDeserializer::~CompositorStateDeserializer() = default;
+
+Layer* CompositorStateDeserializer::GetLayerForEngineId(
+    int engine_layer_id) const {
+  EngineIdToLayerMap::const_iterator layer_it =
+      engine_id_to_layer_.find(engine_layer_id);
+  return layer_it != engine_id_to_layer_.end() ? layer_it->second.get()
+                                               : nullptr;
+}
+
+void CompositorStateDeserializer::DeserializeCompositorUpdate(
+    const proto::LayerTreeHost& layer_tree_host_proto) {
+  SychronizeLayerTreeState(layer_tree_host_proto.layer_tree());
+
+  const proto::LayerUpdate& layer_updates =
+      layer_tree_host_proto.layer_updates();
+  for (int i = 0; i < layer_updates.layers_size(); ++i) {
+    SynchronizeLayerState(layer_updates.layers(i));
+  }
+}
+
+void CompositorStateDeserializer::SetLayerFactoryForTesting(
+    std::unique_ptr<LayerFactory> layer_factory) {
+  layer_factory_ = std::move(layer_factory);
+}
+
+void CompositorStateDeserializer::SychronizeLayerTreeState(
+    const proto::LayerTree& layer_tree_proto) {
+  LayerTree* layer_tree = layer_tree_host_->GetLayerTree();
+
+  // Synchronize the tree hierarchy first.
+  EngineIdToLayerMap new_engine_id_to_layer;
+  if (layer_tree_proto.has_root_layer()) {
+    const proto::LayerNode& root_layer_node = layer_tree_proto.root_layer();
+    layer_tree->SetRootLayer(
+        GetLayerAndAddToNewMap(root_layer_node, &new_engine_id_to_layer));
+    SynchronizeLayerHeirarchyRecursive(

[ajuma, 2016/10/04 15:45:10]

Is this happening every frame? Are there plans to serialize only when the
hierarchy changes? (e.g. if a page is just repainting a composited layer or
changing its transform, there's no need to re-serialize the layer hierarchy)

[Khushal, 2016/10/04 18:34:47]

Yeah, the existing code was doing this so I didn't change. Add a bug about it.
Thanks!

