Refactored to use flow instead of snapshot maps

build.gradle.kts

@@ -9,7 +9,7 @@ val kmathVersion: String by extra("0.4.0")
 
 allprojects {
     group = "space.kscience"
-    version = "0.3.1-dev"
+    version = "0.4.0-dev"
 
     repositories {
         mavenLocal()

demo/maps-wasm/src/wasmJsMain/kotlin/Main.kt

@@ -1,4 +1,4 @@
-@file:OptIn(ExperimentalComposeUiApi::class, ExperimentalResourceApi::class)
+@file:OptIn(ExperimentalResourceApi::class, ExperimentalComposeUiApi::class)
 
 import androidx.compose.runtime.*
 import androidx.compose.ui.ExperimentalComposeUiApi
@@ -10,7 +10,7 @@ import kotlinx.coroutines.launch
 import org.jetbrains.compose.resources.ExperimentalResourceApi
 import org.jetbrains.compose.resources.painterResource
 import space.kscience.kmath.geometry.Angle
-import space.kscience.maps.features.FeatureGroup
+import space.kscience.maps.features.FeatureStore
 import space.kscience.maps.features.ViewConfig
 import space.kscience.maps.features.ViewPoint
 import space.kscience.maps.features.color
@@ -25,7 +25,7 @@ fun App() {
     val scope = rememberCoroutineScope()
 
 
-    val features: FeatureGroup<XY> = FeatureGroup.remember(XYCoordinateSpace) {
+    val features = FeatureStore.remember(XYCoordinateSpace) {
         background(1600f, 1200f) {
             painterResource(Res.drawable.middle_earth)
         }

demo/maps/src/jvmMain/kotlin/Main.kt

@@ -73,7 +73,7 @@ fun App() {
 
             geoJson(javaClass.getResource("/moscow.geo.json")!!)
                 .color(Color.Blue)
-                .modifyAttribute(AlphaAttribute, 0.4f)
+                .alpha(0.4f)
 
             icon(pointOne, Icons.Filled.Home)
 
@@ -166,13 +166,13 @@ fun App() {
             }.launchIn(scope)
 
             //Add click listeners for all polygons
-            forEachWithType<Gmc, PolygonFeature<Gmc>> { ref ->
+            forEachWithType<Gmc, PolygonFeature<Gmc>> { ref, polygon: PolygonFeature<Gmc> ->
                 ref.onClick(PointerMatcher.Primary) {
                     println("Click on ${ref.id}")
                     //draw in top-level scope
                     with(this@MapView) {
                         multiLine(
-                            ref.resolve().points,
+                            polygon.points,
                             attributes = Attributes(ZAttribute, 10f),
                             id = "selected",
                         ).modifyAttribute(StrokeAttribute, 4f).color(Color.Magenta)

demo/polygon-editor/src/jvmMain/kotlin/Main.kt

@@ -24,7 +24,7 @@ fun App() {
 
         val myPolygon: SnapshotStateList<XY> = remember { mutableStateListOf<XY>() }
 
-        val featureState: FeatureGroup<XY> = FeatureGroup.remember(XYCoordinateSpace) {
+        val featureState = FeatureStore.remember(XYCoordinateSpace) {
             multiLine(
                 listOf(XY(0f, 0f), XY(0f, 1f), XY(1f, 1f), XY(1f, 0f), XY(0f, 0f)),
                 id = "frame"

demo/scheme/src/jvmMain/kotlin/Main.kt

@@ -12,7 +12,7 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import space.kscience.kmath.geometry.Angle
-import space.kscience.maps.features.FeatureGroup
+import space.kscience.maps.features.FeatureStore
 import space.kscience.maps.features.ViewConfig
 import space.kscience.maps.features.ViewPoint
 import space.kscience.maps.features.color
@@ -29,7 +29,7 @@ fun App() {
     MaterialTheme {
         val scope = rememberCoroutineScope()
 
-        val features: FeatureGroup<XY> = FeatureGroup.remember(XYCoordinateSpace) {
+        val features = FeatureStore.remember(XYCoordinateSpace) {
             background(1600f, 1200f) { painterResource("middle-earth.jpg") }
             circle(410.52737 to 868.7676).color(Color.Blue)
             text(410.52737 to 868.7676, "Shire").color(Color.Blue)

demo/trajectory-playground/src/jvmMain/kotlin/Main.kt

@@ -22,7 +22,7 @@ private fun Vector2D<out Number>.toXY() = XY(x.toFloat(), y.toFloat())
 
 private val random = Random(123)
 
