Android WebView: flush input events during onVSync

content/browser/renderer_host/render_widget_host_view_android.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 "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 165 matching lines @@
     uint32 output_id,
     scoped_ptr<cc::CompositorFrame> output_frame)
     : output_surface_id(output_id), frame(output_frame.Pass()) {}
 
 RenderWidgetHostViewAndroid::LastFrameInfo::~LastFrameInfo() {}
 
 RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
     RenderWidgetHostImpl* widget_host,
     ContentViewCoreImpl* content_view_core)
     : host_(widget_host),
-      needs_begin_frame_(false),
       is_showing_(!widget_host->is_hidden()),
       content_view_core_(NULL),
       ime_adapter_android_(this),
       cached_background_color_(SK_ColorWHITE),
       last_output_surface_id_(kUndefinedOutputSurfaceId),
       weak_ptr_factory_(this),
       overscroll_effect_enabled_(!CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableOverscrollEdgeEffect)),
       gesture_provider_(CreateGestureProviderConfig(), this),
       gesture_text_selector_(this),
       touch_scrolling_(false),
       potentially_active_fling_count_(0),
-      flush_input_requested_(false),
       accelerated_surface_route_id_(0),
       using_synchronous_compositor_(SynchronousCompositorImpl::FromID(
                                         widget_host->GetProcess()->GetID(),
                                         widget_host->GetRoutingID()) != NULL),
+      vsync_subscribers_bitmask_(0),
       frame_evictor_(new DelegatedFrameEvictor(this)),
-      locks_on_frame_count_(0),
-      observing_root_window_(false) {
+      locks_on_frame_count_(0) {
   host_->SetView(this);
   SetContentViewCore(content_view_core);
   ImageTransportFactoryAndroid::AddObserver(this);
 }
 
 RenderWidgetHostViewAndroid::~RenderWidgetHostViewAndroid() {
   ImageTransportFactoryAndroid::RemoveObserver(this);
   SetContentViewCore(NULL);
   DCHECK(ack_callbacks_.empty());
   if (resource_collection_.get())
@@ skipping 35 matching lines @@
 RenderWidgetHostViewAndroid::GetRenderWidgetHost() const {
   return host_;
 }
 
 void RenderWidgetHostViewAndroid::WasShown() {
   if (!host_ || !host_->is_hidden())
     return;
 
   host_->WasShown(ui::LatencyInfo());
 
-  if (content_view_core_ && !using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->AddObserver(this);
-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-    observing_root_window_ = true;
-  }
+  if (content_view_core_ && !using_synchronous_compositor_)
+    SubscribeToVSync(INPUT | BEGIN_FRAME);
 }
 
 void RenderWidgetHostViewAndroid::WasHidden() {
   RunAckCallbacks();
 
   if (!host_ || host_->is_hidden())
     return;
 
   // Inform the renderer that we are being hidden so it can reduce its resource
   // utilization.
   host_->WasHidden();
 
-  if (content_view_core_ && !using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->RemoveObserver(this);
-    observing_root_window_ = false;
-  }
+  if (content_view_core_ && !using_synchronous_compositor_)
+    UnsubscribeToVSync(INPUT | BEGIN_FRAME);
 }
 
 void RenderWidgetHostViewAndroid::WasResized() {
   host_->WasResized();
 }
 
 void RenderWidgetHostViewAndroid::SetSize(const gfx::Size& size) {
   // Ignore the given size as only the Java code has the power to
   // resize the view on Android.
   default_size_ = size;
@@ skipping 251 matching lines @@
     SkColor color) {
   if (cached_background_color_ == color)
     return;
 
   cached_background_color_ = color;
   if (content_view_core_)
     content_view_core_->OnBackgroundColorChanged(color);
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame(bool enabled) {
-  if (enabled == needs_begin_frame_)
+  if (enabled == IsSubscribedToType(BEGIN_FRAME) || !content_view_core_)

[boliu, 2014/08/20 20:30:00]

No need to check for !content_view_core_ here.

     return;
 
