Feature builder. Color modification example

src/commonMain/kotlin/centre/sciprog/maps/compose/FeatureBuilder.kt

@@ -0,0 +1,63 @@
+package centre.sciprog.maps.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateMapOf
+import androidx.compose.runtime.snapshots.SnapshotStateMap
+import androidx.compose.ui.geometry.Size
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.vector.ImageVector
+
+typealias FeatureId = String
+
+interface FeatureBuilder {
+    fun addFeature(id: FeatureId?, feature: MapFeature): FeatureId
+
+    fun build(): SnapshotStateMap<FeatureId, MapFeature>
+}
+
+internal class MapFeatureBuilder(private val content: SnapshotStateMap<FeatureId, MapFeature> = mutableStateMapOf()) : FeatureBuilder {
+    private fun generateID(feature: MapFeature): FeatureId = "@feature[${feature.hashCode().toUInt()}]"
+
+    override fun addFeature(id: FeatureId?, feature: MapFeature): FeatureId {
+        val safeId = id ?: generateID(feature)
+        content[id ?: generateID(feature)] = feature
+        return safeId
+    }
+
+    override fun build(): SnapshotStateMap<FeatureId, MapFeature> = content
+}
+
+fun FeatureBuilder.circle(
+    centerCoordinates: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    size: Float = 5f,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(
+    id, MapCircleFeature(centerCoordinates.toCoordinates(), zoomRange, size, color)
+)
+
+fun FeatureBuilder.line(
+    aCoordinates: Pair<Double, Double>,
+    bCoordinates: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(id, MapLineFeature(aCoordinates.toCoordinates(), bCoordinates.toCoordinates(), zoomRange, color))
+
+fun FeatureBuilder.text(
+    position: Pair<Double, Double>,
+    text: String,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(id, MapTextFeature(position.toCoordinates(), text, zoomRange, color))
+
+@Composable
+fun FeatureBuilder.image(
+    position: Pair<Double, Double>,
+    image: ImageVector,
+    size: Size = Size(20f, 20f),
+    zoomRange: IntRange = defaultZoomRange,
+    id: FeatureId? = null,
+) = addFeature(id, MapVectorImageFeature(position.toCoordinates(), image, size, zoomRange))

src/commonMain/kotlin/centre/sciprog/maps/compose/MapFeature.kt

@@ -15,7 +15,7 @@ sealed class MapFeature(val zoomRange: IntRange)
 
 internal fun Pair<Double, Double>.toCoordinates() = GeodeticMapCoordinates.ofDegrees(first, second)
 
-private val defaultZoomRange = 1..18
+internal val defaultZoomRange = 1..18
 
 /**
  * A feature that decides what to show depending on the zoom value (it could change size of shape)
@@ -29,18 +29,6 @@ class MapCircleFeature(
     val color: Color = Color.Red,
 ) : MapFeature(zoomRange)
 
-fun MapCircleFeature(
-    centerCoordinates: Pair<Double, Double>,
-    zoomRange: IntRange = defaultZoomRange,
-    size: Float = 5f,
-    color: Color = Color.Red,
-) = MapCircleFeature(
-    centerCoordinates.toCoordinates(),
-    zoomRange,
-    size,
-    color
-)
-
 class MapLineFeature(
     val a: GeodeticMapCoordinates,
     val b: GeodeticMapCoordinates,
@@ -48,13 +36,6 @@ class MapLineFeature(
     val color: Color = Color.Red,
 ) : MapFeature(zoomRange)
 
-fun MapLineFeature(
-    aCoordinates: Pair<Double, Double>,
-    bCoordinates: Pair<Double, Double>,
-    zoomRange: IntRange = defaultZoomRange,
-    color: Color = Color.Red,
-) = MapLineFeature(aCoordinates.toCoordinates(), bCoordinates.toCoordinates(), zoomRange, color)
-
 class MapTextFeature(
     val position: GeodeticMapCoordinates,
     val text: String,

src/commonMain/kotlin/centre/sciprog/maps/compose/MapView.kt

@@ -2,6 +2,8 @@ package centre.sciprog.maps.compose
 
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateMapOf
+import androidx.compose.runtime.snapshots.SnapshotStateMap
 import androidx.compose.ui.Modifier
 import centre.sciprog.maps.GeodeticMapCoordinates
 import centre.sciprog.maps.MapViewPoint
@@ -10,7 +12,20 @@ import centre.sciprog.maps.MapViewPoint
 expect fun MapView(
     initialViewPoint: MapViewPoint,
     mapTileProvider: MapTileProvider,
-    features: Collection<MapFeature> = emptyList(),
+    features: SnapshotStateMap<FeatureId, MapFeature> = mutableStateMapOf(),
+    onClick: (GeodeticMapCoordinates) -> Unit = {},
+    modifier: Modifier = Modifier.fillMaxSize(),
+)
+
+@Composable
+fun MapView(
+    initialViewPoint: MapViewPoint,
+    mapTileProvider: MapTileProvider,
     modifier: Modifier = Modifier.fillMaxSize(),
     onClick: (GeodeticMapCoordinates) -> Unit = {},
-)
+    addFeatures: @Composable FeatureBuilder.() -> Unit,
+) {
+    val featuresBuilder = MapFeatureBuilder()
+    featuresBuilder.addFeatures()
+    MapView(initialViewPoint, mapTileProvider, featuresBuilder.build(), onClick, modifier)
+}

