Short-term fix for Aura Desktop/Window capture.

content/browser/media/capture/aura_window_capture_machine.cc

 // Copyright 2013 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/media/capture/aura_window_capture_machine.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/logging.h"
@@ skipping 62 matching lines @@
     return false;
 
   DCHECK(oracle_proxy);
   oracle_proxy_ = oracle_proxy;
   capture_params_ = params;
 
   // Update capture size.
   UpdateCaptureSize();
 
   // Start observing compositor updates.
-  if (desktop_window_->GetHost())
-    desktop_window_->GetHost()->compositor()->AddObserver(this);
+  if (aura::WindowTreeHost* host = desktop_window_->GetHost()) {
+    if (ui::Compositor* compositor = host->compositor())
+      compositor->AddAnimationObserver(this);
+  }

[GeorgeZ, 2016/04/27 16:44:34]

The function may return false if host or compositor is nullptr.

[miu, 2016/04/27 19:01:24]

Done.

 
   power_save_blocker_.reset(
       PowerSaveBlocker::Create(
           PowerSaveBlocker::kPowerSaveBlockPreventDisplaySleep,
           PowerSaveBlocker::kReasonOther,
           "DesktopCaptureDevice is running").release());
 
   return true;
 }
 
 void AuraWindowCaptureMachine::Stop(const base::Closure& callback) {
   // Stops the capture machine asynchronously.
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE, base::Bind(
           &AuraWindowCaptureMachine::InternalStop,
           base::Unretained(this),
           callback));
 }
 
 void AuraWindowCaptureMachine::InternalStop(const base::Closure& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   // Cancel any and all outstanding callbacks owned by external modules.
   weak_factory_.InvalidateWeakPtrs();
 
   power_save_blocker_.reset();
 
   // Stop observing compositor and window events.
   if (desktop_window_) {
-    aura::WindowTreeHost* window_host = desktop_window_->GetHost();
-    // In the host destructor the compositor is destroyed before the window.
-    if (window_host && window_host->compositor())
-      window_host->compositor()->RemoveObserver(this);
+    if (aura::WindowTreeHost* host = desktop_window_->GetHost()) {
+      if (ui::Compositor* compositor = host->compositor())
+        compositor->RemoveAnimationObserver(this);
+    }
     desktop_window_->RemoveObserver(this);
     desktop_window_ = NULL;
     cursor_renderer_.reset();
   }
 
   callback.Run();
 }
 
 void AuraWindowCaptureMachine::MaybeCaptureForRefresh() {
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&AuraWindowCaptureMachine::Capture,
                  // Use of Unretained() is safe here since this task must run
                  // before InternalStop().
                  base::Unretained(this),
-                 false));
+                 base::TimeTicks()));
 }
 
 void AuraWindowCaptureMachine::SetWindow(aura::Window* window) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   DCHECK(!desktop_window_);
   desktop_window_ = window;
   cursor_renderer_.reset(new CursorRendererAura(window, kCursorAlwaysEnabled));
 
   // Start observing window events.
   desktop_window_->AddObserver(this);
 
   // We must store this for the UMA reporting in DidCopyOutput() as
   // desktop_window_ might be destroyed at that point.
   screen_capture_ = window->IsRootWindow();
   IncrementDesktopCaptureCounter(screen_capture_ ? SCREEN_CAPTURER_CREATED
                                                  : WINDOW_CAPTURER_CREATED);
 }
 
 void AuraWindowCaptureMachine::UpdateCaptureSize() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   if (oracle_proxy_ && desktop_window_) {
      ui::Layer* layer = desktop_window_->layer();
      oracle_proxy_->UpdateCaptureSize(ui::ConvertSizeToPixel(
          layer, layer->bounds().size()));
   }
   cursor_renderer_->Clear();
 }
 
-void AuraWindowCaptureMachine::Capture(bool dirty) {
+void AuraWindowCaptureMachine::Capture(base::TimeTicks event_time) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   // Do not capture if the desktop window is already destroyed.
   if (!desktop_window_)
     return;
 
   scoped_refptr<media::VideoFrame> frame;
   media::ThreadSafeCaptureOracle::CaptureFrameCallback capture_frame_cb;
 
