android - Circular reveal transition for new activity

Question

As per https://developer.android.com/training/material/animations.html

The ViewAnimationUtils.createCircularReveal() method enables you to animate a clipping circle to reveal or hide a view.

To reveal a previously invisible view using this effect:

// previously invisible view
View myView = findViewById(R.id.my_view);

// get the center for the clipping circle
int cx = (myView.getLeft() + myView.getRight()) / 2;
int cy = (myView.getTop() + myView.getBottom()) / 2;

// get the final radius for the clipping circle
int finalRadius = Math.max(myView.getWidth(), myView.getHeight());

// create the animator for this view (the start radius is zero)
Animator anim =
    ViewAnimationUtils.createCircularReveal(myView, cx, cy, 0, finalRadius);

// make the view visible and start the animation
myView.setVisibility(View.VISIBLE);
anim.start();

This is meant to reveal a view. How can I use this to circularly reveal an entire activity, without any shared elements?

Specifically, I'd like my searchActivity to circularly reveal from the search action button in the toolbar.

Answer 1

After looking for a solution for half a day without a result, I came up with an own implementation. I'm using a transparent activity with a matching root layout. The root layout is a view which can then be revealed with createCircularReveal().

My code looks like this:

Theme Definition in styles.xml

<style name="Theme.Transparent" parent="Theme.AppCompat.Light.NoActionBar">
    <item name="android:windowIsTranslucent">true</item>
    <item name="android:statusBarColor">@android:color/transparent</item>
    <item name="android:windowBackground">@android:color/transparent</item>
</style>

Activity Definition in AndroidManifest.xml

<activity
        android:name=".ui.CircularRevealActivity"
        android:theme="@style/Theme.Transparent"
        android:launchMode="singleTask"
        />

then I declared a layout for my activity (I've chosen DrawerLayout, so that I can have a NavDrawer. Every layout should work here.)

<android.support.v4.widget.DrawerLayout
    android:id="@+id/drawer_layout"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <FrameLayout
        android:id="@+id/root_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/honey_melon"
        >

        <!-- Insert your actual layout here -->

    </FrameLayout>

</android.support.v4.widget.DrawerLayout>

Important is the FrameLayout with the id root_layout. This view will be revealed in the activity.

Finally I implemented CircularRevealActivity and overwrote onCreate():

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    overridePendingTransition(R.anim.do_not_move, R.anim.do_not_move);

    setContentView(R.layout.activity_reveal_circular);

    if (savedInstanceState == null) {
        rootLayout.setVisibility(View.INVISIBLE);

        ViewTreeObserver viewTreeObserver = rootLayout.getViewTreeObserver();
        if (viewTreeObserver.isAlive()) {
            viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    circularRevealActivity();
                    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
                        rootLayout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                    } else {
                        rootLayout.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                    } 
                }
            });
        }
    }
}

It was important to put circularRevealActivity() into a OnGlobalLayoutListener, because the view needs to be drawn for the animation.

circularRevealActivity() looks like Ishaan's proposal:

private void circularRevealActivity() {

    int cx = rootLayout.getWidth() / 2;
    int cy = rootLayout.getHeight() / 2;

    float finalRadius = Math.max(rootLayout.getWidth(), rootLayout.getHeight());

    // create the animator for this view (the start radius is zero)
    Animator circularReveal = ViewAnimationUtils.createCircularReveal(rootLayout, cx, cy, 0, finalRadius);
    circularReveal.setDuration(1000);

    // make the view visible and start the animation
    rootLayout.setVisibility(View.VISIBLE);
    circularReveal.start();
}

Edit 1

The definition for R.anim.do_not_move was added. However, it should work without that line too, if your design does not specify default transitions for activities. Let me know

R.anim.do_not_move:

<set xmlns:android="http://schemas.android.com/apk/res/android">
<translate
    android:fromYDelta="0"
    android:toYDelta="0"
    android:duration="@android:integer/config_mediumAnimTime"
    />
</set>