View source for 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);