Bug 1547737 - Make RecvRequestScreenPixels work with WR. r=jnicol

Differential Revision: https://phabricator.services.mozilla.com/D49492

--HG--
extra : moz-landing-system : lando

Author: Kris Taeleman

gfx/layers/ipc/UiCompositorControllerParent.cpp

@@ -14,6 +14,7 @@
 #include "mozilla/layers/CompositorThread.h"
 #include "mozilla/layers/LayerManagerComposite.h"
 #include "mozilla/layers/UiCompositorControllerMessageTypes.h"
+#include "mozilla/layers/WebRenderBridgeParent.h"
 #include "mozilla/gfx/Types.h"
 #include "mozilla/Move.h"
 #include "mozilla/Unused.h"
@@ -175,6 +176,9 @@ UiCompositorControllerParent::RecvRequestScreenPixels() {
     state->mLayerManager->RequestScreenPixels(this);
     state->mParent->Invalidate();
     state->mParent->ScheduleComposition();
+  } else if (state && state->mWrBridge) {
+    state->mWrBridge->RequestScreenPixels(this);
+    state->mWrBridge->ScheduleForcedGenerateFrame();
   }
 #endif  // defined(MOZ_WIDGET_ANDROID)
 

gfx/layers/wr/WebRenderBridgeParent.cpp

@@ -333,6 +333,9 @@ WebRenderBridgeParent::WebRenderBridgeParent(
       mWrEpoch{0},
       mIdNamespace(aApis[0]->GetNamespace()),
       mRenderRootRectMutex("WebRenderBridgeParent::mRenderRootRectMutex"),
+#if defined(MOZ_WIDGET_ANDROID)
+      mScreenPixelsTarget(nullptr),
+#endif
       mPaused(false),
       mDestroyed(false),
       mReceivedDisplayList(false),
@@ -1717,6 +1720,49 @@ void WebRenderBridgeParent::FlushFramePresentation() {
   mApis[wr::RenderRoot::Default]->WaitFlushed();
 }
 
+#if defined(MOZ_WIDGET_ANDROID)
+void WebRenderBridgeParent::RequestScreenPixels(
+    UiCompositorControllerParent* aController) {
+  mScreenPixelsTarget = aController;
+}
+
+void WebRenderBridgeParent::MaybeCaptureScreenPixels() {
+  if (!mScreenPixelsTarget) {
+    return;
+  }
+
+  if (mDestroyed) {
+    return;
+  }
+  MOZ_ASSERT(!mPaused);
+
+  // This function should only get called in the root WRBP.
+  MOZ_ASSERT(IsRootWebRenderBridgeParent());
+
+  SurfaceFormat format = SurfaceFormat::R8G8B8A8;  // On android we use RGBA8
+  auto client_size = mWidget->GetClientSize();
+  size_t buffer_size =
+      client_size.width * client_size.height * BytesPerPixel(format);
+
+  ipc::Shmem mem;
+  if (!mScreenPixelsTarget->AllocPixelBuffer(buffer_size, &mem)) {
+    // Failed to alloc shmem, Just bail out.
+    return;
+  }
+
+  IntSize size(client_size.width, client_size.height);
+
+  mApis[wr::RenderRoot::Default]->Readback(
+      TimeStamp::Now(), size, format,
+      Range<uint8_t>(mem.get<uint8_t>(), buffer_size));
+
+  Unused << mScreenPixelsTarget->SendScreenPixels(
+      std::move(mem), ScreenIntSize(client_size.width, client_size.height));
+
+  mScreenPixelsTarget = nullptr;
+}
+#endif
+
 mozilla::ipc::IPCResult WebRenderBridgeParent::RecvGetSnapshot(
     PTextureParent* aTexture) {
   if (mDestroyed) {
@@ -2357,6 +2403,10 @@ void WebRenderBridgeParent::MaybeGenerateFrame(VsyncId aId,
   }
   wr::WebRenderAPI::SendTransactions(mApis, generateFrameTxns);
 
+#if defined(MOZ_WIDGET_ANDROID)
+  MaybeCaptureScreenPixels();
+#endif
+
   mMostRecentComposite = TimeStamp::Now();
 }
 

gfx/layers/wr/WebRenderBridgeParent.h

@@ -298,6 +298,14 @@ class WebRenderBridgeParent final
    */
   void WriteCollectedFrames();
 
+#if defined(MOZ_WIDGET_ANDROID)
+  /**
+   * Request a screengrab for android
+   */
+  void RequestScreenPixels(UiCompositorControllerParent* aController);
+  void MaybeCaptureScreenPixels();
+#endif
+
  private:
   class ScheduleSharedSurfaceRelease;
 
@@ -548,6 +556,9 @@ class WebRenderBridgeParent final
   wr::NonDefaultRenderRootArray<ScreenRect> mRenderRootRects;
 
   Maybe<wr::RenderRoot> mRenderRoot;
+#if defined(MOZ_WIDGET_ANDROID)
+  UiCompositorControllerParent* mScreenPixelsTarget;
+#endif
   bool mPaused;
   bool mDestroyed;
   bool mReceivedDisplayList;