User:Shellylin/Async Animations and OMTA

Add layers::Animation into mAnimations of Layer

 nsDisplayTransform::BuildLayer()
 |-> AddAnimationsAndTransitionsToLayer(Layer* aLayer, nsDisplayListBuilder* aBuilder, nsDisplayItem* aItem, nsCSSProperty aProperty)
   |-> aLayer->ClearAnimations();

Rest of the part below is skipped if OMTA is not supported nor async animations is not supported.

1. Check to see if the animations(transitions) can perform on compositor thread.

   |-> ElementTransitions* et = nsTransitionManager::GetTransitionsForCompositor(content, aProperty);
   
       ElementAnimations* ea = nsAnimationManager::GetAnimationsForCompositor(content, aProperty);

2. Check to see if async animations is enabled (Can draw by GPU), but only Display type of Transform and Opacity adapt OMTA (Type check at Layers::SetAnimations()).

   |-> aItem->CanUseAsyncAnimations(aBuilder)

3. Set up some extra information for transformation, so that a gfx3DMatrix can applied directly to the layer. (defined in LayersMessage.ipdlh)

   |-> some implementation here.
   |-> AnimationData data = TransformData(...);
   |

4. For each ElementPropertyTransition in et, convert its transition properties into a ElementAnimation, and add it to aLayer (details describe in section 5).

   |-> ElementPropertyTransition* pt = &et->mPropertyTransitions[tranIdx];
   |-> ElementAnimation anim;
   |-> AddAnimationsForProperty(frame, aProperty, &anim, aLayer, data);

5. For each ElementAnimation (anim) in ElementAnimations (ea), extract some data out from anim, create a layers::Animation from those data, and append this new created layers::Animation to the animation list of aLayer (mAnimations).

   |-> ElementAnimation* anim = &ea->mAnimations[animIdx];
   |-> AddAnimationsForProperty(frame, aProperty, anim, aLayer, data);
       |-> layers::Animation* animation = aLayer->AddAnimation(startTime, duration,
                                                               iterations, direction,
                                                               aProperty, aData)

5.1 For each segment in a anim:

           |-> AddTransformFunctions()

6. Update the number of generated animations.

   |-> aLayer->SetAnimationGeneration(a number);