   // TODO(miu): Need to fix this so the compositor is providing the presentation
   // timestamps and damage regions, to leverage the frame timestamp rewriting
   // logic.  http://crbug.com/492839
   const base::TimeTicks start_time = base::TimeTicks::Now();
-  const media::VideoCaptureOracle::Event event =
-      dirty ? media::VideoCaptureOracle::kCompositorUpdate
-            : media::VideoCaptureOracle::kActiveRefreshRequest;
+  media::VideoCaptureOracle::Event event;
+  if (event_time.is_null()) {
+    event = media::VideoCaptureOracle::kActiveRefreshRequest;
+    event_time = start_time;
+  } else {
+    event = media::VideoCaptureOracle::kCompositorUpdate;
+  }
   if (oracle_proxy_->ObserveEventAndDecideCapture(
-          event, gfx::Rect(), start_time, &frame, &capture_frame_cb)) {
+          event, gfx::Rect(), event_time, &frame, &capture_frame_cb)) {
     std::unique_ptr<cc::CopyOutputRequest> request =
         cc::CopyOutputRequest::CreateRequest(base::Bind(
             &AuraWindowCaptureMachine::DidCopyOutput,
-            weak_factory_.GetWeakPtr(), frame, start_time, capture_frame_cb));
+            weak_factory_.GetWeakPtr(), frame, event_time, start_time,
+            capture_frame_cb));
     gfx::Rect window_rect = gfx::Rect(desktop_window_->bounds().width(),
                                       desktop_window_->bounds().height());
     request->set_area(window_rect);
     desktop_window_->layer()->RequestCopyOfOutput(std::move(request));
   }
 }
 
 void AuraWindowCaptureMachine::DidCopyOutput(
     scoped_refptr<media::VideoFrame> video_frame,
+    base::TimeTicks event_time,
     base::TimeTicks start_time,
     const CaptureFrameCallback& capture_frame_cb,
     std::unique_ptr<cc::CopyOutputResult> result) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   static bool first_call = true;
 
   const bool succeeded = ProcessCopyOutputResponse(
-      video_frame, start_time, capture_frame_cb, std::move(result));
+      video_frame, event_time, capture_frame_cb, std::move(result));
 
-  base::TimeDelta capture_time = base::TimeTicks::Now() - start_time;
+  const base::TimeDelta capture_time = base::TimeTicks::Now() - start_time;
 
   // The two UMA_ blocks must be put in its own scope since it creates a static
   // variable which expected constant histogram name.
   if (screen_capture_) {
     UMA_HISTOGRAM_TIMES(kUmaScreenCaptureTime, capture_time);
   } else {
     UMA_HISTOGRAM_TIMES(kUmaWindowCaptureTime, capture_time);
   }
 
   if (first_call) {
     first_call = false;
     if (screen_capture_) {
       IncrementDesktopCaptureCounter(succeeded ? FIRST_SCREEN_CAPTURE_SUCCEEDED
                                                : FIRST_SCREEN_CAPTURE_FAILED);
     } else {
       IncrementDesktopCaptureCounter(succeeded
                                          ? FIRST_WINDOW_CAPTURE_SUCCEEDED
                                          : FIRST_WINDOW_CAPTURE_FAILED);
     }
   }
 
   // If ProcessCopyOutputResponse() failed, it will not run |capture_frame_cb|,
   // so do that now.
   if (!succeeded)
-    capture_frame_cb.Run(video_frame, start_time, false);
+    capture_frame_cb.Run(video_frame, event_time, false);
 }
 
 bool AuraWindowCaptureMachine::ProcessCopyOutputResponse(
     scoped_refptr<media::VideoFrame> video_frame,
-    base::TimeTicks start_time,
+    base::TimeTicks event_time,
     const CaptureFrameCallback& capture_frame_cb,
     std::unique_ptr<cc::CopyOutputResult> result) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
-  if (result->IsEmpty() || result->size().IsEmpty() || !desktop_window_)
+  if (!desktop_window_) {
+    VLOG(1) << "Ignoring CopyOutputResult: Capture target has gone away.";
     return false;
+  }
+  if (result->IsEmpty()) {
+    VLOG(1) << "CopyOutputRequest failed: No texture or bitmap in result.";
+    return false;
+  }
+  if (result->size().IsEmpty()) {
+    VLOG(1) << "CopyOutputRequest failed: Zero-area texture/bitmap result.";
+    return false;
+  }
   DCHECK(video_frame);
 