-fun FeatureGroup<XY>.trajectory(
+fun FeatureBuilder<XY>.trajectory(
     trajectory: Trajectory2D,
     colorPicker: (Trajectory2D) -> Color = { Color.Blue },
 ): FeatureRef<XY, FeatureGroup<XY>> = group {
@@ -54,12 +54,12 @@ fun FeatureGroup<XY>.trajectory(
     }
 }
 
-fun FeatureGroup<XY>.obstacle(obstacle: Obstacle, colorPicker: (Trajectory2D) -> Color = { Color.Red }) {
+fun FeatureBuilder<XY>.obstacle(obstacle: Obstacle, colorPicker: (Trajectory2D) -> Color = { Color.Red }) {
     trajectory(obstacle.circumvention, colorPicker)
     polygon(obstacle.arcs.map { it.center.toXY() }).color(Color.Gray)
 }
 
-fun FeatureGroup<XY>.pose(pose2D: Pose2D) = with(Float64Space2D) {
+fun FeatureBuilder<XY>.pose(pose2D: Pose2D) = with(Float64Space2D) {
     line(pose2D.toXY(), (pose2D + Pose2D.bearingToVector(pose2D.bearing)).toXY())
 }
 

maps-kt-compose/src/commonMain/kotlin/space/kscience/maps/compose/MapView.kt

@@ -33,7 +33,7 @@ private val logger = KotlinLogging.logger("MapView")
 public fun MapView(
     mapState: MapCanvasState,
     mapTileProvider: MapTileProvider,
-    features: FeatureGroup<Gmc>,
+    featureStore: FeatureStore<Gmc>,
     modifier: Modifier,
 ) {
     val mapTiles = remember(mapTileProvider) {
@@ -87,7 +87,7 @@ public fun MapView(
     }
 
 
-    FeatureCanvas(mapState, features, modifier = modifier.canvasControls(mapState, features)) {
+    FeatureCanvas(mapState, featureStore.featureFlow, modifier = modifier.canvasControls(mapState, featureStore)) {
         val tileScale = mapState.tileScale
 
         clipRect {
@@ -112,19 +112,19 @@ public fun MapView(
 }
 
 /**
- * Create a [MapView] with given [features] group.
+ * Create a [MapView] with given [featureStore] group.
  */
 @Composable
 public fun MapView(
     mapTileProvider: MapTileProvider,
     config: ViewConfig<Gmc>,
-    features: FeatureGroup<Gmc>,
+    featureStore: FeatureStore<Gmc>,
     initialViewPoint: ViewPoint<Gmc>? = null,
     initialRectangle: Rectangle<Gmc>? = null,
     modifier: Modifier,
 ) {
     val mapState = MapCanvasState.remember(mapTileProvider, config, initialViewPoint, initialRectangle)
-    MapView(mapState, mapTileProvider, features, modifier)
+    MapView(mapState, mapTileProvider, featureStore, modifier)
 }
 
 /**
@@ -141,9 +141,9 @@ public fun MapView(
     initialViewPoint: ViewPoint<Gmc>? = null,
     initialRectangle: Rectangle<Gmc>? = null,
     modifier: Modifier = Modifier.fillMaxSize(),
-    buildFeatures: FeatureGroup<Gmc>.() -> Unit = {},
+    buildFeatures: FeatureStore<Gmc>.() -> Unit = {},
 ) {
-    val featureState = FeatureGroup.remember(WebMercatorSpace, buildFeatures)
+    val featureState = FeatureStore.remember(WebMercatorSpace, buildFeatures)
     val computedRectangle = initialRectangle ?: featureState.getBoundingBox()
     MapView(mapTileProvider, config, featureState, initialViewPoint, computedRectangle, modifier)
 }

maps-kt-compose/src/commonMain/kotlin/space/kscience/maps/compose/mapFeatures.kt

@@ -13,12 +13,12 @@ import space.kscience.maps.features.*
 import kotlin.math.ceil
 