   TRACE_EVENT1("cc", "RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame",
                "enabled", enabled);
-  if (content_view_core_ && enabled)
-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-
-  needs_begin_frame_ = enabled;
+  if (enabled)
+    SubscribeToVSync(BEGIN_FRAME);
+  else
+    UnsubscribeToVSync(BEGIN_FRAME);
 }
 
 void RenderWidgetHostViewAndroid::OnStartContentIntent(
     const GURL& content_url) {
   if (content_view_core_)
     content_view_core_->StartContentIntent(content_url);
 }
 
 void RenderWidgetHostViewAndroid::OnSmartClipDataExtracted(
     const base::string16& text,
@@ skipping 231 matching lines @@
 void RenderWidgetHostViewAndroid::ShowDisambiguationPopup(
     const gfx::Rect& target_rect, const SkBitmap& zoomed_bitmap) {
   if (!content_view_core_)
     return;
 
   content_view_core_->ShowDisambiguationPopup(target_rect, zoomed_bitmap);
 }
 
 scoped_ptr<SyntheticGestureTarget>
 RenderWidgetHostViewAndroid::CreateSyntheticGestureTarget() {
+  DCHECK(content_view_core_);
+  if (using_synchronous_compositor_)
+    SubscribeToVSync(INPUT);
+
   return scoped_ptr<SyntheticGestureTarget>(new SyntheticGestureTargetAndroid(
       host_, content_view_core_->CreateTouchEventSynthesizer()));
 }
 
 void RenderWidgetHostViewAndroid::SendDelegatedFrameAck(
     uint32 output_surface_id) {
   DCHECK(host_);
   cc::CompositorFrameAck ack;
   if (resource_collection_.get())
     resource_collection_->TakeUnusedResourcesForChildCompositor(&ack.resources);
@@ skipping 469 matching lines @@
 
   SynchronousCompositorImpl* compositor =
       SynchronousCompositorImpl::FromID(host_->GetProcess()->GetID(),
                                           host_->GetRoutingID());
   if (compositor)
     return compositor->HandleInputEvent(input_event);
   return INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
-  if (flush_input_requested_ || !content_view_core_)
+  if ((IsSubscribedToType(INPUT)) || !content_view_core_)
     return;
+
   TRACE_EVENT0("input", "RenderWidgetHostViewAndroid::OnSetNeedsFlushInput");

[boliu, 2014/08/20 20:30:00]

unrelated side note, this should be an instant event, requesting a vsync is fast

-  flush_input_requested_ = true;
-  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+  SubscribeToVSync(INPUT);
 }
 
 BrowserAccessibilityManager*
     RenderWidgetHostViewAndroid::CreateBrowserAccessibilityManager(
         BrowserAccessibilityDelegate* delegate) {
   base::android::ScopedJavaLocalRef<jobject> obj;
   if (content_view_core_)
     obj = content_view_core_->GetJavaObject();
   return new BrowserAccessibilityManagerAndroid(
       obj,
@@ skipping 20 matching lines @@
 
 void RenderWidgetHostViewAndroid::SendTouchEvent(
     const blink::WebTouchEvent& event) {
   if (host_)
     host_->ForwardTouchEventWithLatencyInfo(event, CreateLatencyInfo(event));
 
   // Send a proactive BeginFrame on the next vsync to reduce latency.
   // This is good enough as long as the first touch event has Begin semantics
   // and the actual scroll happens on the next vsync.
   // TODO: Is this actually still needed?
-  if (content_view_core_) {

[boliu, 2014/08/20 20:30:00]

You need to rebase, I added something here to not request vsync in webview.

-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-  }
+  if (content_view_core_)
+    SubscribeToVSync(BEGIN_FRAME);

[boliu, 2014/08/20 20:30:00]

This is not the same as simply calling RequestVSyncUpdate. Now any touch event
is going to start producing begin frames forever.

 }
 
 void RenderWidgetHostViewAndroid::SendMouseEvent(
     const blink::WebMouseEvent& event) {
   if (host_)
     host_->ForwardMouseEvent(event);
 }
 
 void RenderWidgetHostViewAndroid::SendMouseWheelEvent(
     const blink::WebMouseWheelEvent& event) {
@@ skipping 72 matching lines @@
     OnContentScrollingChange();
   }
 
   if (content_view_core_)
     content_view_core_->DidStopFlinging();
 }
 
 void RenderWidgetHostViewAndroid::SetContentViewCore(
     ContentViewCoreImpl* content_view_core) {
   RemoveLayers();
-  if (observing_root_window_ && content_view_core_) {
-    content_view_core_->GetWindowAndroid()->RemoveObserver(this);
-    observing_root_window_ = false;
-  }
+  if (vsync_subscribers_bitmask_ && content_view_core_)
+    UnsubscribeToVSync(INPUT | BEGIN_FRAME);

[boliu, 2014/08/20 20:30:00]

I think we need an catch all enum value here.

 
   bool resize = false;
   if (content_view_core != content_view_core_) {
     selection_controller_.reset();
     ReleaseLocksOnSurface();
     resize = true;
   }
 
   content_view_core_ = content_view_core;
 