   // Compute the dest size we want after the letterboxing resize. Make the
   // coordinates and sizes even because we letterbox in YUV space
   // (see CopyRGBToVideoFrame). They need to be even for the UV samples to
   // line up correctly.
   // The video frame's visible_rect() and the result's size() are both physical
   // pixels.
   gfx::Rect region_in_frame = media::ComputeLetterboxRegion(
       video_frame->visible_rect(), result->size());
   region_in_frame = gfx::Rect(region_in_frame.x() & ~1,
                               region_in_frame.y() & ~1,
                               region_in_frame.width() & ~1,
                               region_in_frame.height() & ~1);
-  if (region_in_frame.IsEmpty())
+  if (region_in_frame.IsEmpty()) {
+    VLOG(1) << "Aborting capture: Computed empty letterboxed content region.";
     return false;
+  }
 
   ImageTransportFactory* factory = ImageTransportFactory::GetInstance();
   display_compositor::GLHelper* gl_helper = factory->GetGLHelper();
-  if (!gl_helper)
+  if (!gl_helper) {
+    VLOG(1) << "Aborting capture: No GLHelper available for YUV readback.";
     return false;
+  }
 
   cc::TextureMailbox texture_mailbox;
   std::unique_ptr<cc::SingleReleaseCallback> release_callback;
   result->TakeTexture(&texture_mailbox, &release_callback);
   DCHECK(texture_mailbox.IsTexture());
-  if (!texture_mailbox.IsTexture())
+  if (!texture_mailbox.IsTexture()) {
+    VLOG(1) << "Aborting capture: Failed to take texture from mailbox.";
     return false;
+  }
 
   gfx::Rect result_rect(result->size());
   if (!yuv_readback_pipeline_ ||
       yuv_readback_pipeline_->scaler()->SrcSize() != result_rect.size() ||
       yuv_readback_pipeline_->scaler()->SrcSubrect() != result_rect ||
       yuv_readback_pipeline_->scaler()->DstSize() != region_in_frame.size()) {
     yuv_readback_pipeline_.reset(gl_helper->CreateReadbackPipelineYUV(
         display_compositor::GLHelper::SCALER_QUALITY_FAST, result_rect.size(),
         result_rect, region_in_frame.size(), true, true));
   }
 
   cursor_renderer_->SnapshotCursorState(region_in_frame);
   yuv_readback_pipeline_->ReadbackYUV(
       texture_mailbox.mailbox(), texture_mailbox.sync_token(),
       video_frame->visible_rect(),
       video_frame->stride(media::VideoFrame::kYPlane),
       video_frame->data(media::VideoFrame::kYPlane),
       video_frame->stride(media::VideoFrame::kUPlane),
       video_frame->data(media::VideoFrame::kUPlane),
       video_frame->stride(media::VideoFrame::kVPlane),
       video_frame->data(media::VideoFrame::kVPlane), region_in_frame.origin(),
       base::Bind(&CopyOutputFinishedForVideo, weak_factory_.GetWeakPtr(),
-                 start_time, capture_frame_cb, video_frame,
+                 event_time, capture_frame_cb, video_frame,
                  base::Passed(&release_callback)));
   media::LetterboxYUV(video_frame.get(), region_in_frame);
   return true;
 }
 
 using CaptureFrameCallback =
     media::ThreadSafeCaptureOracle::CaptureFrameCallback;
 
 void AuraWindowCaptureMachine::CopyOutputFinishedForVideo(
     base::WeakPtr<AuraWindowCaptureMachine> machine,
-    base::TimeTicks start_time,
+    base::TimeTicks event_time,
     const CaptureFrameCallback& capture_frame_cb,
     const scoped_refptr<media::VideoFrame>& target,
     std::unique_ptr<cc::SingleReleaseCallback> release_callback,
     bool result) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   release_callback->Run(gpu::SyncToken(), false);
 