 
-internal fun FeatureGroup<Gmc>.coordinatesOf(pair: Pair<Number, Number>) =
+internal fun FeatureBuilder<Gmc>.coordinatesOf(pair: Pair<Number, Number>) =
     GeodeticMapCoordinates.ofDegrees(pair.first.toDouble(), pair.second.toDouble())
 
 public typealias MapFeature = Feature<Gmc>
 
-public fun FeatureGroup<Gmc>.circle(
+public fun FeatureBuilder<Gmc>.circle(
     centerCoordinates: Pair<Number, Number>,
     size: Dp = 5.dp,
     id: String? = null,
@@ -26,7 +26,7 @@ public fun FeatureGroup<Gmc>.circle(
     id, CircleFeature(space, coordinatesOf(centerCoordinates), size)
 )
 
-public fun FeatureGroup<Gmc>.rectangle(
+public fun FeatureBuilder<Gmc>.rectangle(
     centerCoordinates: Pair<Number, Number>,
     size: DpSize = DpSize(5.dp, 5.dp),
     id: String? = null,
@@ -35,7 +35,7 @@ public fun FeatureGroup<Gmc>.rectangle(
 )
 
 
-public fun FeatureGroup<Gmc>.draw(
+public fun FeatureBuilder<Gmc>.draw(
     position: Pair<Number, Number>,
     id: String? = null,
     draw: DrawScope.() -> Unit,
@@ -45,7 +45,7 @@ public fun FeatureGroup<Gmc>.draw(
 )
 
 
-public fun FeatureGroup<Gmc>.line(
+public fun FeatureBuilder<Gmc>.line(
     curve: GmcCurve,
     id: String? = null,
 ): FeatureRef<Gmc, LineFeature<Gmc>> = feature(
@@ -56,7 +56,7 @@ public fun FeatureGroup<Gmc>.line(
 /**
  * A segmented geodetic curve
  */
-public fun FeatureGroup<Gmc>.geodeticLine(
+public fun FeatureBuilder<Gmc>.geodeticLine(
     curve: GmcCurve,
     ellipsoid: GeoEllipsoid = GeoEllipsoid.WGS84,
     maxLineDistance: Distance = 100.kilometers,
@@ -79,7 +79,7 @@ public fun FeatureGroup<Gmc>.geodeticLine(
     multiLine(points.map { it.coordinates }, id = id)
 }
 
-public fun FeatureGroup<Gmc>.geodeticLine(
+public fun FeatureBuilder<Gmc>.geodeticLine(
     from: Gmc,
     to: Gmc,
     ellipsoid: GeoEllipsoid = GeoEllipsoid.WGS84,
@@ -87,7 +87,7 @@ public fun FeatureGroup<Gmc>.geodeticLine(
     id: String? = null,
 ): FeatureRef<Gmc, Feature<Gmc>> = geodeticLine(ellipsoid.curveBetween(from, to), ellipsoid, maxLineDistance, id)
 
-public fun FeatureGroup<Gmc>.line(
+public fun FeatureBuilder<Gmc>.line(
     aCoordinates: Pair<Double, Double>,
     bCoordinates: Pair<Double, Double>,
     id: String? = null,
@@ -96,7 +96,7 @@ public fun FeatureGroup<Gmc>.line(
     LineFeature(space, coordinatesOf(aCoordinates), coordinatesOf(bCoordinates))
 )
 
-public fun FeatureGroup<Gmc>.arc(
+public fun FeatureBuilder<Gmc>.arc(
     center: Pair<Double, Double>,
     radius: Distance,
     startAngle: Angle,
@@ -112,17 +112,17 @@ public fun FeatureGroup<Gmc>.arc(
     )
 )
 
-public fun FeatureGroup<Gmc>.points(
+public fun FeatureBuilder<Gmc>.points(
     points: List<Pair<Double, Double>>,
     id: String? = null,
 ): FeatureRef<Gmc, PointsFeature<Gmc>> = feature(id, PointsFeature(space, points.map(::coordinatesOf)))
 
-public fun FeatureGroup<Gmc>.multiLine(
+public fun FeatureBuilder<Gmc>.multiLine(
     points: List<Pair<Double, Double>>,
     id: String? = null,
 ): FeatureRef<Gmc, MultiLineFeature<Gmc>> = feature(id, MultiLineFeature(space, points.map(::coordinatesOf)))
 
-public fun FeatureGroup<Gmc>.icon(
+public fun FeatureBuilder<Gmc>.icon(
     position: Pair<Double, Double>,
     image: ImageVector,
     size: DpSize = DpSize(20.dp, 20.dp),
@@ -137,7 +137,7 @@ public fun FeatureGroup<Gmc>.icon(
     )
 )
 
