For Medium article "Animate Everything! (Android Animation Showcase)"

ArcView.kt

override fun onDraw(canvas: Canvas) {
    canvas?.drawOval(defRect, backgroundPaint)
    canvas?.drawOval(animatedRect, foregroundPaint)
}

fun startAnimation() {
    // ...
    val animateLeft = ObjectAnimator.ofFloat(animatedRect, "left", animatedRect.left, toRect.left)
    val animateTop = ObjectAnimator.ofFloat(animatedRect, "top", animatedRect.top, toRect.top)
    val animateRight = ObjectAnimator.ofFloat(animatedRect, "right", animatedRect.right, toRect.right)
    val animateBottom = ObjectAnimator.ofFloat(animatedRect, "bottom", animatedRect.bottom, toRect.bottom)

    val foregroundColorAnimator = ValueAnimator().apply { /* init animator */ }
    val backgroundColorAnimator = ValueAnimator().apply { /* init animator */ }

    animatorSet.apply {
        // init animator set
        playTogether(animateLeft, animateTop, animateRight, animateBottom, foregroundColorAnimator, backgroundColorAnimator)
        duration = ANIMATION_DURATION
        start()
    }
}