   // Render the cursor and deliver the captured frame if the
   // AuraWindowCaptureMachine has not been stopped (i.e., the WeakPtr is
   // still valid).
   if (machine) {
     if (machine->cursor_renderer_ && result)
       machine->cursor_renderer_->RenderOnVideoFrame(target);
   } else {
+    VLOG(1) << "Aborting capture: AuraWindowCaptureMachine has gone away.";
     result = false;
   }
 
-  capture_frame_cb.Run(target, start_time, result);
+  capture_frame_cb.Run(target, event_time, result);
 }
 
 void AuraWindowCaptureMachine::OnWindowBoundsChanged(
     aura::Window* window,
     const gfx::Rect& old_bounds,
     const gfx::Rect& new_bounds) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(desktop_window_ && window == desktop_window_);
 
   // Post a task to update capture size after first returning to the event loop.
   BrowserThread::PostTask(BrowserThread::UI, FROM_HERE, base::Bind(
       &AuraWindowCaptureMachine::UpdateCaptureSize,
       weak_factory_.GetWeakPtr()));
 }
 
 void AuraWindowCaptureMachine::OnWindowDestroying(aura::Window* window) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   InternalStop(base::Bind(&base::DoNothing));
 
   oracle_proxy_->ReportError(FROM_HERE, "OnWindowDestroying()");
 }
 
 void AuraWindowCaptureMachine::OnWindowAddedToRootWindow(
     aura::Window* window) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(window == desktop_window_);
 
-  window->GetHost()->compositor()->AddObserver(this);
+  if (aura::WindowTreeHost* host = window->GetHost()) {
+    if (ui::Compositor* compositor = host->compositor())
+      compositor->AddAnimationObserver(this);
+  }
 }
 
 void AuraWindowCaptureMachine::OnWindowRemovingFromRootWindow(
     aura::Window* window,
     aura::Window* new_root) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(window == desktop_window_);
 
-  window->GetHost()->compositor()->RemoveObserver(this);
+  if (aura::WindowTreeHost* host = window->GetHost()) {
+    if (ui::Compositor* compositor = host->compositor())
+      compositor->RemoveAnimationObserver(this);
+  }
 }
 
-void AuraWindowCaptureMachine::OnCompositingEnded(
+void AuraWindowCaptureMachine::OnAnimationStep(base::TimeTicks timestamp) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(!timestamp.is_null());
+
+  // HACK: The compositor invokes this observer method to step layer animation
+  // forward. Scheduling frame capture was not the intention, and so invoking
+  // this method does not actually indicate the content has changed. However,
+  // this is the only reliable way to ensure all screen changes are captured, as
+  // of this writing.
+  // http://crbug.com/600031
+  //
+  // TODO(miu): Need a better observer callback interface from the compositor
+  // for this use case. The solution here will always capture frames at the
+  // maximum framerate, which means CPU/GPU is being wasted on redundant
+  // captures and quality/smoothness of animating content will suffer
+  // significantly.
+  // http://crbug.com/492839
+  Capture(timestamp);
+}
+
+void AuraWindowCaptureMachine::OnCompositingShuttingDown(
     ui::Compositor* compositor) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-
-  // TODO(miu): The CopyOutputRequest should be made earlier, at WillCommit().
-  // http://crbug.com/492839
-  BrowserThread::PostTask(
-      BrowserThread::UI,
-      FROM_HERE,
-      base::Bind(&AuraWindowCaptureMachine::Capture, weak_factory_.GetWeakPtr(),
-                 true));
+  compositor->RemoveAnimationObserver(this);
 }
 
 }  // namespace content