-public fun FeatureGroup<Gmc>.text(
+public fun FeatureBuilder<Gmc>.text(
     position: Pair<Double, Double>,
     text: String,
     font: Font.() -> Unit = { size = 16f },
@@ -147,7 +147,7 @@ public fun FeatureGroup<Gmc>.text(
     TextFeature(space, coordinatesOf(position), text, fontConfig = font)
 )
 
-public fun FeatureGroup<Gmc>.pixelMap(
+public fun FeatureBuilder<Gmc>.pixelMap(
     rectangle: Rectangle<Gmc>,
     latitudeDelta: Angle,
     longitudeDelta: Angle,

maps-kt-features/build.gradle.kts

@@ -35,5 +35,6 @@ kscience {
         api(compose.material)
         api(compose.ui)
         api("io.github.oshai:kotlin-logging:6.0.3")
+        api("com.benasher44:uuid:0.8.4")
     }
 }

maps-kt-features/src/commonMain/kotlin/space/kscience/maps/compose/canvasControls.kt

@@ -18,7 +18,7 @@ import kotlin.math.min
  */
 public fun <T : Any> Modifier.canvasControls(
     state: CanvasState<T>,
-    features: FeatureGroup<T>,
+    features: FeatureStore<T>,
 ): Modifier = with(state) {
 
 //    //selecting all tapabales ahead of time
@@ -36,7 +36,7 @@ public fun <T : Any> Modifier.canvasControls(
                 val point = state.space.ViewPoint(coordinates, zoom)
 
                 if (event.type == PointerEventType.Move) {
-                    features.forEachWithAttribute(HoverListenerAttribute) { _, feature, listeners ->
+                    features.forEachWithAttribute(HoverListenerAttribute) { id, feature, listeners ->
                         if (point in feature as DomainFeature) {
                             listeners.forEach { it.handle(event, point) }
                             return@forEachWithAttribute

maps-kt-features/src/commonMain/kotlin/space/kscience/maps/features/FeatureDrawScope.kt

@@ -2,6 +2,9 @@ package space.kscience.maps.features
 
 import androidx.compose.foundation.Canvas
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.key
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.graphics.Color
@@ -16,6 +19,7 @@ import androidx.compose.ui.text.drawText
 import androidx.compose.ui.text.rememberTextMeasurer
 import androidx.compose.ui.unit.DpRect
 import io.github.oshai.kotlinlogging.KotlinLogging
+import kotlinx.coroutines.flow.StateFlow
 import space.kscience.attributes.Attributes
 
 /**
@@ -52,6 +56,7 @@ public class ComposeFeatureDrawScope<T : Any>(
 ) : FeatureDrawScope<T>(state), DrawScope by drawScope {
     override fun drawText(text: String, position: Offset, attributes: Attributes) {
         try {
+            //TODO don't draw text that is not on screen
             drawText(textMeasurer ?: error("Text measurer not defined"), text, position)
         } catch (ex: Exception) {
             logger.error(ex) { "Failed to measure text" }
@@ -73,15 +78,19 @@ public class ComposeFeatureDrawScope<T : Any>(
 @Composable
 public fun <T : Any> FeatureCanvas(
     state: CanvasState<T>,
-    features: FeatureGroup<T>,
+    featureFlow: StateFlow<Map<String, Feature<T>>>,
     modifier: Modifier = Modifier,
     draw: FeatureDrawScope<T>.() -> Unit = {},
 ) {
     val textMeasurer = rememberTextMeasurer(0)
 
-    val painterCache: Map<PainterFeature<T>, Painter> = features.features.flatMap {
+    val features by featureFlow.collectAsState()
-        if (it is FeatureGroup) it.features else listOf(it)
+
-    }.filterIsInstance<PainterFeature<T>>().associateWith { it.getPainter() }
+    val painterCache = key(features) {
+        features.values
+            .filterIsInstance<PainterFeature<T>>()
+            .associateWith { it.getPainter() }
+    }
 
     Canvas(modifier) {
         if (state.canvasSize != size.toDpSize()) {
@@ -89,7 +98,7 @@ public fun <T : Any> FeatureCanvas(
         }
         ComposeFeatureDrawScope(this, state, painterCache, textMeasurer).apply(draw).apply {
             clipRect {
-                features.featureMap.values.sortedBy { it.z }
+                features.values.sortedBy { it.z }
                     .filter { state.viewPoint.zoom in it.zoomRange }
                     .forEach { feature ->
                         this@apply.drawFeature(feature)

maps-kt-features/src/commonMain/kotlin/space/kscience/maps/features/FeatureStore.kt

