Reverse Animation With Recursive Function

Question

What is the best practice to reverse animation direction on android? Also, I track ram usage on the profiler and the result was normal as it is. I did like the below code:

 var flagHeight: Int = 100
    private fun startAnimation() {
        val animation = tv_hello_world.animate().apply {
            translationYBy(flagHeight.toFloat())
            setListener(object : Animator.AnimatorListener {
                override fun onAnimationStart(p0: Animator?) {
                    // do nothing
                }

                override fun onAnimationEnd(p0: Animator?) {
                    flagHeight = flagHeight.not()
                    startAnimation()
                }

                override fun onAnimationCancel(p0: Animator?) {
                    // do nothing
                }

                override fun onAnimationRepeat(p0: Animator?) {
                    // do nothing
                }
            })
            duration = 1000
        }
        animation.start()
    }

    fun Int.not() = run { if (this > 0) -this else (this * -1) }



   

Answer 1

The proper way to do it by using ValueAnimator instead on PropertyAnimator since you have more control over it. Try it this way:

val animator = ValueAnimator.ofFloat(0f, 100f).apply {
        duration = 1000
        repeatCount = ValueAnimator.INFINITE
        repeatMode = ValueAnimator.REVERSE
        addUpdateListener {
            tv_hello_world.translationY = it.animatedValue as Float
        }
    }
    animator.start()