rlay3 rlay3 - 3 months ago 113
Android Question

How do I prevent the status bar and navigation bar from animating during an activity scene animation transition?

Firstly, my status bar background is set to dark brown, and my navigation bar background is default black. I'm using the Material light theme.

I'm starting a new activity using

ActivityOptions.makeSceneTransitionAnimation
with default transitions, and I notice that both the status and navigation bars briefly fade to white and then back to the correct colors.

According to the documentation:


To get the full effect of a transition, you must enable window content transitions on both the calling and called activities. Otherwise, the calling activity will start the exit transition, but then you'll see a window transition (like scale or fade)


I am using getWindow().requestFeature(Window.FEATURE_CONTENT_TRANSITIONS); on both the calling and called activities.

Similarly, if I change the enter transition to a slide, both the status and navigation bars briefly have a slide transition with a white background.

How do I prevent the status bar and navigation bar from animating during an activity scene animation transition?

Answer

There are two approaches you can use that I know of to prevent the navigation/status bar from animating during the transition:

Approach #1: Exclude the status bar and navigation bar from the window's default exit/enter fade transition

The reason why the navigation/status bar are fading in and out during the transition is because by default all non-shared views (including the navigation/status bar backgrounds) will fade out/in in your calling/called Activitys respectively once the transition begins. You can, however, easily get around this by excluding the navigation/status bar backgrounds from the window's default exit/enter Fade transition. Simply add the following code to your Activitys' onCreate() methods:

Transition fade = new Fade();
fade.excludeTarget(android.R.id.statusBarBackground, true);
fade.excludeTarget(android.R.id.navigationBarBackground, true);
getWindow().setExitTransition(fade);
getWindow().setEnterTransition(fade);

This transition could also be declared in the activity's theme using XML (i.e. in your own res/transition/window_fade.xml file):

<?xml version="1.0" encoding="utf-8"?>
<fade xmlns:android="http://schemas.android.com/apk/res/android">
    <targets>
        <target android:excludeId="@android:id/statusBarBackground"/>
        <target android:excludeId="@android:id/navigationBarBackground"/>
    </targets>
</fade>

Approach #2: Add the status bar and navigation bar as shared elements

This approach builds off of klmprt's answer, which almost worked for me... although I still needed to make a couple of modifications.

In my calling Activity, I used the following code to start the Activity:

View statusBar = findViewById(android.R.id.statusBarBackground);
View navigationBar = findViewById(android.R.id.navigationBarBackground);

List<Pair<View, String>> pairs = new ArrayList<>();
pairs.add(Pair.create(statusBar, Window.STATUS_BAR_BACKGROUND_TRANSITION_NAME));
pairs.add(Pair.create(navigationBar, Window.NAVIGATION_BAR_BACKGROUND_TRANSITION_NAME));
pairs.add(Pair.create(mSharedElement, mSharedElement.getTransitionName()));

Bundle options = ActivityOptions.makeSceneTransitionAnimation(activity, 
        pairs.toArray(new Pair[pairs.size()])).toBundle();
startActivity(new Intent(context, NextActivity.class), options);

So far this is essentially the same thing that klmprt suggested in his answer. However, I also needed to add the following code in my called Activity's onCreate() method in order to prevent the status bar and navigation bar from "blinking" during the transition:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_next);

    // Postpone the transition until the window's decor view has
    // finished its layout.
    postponeEnterTransition();

    final View decor = getWindow().getDecorView();
    decor.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
        @Override
        public boolean onPreDraw() {
            decor.getViewTreeObserver().removeOnPreDrawListener(this);
            startPostponedEnterTransition();
            return true;
        }
    });
}

Adding the status bar and navigation bar backgrounds as shared elements will force them to be drawn on top of the window's default exit/enter fade transition, meaning that they will not fade during the transition. More discussion about this approach can be found in this Google+ post.