Bug 1961115 - Skip compositor-related work when rendering without presenting. r=gfx-reviewers,gw

Differential Revision: https://phabricator.services.mozilla.com/D245565

gfx/webrender_bindings/RendererOGL.cpp

@@ -169,31 +169,49 @@ RenderedFrameId RendererOGL::UpdateAndRender(
   widgetContext.mGL = mCompositor->gl();
 #endif
 
-  if (!mCompositor->GetWidget()->PreRender(&widgetContext)) {
+  // If present is false, WebRender needs to render some offscreen content
-    // XXX This could cause oom in webrender since pending_texture_updates is
+  // but we don't want to touch the window, so we avoid most interactions
-    // not handled. It needs to be addressed.
+  // with mCompositor.
-    return RenderedFrameId();
+  bool present = aFrameParams.present;
-  }
-  // XXX set clear color if MOZ_WIDGET_ANDROID is defined.
 
-  if (mThread->IsHandlingDeviceReset() || !mCompositor->BeginFrame()) {
+  LayoutDeviceIntSize size(0, 0);
+  auto bufferAge = 0;
+  bool fullRender = false;
+
+  bool beginFrame = !mThread->IsHandlingDeviceReset();
+
+  if (beginFrame && present) {
+    if (!mCompositor->GetWidget()->PreRender(&widgetContext)) {
+      // XXX This could cause oom in webrender since pending_texture_updates is
+      // not handled. It needs to be addressed.
+      return RenderedFrameId();
+    }
+    // XXX set clear color if MOZ_WIDGET_ANDROID is defined.
+
+    if (!mCompositor->BeginFrame()) {
+      beginFrame = false;
+    }
+
+    size = mCompositor->GetBufferSize();
+    bufferAge = mCompositor->GetBufferAge();
+
+    fullRender = mCompositor->RequestFullRender();
+    // When we're rendering to an external target, we want to render everything.
+    if (mCompositor->UsePartialPresent() &&
+        (aReadbackBuffer.isSome() ||
+         layers::ProfilerScreenshots::IsEnabled())) {
+      fullRender = true;
+    }
+  }
+
+  if (!beginFrame) {
     CheckGraphicsResetStatus(gfx::DeviceResetDetectPlace::WR_BEGIN_FRAME,
                              /* aForce */ true);
-    mCompositor->GetWidget()->PostRender(&widgetContext);
     return RenderedFrameId();
   }
 
-  auto size = mCompositor->GetBufferSize();
-  auto bufferAge = mCompositor->GetBufferAge();
-
   wr_renderer_update(mRenderer);
 
-  bool fullRender = mCompositor->RequestFullRender();
-  // When we're rendering to an external target, we want to render everything.
-  if (mCompositor->UsePartialPresent() &&
-      (aReadbackBuffer.isSome() || layers::ProfilerScreenshots::IsEnabled())) {
-    fullRender = true;
-  }
   if (fullRender) {
     wr_renderer_force_redraw(mRenderer);
   }
@@ -203,42 +221,47 @@ RenderedFrameId RendererOGL::UpdateAndRender(
                                      bufferAge, aOutStats, &dirtyRects);
   FlushPipelineInfo();
   if (!rendered) {
-    mCompositor->CancelFrame();
+    if (present) {
+      mCompositor->CancelFrame();
+      mCompositor->GetWidget()->PostRender(&widgetContext);
+    }
     RenderThread::Get()->HandleWebRenderError(WebRenderError::RENDER);
-    mCompositor->GetWidget()->PostRender(&widgetContext);
     return RenderedFrameId();
   }
 
