CircleState

CircleState manages the configuration and behavior of circular overlays on the map. It provides reactive properties for center position, radiusMeters, styling, and interaction settings.

Constructor

CircleState(
    center: GeoPointInterface,
    radiusMeters: Double,
    clickable: Boolean = true,
    strokeColor: Color = Color.Red,
    strokeWidth: Dp = 1.dp,
    fillColor: Color = Color(red = 255, green = 255, blue = 255, alpha = 127),
    id: String? = null,
    zIndex: Int? = null,
    extra: Serializable? = null
)

Properties

Core Properties

• id: String: Unique identifier (auto-generated if not provided)
• center: GeoPointInterface: Geographic center of the circle
• radiusMeters: Double: radiusMeters in meters
• clickable: Boolean: Whether the circle responds to click events
• extra: Serializable?: Additional data attached to the circle

Visual Properties

• strokeColor: Color: Border color
• strokeWidth: Dp: Border width
• fillColor: Color: Interior fill color
• zIndex: Int?: Drawing order (higher values drawn on top)

Methods

fun copy(...): CircleState // Create a modified copy
fun fingerPrint(): CircleFingerPrint // Change detection
fun asFlow(): Flow<CircleFingerPrint> // Reactive updates

Usage Examples

Basic Circle

val circleState = CircleState(
    center = GeoPoint.fromLatLong(37.7749, -122.4194),
    radiusMeters = 1000,
    strokeColor = Color.Blue,
    fillColor = Color.Blue.copy(alpha = 0.3f)
)

MapView(state = mapViewState) {
    Circle(circleState)
}

Interactive Circle

@Composable
fun InteractiveCircleExample() {
    var circleState by remember {
        mutableStateOf(
            CircleState(
                center = GeoPoint.fromLatLong(37.7749, -122.4194),
                radiusMeters = 500,
                strokeColor = Color.Red,
                fillColor = Color.Red.copy(alpha = 0.2f),
                clickable = true,
                onClick = { event ->
                    println("Circle clicked at: ${event.clicked}")
                }
            )
        )
    }

    Column {
        Slider(
            value = circleState.radiusMeters.toFloat(),
            onValueChange = {
                circleState = circleState.copy(radiusMeters = it.toDouble())
            },
            valueRange = 100f..2000f
        )

        MapView(
            state = mapViewState
        ) {
            Circle(circleState)
        }
    }
}

Multiple Circles with Z-Index

val circles = listOf(
    CircleState(
        center = GeoPoint.fromLatLong(37.7749, -122.4194),
        radiusMeters = 1000,
        fillColor = Color.Red.copy(alpha = 0.3f),
        zIndex = 1
    ),
    CircleState(
        center = GeoPoint.fromLatLong(37.7749, -122.4194),
        radiusMeters = 500,
        fillColor = Color.Blue.copy(alpha = 0.5f),
        zIndex = 2
    )
)

MapView(state = mapViewState) {
    circles.forEach { circleState ->
        Circle(circleState)
    }
}

Event Handling

Circle events provide both the state and click location:

data class CircleEvent(
    val state: CircleState,
    val clicked: GeoPointInterface
)

typealias OnCircleEventHandler = (CircleEvent) -> Unit

Best Practices

1. Radius Units: Always specify radius in meters for consistency
2. Color Alpha: Use alpha transparency for better map visibility
3. Z-Index: Use z-index to control overlapping circles
4. Performance: Avoid creating too many large circles
5. Reactivity: Update properties directly for efficient re-rendering