Implement a spring animation

We are going to apply the spring animation to our avatar view in the Detail activity.

First we need to set the stiffness and the damping ratio of our animation. To do so we are going to create a SpringForce object.

Different level of stiffnesses

Different levels of damping ratios

In the SpringForce object we are going to set the stiffness level to STIFFNESS_LOW and the damping ratio to DAMPING_RATIO_HIGH_BOUNCY. The final position should be 0f since we don't want our view to translate at the end of the animation, but instead to return to the position it was before the animation.

Once you're done, we will create 2 SpringAnimation objects: one with DynamicAnimation.TRANSLATION_X and the other one with DynamicAnimation.TRANSLATION_Y. To both of them we need to apply the SpringForce object we just created as their spring.

Finally, we need a onTouchListener for getting coordinates of our view and for applying our animations.

DetailActivity.kt

var dX = 0f
var dY = 0f

root.setOnTouchListener { view, motionEvent ->
    when (motionEvent?.action) {
        MotionEvent.ACTION_DOWN -> {
            dX = motionEvent.rawX
            dY = motionEvent.rawY
        }

        MotionEvent.ACTION_MOVE -> {
            val newX = motionEvent.rawX - dX
            val newY = motionEvent.rawY - dY
            iv_avatar.animate().translationX(newX).translationY(newY).duration = 0
            springAnimationX.animateToFinalPosition(0f)
            springAnimationY.animateToFinalPosition(0f)
        }
    }
    true
}