Bug 1725267 - Split Paint entry points to make them easier to understand. r=tnikkel

Differential Revision: https://phabricator.services.mozilla.com/D125800

dom/base/nsDOMWindowUtils.cpp

@@ -360,7 +360,8 @@ nsDOMWindowUtils::UpdateLayerTree() {
     RefPtr<nsViewManager> vm = presShell->GetViewManager();
     if (nsView* view = vm->GetRootView()) {
       nsAutoScriptBlocker scriptBlocker;
-      presShell->Paint(view, PaintFlags::PaintSyncDecodeImages);
+      presShell->PaintAndRequestComposite(view,
+                                          PaintFlags::PaintSyncDecodeImages);
       presShell->GetWindowRenderer()->WaitOnTransactionProcessed();
     }
   }

dom/ipc/BrowserChild.cpp

@@ -2734,7 +2734,7 @@ mozilla::ipc::IPCResult BrowserChild::RecvRenderLayers(
   } else {
     RefPtr<nsViewManager> vm = presShell->GetViewManager();
     if (nsView* view = vm->GetRootView()) {
-      presShell->Paint(view, PaintFlags::None);
+      presShell->PaintAndRequestComposite(view, PaintFlags::None);
     }
   }
   presShell->SuppressDisplayport(false);

layout/base/PresShell.cpp

@@ -6195,22 +6195,47 @@ void PresShell::RemoveFrameFromApproximatelyVisibleList(nsIFrame* aFrame) {
   }
 }
 
-class nsAutoNotifyDidPaint {
- public:
-  nsAutoNotifyDidPaint(PresShell* aShell, PaintFlags aFlags)
-      : mShell(aShell), mFlags(aFlags) {}
-  ~nsAutoNotifyDidPaint() {
-    if (!!(mFlags & PaintFlags::PaintComposite)) {
-      mShell->GetPresContext()->NotifyDidPaintForSubtree();
-    }
+void PresShell::PaintAndRequestComposite(nsView* aView, PaintFlags aFlags) {
+  if (!mIsActive) {
+    return;
   }
 
- private:
-  PresShell* mShell;
-  PaintFlags mFlags;
-};
+  WindowRenderer* renderer = aView->GetWidget()->GetWindowRenderer();
+  NS_ASSERTION(renderer, "Must be in paint event");
+  if (renderer->AsFallback()) {
+    // The fallback renderer doesn't do any retaining, so we
+    // just need to notify the view and widget that we're invalid, and
+    // we'll do a paint+composite from the PaintWindow callback.
+    GetViewManager()->InvalidateView(aView);
+    return;
+  }
 
-void PresShell::Paint(nsView* aViewToPaint, PaintFlags aFlags) {
+  // Otherwise we're a retained WebRenderLayerManager, so we want to call
+  // Paint to update with any changes and push those to WR.
+  PaintInternalFlags flags = PaintInternalFlags::None;
+  if (aFlags & PaintFlags::PaintSyncDecodeImages) {
+    flags |= PaintInternalFlags::PaintSyncDecodeImages;
+  }
+  PaintInternal(aView, flags);
+}
+
+void PresShell::SyncPaintFallback(nsView* aView) {
+  if (!mIsActive) {
+    return;
+  }
+
+  WindowRenderer* renderer = aView->GetWidget()->GetWindowRenderer();
+  NS_ASSERTION(renderer->AsFallback(),
+               "Can't do Sync paint for remote renderers");
+  if (!renderer->AsFallback()) {
+    return;
+  }
+
+  PaintInternal(aView, PaintInternalFlags::PaintComposite);
+  GetPresContext()->NotifyDidPaintForSubtree();
+}
+
+void PresShell::PaintInternal(nsView* aViewToPaint, PaintInternalFlags aFlags) {
   nsCString url;
   nsIURI* uri = mDocument->GetDocumentURI();
   Document* contentRoot = GetPrimaryContentDocument();
@@ -6226,7 +6251,7 @@ void PresShell::Paint(nsView* aViewToPaint, PaintFlags aFlags) {
   // assert there. However, we don't rely on this assertion on Android because
   // we don't paint while JS is running.
 #if !defined(MOZ_WIDGET_ANDROID)
-  if (!(aFlags & PaintFlags::PaintComposite)) {
+  if (!(aFlags & PaintInternalFlags::PaintComposite)) {
     // We need to allow content JS when the flag is set since we may trigger
     // MozAfterPaint events in content in those cases.
     nojs.emplace(dom::danger::GetJSContext());
@@ -6258,9 +6283,6 @@ void PresShell::Paint(nsView* aViewToPaint, PaintFlags aFlags) {
   WindowRenderer* renderer = aViewToPaint->GetWidget()->GetWindowRenderer();
   NS_ASSERTION(renderer, "Must be in paint event");
   WebRenderLayerManager* layerManager = renderer->AsWebRender();
-  bool shouldInvalidate = renderer->NeedsWidgetInvalidation();
-
-  nsAutoNotifyDidPaint notifyDidPaint(this, aFlags);
 
   // Whether or not we should set first paint when painting is suppressed
   // is debatable. For now we'll do it because B2G relied on first paint
@@ -6277,13 +6299,6 @@ void PresShell::Paint(nsView* aViewToPaint, PaintFlags aFlags) {
   }
 
   if (!renderer->BeginTransaction(url)) {
-    if (renderer->AsFallback() && !(aFlags & PaintFlags::PaintComposite)) {
-      // The fallback renderer doesn't do any retaining, and so always
-      // fails when called without PaintComposite (from the refresh driver).
-      // We just need to notify the view and widget that we're invalid, and
-      // we'll do a paint+composite from the PaintWindow callback.
-      aViewToPaint->GetViewManager()->InvalidateView(aViewToPaint);
-    }
     return;
   }
 
