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

The saved state of Fragments has been split entirely between private library state (custom Parcelable classes) and state provided by you, the developer, which is now always stored in a Bundle that allows determining exactly which part of the fragment's state is too large.

The final structure is as follows:

In the Activity's onSaveInstanceState, the "android:support:fragments" key now contains a Bundle that contains the following information:

• "state" - the private Parcelable storing the FragmentManager's saved state (e.g., the fragment back stack info)
• For each Fragment Result that has been set via setFragmentResult but has not yet been delivered: "result_$name" -> (user defined Bundle)
• For each Fragment (where the fragment_id matches the UUIDs found in the debug logging): "fragment_$fragment_id" -> Bundle
  • "state" -> the private Parcelable storing the Fragment's saved state (e.g., the class name, max lifecycle, etc.)
  • "arguments" -> (Bundle of arguments)
  • "savedInstanceState" -> (onSaveInstanceState filled Bundle)
  • "registryState" -> (SavedStateRegistry filled Bundle)
  • "childFragmentManager" -> The “android:support:fragments” equivalent Bundle of the child FragmentManager, which would lead us recursively down the tree
  • "viewState" -> the SparseArray<Parcelable> returned by View.saveHierarchyState representing the Fragment View state
  • "viewRegistryState" -> (View SavedStateRegistry filled Bundle)

This will be fully available in Fragment 1.6.0-alpha01.