+        layer_tree->root_layer(), root_layer_node, &new_engine_id_to_layer);
+  } else {
+    layer_tree->SetRootLayer(nullptr);
+  }
+  engine_id_to_layer_.swap(new_engine_id_to_layer);
+
+  // Synchronize rest of the tree state.
+  layer_tree->RegisterViewportLayers(
+      GetLayer(layer_tree_proto.overscroll_elasticity_layer_id()),
+      GetLayer(layer_tree_proto.page_scale_layer_id()),
+      GetLayer(layer_tree_proto.inner_viewport_scroll_layer_id()),
+      GetLayer(layer_tree_proto.outer_viewport_scroll_layer_id()));
+
+  layer_tree->SetDeviceScaleFactor(layer_tree_proto.device_scale_factor());
+  layer_tree->SetPaintedDeviceScaleFactor(
+      layer_tree_proto.painted_device_scale_factor());
+
+  float min_page_scale_factor = layer_tree_proto.min_page_scale_factor();
+  float max_page_scale_factor = layer_tree_proto.max_page_scale_factor();
+  float page_scale_factor = layer_tree_proto.page_scale_factor();
+  if (client_->ShouldRetainClientPageScale(page_scale_factor))
+    page_scale_factor = layer_tree->page_scale_factor();
+  layer_tree->SetPageScaleFactorAndLimits(
+      page_scale_factor, min_page_scale_factor, max_page_scale_factor);
+
+  layer_tree->set_background_color(layer_tree_proto.background_color());
+  layer_tree->set_has_transparent_background(
+      layer_tree_proto.has_transparent_background());
+
+  LayerSelection selection;
+  LayerSelectionFromProtobuf(&selection, layer_tree_proto.selection());
+  layer_tree->RegisterSelection(selection);
+  layer_tree->SetViewportSize(
+      ProtoToSize(layer_tree_proto.device_viewport_size()));
+
+  layer_tree->SetHaveScrollEventHandlers(
+      layer_tree_proto.have_scroll_event_handlers());
+  layer_tree->SetEventListenerProperties(
+      EventListenerClass::kMouseWheel,
+      static_cast<EventListenerProperties>(
+          layer_tree_proto.wheel_event_listener_properties()));
+  layer_tree->SetEventListenerProperties(
+      EventListenerClass::kTouchStartOrMove,
+      static_cast<EventListenerProperties>(
+          layer_tree_proto.touch_start_or_move_event_listener_properties()));
+  layer_tree->SetEventListenerProperties(
+      EventListenerClass::kTouchEndOrCancel,
+      static_cast<EventListenerProperties>(
+          layer_tree_proto.touch_end_or_cancel_event_listener_properties()));
+}
+
+void CompositorStateDeserializer::SynchronizeLayerState(
+    const proto::LayerProperties& layer_properties_proto) {
+  int engine_layer_id = layer_properties_proto.id();
+  Layer* layer = GetLayerForEngineId(engine_layer_id);
+
+  const proto::BaseLayerProperties& base = layer_properties_proto.base();
+
+  layer->SetNeedsDisplayRect(ProtoToRect(base.update_rect()));
+  layer->SetBounds(ProtoToSize(base.bounds()));
+  layer->SetMasksToBounds(base.masks_to_bounds());
+  layer->SetOpacity(base.opacity());
+  layer->SetBlendMode(SkXfermodeModeFromProto(base.blend_mode()));
+  layer->SetIsRootForIsolatedGroup(base.is_root_for_isolated_group());
+  layer->SetContentsOpaque(base.contents_opaque());
+  layer->SetPosition(ProtoToPointF(base.position()));
+  layer->SetTransform(ProtoToTransform(base.transform()));
+  layer->SetTransformOrigin(ProtoToPoint3F(base.transform_origin()));
+  layer->SetIsDrawable(base.is_drawable());
+  layer->SetDoubleSided(base.double_sided());
+  layer->SetShouldFlattenTransform(base.should_flatten_transform());
+  layer->Set3dSortingContextId(base.sorting_context_id());
+  layer->SetUseParentBackfaceVisibility(base.use_parent_backface_visibility());
+  layer->SetBackgroundColor(base.background_color());
+
+  gfx::ScrollOffset scroll_offset = ProtoToScrollOffset(base.scroll_offset());
+  if (client_->ShouldRetainClientScroll(engine_layer_id, scroll_offset))
+    scroll_offset = layer->scroll_offset();
+  layer->SetScrollOffset(scroll_offset);
+
+  layer->SetScrollClipLayerId(
+      GetClientIdFromEngineId(base.scroll_clip_layer_id()));
+  layer->SetUserScrollable(base.user_scrollable_horizontal(),
+                           base.user_scrollable_vertical());
+
+  if (layer->main_thread_scrolling_reasons()) {
+    layer->ClearMainThreadScrollingReasons(
+        layer->main_thread_scrolling_reasons());
+  }
+  if (base.main_thread_scrolling_reasons()) {
+    layer->AddMainThreadScrollingReasons(base.main_thread_scrolling_reasons());
+  }
+
+  layer->SetNonFastScrollableRegion(
+      RegionFromProto(base.non_fast_scrollable_region()));
+  layer->SetTouchEventHandlerRegion(
+      RegionFromProto(base.touch_event_handler_region()));
+
+  layer->SetIsContainerForFixedPositionLayers(
+      base.is_container_for_fixed_position_layers());
+
+  LayerPositionConstraint position_constraint;
+  position_constraint.FromProtobuf(base.position_constraint());
+  layer->SetPositionConstraint(position_constraint);
+
+  LayerStickyPositionConstraint sticky_position_constraint;
+  sticky_position_constraint.FromProtobuf(base.sticky_position_constraint());
+  layer->SetStickyPositionConstraint(sticky_position_constraint);
+  layer->SetScrollParent(GetLayerForEngineId(base.scroll_parent_id()));
+  layer->SetClipParent(GetLayerForEngineId(base.clip_parent_id()));
+
+  layer->SetHasWillChangeTransformHint(base.has_will_change_transform_hint());
+  layer->SetHideLayerAndSubtree(base.hide_layer_and_subtree());
+}
+
+void CompositorStateDeserializer::SynchronizeLayerHeirarchyRecursive(

