Extensions for Android Animation package.

AnimationKtx.kt

data class AnimationListenerChain(val animation: Animation, val listener: Animation.AnimationListener = object : Animation.AnimationListener() {
    override fun onAnimationStart(animation: Animation?) {}

    override fun onAnimationEnd(animation: Animation?) {}

    override fun onAnimationRepeat(animation: Animation?) {}
})

inline fun Animation.doOnStart(crossinline onStart: () -> Unit): AnimationListenerChain {
    val chain = AnimationListenerChain(this)
    return chain.doOnStart(onStart)
}

inline fun Animation.doOnEnd(crossinline onEnd: () -> Unit): AnimationListenerChain {
    val chain = AnimationListenerChain(this)
    return chain.doOnEnd(onEnd)
}

inline fun AnimationListenerChain.doOnEnd(crossinline onEnd: () -> Unit): AnimationListenerChain {
    val nextListener: Animation.AnimationListener = object : AnimationListenerAdapter() {
        override fun onAnimationEnd(animation: Animation?) {
            onEnd()
        }

        override fun onAnimationRepeat(animation: Animation?) {
            listener.onAnimationRepeat(animation)
        }

        override fun onAnimationStart(animation: Animation?) {
            listener.onAnimationStart(animation)
        }
    }
    animation.setAnimationListener(nextListener)
    return copy(listener = nextListener)
}

inline fun AnimationListenerChain.doOnStart(crossinline onStart: () -> Unit): AnimationListenerChain {
    val nextListener: Animation.AnimationListener = object : Animation.AnimationListener {
        override fun onAnimationEnd(animation: Animation?) {
            listener.onAnimationEnd(animation)
        }

        override fun onAnimationRepeat(animation: Animation?) {
            listener.onAnimationRepeat(animation)
        }

        override fun onAnimationStart(animation: Animation?) {
            onStart()
        }
    }
    animation.setAnimationListener(nextListener)
    return copy(listener = nextListener)
}

inline fun AnimationListenerChain.doOnRepeat(crossinline onRepeat: () -> Unit): AnimationListenerChain {
    val nextListener: Animation.AnimationListener = object : Animation.AnimationListener {
        override fun onAnimationEnd(animation: Animation?) {
            listener.onAnimationEnd(animation)
        }

        override fun onAnimationRepeat(animation: Animation?) {
            onRepeat()
        }

        override fun onAnimationStart(animation: Animation?) {
            listener.onAnimationStart(animation)
        }
    }
    animation.setAnimationListener(nextListener)
    return copy(listener = nextListener)
}