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Interesting. And no reason for us to wrap it in set either. We removed and it works as you mentioned in our main app as well.

I have this bug and I don't use nested <set> in animation files. It doesn't happens every time. Also it doesn't happens with FragmentManager.enableNewStateManager(false)

Sample project and video attached.

Re #5 - you are indeed using a <set> in your animation files, so this is the same issue:

The reason this occurs in your case is that you are wrapping your <translate> in a <set> and the new state manager wraps your Animation in its own AnimationSet at runtime to properly receive callbacks from the Animation, meaning there's a total of two nested sets.

So you'd see the same behavior with the old state manager if you manually wrapped your animations in another <set>, as the example in #2 explained.

I see. Thanks for explanation. I understood #2 a bit wrong then.

Bad news: Nested AnimationSet instances are broken at a fundamental layer that Fragments can't work around. We strongly recommend switching to Animator or AndroidX Transition and are doing that internally in Fragment and Navigation.

Good news: We're reverting to the equivalent behavior of the old state manager in that we won't use an additional layer of AnimationSet for entering Animations. This means that unlike Animators or Transitions, a Fragment using Animation will immediately move to RESUMED before the Animation completes when using the new state manager.

The only reason why I'm using Animation is that I need to use percent values, as in the animation of #comment2. Given that FragmentTransaction (and by extension Navigation) only accepts @AnimatorRes and @AnimRes, I can't create the animation programmatically.

Is there any alternative to Animation in this case?

Re #10 - note that even when you do not pass a resource ID, you can still override onCreateAnimation() or onCreateAnimator() on your Fragment and return any custom Animation or Animator you want - there is no requirement that you only use Animations/Animators inflated from XML when using Fragments (and by extension, when using Navigation).

Thank you, that does the trick. I even used to patch animations on the fly before you fixed all the issues I had with FragmentContainerView, how could not I think of doing that.

For those reading that might be in a similar situation: I have few animations that I use throughout the applications and they are all defined in the actions of the navigation graph. Since I have a common base Fragment class, I added something like the following to that base class (using the animation in #comment2 as reference):

    @Nullable
    @Override
    public Animator onCreateAnimator(int transit, boolean enter, int nextAnim) {
        if (nextAnim == R.anim.transition_slide_left_show) {
            int width = requireActivity().getWindow().getDecorView().getWidth();
            ObjectAnimator anim = ObjectAnimator.ofFloat(getView(), View.TRANSLATION_X, -width, 0);
            anim.setStartDelay(300);
            anim.setDuration(300);
            anim.setInterpolator(new DecelerateInterpolator());
            return anim;
        } else {
            return super.onCreateAnimator(transit, enter, nextAnim);
        }
    }

This is probably not ideal given that now the XML animation is ignored, that could be not very obvious (you could also not outright ignore it), but it's a quick and easy solution to turn several XML based Animations into Animators.

For full screen slides, you should strongly consider using a Slide Transition which does all that for you.

I have got this bug with 'sharedElementReturnTransition', it causes blinking too. Also it doesn't happens with FragmentManager.enableNewStateManager(false). Any ideas? I don't want to use it unless I have to.

Re #14 - Transitions do not use Animations so that would be unrelated to this issue. Please file a new issue with a sample project that reproduces your issue using the latest Fragment 1.3.2.

I have tried to make a sample depends in https://github.com/android/animation-samples/tree/master/GridToPager and change it to Fragment 1.3.2

but I can't found the blinking, maybe there is something wrong in my project, I will try more, anyway ,thanks for reply!

Re #15 - I have figured out the problem! It's just because I did some Job at "onPause()" in the return blinking Fragment!