Devtools Animations: Update transition timing on timeline interaction

Source/core/inspector/InspectorAnimationAgent.cpp

Index: Source/core/inspector/InspectorAnimationAgent.cpp
diff --git a/Source/core/inspector/InspectorAnimationAgent.cpp b/Source/core/inspector/InspectorAnimationAgent.cpp
index 7d3068ba83fd43dba20412ccbd001dd69b5cb3bb..ee6c2911508b5c20ec7243acb63280b7be359a30 100644
--- a/Source/core/inspector/InspectorAnimationAgent.cpp
+++ b/Source/core/inspector/InspectorAnimationAgent.cpp
@@ -246,17 +246,39 @@ void InspectorAnimationAgent::setCurrentTime(ErrorString*, double currentTime)
     m_pageAgent->inspectedFrame()->document()->timeline().setCurrentTime(currentTime);
 }
 
-void InspectorAnimationAgent::setTiming(ErrorString* errorString, const String& playerId, double duration, double delay)
+void InspectorAnimationAgent::setTiming(ErrorString* errorString, const String& playerId, double duration, double delay, bool isTransition)

[dgozman, 2015/03/31 05:11:29]

Can you check |isTransition| flag here on backend instead of passing it from
frontend? If you can, let's remove it.

[samli, 2015/03/31 06:17:00]

No. The way I classify if a created animation is a transition is quite
complicated. (Look up the targeted elements style resolver and check if it is
there). When this call is made, it is likely that it is no longer in this list
because it may have finished or its priority has changed.

The only way I could do this in the backend is to create a new map of the type
in the AnimationAgent and store it when I create it, but this seems unnecessary.

Another option would be to create separate setTiming() methods:
setTimingForTransition(), setTimingForWebAnimation() since they don't really
reuse any code.

WDYT?

 {
     AnimationPlayer* player = assertAnimationPlayer(errorString, playerId);
     if (!player)
         return;
 
-    RefPtrWillBeRawPtr<AnimationNodeTiming> timing = player->source()->timing();
-    UnrestrictedDoubleOrString unrestrictedDuration;
-    unrestrictedDuration.setUnrestrictedDouble(duration);
-    timing->setDuration(unrestrictedDuration);
-    timing->setDelay(delay);
+    if (isTransition) {
+        Animation* animation = toAnimation(player->source());
+        ASSERT(animation->effect()->isKeyframeEffectModel());
+        KeyframeEffectModelBase* effect = toKeyframeEffectModelBase(animation->effect());
+        ASSERT(effect->isAnimatableValueKeyframeEffectModel());
+        const AnimatableValueKeyframeEffectModel* oldEffect = toAnimatableValueKeyframeEffectModel(effect);
+        // Refer to CSSAnimations::calculateTransitionUpdateForProperty() for the structure of transitions.
+        const KeyframeVector& frames = oldEffect->getFrames();
+        ASSERT(frames.size() == 3);
+        KeyframeVector newFrames;
+        for (int i = 0; i < 3; i++)
+            newFrames.append(toAnimatableValueKeyframe(frames[i]->clone().get()));
+        // Update delay, represented by the distance between the first two keyframes.
+        newFrames[1]->setOffset(delay / (delay + duration));
+        effect->setFrames(newFrames);
+
+        RefPtrWillBeRawPtr<AnimationNodeTiming> timing = player->source()->timing();
+        UnrestrictedDoubleOrString unrestrictedDuration;
+        unrestrictedDuration.setUnrestrictedDouble(duration + delay);
+        timing->setDuration(unrestrictedDuration);
+    } else {
+        RefPtrWillBeRawPtr<AnimationNodeTiming> timing = player->source()->timing();
+        UnrestrictedDoubleOrString unrestrictedDuration;
+        unrestrictedDuration.setUnrestrictedDouble(duration);
+        timing->setDuration(unrestrictedDuration);
+        timing->setDelay(delay);
+    }
 }
 
 void InspectorAnimationAgent::didCreateAnimationPlayer(AnimationPlayer* player)