@@ -1,7 +1,7 @@
 package space.kscience.maps.features
 
-import androidx.compose.runtime.*
+import androidx.compose.runtime.Composable
-import androidx.compose.runtime.snapshots.SnapshotStateMap
+import androidx.compose.runtime.remember
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.graphics.painter.Painter
@@ -9,89 +9,103 @@ import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.DpSize
 import androidx.compose.ui.unit.dp
+import com.benasher44.uuid.Uuid
+import com.benasher44.uuid.uuid4
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
 import org.jetbrains.skia.Font
 import space.kscience.attributes.Attribute
 import space.kscience.attributes.Attributes
 import space.kscience.kmath.geometry.Angle
 import space.kscience.kmath.nd.*
 import space.kscience.kmath.structures.Buffer
+import space.kscience.maps.features.FeatureStore.Companion.generateId
 
 //@JvmInline
 //public value class FeatureId<out F : Feature<*>>(public val id: String)
 
-public class FeatureRef<T : Any, out F : Feature<T>>(public val id: String, public val parent: FeatureGroup<T>)
+public class FeatureRef<T : Any, out F : Feature<T>>(public val store: FeatureStore<T>, public val id: String)
 
 @Suppress("UNCHECKED_CAST")
 public fun <T : Any, F : Feature<T>> FeatureRef<T, F>.resolve(): F =
-    parent.featureMap[id]?.let { it as F } ?: error("Feature with id=$id not found")
+    store.features[id]?.let { it as F } ?: error("Feature with id=$id not found")
 
 public val <T : Any, F : Feature<T>> FeatureRef<T, F>.attributes: Attributes get() = resolve().attributes
 
+public fun Uuid.toIndex(): String = leastSignificantBits.toString(16)
+
+public interface FeatureBuilder<T : Any> {
+    public val space: CoordinateSpace<T>
+    public fun <F : Feature<T>> feature(id: String?, feature: F): FeatureRef<T, F>
+
+    public fun group(
+        id: String? = null,
+        attributes: Attributes = Attributes.EMPTY,
+        builder: FeatureGroup<T>.() -> Unit,
+    ): FeatureRef<T, FeatureGroup<T>>
+
+    public fun removeFeature(id: String)
+}
+
+public interface FeatureSet<T : Any> {
+    public val features: Map<String, Feature<T>>
+
     /**
- * A group of other features
+     * Create a reference
      */
-public data class FeatureGroup<T : Any>(
+    public fun <F: Feature<T>> ref(id: String): FeatureRef<T, F>
+}
+
+
+public class FeatureStore<T : Any>(
     override val space: CoordinateSpace<T>,
-    public val featureMap: SnapshotStateMap<String, Feature<T>> = mutableStateMapOf(),
+) : CoordinateSpace<T> by space, FeatureBuilder<T>, FeatureSet<T> {
-) : CoordinateSpace<T> by space, Feature<T> {
+    private val _featureFlow = MutableStateFlow<Map<String, Feature<T>>>(emptyMap())
 
-    private val attributesState: MutableState<Attributes> = mutableStateOf(Attributes.EMPTY)
+    public val featureFlow: StateFlow<Map<String, Feature<T>>> get() = _featureFlow
 
-    override val attributes: Attributes get() = attributesState.value
+    override val features: Map<String, Feature<T>> get() = featureFlow.value
 
-//
+    override fun <F : Feature<T>> feature(id: String?, feature: F): FeatureRef<T, F> {
-//    @Suppress("UNCHECKED_CAST")
+        val safeId = id ?: generateId(feature)
-//    public operator fun <F : Feature<T>> get(id: FeatureId<F>): F =
+        _featureFlow.value += (safeId to feature)
-//        featureMap[id.id]?.let { it as F } ?: error("Feature with id=$id not found")
+        return FeatureRef(this, safeId)
-
-    private var uidCounter = 0
-
-    private fun generateUID(feature: Feature<T>?): String = if (feature == null) {
-        "@group[${uidCounter++}]"
-    } else {
-        "@${feature::class.simpleName}[${uidCounter++}]"
     }
 