   BrowserAccessibilityManager* manager = NULL;
   if (host_)
     manager = host_->GetRootBrowserAccessibilityManager();
   if (manager) {
     base::android::ScopedJavaLocalRef<jobject> obj;
     if (content_view_core_)
       obj = content_view_core_->GetJavaObject();
     manager->ToBrowserAccessibilityManagerAndroid()->SetContentViewCore(obj);
   }
 
   AttachLayers();
 
   if (!content_view_core_)
     return;
 
-  if (!using_synchronous_compositor_) {
-    content_view_core_->GetWindowAndroid()->AddObserver(this);
-    observing_root_window_ = true;
-    if (needs_begin_frame_)
-      content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
-  }
+  if (!using_synchronous_compositor_)
+    SubscribeToVSync(INPUT | BEGIN_FRAME);

[boliu, 2014/08/20 20:30:00]

Only subscribe to what was subscribed before.

+
 
   if (resize)
     WasResized();
 
   if (!selection_controller_)
     selection_controller_.reset(new TouchSelectionController(this));
 
   if (!content_view_core_) {
     overscroll_effect_.reset();
   } else if (overscroll_effect_enabled_ && !overscroll_effect_) {
@@ skipping 23 matching lines @@
 void RenderWidgetHostViewAndroid::OnCompositingDidCommit() {
   RunAckCallbacks();
 }
 
 void RenderWidgetHostViewAndroid::OnDetachCompositor() {
   DCHECK(content_view_core_);
   DCHECK(!using_synchronous_compositor_);
   RunAckCallbacks();
 }
 
+void RenderWidgetHostViewAndroid::SubscribeToVSync(uint32 type) {
+  if (!vsync_subscribers_bitmask_)
+    content_view_core_->GetWindowAndroid()->AddObserver(this);
+
+  vsync_subscribers_bitmask_ |= type;
+
+  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+
+  // Synchronous compositor does not request begin frames OnVSync.
+  DCHECK(!using_synchronous_compositor_ || !IsSubscribedToType(BEGIN_FRAME));
+}
+
+void RenderWidgetHostViewAndroid::UnsubscribeToVSync(uint32 type) {
+  vsync_subscribers_bitmask_ &= ~type;
+  if (!vsync_subscribers_bitmask_)
+    content_view_core_->GetWindowAndroid()->RemoveObserver(this);
+}
+
+bool RenderWidgetHostViewAndroid::IsSubscribedToType(uint32 type) {

[boliu, 2014/08/20 20:30:00]

const

+  return !!(vsync_subscribers_bitmask_ & type);
+}
+
 void RenderWidgetHostViewAndroid::OnVSync(base::TimeTicks frame_time,
                                           base::TimeDelta vsync_period) {
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::OnVSync");
   if (!host_)
     return;
 
-  if (flush_input_requested_) {
-    flush_input_requested_ = false;
+  if (IsSubscribedToType(INPUT)) {
+    // Need to unsubscribe before host_->FlushInput(), because FlushInput()
+    // could cause RWHVA to subscribe to input again.
+    UnsubscribeToVSync(INPUT);
     host_->FlushInput();
   }
 
+  if (!IsSubscribedToType(BEGIN_FRAME))
+    return;
+
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::SendBeginFrame");
   base::TimeTicks display_time = frame_time + vsync_period;
 
   // TODO(brianderson): Use adaptive draw-time estimation.
   base::TimeDelta estimated_browser_composite_time =
       base::TimeDelta::FromMicroseconds(
           (1.0f * base::Time::kMicrosecondsPerSecond) / (3.0f * 60));
 
   base::TimeTicks deadline = display_time - estimated_browser_composite_time;
 
   host_->Send(new ViewMsg_BeginFrame(
       host_->GetRoutingID(),
       cc::BeginFrameArgs::Create(frame_time, deadline, vsync_period)));
 
-  if (needs_begin_frame_)
-    content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();
+  content_view_core_->GetWindowAndroid()->RequestVSyncUpdate();

[boliu, 2014/08/20 20:30:00]

This is still called outside of SubscribeToVSync.

 }
 
 void RenderWidgetHostViewAndroid::OnAnimate(base::TimeTicks begin_frame_time) {
   if (Animate(begin_frame_time))
     SetNeedsAnimate();
 }
 
 void RenderWidgetHostViewAndroid::OnLostResources() {
   ReleaseLocksOnSurface();
   if (layer_.get())
@@ skipping 133 matching lines @@
   results->orientationAngle = display.RotationAsDegree();
   results->orientationType =
       RenderWidgetHostViewBase::GetOrientationTypeForMobile(display);
   gfx::DeviceDisplayInfo info;
   results->depth = info.GetBitsPerPixel();
   results->depthPerComponent = info.GetBitsPerComponent();
   results->isMonochrome = (results->depthPerComponent == 0);
 }
 
 } // namespace content