2dscroll.kt

@Composable 
fun scroll2d() {
  val offset = remember { Animatable(Offset(0f, 0f), Offset.VectorConverter) }
  Box(
        modifier = modifier
            .pointerInput(Unit) {
                coroutineScope {
                    while (true) {
                        val pointerId = awaitPointerEventScope {
                            awaitFirstDown().id
                        }
                        val velocityTracker = VelocityTracker()
                        awaitPointerEventScope {
                            drag(pointerId) {
                                launch {
                                    val change = it.positionChange()
                                    offset.snapTo(Offset(
                                        (offset.value.x + change.x).coerceIn(-maxWidth.toFloat() + width, 0f),
                                        (offset.value.y + change.y).coerceIn(-maxHeight.toFloat() + height, 0f)
                                    ))
                                }
                                velocityTracker.addPosition(it.uptimeMillis, it.position)
                            }
                        }
                        val (x, y) = velocityTracker.calculateVelocity()
                        offset.updateBounds(
                            Offset(-maxWidth.toFloat() + width, -maxHeight.toFloat() + height),
                            Offset(0f, 0f)
                        )
                        launch {
                            var startVelocity = Offset(x, y)
                            do {
                                val result = offset.animateDecay(startVelocity, exponentialDecay())
                                startVelocity = result.endState.velocity
                                with(offset) {
                                    if (value.x == upperBound?.x || value.x == lowerBound?.x) {
                                        startVelocity = startVelocity.copy(x = 0f)
                                    }
                                    if (value.y == upperBound?.y || value.y == lowerBound?.y) {
                                        startVelocity = startVelocity.copy(y = 0f)
                                    }
                                }
                            } while (result.endReason == AnimationEndReason.BoundReached)
                        }
                    }
                }
            }
    )
}