Generalize layer mirroring for phantom windows

ui/compositor/layer.cc

 // Copyright (c) 2012 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 "ui/compositor/layer.h"
 
 #include <algorithm>
 #include <memory>
 #include <utility>
 
@@ skipping 10 matching lines @@
 #include "cc/layers/texture_layer.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/output/filter_operation.h"
 #include "cc/output/filter_operations.h"
 #include "cc/playback/display_item_list_settings.h"
 #include "cc/resources/transferable_resource.h"
 #include "cc/trees/layer_tree_settings.h"
 #include "ui/compositor/compositor_switches.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/compositor/layer_animator.h"
-#include "ui/compositor/layer_observer.h"
+#include "ui/compositor/layer_owner.h"
 #include "ui/compositor/paint_context.h"
 #include "ui/gfx/animation/animation.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/geometry/point3_f.h"
 #include "ui/gfx/geometry/point_conversions.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/interpolated_transform.h"
 
 namespace {
 
 const ui::Layer* GetRoot(const ui::Layer* layer) {
   while (layer->parent())
     layer = layer->parent();
   return layer;
 }
 
 }  // namespace
 
 namespace ui {
 
+class Layer::LayerMirror : public ui::LayerOwner,

[sky, 2016/10/19 19:27:14]

I find this code confusing. In particular it's a LayerOwner, yet the layer is
immediately released in AcquireLayer. What do you gain by making this class a
LayerOwner? Additionally why not make this class directly be the LayerObserver?
That way Layer itself isn't a LayerObserver only for some rare cases and
additionally Layer::LayerDestroyed() wouldn't need to lookup the LayerMirror.

[Dominik Laskowski, 2016/10/19 22:46:38]

The LayerOwner inheritance was just to reduce boilerplate, but I've removed it
for clarity. The Layer class must be the observer, because it must remove
destroyed LayerMirror instances from its list of mirrors.

[sky, 2016/10/19 23:44:26]

I was suggesting you make this class the LayerObserver and in OnLayerDestroyed
call a private function in the host layer, e.g. OnMirroredLayerDestroyed(this).

[Dominik Laskowski, 2016/10/20 02:12:30]

Done.

+                           public ui::LayerDelegate {
+ public:
+  explicit LayerMirror(ui::Layer* mirrored) : mirrored_(mirrored) {
+    SetLayer(mirrored->Clone());
+    layer()->AddObserver(mirrored);
+    layer()->set_delegate(this);
+  }
+
+  ~LayerMirror() override {
+    layer()->RemoveObserver(mirrored_);
+    layer()->set_delegate(nullptr);
+  }
+
+  // ui::LayerDelegate:
+  void OnPaintLayer(const ui::PaintContext& context) override {
+    if (const auto delegate = mirrored_->delegate())
+      delegate->OnPaintLayer(context);
+  }
+  void OnDelegatedFrameDamage(const gfx::Rect& damage_rect_in_dip) override {}
+  void OnDeviceScaleFactorChanged(float device_scale_factor) override {}
+
+ private:
+  ui::Layer* const mirrored_;
+
+  DISALLOW_COPY_AND_ASSIGN(LayerMirror);
+};
+
 Layer::Layer()
     : type_(LAYER_TEXTURED),
       compositor_(NULL),
       parent_(NULL),
       visible_(true),
       fills_bounds_opaquely_(true),
       fills_bounds_completely_(false),
       background_blur_radius_(0),
       layer_saturation_(0.0f),
       layer_brightness_(0.0f),
@@ skipping 50 matching lines @@
   if (layer_mask_back_link_)
     layer_mask_back_link_->SetMaskLayer(NULL);
   for (size_t i = 0; i < children_.size(); ++i)
     children_[i]->parent_ = NULL;
 
   cc_layer_->RemoveFromParent();
   if (mailbox_release_callback_)
     mailbox_release_callback_->Run(gpu::SyncToken(), false);
 }
 
+std::unique_ptr<Layer> Layer::Clone() const {
+  auto clone = base::MakeUnique<Layer>(type_);
+
+  clone->SetTransform(GetTargetTransform());
+  clone->SetBounds(bounds_);
+  clone->SetSubpixelPositionOffset(subpixel_position_offset_);
+  clone->SetMasksToBounds(GetMasksToBounds());
+  clone->SetOpacity(GetTargetOpacity());
+  clone->SetVisible(GetTargetVisibility());
+  clone->SetFillsBoundsOpaquely(fills_bounds_opaquely_);
+  clone->SetFillsBoundsCompletely(fills_bounds_completely_);
+  clone->set_name(name_);
+
+  // Background filters.
+  clone->SetBackgroundBlur(background_blur_radius_);
+  clone->SetBackgroundZoom(zoom_, zoom_inset_);
+
+  // Filters.
+  clone->SetLayerSaturation(layer_saturation_);
+  clone->SetLayerBrightness(GetTargetBrightness());
+  clone->SetLayerGrayscale(GetTargetGrayscale());
+  clone->SetLayerInverted(layer_inverted_);
+  if (alpha_shape_)
+    clone->SetAlphaShape(base::MakeUnique<SkRegion>(*alpha_shape_));
+
+  // cc::Layer state.
+  if (surface_layer_ && !surface_layer_->surface_id().is_null()) {
+    clone->SetShowSurface(
+        surface_layer_->surface_id(),
+        surface_layer_->satisfy_callback(),
+        surface_layer_->require_callback(),
+        surface_layer_->surface_size(),
+        surface_layer_->surface_scale(),
+        frame_size_in_dip_);
+  } else if (type_ == LAYER_SOLID_COLOR) {
+    clone->SetColor(GetTargetColor());
+  }
+  return clone;
+}
+
 const Compositor* Layer::GetCompositor() const {
   return GetRoot(this)->compositor_;
 }
 
