MapDrawerFull

MapDrawerFull.kt

enum class DrawerMotionEvent { idle, down, up, move }

data class MapDrawState(
    val currentPosition: Offset = Offset.Unspecified,
    val event: MotionEvent = MotionEvent.idle
)

@Composable
fun MapDrawer() {
    var state by remember { mutableStateOf(MapDrawState()) }
    val brush = remember { SolidColor(Color.Black) }
    val path = remember { Path() }
    Canvas(
        modifier = Modifier
            .fillMaxSize()
            .pointerInput(Unit) {
                awaitEachGesture {
                    awaitPointerEvent().changes.first().also { changes ->
                        val position = changes.position
                        state = state.copy(
                            currentPosition = position,
                            event = DrawerMotionEvent.down
                        )
                    }
                    do {
                        val event: PointerEvent = awaitPointerEvent()
                        event.changes.forEach { changes ->
                            val position = changes.position
                            state = state.copy(
                                currentPosition = position,
                                event = DrawerMotionEvent.move
                            )
                        }
                    } while (event.changes.any { it.pressed })

                    // Touch Up event
                    state = state.copy(
                        currentPosition = currentEvent.changes.first().position,
                        event = DrawerMotionEvent.up
                    )
                }
            },
        onDraw = {
            when (state.event) {
                DrawerMotionEvent.idle -> Unit
                DrawerMotionEvent.up, DrawerMotionEvent.move -> path.lineTo(
                    state.currentPosition.x,
                    state.currentPosition.y
                )
                DrawerMotionEvent.down -> path.moveTo(state.currentPosition.x, state.currentPosition.y)
            }
            drawPath(
                path = path,
                brush = brush,
                style = Stroke(width = 5f)
            )
        }
    )
}