src/jvmMain/kotlin/Main.kt

@@ -6,6 +6,7 @@ import androidx.compose.material.Text
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Home
 import androidx.compose.runtime.*
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.window.Window
 import androidx.compose.ui.window.application
 import centre.sciprog.maps.GeodeticMapCoordinates
@@ -14,24 +15,11 @@ import centre.sciprog.maps.compose.*
 import io.ktor.client.HttpClient
 import io.ktor.client.engine.cio.CIO
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
 import java.nio.file.Path
 import kotlin.random.Random
 
-/**
- *  initial set of features
- */
-@Composable
-private fun initialFeatures() = buildList {
-    val pointOne = 55.568548 to 37.568604
-    val pointTwo = 55.929444 to 37.518434
-    add(MapVectorImageFeature(pointOne.toCoordinates(), Icons.Filled.Home))
-//            add(MapCircleFeature(pointOne))
-    add(MapCircleFeature(pointTwo))
-    add(MapLineFeature(pointOne, pointTwo))
-    add(MapTextFeature(pointOne.toCoordinates(), "Home"))
-}
-
-
 @Composable
 @Preview
 fun App() {
@@ -40,24 +28,10 @@ fun App() {
         val viewPoint = remember {
             MapViewPoint(
                 GeodeticMapCoordinates.ofDegrees(55.7558, 37.6173),
-                6.0
+                8.0
             )
         }
 
-        // observable list of features
-        val features = mutableStateListOf<MapFeature>().apply {
-            addAll(initialFeatures())
-        }
-
-//        // test dynamic rendering
-//        LaunchedEffect(features) {
-//            repeat(10000) {
-//                delay(10)
-//                val randomPoint = Random.nextDouble(55.568548, 55.929444) to Random.nextDouble(37.518434, 37.568604)
-//                features.add(MapCircleFeature(randomPoint))
-//            }
-//        }
-
         val scope = rememberCoroutineScope()
         val mapTileProvider = remember { OpenStreetMapTileProvider(scope, HttpClient(CIO), Path.of("mapCache")) }
 
@@ -66,8 +40,30 @@ fun App() {
         Column {
             //display click coordinates
             Text(coordinates?.toString() ?: "")
-            MapView(viewPoint, mapTileProvider, features = features) {
+            MapView(viewPoint, mapTileProvider, onClick = { gmc: GeodeticMapCoordinates -> coordinates = gmc }) {
-                coordinates = it
+                val pointOne = 55.568548 to 37.568604
+                val pointTwo = 55.929444 to 37.518434
+                image(pointOne, Icons.Filled.Home)
+                val circleId: FeatureId = circle(pointTwo)
+                line(pointOne, pointTwo)
+                text(pointOne, "Home")
+
+                scope.launch {
+                    while (isActive){
+                        delay(200)
+                        circle(pointTwo, id = circleId, color = Color(Random.nextFloat(), Random.nextFloat(), Random.nextFloat()))
+                    }
+                }
+
+//                // test dynamic rendering
+//                scope.launch{
+//                    repeat(10000) {
+//                        delay(10)
+//                        val randomPoint =
+//                            Random.nextDouble(55.568548, 55.929444) to Random.nextDouble(37.518434, 37.568604)
+//                        circle(randomPoint)
+//                    }
+//                }
             }
         }
     }

src/jvmMain/kotlin/centre/sciprog/maps/compose/MapViewJvm.kt

@@ -4,6 +4,7 @@ import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.gestures.detectDragGestures
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.runtime.*
+import androidx.compose.runtime.snapshots.SnapshotStateMap
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
@@ -41,9 +42,9 @@ private val logger = KotlinLogging.logger("MapView")
 actual fun MapView(
     initialViewPoint: MapViewPoint,
     mapTileProvider: MapTileProvider,
-    features: Collection<MapFeature>,
+    features: SnapshotStateMap<FeatureId, MapFeature>,
-    modifier: Modifier,
     onClick: (GeodeticMapCoordinates) -> Unit,
+    modifier: Modifier,
 ) {
     var viewPoint by remember { mutableStateOf(initialViewPoint) }
 
@@ -162,7 +163,7 @@ actual fun MapView(
                     topLeft = offset
                 )
             }
-            features.filter { zoom in it.zoomRange }.forEach { feature ->
+            features.values.filter { zoom in it.zoomRange }.forEach { feature ->
                 drawFeature(zoom, feature)
             }
         }