我在一个项目中遇到了一个有趣的问题，在这个项目中，用户应该能够在定义的形状上绘制相同的形状，到目前为止，我已经实现了这一点，但我想判断他/她是否一次性正确绘制了形状.如果手指超出sqaure，则当前绘图应重置，并将toast消息设置为Unscssesfuld，否则表示Successfull，如何判断绘图是否在正方形上？
白色正方形是用drawRect()方法绘制的，由用户自己绘制，由Drawpath()实现.
class DrawingActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContent {
MyDrawing()
}
}
}
@Composable
fun MyDrawing() {
val actionIdle = 0
val actionDown = 1
val actionMove = 2
val actionUp = 3
//Path, current touch position and touch states
val path = remember { Path() }
var motionEvent by remember { mutableStateOf(actionIdle) }
var currentPosition by remember { mutableStateOf(Offset.Unspecified) }
val canvasColor: Color by remember { mutableStateOf(Color.LightGray) }
val drawModifier = Modifier
.fillMaxWidth()
.fillMaxHeight()
.background(canvasColor)
.clipToBounds()
.pointerInput(Unit) {
forEachGesture {
awaitPointerEventScope {
val down: PointerInputChange = awaitFirstDown().also {
motionEvent = actionDown
currentPosition = it.position
}
do {
val event: PointerEvent = awaitPointerEvent()
var eventChanges =
"DOWN changedToDown: ${down.changedToDown()} changedUp: ${down.changedToUp()}\n"
event.changes
.forEachIndexed { index: Int, pointerInputChange: PointerInputChange ->
eventChanges += "Index: $index, id: ${pointerInputChange.id}, " +
"changedUp: ${pointerInputChange.changedToUp()}" +
"pos: ${pointerInputChange.position}\n"
pointerInputChange.consumePositionChange()
}
//gestureText = "EVENT changes size ${event.changes.size}\n" + eventChanges
//gestureColor = Color.Green
motionEvent = actionMove
currentPosition = event.changes.first().position
} while (event.changes.any { it.pressed })
motionEvent = actionUp
//canvasColor = Color.LightGray
//gestureText += "UP changedToDown: ${down.changedToDown()} " + "changedUp: ${down.changedToUp()}\n"
}
}
}
Canvas(
modifier = drawModifier
.padding(20.dp)
.size(500.dp)
) {
val canvasWidth = size.width
val canvasHeight = size.height
val line = 1.5
val squareSize = canvasWidth/line
drawRect(
color = Color.White,
topLeft = Offset(center.x - canvasWidth / 3, center.y - canvasHeight / 6),
size = Size(width = squareSize.toFloat(), squareSize.toFloat()),
style = Stroke(
width = 50.dp.toPx()
),
)
when(motionEvent){
actionDown->{
path.moveTo(currentPosition.x,currentPosition.y)
}
actionMove->{
if (currentPosition!= Offset.Unspecified){
path.lineTo(currentPosition.x,currentPosition.y)
}
}
actionUp->{
path.lineTo(currentPosition.x,currentPosition.y)
motionEvent = actionIdle
}
else-> Unit
}
drawPath(
color = Color.Cyan,
path = path,
style = Stroke(width = 5.dp.toPx(), join = StrokeJoin.Round)
)
}
}
