Activity navigation: custom animation with popEnte

问题:

Changing activities with an animation is possible using the code below:

Bundle animation = ActivityOptions.makeCustomAnimation(App.getContext(), R.anim.enter_from_right, R.anim.exit_to_left).toBundle();
startActivity(intent, animation);

For fragments you can do something similar on FragmentTransaction:

// ...
transaction.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left);
// ...

This works! But I'd like to have an animation when pressing back (pop from backstack). For fragments you simply add 2 anim resources (popEnter & popExit):

transaction.setCustomAnimations(R.anim.enter_from_right, R.anim.exit_to_left, R.anim.enter_from_left, R.anim.exit_to_right);

How can I create the same 'back-animation' for activities?

回答1:

I've found a different though simple approach that seems to work quite well. Animations for activities can also be performed using overridePendingTransition, so when the activity finishes you'll simply use that method.

It would be most effective to implement these overrides in a BaseActivity, which is extended by all activities in your project. Now all your activities will automatically include an exit animation and an animation when starting new activities:

public abstract class BaseActivity extends AppCompatActivity {

    @Override
    public void finish() {
        super.finish();
        onLeaveThisActivity();
    }

    protected void onLeaveThisActivity() {
        overridePendingTransition(R.anim.enter_from_left, R.anim.exit_to_right);
    }

    // It's cleaner to animate the start of new activities the same way.
    // Override startActivity(), and call *overridePendingTransition*
    // right after the super, so every single activity transaction will be animated:

    @Override
    public void startActivity(Intent intent) {
        super.startActivity(intent);
        onStartNewActivity();
    }

    @Override
    public void startActivity(Intent intent, Bundle options) {
        super.startActivity(intent, options);
        onStartNewActivity();
    }

    protected void onStartNewActivity() {
        overridePendingTransition(R.anim.enter_from_right, R.anim.exit_to_left);
    }
}

To round things up, I'll include the 4 anim resources:

enter_from_right

<translate xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="500"
    android:fromXDelta="100%p"
    android:toXDelta="0%p"/>

exit_to_left

<translate xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="500"
    android:fromXDelta="0%p"
    android:toXDelta="-100%p"/>

enter_from_left

<translate xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="500"
    android:fromXDelta="-100%p"
    android:toXDelta="0%p"/>

exit_to_right

<translate xmlns:android="http://schemas.android.com/apk/res/android"
    android:duration="500"
    android:fromXDelta="0%p"
    android:toXDelta="100%p"/>

ps. You'd probably like to exclude the exit-animation in your starting / main activity ;-)

public class MainMenuActivity extends BaseActivity {
    ....
    @Override
    protected void onLeaveThisActivity() {
        // Don't use an exit animation when leaving the main activity!
    }
}