Bug 780342 - Don't allow compositor-driven animation of frames that are not prerendered, provide diagnostics for when that happens r=cjones

layout/base/nsDisplayList.cpp

@@ -326,12 +326,13 @@ AddAnimationsForProperty(nsIFrame* aFrame, nsCSSProperty aProperty,
 }
 
 static void
-AddAnimationsAndTransitionsToLayer(Layer* aLayer, nsDisplayItem* aItem,
-                                   nsCSSProperty aProperty)
+AddAnimationsAndTransitionsToLayer(Layer* aLayer, nsDisplayListBuilder* aBuilder,
+                                   nsDisplayItem* aItem, nsCSSProperty aProperty)
 {
   aLayer->ClearAnimations();
 
   nsIFrame* frame = aItem->GetUnderlyingFrame();
+
   nsIContent* aContent = frame->GetContent();
   ElementTransitions* et =
     nsTransitionManager::GetTransitionsForCompositor(aContent, aProperty);
@@ -343,6 +344,23 @@ AddAnimationsAndTransitionsToLayer(Layer* aLayer, nsDisplayItem* aItem,
     return;
   }
 
+  // If the frame is not prerendered, bail out.  Layout will still perform the
+  // animation.
+  if (!nsDisplayTransform::ShouldPrerenderTransformedContent(aBuilder, frame)) {
+    if (nsLayoutUtils::IsAnimationLoggingEnabled()) {
+      nsIContent* aContent = frame->GetContent();
+      printf_stderr("Performance warning: Async animation disabled because the frame for element '%s'",
+                    nsAtomCString(aContent->Tag()).get());
+      nsIAtom* id = aContent->GetID();
+      if (id) {
+        printf_stderr(" with id '%s'",
+                      nsAtomCString(aContent->GetID()).get());
+      }
+      printf_stderr(" is not prerendered\n");
+    }
+    return;
+  }
+
   mozilla::TimeStamp currentTime =
     frame->PresContext()->RefreshDriver()->MostRecentRefresh();
   AnimationData data;
@@ -2352,7 +2370,8 @@ nsDisplayOpacity::BuildLayer(nsDisplayListBuilder* aBuilder,
     return nullptr;
 
   container->SetOpacity(mFrame->GetStyleDisplay()->mOpacity);
-  AddAnimationsAndTransitionsToLayer(container, this, eCSSProperty_opacity);
+  AddAnimationsAndTransitionsToLayer(container, aBuilder,
+                                     this, eCSSProperty_opacity);
 
   return container.forget();
 }
@@ -3364,7 +3383,8 @@ already_AddRefed<Layer> nsDisplayTransform::BuildLayer(nsDisplayListBuilder *aBu
     container->SetContentFlags(container->GetContentFlags() | Layer::CONTENT_PRESERVE_3D);
   }
 
-  AddAnimationsAndTransitionsToLayer(container, this, eCSSProperty_transform);
+  AddAnimationsAndTransitionsToLayer(container, aBuilder,
+                                     this, eCSSProperty_transform);
   return container.forget();
 }
 

layout/base/nsLayoutUtils.cpp

@@ -188,6 +188,21 @@ nsLayoutUtils::AreTransformAnimationsEnabled()
   return sAreTransformAnimationsEnabled && CompositorParent::CompositorLoop();
 }
 
+bool
+nsLayoutUtils::IsAnimationLoggingEnabled()
+{
+  static bool sShouldLog;
+  static bool sShouldLogPrefCached;
+
+  if (!sShouldLogPrefCached) {
+    sShouldLogPrefCached = true;
+    Preferences::AddBoolVarCache(&sShouldLog,
+                                 "layers.offmainthreadcomposition.log-animations");
+  }
+
+  return sShouldLog;
+}
+
 bool
 nsLayoutUtils::UseBackgroundNearestFiltering()
 {

layout/base/nsLayoutUtils.h

@@ -1515,6 +1515,11 @@ public:
   static bool AreOpacityAnimationsEnabled();
   static bool AreTransformAnimationsEnabled();
 
+  /**
+   * Checks if we should warn about animations that can't be async
+   */
+  static bool IsAnimationLoggingEnabled();
+
   /**
    * Checks if we should forcibly use nearest pixel filtering for the
    * background.

layout/style/AnimationCommon.cpp

@@ -220,22 +220,14 @@ bool
 CommonElementAnimationData::CanAnimatePropertyOnCompositor(const dom::Element *aElement,
                                                            nsCSSProperty aProperty)
 {
-  static bool sShouldLog;
-  static bool sShouldLogPrefCached;
-
-  if (!sShouldLogPrefCached) {
-    sShouldLogPrefCached = true;
-    Preferences::AddBoolVarCache(&sShouldLog,
-                                 "layers.offmainthreadcomposition.log-animations");
-  }
-
+  bool shouldLog = nsLayoutUtils::IsAnimationLoggingEnabled();
   nsIFrame* frame = aElement->GetPrimaryFrame();
   if (aProperty == eCSSProperty_visibility) {
     return true;
   }
   if (aProperty == eCSSProperty_opacity) {
     bool enabled = nsLayoutUtils::AreOpacityAnimationsEnabled();
-    if (!enabled && sShouldLog) {
+    if (!enabled && shouldLog) {
       printf_stderr("Performance warning: Async animation of 'opacity' is disabled\n");
     }
     return enabled;
@@ -244,24 +236,24 @@ CommonElementAnimationData::CanAnimatePropertyOnCompositor(const dom::Element *a
     if (frame &&
         frame->Preserves3D() &&
         frame->Preserves3DChildren()) {
-      if (sShouldLog) {
+      if (shouldLog) {
         printf_stderr("Gecko bug: Async animation of 'preserve-3d' transforms is not supported.  See bug 779598\n");
       }
       return false;
     }
     if (frame && frame->IsSVGTransformed()) {
-      if (sShouldLog) {
+      if (shouldLog) {
         printf_stderr("Gecko bug: Async 'transform' animations of frames with SVG transforms is not supported.  See bug 779599\n");
       }
       return false;
     }
     bool enabled = nsLayoutUtils::AreTransformAnimationsEnabled();
-    if (!enabled && sShouldLog) {
+    if (!enabled && shouldLog) {
       printf_stderr("Performance warning: Async animation of 'transform' is disabled\n");
     }
     return enabled;
   }
-  if (sShouldLog) {
+  if (shouldLog) {
     const nsAFlatCString propName = nsCSSProps::GetStringValue(aProperty);
     printf_stderr("Performance warning: Async animation cancelled because of unsupported property '%s'\n", propName.get());
   }

modules/libpref/src/init/all.js

@@ -3522,6 +3522,7 @@ pref("layers.acceleration.draw-fps", false);
 // Whether to animate simple opacity and transforms on the compositor
 pref("layers.offmainthreadcomposition.animate-opacity", false);
 pref("layers.offmainthreadcomposition.animate-transform", false);
+pref("layers.offmainthreadcomposition.log-animations", false);
 
 #ifdef MOZ_X11
 #ifdef MOZ_WIDGET_GTK2