-    public fun <F : Feature<T>> feature(id: String?, feature: F): FeatureRef<T, F> {
+    override fun group(
-        val safeId = id ?: generateUID(feature)
+        id: String?,
-        featureMap[safeId] = feature
+        attributes: Attributes,
-        return FeatureRef(safeId, this)
+        builder: FeatureGroup<T>.() -> Unit,
+    ): FeatureRef<T, FeatureGroup<T>> {
+        val safeId = id ?: generateId(null)
+        return feature(safeId, FeatureGroup(this, safeId, attributes).apply(builder))
     }
 
-    public fun removeFeature(id: String) {
+    override fun removeFeature(id: String) {
-        featureMap.remove(id)
+        _featureFlow.value -= id
     }
 
-//    public fun <F : Feature<T>> feature(id: FeatureId<F>, feature: F): FeatureId<F> = feature(id.id, feature)
+    override fun <F: Feature<T>> ref(id: String): FeatureRef<T, F> = FeatureRef(this, id)
 
-    public val features: Collection<Feature<T>> get() = featureMap.values.sortedByDescending { it.z }
+    public fun getBoundingBox(zoom: Float = Float.MAX_VALUE): Rectangle<T>? = with(space) {
-
+        features.values.mapNotNull { it.getBoundingBox(zoom) }.wrapRectangles()
-
-    //
-//    @Suppress("UNCHECKED_CAST")
-//    public fun <A> getAttribute(id: FeatureId<Feature<T>>, key: Attribute<A>): A? =
-//        get(id).attributes[key]
-
-
-    override fun getBoundingBox(zoom: Float): Rectangle<T>? = with(space) {
-        featureMap.values.mapNotNull { it.getBoundingBox(zoom) }.wrapRectangles()
-    }
-
-    override fun withAttributes(modify: Attributes.() -> Attributes): Feature<T> {
-        attributesState.value = attributes.modify()
-        return this
     }
 
 
     public companion object {
+        internal fun generateId(feature: Feature<*>?): String = if (feature == null) {
+            "@group[${uuid4().toIndex()}]"
+        } else {
+            "${feature::class.simpleName}[${uuid4().toIndex()}]"
+        }
 
         /**
          * Build, but do not remember map feature state
          */
         public fun <T : Any> build(
             coordinateSpace: CoordinateSpace<T>,
-            builder: FeatureGroup<T>.() -> Unit = {},
+            builder: FeatureStore<T>.() -> Unit = {},
-        ): FeatureGroup<T> = FeatureGroup(coordinateSpace).apply(builder)
+        ): FeatureStore<T> = FeatureStore(coordinateSpace).apply(builder)
 
         /**
          * Build and remember map feature state
@@ -99,79 +113,100 @@ public data class FeatureGroup<T : Any>(
         @Composable
         public fun <T : Any> remember(
             coordinateSpace: CoordinateSpace<T>,
-            builder: FeatureGroup<T>.() -> Unit = {},
+            builder: FeatureStore<T>.() -> Unit = {},
-        ): FeatureGroup<T> = remember {
+        ): FeatureStore<T> = remember {
             build(coordinateSpace, builder)
         }
-
     }
 }
 