 float Layer::opacity() const {
   return cc_layer_->opacity();
 }
 
 void Layer::SetCompositor(Compositor* compositor,
                           scoped_refptr<cc::Layer> root_layer) {
@@ skipping 454 matching lines @@
 
   scoped_refptr<cc::SurfaceLayer> new_layer =
       cc::SurfaceLayer::Create(satisfy_callback, require_callback);
   new_layer->SetSurfaceId(surface_id, scale, surface_size);
   SwitchToLayer(new_layer);
   surface_layer_ = new_layer;
 
   frame_size_in_dip_ = frame_size_in_dip;
   RecomputeDrawsContentAndUVRect();
 
-  for (auto& observer : observer_list_)
-    observer.SurfaceChanged(this);
+  for (const auto& mirror : mirrors_) {
+    mirror->layer()->SetShowSurface(
+        surface_id, satisfy_callback, require_callback,
+        surface_size, scale, frame_size_in_dip);
+  }
+}
+
+std::unique_ptr<Layer> Layer::Mirror() {
+  mirrors_.emplace_back(base::MakeUnique<LayerMirror>(this));
+  return mirrors_.back()->AcquireLayer();
 }
 
 void Layer::SetShowSolidColorContent() {
   DCHECK_EQ(type_, LAYER_SOLID_COLOR);
 
   if (solid_color_layer_.get())
     return;
 
   scoped_refptr<cc::SolidColorLayer> new_layer = cc::SolidColorLayer::Create();
   SwitchToLayer(new_layer);
@@ skipping 36 matching lines @@
   nine_patch_layer_->SetBorder(border);
 }
 
 void Layer::UpdateNinePatchOcclusion(const gfx::Rect& occlusion) {
   DCHECK(type_ == LAYER_NINE_PATCH && nine_patch_layer_.get());
   nine_patch_layer_->SetLayerOcclusion(occlusion);
 }
 
 void Layer::SetColor(SkColor color) { GetAnimator()->SetColor(color); }
 
-SkColor Layer::GetTargetColor() {
-  if (GetAnimator()->IsAnimatingProperty(LayerAnimationElement::COLOR))
-    return GetAnimator()->GetTargetColor();
+SkColor Layer::GetTargetColor() const {
+  if (animator_.get() && animator_->IsAnimatingProperty(
+      LayerAnimationElement::COLOR))
+    return animator_->GetTargetColor();
   return cc_layer_->background_color();
 }
 
 SkColor Layer::background_color() const {
   return cc_layer_->background_color();
 }
 
 bool Layer::SchedulePaint(const gfx::Rect& invalid_rect) {
   if ((type_ == LAYER_SOLID_COLOR && !texture_layer_.get()) ||
       type_ == LAYER_NINE_PATCH || (!delegate_ && !mailbox_.IsValid()))
@@ skipping 242 matching lines @@
 
   if (bounds.size() == old_bounds.size()) {
     // Don't schedule a draw if we're invisible. We'll schedule one
     // automatically when we get visible.
     if (IsDrawn())
       ScheduleDraw();
   } else {
     // Always schedule a paint, even if we're invisible.
     SchedulePaint(gfx::Rect(bounds.size()));
   }
+
+  if (sync_bounds_) {
+    for (const auto& mirror : mirrors_)
+      mirror->layer()->SetBounds(bounds);
+  }
 }
 
 void Layer::SetTransformFromAnimation(const gfx::Transform& transform) {
   cc_layer_->SetTransform(transform);
 }
 
 void Layer::SetOpacityFromAnimation(float opacity) {
   cc_layer_->SetOpacity(opacity);
   ScheduleDraw();
 }
@@ skipping 69 matching lines @@
 
 cc::Layer* Layer::GetCcLayer() const {
   return cc_layer_;
 }
 
 LayerThreadedAnimationDelegate* Layer::GetThreadedAnimationDelegate() {
   DCHECK(animator_);
   return animator_.get();
 }
 
+void Layer::LayerDestroyed(Layer* layer) {
+  const auto it = std::find_if(mirrors_.begin(), mirrors_.end(),
+      [layer](const std::unique_ptr<LayerMirror>& mirror) {
+        return mirror->layer() == layer;
+      });
+
+  DCHECK(it != mirrors_.end());
+  mirrors_.erase(it);
+}
+
 void Layer::CreateCcLayer() {
   if (type_ == LAYER_SOLID_COLOR) {
     solid_color_layer_ = cc::SolidColorLayer::Create();
     cc_layer_ = solid_color_layer_.get();
   } else if (type_ == LAYER_NINE_PATCH) {
     nine_patch_layer_ = cc::NinePatchLayer::Create();
     cc_layer_ = nine_patch_layer_.get();
   } else {
     content_layer_ = cc::PictureLayer::Create(this);
     cc_layer_ = content_layer_.get();
@@ skipping 52 matching lines @@
   if (animator_) {
     animator_->DetachLayerAndTimeline(compositor);
     animator_->RemoveFromCollection(collection);
   }
 
   for (auto* child : children_)
     child->ResetCompositorForAnimatorsInTree(compositor);
 }
 
 }  // namespace ui