-  if (aReadbackBuffer.isSome()) {
+  RenderedFrameId frameId;
-    MOZ_ASSERT(aReadbackSize.isSome());
+
-    MOZ_ASSERT(aReadbackFormat.isSome());
+  if (present) {
-    if (!mCompositor->MaybeReadback(aReadbackSize.ref(), aReadbackFormat.ref(),
+    if (aReadbackBuffer.isSome()) {
-                                    aReadbackBuffer.ref(), aNeedsYFlip)) {
+      MOZ_ASSERT(aReadbackSize.isSome());
-      wr_renderer_readback(mRenderer, aReadbackSize.ref().width,
+      MOZ_ASSERT(aReadbackFormat.isSome());
-                           aReadbackSize.ref().height, aReadbackFormat.ref(),
+      if (!mCompositor->MaybeReadback(aReadbackSize.ref(),
-                           &aReadbackBuffer.ref()[0],
+                                      aReadbackFormat.ref(),
-                           aReadbackBuffer.ref().length());
+                                      aReadbackBuffer.ref(), aNeedsYFlip)) {
-      if (aNeedsYFlip) {
+        wr_renderer_readback(mRenderer, aReadbackSize.ref().width,
-        *aNeedsYFlip = !mCompositor->SurfaceOriginIsTopLeft();
+                             aReadbackSize.ref().height, aReadbackFormat.ref(),
+                             &aReadbackBuffer.ref()[0],
+                             aReadbackBuffer.ref().length());
+        if (aNeedsYFlip != nullptr) {
+          *aNeedsYFlip = !mCompositor->SurfaceOriginIsTopLeft();
+        }
       }
     }
-  }
 
-  if (size.Width() != 0 && size.Height() != 0) {
+    if (size.Width() != 0 && size.Height() != 0) {
-    if (!mCompositor->MaybeGrabScreenshot(size.ToUnknownSize())) {
+      if (!mCompositor->MaybeGrabScreenshot(size.ToUnknownSize())) {
-      mScreenshotGrabber.MaybeGrabScreenshot(this, size.ToUnknownSize());
+        mScreenshotGrabber.MaybeGrabScreenshot(this, size.ToUnknownSize());
+      }
     }
+
+    // Frame recording must happen before EndFrame, as we must ensure we read
+    // the contents of the back buffer before any calls to SwapBuffers which
+    // might invalidate it.
+    MaybeRecordFrame(mLastPipelineInfo);
+    frameId = mCompositor->EndFrame(dirtyRects);
+    mCompositor->GetWidget()->PostRender(&widgetContext);
   }
 
-  // Frame recording must happen before EndFrame, as we must ensure we read the
-  // contents of the back buffer before any calls to SwapBuffers which might
-  // invalidate it.
-  MaybeRecordFrame(mLastPipelineInfo);
-
-  RenderedFrameId frameId = mCompositor->EndFrame(dirtyRects);
-
-  mCompositor->GetWidget()->PostRender(&widgetContext);
-
 #if defined(ENABLE_FRAME_LATENCY_LOG)
   if (mFrameStartTime) {
     uint32_t latencyMs =
@@ -249,8 +272,10 @@ RenderedFrameId RendererOGL::UpdateAndRender(
   mFrameStartTime = TimeStamp();
 #endif
 
-  if (!mCompositor->MaybeProcessScreenshotQueue()) {
+  if (present) {
-    mScreenshotGrabber.MaybeProcessQueue(this);
+    if (!mCompositor->MaybeProcessScreenshotQueue()) {
+      mScreenshotGrabber.MaybeProcessQueue(this);
+    }
   }
 
   // TODO: Flush pending actions such as texture deletions/unlocks and

gfx/wr/webrender/src/renderer/mod.rs

@@ -1274,10 +1274,16 @@ impl Renderer {
                     .remove(&doc_id)
                     .unwrap();
 
+                let size = if !device_size.is_empty() {
+                    Some(device_size)
+                } else {
+                    None
+                };
+
                 let result = self.render_impl(
                     doc_id,
                     &mut doc,
-                    Some(device_size),
+                    size,
                     buffer_age,
                 );
 
@@ -3127,7 +3133,7 @@ impl Renderer {
                             &mut self.renderer_errors,
                             &mut self.profile,
                         );
-                
+
                     ( textures, instance )
                 },
                 ResolvedExternalSurfaceColorData::Rgb{ ref plane, .. } => {