IssueTracker

Jeremy, is this still an issue? I think the problem was that you had two transitions targeting the same View for the same action (e.g. two Slide() transitions).

I have a similar issue with plain AnimatorSet:

set.start()
set.pause()
set.setCurrentPlayTime(100)
set.setCurrentPlayTime(0)
set.setCurrentPlayTime(100)
set.resume()

doesn't play animation in resume().

Should clarify that if I filter out setCurrentPlayTime(0) (or replace it with setCurrentPlayTime(1)) it works well.

Also even with setCurrentPlayTime(0), onAnimationEnd is notified with correct delay (as if the animation has played).

@ #4:

I think that is intended for Animator. If you set the currentPlayTime to 0 or the total duration the animator completes. We do some special checks in fragments to handle it.

Did some investigation on the Fragment side and it seems like the merged transition is targeting correctly.

Exiting Transition: Slide@aa9288e: tgts(android.widget.LinearLayout{f9add3d})
>>>>> ExitingViews <<<<<
View: android.widget.LinearLayout{f9add3d}
Entering Transition: Slide@35b8af: tgts(android.widget.LinearLayout{b7f24bc})
>>>>> EnteringViews <<<<<
View: android.widget.LinearLayout{b7f24bc}
Final merged transition: TransitionSet@7bc1c45: 
      TransitionSet@e133f9a: 
        Slide@aa9288e: tgts(android.widget.LinearLayout{f9add3d})
      Slide@35b8af: tgts(android.widget.LinearLayout{b7f24bc})
merged transition passed to controlDelayedTransition: TransitionSet@7bc1c45: 
      TransitionSet@e133f9a: 
        Slide@aa9288e: tgts(android.widget.LinearLayout{f9add3d})
      Slide@35b8af: tgts(android.widget.LinearLayout{b7f24bc})

Still digging.

So I have isolated this outside of fragment into something much simpler and I think it breaks down when it comes to the adding and removing of Views with animateToStart.

The attached sample is a simple add that goes between two screens BLUE and GREEN. It has code for both the 1.5.0-alpha03 and 1.5.0-alpha04 versions, but I think alpha04 is currently broken in another way so I will upload the alpha03 version here.

This is integrated with predictive back similar to how fragment is, so upon cancelling we call animateToStart, then we do a beginDelayedTransition on a 0 duration Fade() and we reverse the view visibility back to what it was prior to starting the transition.

If you only do visibility, cancel always works the view never goes away, it is wonderful, but when you do adding and removing views like we need to in fragment it fails.

First the code for beginDelayedTransition goes from this:

TransitionManager.beginDelayedTransition(container, Fade().apply {
  duration = 0
})
reverseViews()

to this:

TransitionManager.beginDelayedTransition(container, Fade().apply {
  duration = 0
  addListener(onEnd = {
    reverseViews()
    blueScreen.visibility = View.VISIBLE
    greenScreen.visibility = View.VISIBLE
  })
})
reverseViews(useVisibility = true)

We need to make this change because after the animateToStart() view is still parented by the overlay, so we call reverseViews(useVisibility = true) to only change the visibility and then once the transition finishes we can call reverseViews() to parent the view properly, then we make both views visible again.

From our perspective after the 0 duration transition our views are back in the proper state, but they do not transition properly after a cancel.

If the app is doing this wrong and we can make the appropriate fixes, doing the same in fragment should resolve this. There is logging available that shows the state of the views when we start the transition.

The API has changed since that project was created in a way that makes the API more robust. I'm hoping that has fixed this...

There appears to be a problem with the order of operations. I'm going to look into fixing that.

The following release(s) address this bug.It is possible this bug has only been partially addressed:

• androidx.transition:transition:1.5.0-alpha05

Noting that we will not be able to convert LiveData or its sub-classes to Kotlin due to the generics on those classes and the setValue/getValue nullability. Currently, kotlin does not allow for setters and getters to have differing nullability. Once this is changed, these classes can be converted. Filed a bug for this issue: https://b.corp.google.com/issues/262631039

This bug has been fixed and will be available in androidx-lifecycle-2.6.0-beta01.

ViewModel's conversion to kotlin has been moved to a future release because we need to make some imperative API changes before doing that conversion.

Re comment#111 - as per this comment, onChanged absolutely supports nullable values for values of T that are nullable types.

The following release(s) address this bug.It is possible this bug has only been partially addressed:

• androidx.camera:camera-camera2:1.3.0-alpha04
• androidx.camera:camera-extensions:1.3.0-alpha04

The following release(s) address this bug.It is possible this bug has only been partially addressed:

• androidx.savedstate:savedstate:1.2.1

The following release(s) address this bug.It is possible this bug has only been partially addressed:

• androidx.work:work-runtime:2.9.0-alpha01