startGestureModifier.kt

@Composable
fun Modifier.startGesture(
    onStart: (offsetX: Float) -> Unit
): Modifier {
    val interactionSource = remember { MutableInteractionSource() }
    return this.pointerInput(interactionSource) {
        forEachGesture { 
            coroutineScope { 
                awaitPointerEventScope { 
                    val touch = awaitFirstDown().also { it.consumeDownChange() }
                    onStart(touch.position.x)
                }
            }
        }
    }
}