Pop the fragment backstack without playing the Pop

Question

I push a fragment on the fragment stack using the following code:

FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_right,
     R.anim.slide_in_left, R.anim.slide_out_left);
fragmentTransaction.replace(getId(), newFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();

This way, when the fragment stack is popped, e.g. by pressing the back button, a fragment pop animation is played. However, there are situations in which i would like to pop the fragment backstack without showing this animation, e.g. because I just returned from another activity and want to display the previous fragment at once, without animation.

An example navigation could look like this:

• The user is on the start screen with the root fragment
• He selects an item on the root fragment which then displays a new fragment to show details of that item. It does so using a fragment transaction that sets animations both for the push and the pop case (so when the user presses the back button, the transition is animated)
• From this fragment he starts an activity which (for whatever reason) deletes the item that was just shown
• When this activity finishes, I would like to return to the root fragment without showing the "pop animation" of the "detail fragment"

Is there a way to pop the fragment backstack without playing the specified pop animation?

Answer 1

The user is on the start screen with the root fragment

Lets say the root fragment is contained in Activity A.

He selects an item on the root fragment which then displays a new fragment to show details of that item. It does so using a fragment transaction that sets animations both for the push and the pop case (so when the user presses the back button, the transition is animated)

The transaction is added to the back stack. Which means that when the back button is pressed from detail fragment, the popping process is animated.

From this fragment he starts an activity which (for whatever reason) deletes the item that was just shown.

Lets say it is Activity B

When this activity finishes, I would like to return to the root fragment without showing the "pop animation" of the "detail fragment"

One way of getting this behavior is by doing this in Activity B :

Intent intent = new Intent(this, A.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
finish();

This will start the Activity A resetting it to its root state according to the documentation.(check the last paragraph in the section which says "This launch mode can also be used to good effect in conjunction with FLAG_ACTIVITY_NEW_TASK:......")

With this configuration, the animation will be present in the default case while in the special case you can control the animation using :

intent.addFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);

Which starts new activity without any animations. If you do want any animation, you can do it using the overridePendingTransition method.

Answer 2

Before answering your question, I need to ask a question myself.

In the onBackPressed() method of the second activity, can you access the backstack of the first activity?

If yes, then you can call popBackStackImmediate(String trnaisiotnName, int inclusive) and it will remove the fragment transition from the backstack, and you dont need to worry about animations.

I am assuming you can access backstack of the previous activity, otherwise this wont work

Answer 3

So for the support library following works:

In the fragment which should have a custom pop animation you override the onCreateAnimation with your own custom one. You could get it and set some kind of parameter depending on what you want. There might need to be done some extra work to make it work with regular fragments.

Here is the example where I'm overriding it and changing the set duration:

@Override
public Animation onCreateAnimation(int transit, boolean enter, int nextAnim) {
    Animation anim = (Animation) super.onCreateAnimation(transit, enter, nextAnim);
    if(!enter) {
        if(anim != null) {
            anim.setDuration(0); // This doesn't seem to be called.
            return anim;
        } else {
            Animation test = new TestAnimation();
            test.setDuration(0);
            return test;
        }
    }
    return anim;
}

private class TestAnimation extends Animation {

}

Answer 4

So, I'd like to suggest a small change to @Geoff's answer.

Instead of having a global static boolean, I'd rather have a local non-static one. This is what I came up with.

Create an interface

public interface TransitionAnimator {
    void disableTransitionAnimation();
    void enableTransitionAnimation();
}

Make the fragment implement that interface.

public class MyFragment extends Fragment implements TransitionAnimator {

    private boolean mTransitionAnimation;

    @Override
    public void disableTransitionAnimation() {
        mTransitionAnimation = false;
    }

    @Override
    public void enableTransitionAnimation() {
        mTransitionAnimation = true;
    }

    @Override
    public Animation onCreateAnimation(int transit, boolean enter, int nextAnim) {
        Animation result;
        if (!mTransitionAnimation) {
            Animation dummyAnimation = new Animation() {
            };
            dummyAnimation.setDuration(0);
            result = dummyAnimation;
        } else {
            result = super.onCreateAnimation(transit, enter, nextAnim);
        }
        return result;
    }

And then, when you want to disable the transition animations for a fragment, just do

if (fragment instanceof TransitionAnimator) {
    ((TransitionAnimator) fragment).disableTransitionAnimation();
}

to enable them, just do

if (fragment instanceof TransitionAnimator) {
    ((TransitionAnimator) fragment).enableTransitionAnimation();
}

If you want to do the same for all the fragments in the fragment manager, just do

List<Fragment> fragments = getSupportFragmentManager().getFragments();
for (Fragment fragment : fragments) {
    if (fragment instanceof TransitionAnimator) {
        // disable animations
        ((TransitionAnimator) fragment).disableTransitionAnimation();
    }
}

Very similar, but without static fields.