verticalscroll-event-handler-compose

gistfile1.txt

 .pointerInput(Unit) {
                detectVerticalDragGestures(
                    onDragStart = { offset ->
                        draggingItemIndex = (offset.y / itemHeight).toInt()
                    },
                    onDragEnd = {
                        coroutineScope.launch {
                            dragAmount.animateTo(0f, tween(200, easing = EaseInOut))
                            draggingItemIndex = -1
                        }
                    }
                ) { change, dragAmountDelta ->

                    coroutineScope.launch {
                        val currentOffset = scrollState.value
                        val maxOffset = scrollState.maxValue

                        //Prevent Scrolling Top
                        if (currentOffset == 0 && dragAmountDelta > 0) {
                            return@launch
                        }
                        //Prevent Scrolling Bottom
                        if (currentOffset == maxOffset && dragAmountDelta < 0) {
                            return@launch
                        }

                        scrollState.scrollBy(-dragAmountDelta)

                        val clampedDragAmountDelta = dragAmountDelta.coerceIn(-itemHeight, itemHeight)*.5f

                        //When Scrolled Down
                        if (dragAmountDelta > 0) {
                            dragAmount.snapTo((dragAmount.value - clampedDragAmountDelta))
                        }
                        //When Scrolled Up
                        else if (dragAmountDelta < 0) {
                            dragAmount.snapTo(dragAmount.value+ clampedDragAmountDelta)
                        }
                    }
                }
            }