@@ -6294,19 +6309,16 @@ void PresShell::Paint(nsView* aViewToPaint, PaintFlags aFlags) {
   }
 
   if (frame) {
-    if (!(aFlags & PaintFlags::PaintSyncDecodeImages) &&
+    if (!(aFlags & PaintInternalFlags::PaintSyncDecodeImages) &&
         !frame->HasAnyStateBits(NS_FRAME_UPDATE_LAYER_TREE)) {
       if (layerManager) {
         layerManager->SetTransactionIdAllocator(presContext->RefreshDriver());
       }
 
-      if (renderer->EndEmptyTransaction((aFlags & PaintFlags::PaintComposite)
-                                            ? LayerManager::END_DEFAULT
-                                            : LayerManager::END_NO_COMPOSITE)) {
-        if (shouldInvalidate) {
-          aViewToPaint->GetViewManager()->InvalidateView(aViewToPaint);
-        }
-
+      if (renderer->EndEmptyTransaction(
+              (aFlags & PaintInternalFlags::PaintComposite)
+                  ? LayerManager::END_DEFAULT
+                  : LayerManager::END_NO_COMPOSITE)) {
         frame->UpdatePaintCountForPaintedPresShells();
         return;
       }
@@ -6323,7 +6335,7 @@ void PresShell::Paint(nsView* aViewToPaint, PaintFlags aFlags) {
 
   // We force sync-decode for printing / print-preview (printing already does
   // this from nsPageSequenceFrame::PrintNextSheet).
-  if (aFlags & PaintFlags::PaintSyncDecodeImages ||
+  if (aFlags & PaintInternalFlags::PaintSyncDecodeImages ||
       mDocument->IsStaticDocument()) {
     flags |= PaintFrameFlags::SyncDecodeImages;
   }
@@ -6356,7 +6368,7 @@ void PresShell::Paint(nsView* aViewToPaint, PaintFlags aFlags) {
   FallbackRenderer* fallback = renderer->AsFallback();
   MOZ_ASSERT(fallback);
 
-  if (aFlags & PaintFlags::PaintComposite) {
+  if (aFlags & PaintInternalFlags::PaintComposite) {
     nsIntRect bounds = presContext->GetVisibleArea().ToOutsidePixels(
         presContext->AppUnitsPerDevPixel());
     fallback->EndTransactionWithColor(bounds, ToDeviceColor(bgcolor));

layout/base/PresShell.h

@@ -90,6 +90,7 @@ struct nsCallbackEventRequest;
 namespace mozilla {
 class nsDisplayList;
 class nsDisplayListBuilder;
+class FallbackRenderer;
 
 class AccessibleCaretEventHub;
 class EventStates;
@@ -1265,8 +1266,21 @@ class PresShell final : public nsStubDocumentObserver,
 
   void BackingScaleFactorChanged() { mPresContext->UIResolutionChangedSync(); }
 
+  /**
+   * Does any painting work required to update retained paint state, and pushes
+   * it the compositor (if any). Requests a composite, either by scheduling a
+   * remote composite, or invalidating the widget so that we get a call to
+   * SyncPaintFallback from the widget paint event.
+   */
   MOZ_CAN_RUN_SCRIPT
-  void Paint(nsView* aViewToPaint, PaintFlags aFlags);
+  void PaintAndRequestComposite(nsView* aView, PaintFlags aFlags);
+
+  /**
+   * Does an immediate paint+composite using the FallbackRenderer (which must
+   * be the current WindowRenderer for the root frame's widget).
+   */
+  MOZ_CAN_RUN_SCRIPT
+  void SyncPaintFallback(nsView* aView);
 
   /**
    * Notify that we're going to call Paint with PaintFlags::PaintLayers
@@ -1699,6 +1713,9 @@ class PresShell final : public nsStubDocumentObserver,
   void SetIsActive(bool aIsActive);
   bool ShouldBeActive() const;
 
+  MOZ_CAN_RUN_SCRIPT
+  void PaintInternal(nsView* aViewToPaint, PaintInternalFlags aFlags);
+
   /**
    * Refresh observer management.
    */

layout/base/PresShellForwards.h

@@ -188,14 +188,22 @@ MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(AddCanvasBackgroundColorFlags)
 
 enum class PaintFlags {
   None = 0,
-  /* Composite layers to the window. */
-  PaintComposite = 1 << 1,
   /* Sync-decode images. */
-  PaintSyncDecodeImages = 1 << 2,
+  PaintSyncDecodeImages = 1 << 1,
 };
 
 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(PaintFlags)
 
+enum class PaintInternalFlags {
+  None = 0,
+  /* Sync-decode images. */
+  PaintSyncDecodeImages = 1 << 1,
+  /* Composite layers to the window. */
+  PaintComposite = 1 << 2,
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(PaintInternalFlags)
+
 // This is a private enum class of PresShell, but currently,
 // MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS isn't available in class definition.
 // Therefore, we need to put this here.

view/nsViewManager.cpp

@@ -318,7 +318,7 @@ void nsViewManager::Refresh(nsView* aView,
       if (!renderer->NeedsWidgetInvalidation()) {
         renderer->FlushRendering();
       } else {
-        presShell->Paint(aView, PaintFlags::PaintComposite);
+        presShell->SyncPaintFallback(aView);
       }
 #ifdef MOZ_DUMP_PAINTING
       if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
@@ -441,7 +441,7 @@ void nsViewManager::ProcessPendingUpdatesPaint(nsIWidget* aWidget) {
       }
 #endif
 
-      presShell->Paint(view, PaintFlags::None);
+      presShell->PaintAndRequestComposite(view, PaintFlags::None);
       view->SetForcedRepaint(false);
 
 #ifdef MOZ_DUMP_PAINTING