1. Transitions between Activities

Animate existing activity layout content

When transitioning from Activity A to Activity B content layout is animated according to defined transition. There are three predefined transitions available on android.transition.Transition you can use: Explode, Slide and Fade. All these transitions track changes to the visibility of target views in activity layout and animate those views to follow transition rules.

Explode	Slide	Fade

You can define these transitions declarative using XML or programmatically. For the Fade Transition sample, it would look like this:

Declarative

Transitions are defined on XML files in res/transition

res/transition/activity_fade.xml

<?xml version="1.0" encoding="utf-8"?>
<fade xmlns:android="http://schemas.android.com/apk/res/"
    android:duration="1000"/>

res/transition/activity_slide.xml

<?xml version="1.0" encoding="utf-8"?>
<slide xmlns:android="http://schemas.android.com/apk/res/"
    android:duration="1000"/>

To use these transitions you need to inflate them using TransitionInflater

MainActivity.java

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

    private void setupWindowAnimations() {
        Slide slide = TransitionInflater.from(this).inflateTransition(R.transition.activity_slide);
        getWindow().setExitTransition(slide);
    }

TransitionActivity.java

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

    private void setupWindowAnimations() {
        Fade fade = TransitionInflater.from(this).inflateTransition(R.transition.activity_fade);
        getWindow().setEnterTransition(fade);
    }

Programmatically

MainActivity.java

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

    private void setupWindowAnimations() {
        Slide slide = new Slide();
        slide.setDuration(1000);
        getWindow().setExitTransition(slide);
    }

TransitionActivity.java

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

    private void setupWindowAnimations() {
        Fade fade = new Fade();
        fade.setDuration(1000);
        getWindow().setEnterTransition(fade);
    }

Any of those produce this result:

What is happening step by step:

1. Activity A starts Activity B
2. Transition Framework finds A Exit Transition (slide) and apply it to all visible views.
3. Transition Framework finds B Enter Transition (fade) and apply it to all visible views.
4. On Back Pressed Transition Framework executes Enter and Exit reverse animations respectively (If we had defined output returnTransition and reenterTransition, these have been executed instead)

ReturnTransition & ReenterTransition

Return and Reenter Transitions are the reverse animations for Enter and Exit respectively.

• EnterTransition <--> ReturnTransition
• ExitTransition <--> ReenterTransition

If Return or Reenter are not defined, Android will execute a reversed version of Enter and Exit Transitions. But if you do define them, you can have different transitions for entering and exiting an activity.

We can modify previous Fade sample and define a ReturnTransition for TransitionActivity, in this case, a Slide transition. This way, when returning from B to A, instead of seeing a Fade out (reversed Enter Transition) we will see a Slide outtransition

TransitionActivity.java

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

    private void setupWindowAnimations() {
        Fade fade = new Fade();
        fade.setDuration(1000);
        getWindow().setEnterTransition(fade);
        
        Slide slide = new Slide();
        slide.setDuration(1000);
        getWindow().setReturnTransition(slide);        
    }

Observe that if no Return Transition is defined then a reversed Enter Transition is executed. If a Return Transition is defined that one is executed instead.

Without Return Transition	With Return Transition
Enter: Fade In	Enter: Fade In
Exit: Fade Out	Exit: Slide out