+/**
+ * A group of other features
+ */
+public data class FeatureGroup<T : Any> internal constructor(
+    val store: FeatureStore<T>,
+    val groupId: String,
+    override val attributes: Attributes,
+) : CoordinateSpace<T> by store.space, Feature<T>, FeatureBuilder<T>, FeatureSet<T> {
+
+    override val space: CoordinateSpace<T> get() = store.space
+
+    override fun withAttributes(modify: Attributes.() -> Attributes): FeatureGroup<T> =
+        FeatureGroup(store, groupId, modify(attributes))
+
+
+    override fun <F : Feature<T>> feature(id: String?, feature: F): FeatureRef<T, F> =
+        store.feature("$groupId/${id ?: generateId(feature)}", feature)
+
+    override fun group(
+        id: String?,
+        attributes: Attributes,
+        builder: FeatureGroup<T>.() -> Unit,
+    ): FeatureRef<T, FeatureGroup<T>> {
+        val safeId = id ?: generateId(null)
+        return feature(safeId, FeatureGroup(store, "$groupId/$safeId", attributes).apply(builder))
+    }
+
+    override fun removeFeature(id: String) {
+        store.removeFeature("$groupId/$id")
+    }
+
+    override val features: Map<String, Feature<T>>
+        get() = store.featureFlow.value
+            .filterKeys { it.startsWith("$groupId/") }
+            .mapKeys { it.key.removePrefix("$groupId/") }
+            .toMap()
+
+    override fun getBoundingBox(zoom: Float): Rectangle<T>? = with(space) {
+        features.values.mapNotNull { it.getBoundingBox(zoom) }.wrapRectangles()
+    }
+
+    override fun <F: Feature<T>> ref(id: String): FeatureRef<T, F> = FeatureRef(store, "$groupId/$id")
+}
+
 /**
  * Recursively search for feature until function returns true
  */
-public fun <T : Any> FeatureGroup<T>.forEachUntil(visitor: FeatureGroup<T>.(id: String, feature: Feature<T>) -> Boolean) {
+public fun <T : Any> FeatureSet<T>.forEachUntil(block: FeatureSet<T>.(ref: FeatureRef<T,*>, feature: Feature<T>) -> Boolean) {
-    featureMap.entries.sortedByDescending { it.value.z }.forEach { (key, feature) ->
+    features.entries.sortedByDescending { it.value.z }.forEach { (key, feature) ->
-        if (feature is FeatureGroup<T>) {
+        if (!block(ref<Feature<T>>(key), feature)) return@forEachUntil
-            feature.forEachUntil(visitor)
-        } else {
-            if (!visitor(this, key, feature)) return@forEachUntil
     }
 }
-}
-
-/**
- * Recursively visit all features in this group
- */
-public fun <T : Any> FeatureGroup<T>.forEach(
-    visitor: FeatureGroup<T>.(id: String, feature: Feature<T>) -> Unit,
-): Unit = forEachUntil { id, feature ->
-    visitor(id, feature)
-    true
-}
 
 /**
  * Process all features with a given attribute from the one with highest [z] to lowest
  */
-public fun <T : Any, A> FeatureGroup<T>.forEachWithAttribute(
+public inline fun <T : Any, A> FeatureSet<T>.forEachWithAttribute(
     key: Attribute<A>,
-    block: FeatureGroup<T>.(id: String, feature: Feature<T>, attributeValue: A) -> Unit,
+    block: FeatureSet<T>.(ref: FeatureRef<T,*>, feature: Feature<T>, attribute: A) -> Unit,
 ) {
-    forEach { id, feature ->
+    features.forEach { (id, feature) ->
         feature.attributes[key]?.let {
-            block(id, feature, it)
+            block(ref<Feature<T>>(id), feature, it)
         }
     }
 }
 
-public fun <T : Any, A> FeatureGroup<T>.forEachWithAttributeUntil(
+public inline fun <T : Any, A> FeatureSet<T>.forEachWithAttributeUntil(
     key: Attribute<A>,
-    block: FeatureGroup<T>.(id: String, feature: Feature<T>, attributeValue: A) -> Boolean,
+    block: FeatureSet<T>.(ref: FeatureRef<T,*>, feature: Feature<T>, attribute: A) -> Boolean,
 ) {
-    forEachUntil { id, feature ->
+    features.forEach { (id, feature) ->
         feature.attributes[key]?.let {
-            block(id, feature, it)
+            if (!block(ref<Feature<T>>(id), feature, it)) return@forEachWithAttributeUntil
-        } ?: true
+        }
     }
 }
 
-public inline fun <T : Any, reified F : Feature<T>> FeatureGroup<T>.forEachWithType(
+public inline fun <T : Any, reified F : Feature<T>> FeatureSet<T>.forEachWithType(
-    crossinline block: (FeatureRef<T, F>) -> Unit,
+    crossinline block: FeatureSet<T>.(ref: FeatureRef<T,F>, feature: F) -> Unit,
 ) {
-    forEach { id, feature ->
+    features.forEach { (id, feature) ->
-        if (feature is F) block(FeatureRef(id, this))
+        if (feature is F) block(ref(id), feature)
     }
 }
 