[ajuma, 2016/10/04 15:45:10]

typo: "Hierarchy"

[Khushal, 2016/10/04 18:34:47]

Done.

+    Layer* layer,
+    const proto::LayerNode& layer_node,
+    EngineIdToLayerMap* new_layer_map) {
+  layer->RemoveAllChildren();
+
+  // Children.
+  for (int i = 0; i < layer_node.children_size(); i++) {
+    const proto::LayerNode& child_layer_node = layer_node.children(i);
+    scoped_refptr<Layer> child_layer =
+        GetLayerAndAddToNewMap(child_layer_node, new_layer_map);
+    layer->AddChild(child_layer);
+    SynchronizeLayerHeirarchyRecursive(child_layer.get(), child_layer_node,
+                                       new_layer_map);
+  }
+
+  // Mask Layer.
+  if (layer_node.has_mask_layer()) {
+    const proto::LayerNode& mask_layer_node = layer_node.mask_layer();
+    scoped_refptr<Layer> mask_layer =
+        GetLayerAndAddToNewMap(mask_layer_node, new_layer_map);
+    layer->SetMaskLayer(mask_layer.get());
+    SynchronizeLayerHeirarchyRecursive(mask_layer.get(), mask_layer_node,
+                                       new_layer_map);
+  } else {
+    layer->SetMaskLayer(nullptr);
+  }
+
+  // Scroll callback.
+  layer->set_did_scroll_callback(base::Bind(scroll_callback_, layer_node.id()));
+}
+
+scoped_refptr<Layer> CompositorStateDeserializer::GetLayerAndAddToNewMap(
+    const proto::LayerNode& layer_node,
+    EngineIdToLayerMap* new_layer_map) {
+  DCHECK(new_layer_map->find(layer_node.id()) == new_layer_map->end())
+      << "A LayerNode should have been de-serialized only once";
+
+  EngineIdToLayerMap::iterator layer_map_it =
+      engine_id_to_layer_.find(layer_node.id());
+
+  if (layer_map_it != engine_id_to_layer_.end()) {
+    // We can re-use the old layer.
+    (*new_layer_map)[layer_node.id()] = layer_map_it->second;
+    return layer_map_it->second;
+  }
+
+  // We need to create a new layer.
+  scoped_refptr<Layer> layer;
+  switch (layer_node.type()) {
+    case proto::LayerNode::UNKNOWN:
+      NOTREACHED() << "Unknown Layer type";
+    case proto::LayerNode::LAYER:
+      layer = layer_factory_->CreateLayer(layer_node.id());
+      break;
+    default:
+      // TODO(khushalsagar): Add other Layer types.
+      NOTREACHED();
+  }
+
+  (*new_layer_map)[layer_node.id()] = layer;
+  return layer;
+}
+
+int CompositorStateDeserializer::GetClientIdFromEngineId(int engine_layer_id) {
+  Layer* layer = GetLayerForEngineId(engine_layer_id);
+  return layer ? layer->id() : Layer::LayerIdLabels::INVALID_ID;
+}
+
+scoped_refptr<Layer> CompositorStateDeserializer::GetLayer(
+    int engine_layer_id) {
+  EngineIdToLayerMap::const_iterator layer_it =
+      engine_id_to_layer_.find(engine_layer_id);
+  return layer_it != engine_id_to_layer_.end() ? layer_it->second : nullptr;
+}
+
+}  // namespace cc