Spring Animation

Moving.kt

class SpringPositionView @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : View(context, attrs, defStyleAttr) {

    private companion object Params {
        private const val STIFFNESS = SpringForce.STIFFNESS_MEDIUM
        private const val DAMPING_RATIO = SpringForce.DAMPING_RATIO_HIGH_BOUNCY
    }

    private lateinit var xAnim: SpringAnimation
    private lateinit var yAnim: SpringAnimation

    init {

        viewTreeObserver.addOnGlobalLayoutListener {
            xAnim = SpringAnimation(this, SpringAnimation.X).apply {
                spring = SpringForce(x).apply {
                    stiffness = STIFFNESS
                    dampingRatio = DAMPING_RATIO
                }
            }
            yAnim = SpringAnimation(this, SpringAnimation.Y).apply {
                spring = SpringForce(y).apply {
                    stiffness = STIFFNESS
                    dampingRatio = DAMPING_RATIO
                }
            }
        }

        var dX = 0f
        var dY = 0f
        setOnTouchListener { view, event ->
            when (event.actionMasked) {
                MotionEvent.ACTION_DOWN -> {
                    dX = view.x - event.rawX
                    dY = view.y - event.rawY

                    xAnim.cancel()
                    yAnim.cancel()
                }
                MotionEvent.ACTION_MOVE -> {
                    animate()
                            .x(event.rawX + dX)
                            .y(event.rawY + dY)
                            .setDuration(0)
                            .start()
                }
                MotionEvent.ACTION_UP -> {
                    xAnim.start()
                    yAnim.start()
                }
            }
            true
        }
    }

}