[SPv2] Decomposite otherwise-compositable animations that paint nothing.

third_party/WebKit/Source/core/animation/Animation.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/animation/Animation.h"
 
 #include "core/animation/AnimationTimeline.h"
 #include "core/animation/CompositorPendingAnimations.h"
 #include "core/animation/KeyframeEffectReadOnly.h"
 #include "core/animation/css/CSSAnimations.h"
+#include "core/dom/DOMNodeIds.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/StyleChangeReason.h"
 #include "core/dom/TaskRunnerHelper.h"
 #include "core/events/AnimationPlaybackEvent.h"
 #include "core/frame/UseCounter.h"
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/probe/CoreProbes.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/WebTaskRunner.h"
@@ skipping 199 matching lines @@
 
 double Animation::unlimitedCurrentTimeInternal() const {
 #if DCHECK_IS_ON()
   currentTimeInternal();
 #endif
   return playStateInternal() == Paused || isNull(m_startTime)
              ? currentTimeInternal()
              : calculateCurrentTime();
 }
 
-bool Animation::preCommit(int compositorGroup, bool startOnCompositor) {
+bool Animation::preCommit(
+    int compositorGroup,
+    const Optional<CompositorElementIdSet>& compositedElementIds,
+    bool startOnCompositor) {
   PlayStateUpdateScope updateScope(*this, TimingUpdateOnDemand,
                                    DoNotSetCompositorPending);
 
   bool softChange =
       m_compositorState &&
       (paused() || m_compositorState->playbackRate != m_playbackRate);
   bool hardChange =
       m_compositorState && (m_compositorState->effectChanged ||
                             m_compositorState->startTime != m_startTime);
 
@@ skipping 17 matching lines @@
 
   DCHECK(!m_compositorState || !std::isnan(m_compositorState->startTime));
 
   if (!shouldStart) {
     m_currentTimePending = false;
   }
 
   if (shouldStart) {
     m_compositorGroup = compositorGroup;
     if (startOnCompositor) {
-      if (isCandidateForAnimationOnCompositor())
+      if (isCandidateForAnimationOnCompositor(compositedElementIds))
         createCompositorPlayer();
 
-      if (maybeStartAnimationOnCompositor())
+      if (maybeStartAnimationOnCompositor(compositedElementIds))
         m_compositorState = WTF::wrapUnique(new CompositorState(*this));
       else
         cancelIncompatibleAnimationsOnCompositor();
     }
   }
 
   return true;
 }
 
 void Animation::postCommit(double timelineTime) {
@@ skipping 407 matching lines @@
     return;
   m_outdated = true;
   if (m_timeline)
     m_timeline->setOutdatedAnimation(this);
 }
 
 void Animation::forceServiceOnNextFrame() {
   m_timeline->wake();
 }
 
-bool Animation::canStartAnimationOnCompositor() const {
+bool Animation::canStartAnimationOnCompositor(
+    const Optional<CompositorElementIdSet>& compositedElementIds) const {
   if (m_isCompositedAnimationDisabledForTesting || effectSuppressed())
     return false;
 
   // FIXME: Timeline playback rates should be compositable
   if (m_playbackRate == 0 || (std::isinf(effectEnd()) && m_playbackRate < 0) ||
       (timeline() && timeline()->playbackRate() != 1))
     return false;
 
-  return m_timeline && m_content && m_content->isKeyframeEffectReadOnly() &&
-         playing();
+  if (!m_timeline || !m_content || !m_content->isKeyframeEffectReadOnly())
+    return false;
+
+  // If the optional element id set has no value we must be in SPv1 mode in
+  // which case we trust the compositing logic will create a layer if needed.
+  if (compositedElementIds.has_value()) {
+    DCHECK(RuntimeEnabledFeatures::slimmingPaintV2Enabled());
+    Element* targetElement =
+        toKeyframeEffectReadOnly(m_content.get())->target();
+    if (!targetElement)
+      return false;
+
+    CompositorElementId targetElementId = createCompositorElementId(
+        DOMNodeIds::idForNode(targetElement), CompositorSubElementId::Primary);
+    if (!compositedElementIds->contains(targetElementId))
+      return false;
+  }
+
+  return playing();
 }
 
-bool Animation::isCandidateForAnimationOnCompositor() const {
-  if (!canStartAnimationOnCompositor())
+bool Animation::isCandidateForAnimationOnCompositor(
+    const Optional<CompositorElementIdSet>& compositedElementIds) const {
+  if (!canStartAnimationOnCompositor(compositedElementIds))
     return false;
 
   return toKeyframeEffectReadOnly(m_content.get())
       ->isCandidateForAnimationOnCompositor(m_playbackRate);
 }
 
-bool Animation::maybeStartAnimationOnCompositor() {
-  if (!canStartAnimationOnCompositor())
+bool Animation::maybeStartAnimationOnCompositor(
+    const Optional<CompositorElementIdSet>& compositedElementIds) {
+  if (!canStartAnimationOnCompositor(compositedElementIds))
     return false;
 
   bool reversed = m_playbackRate < 0;
 
   double startTime = timeline()->zeroTime() + startTimeInternal();
   if (reversed) {
     startTime -= effectEnd() / fabs(m_playbackRate);
   }
 
   double timeOffset = 0;
@@ skipping 391 matching lines @@
   DCHECK(!m_compositorPlayer);
 }
 
 void Animation::CompositorAnimationPlayerHolder::detach() {
   DCHECK(m_compositorPlayer);
   m_compositorPlayer->setAnimationDelegate(nullptr);
   m_animation = nullptr;
   m_compositorPlayer.reset();
 }
 }  // namespace blink