AnimationResult

AnimatableAnimationResultSample

fun AnimatableAnimationResultSample() {
    suspend fun CoroutineScope.animateBouncingOffBounds(
        animatable: Animatable<Offset, *>,
        flingVelocity: Offset,
        parentSize: Size,
    ) {
        launch {
            var startVelocity = flingVelocity
            // Set bounds for the animation, so that when it reaches bounds it will stop
            // immediately. We can then inspect the returned `AnimationResult` and decide whether
            // we should start another animation.
            animatable.updateBounds(Offset(0f, 0f), Offset(parentSize.width, parentSize.height))
            do {
                val result = animatable.animateDecay(startVelocity, exponentialDecay())
                // Copy out the end velocity of the previous animation.
                startVelocity = result.endState.velocity
                // Negate the velocity for the dimension that hits the bounds, to create a
                // bouncing off the bounds effect.
                with(animatable) {
                    if (value.x == upperBound?.x || value.x == lowerBound?.x) {
                        // x dimension hits bounds
                        startVelocity = startVelocity.copy(x = -startVelocity.x)
                    }
                    if (value.y == upperBound?.y || value.y == lowerBound?.y) {
                        // y dimension hits bounds
                        startVelocity = startVelocity.copy(y = -startVelocity.y)
                    }
                }
                // Repeat the animation until the animation ends for reasons other than hitting
                // bounds, e.g. if `stop()` is called, or preempted by another animation.
            } while (result.endReason == AnimationEndReason.BoundReached)
        }
    }
}