Shape Android Material Design

Question

I want to ask about how to create animation for changing shape in android material design. And this is video that I got from Android Material Design guidelines.

Material can change shape

Thank you.

Answer 1

This is a quick implementation of that animation you linked to. It's using CardView from the support library, plus a custom PathInterpolator to make it move more like in the video (the default AccelerateDecelerateInterpolator is too abrupt, but you go with that one in pre-Lollipop devices). It's not a work of art, but hopefully this should give you an idea of one possible way these paper animations can be created.

Here's a demo video https://drive.google.com/file/d/0B7TH7VeIpgSQYkx2TVlSakZidXM/view.

final int origSize = getResources().getDimensionPixelSize(R.dimen.original_size);
final int origRadius = getResources().getDimensionPixelSize(R.dimen.original_radius);
final int targetRadius1 = getResources().getDimensionPixelSize(R.dimen.target_radius_1);
final int targetRadius2 = getResources().getDimensionPixelSize(R.dimen.target_radius_2);

final int targetSize1 = origSize * 2;
final int targetSize2 = origSize * 4;

final int ANIMATION_INTERVAL_MS = 600;
final int ANIMATION_DURATION_MS = 700;

private void doMaterialAnimation() {

    ValueAnimator va1 = ObjectAnimator.ofFloat(1, 0);
    va1.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            transformMaterial(origSize, targetSize1, origRadius, targetRadius1, animation);
        }
    });

    ValueAnimator va2 = ObjectAnimator.ofFloat(1, 0);
    va2.setStartDelay(ANIMATION_INTERVAL_MS);
    va2.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            transformMaterial(targetSize1, targetSize2, targetRadius1, targetRadius2, animation);
        }
    });

    ValueAnimator va3 = ObjectAnimator.ofFloat(1, 0);
    va3.setStartDelay(ANIMATION_INTERVAL_MS);
    va3.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            transformMaterial(targetSize2, origSize, targetRadius2, origRadius, animation);
        }
    });

    AnimatorSet aset = new AnimatorSet();
    aset.playSequentially(va1, va2, va3);
    aset.setDuration(ANIMATION_DURATION_MS);
    aset.setInterpolator(new PathInterpolator(0.75f, 0.1f, 0.25f, 0.9f));
    aset.start();
}

private void transformMaterial(int origSize,
                               int targetSize,
                               int origRadius,
                               int targetRadius,
                               ValueAnimator animation) {

    float fraction = (float) animation.getAnimatedValue();
    cardView.setRadius(interpolate(origRadius, targetRadius, fraction));

    cardView.getLayoutParams().width = cardView.getLayoutParams().height
            = (int) ((targetSize - origSize) * (1 - fraction) + origSize);
    cardView.requestLayout();
}

private float interpolate(int from, int to, float fraction) {
    return ((from - to) * fraction) + to;
}

This is the card, just for reference.

<android.support.v7.widget.CardView
    android:id="@+id/card"
    android:background="@color/background_material_light"
    app:cardCornerRadius="@dimen/original_radius"
    android:layout_centerInParent="true"
    android:layout_width="@dimen/original_size"
    android:layout_height="@dimen/original_size"
    >