-public inline fun <T : Any, reified F : Feature<T>> FeatureGroup<T>.forEachWithTypeUntil(
+public fun <T : Any> FeatureBuilder<T>.circle(
-    crossinline block: (FeatureRef<T, F>) -> Boolean,
-) {
-    forEachUntil { id, feature ->
-        if (feature is F) block(FeatureRef(id, this)) else true
-    }
-}
-
-public fun <T : Any> FeatureGroup<T>.circle(
     center: T,
     size: Dp = 5.dp,
     attributes: Attributes = Attributes.EMPTY,
@@ -180,7 +215,7 @@ public fun <T : Any> FeatureGroup<T>.circle(
     id, CircleFeature(space, center, size, attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.rectangle(
+public fun <T : Any> FeatureBuilder<T>.rectangle(
     centerCoordinates: T,
     size: DpSize = DpSize(5.dp, 5.dp),
     attributes: Attributes = Attributes.EMPTY,
@@ -189,7 +224,7 @@ public fun <T : Any> FeatureGroup<T>.rectangle(
     id, RectangleFeature(space, centerCoordinates, size, attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.draw(
+public fun <T : Any> FeatureBuilder<T>.draw(
     position: T,
     attributes: Attributes = Attributes.EMPTY,
     id: String? = null,
@@ -199,7 +234,7 @@ public fun <T : Any> FeatureGroup<T>.draw(
     DrawFeature(space, position, drawFeature = draw, attributes = attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.line(
+public fun <T : Any> FeatureBuilder<T>.line(
     aCoordinates: T,
     bCoordinates: T,
     attributes: Attributes = Attributes.EMPTY,
@@ -209,7 +244,7 @@ public fun <T : Any> FeatureGroup<T>.line(
     LineFeature(space, aCoordinates, bCoordinates, attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.arc(
+public fun <T : Any> FeatureBuilder<T>.arc(
     oval: Rectangle<T>,
     startAngle: Angle,
     arcLength: Angle,
@@ -220,7 +255,7 @@ public fun <T : Any> FeatureGroup<T>.arc(
     ArcFeature(space, oval, startAngle, arcLength, attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.points(
+public fun <T : Any> FeatureBuilder<T>.points(
     points: List<T>,
     attributes: Attributes = Attributes.EMPTY,
     id: String? = null,
@@ -229,7 +264,7 @@ public fun <T : Any> FeatureGroup<T>.points(
     PointsFeature(space, points, attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.multiLine(
+public fun <T : Any> FeatureBuilder<T>.multiLine(
     points: List<T>,
     attributes: Attributes = Attributes.EMPTY,
     id: String? = null,
@@ -238,7 +273,7 @@ public fun <T : Any> FeatureGroup<T>.multiLine(
     MultiLineFeature(space, points, attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.polygon(
+public fun <T : Any> FeatureBuilder<T>.polygon(
     points: List<T>,
     attributes: Attributes = Attributes.EMPTY,
     id: String? = null,
@@ -247,7 +282,7 @@ public fun <T : Any> FeatureGroup<T>.polygon(
     PolygonFeature(space, points, attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.icon(
+public fun <T : Any> FeatureBuilder<T>.icon(
     position: T,
     image: ImageVector,
     size: DpSize = DpSize(image.defaultWidth, image.defaultHeight),
@@ -264,16 +299,7 @@ public fun <T : Any> FeatureGroup<T>.icon(
     )
 )
 
-public fun <T : Any> FeatureGroup<T>.group(
+public fun <T : Any> FeatureBuilder<T>.scalableImage(
-    id: String? = null,
-    builder: FeatureGroup<T>.() -> Unit,
-): FeatureRef<T, FeatureGroup<T>> {
-    val collection = FeatureGroup(space).apply(builder)
-    val feature = FeatureGroup(space, collection.featureMap)
-    return feature(id, feature)
-}
-
-public fun <T : Any> FeatureGroup<T>.scalableImage(
     box: Rectangle<T>,
     attributes: Attributes = Attributes.EMPTY,
     id: String? = null,
@@ -283,7 +309,7 @@ public fun <T : Any> FeatureGroup<T>.scalableImage(
     ScalableImageFeature<T>(space, box, painter = painter, attributes = attributes)
 )
 
-public fun <T : Any> FeatureGroup<T>.text(
+public fun <T : Any> FeatureBuilder<T>.text(
     position: T,
     text: String,
     font: Font.() -> Unit = { size = 16f },
@@ -304,7 +330,7 @@ public inline fun <reified T> Structure2D(rows: Int, columns: Int, initializer:
     return BufferND(strides, Buffer(strides.linearSize) { initializer(strides.index(it)) }).as2D()
 }
 
-public fun <T : Any> FeatureGroup<T>.pixelMap(
+public fun <T : Any> FeatureStore<T>.pixelMap(
     rectangle: Rectangle<T>,
     pixelMap: Structure2D<Color?>,
     attributes: Attributes = Attributes.EMPTY,
@@ -320,7 +346,7 @@ public fun <T : Any> FeatureGroup<T>.pixelMap(
 public fun FeatureGroup<*>.toPrettyString(): String {
     fun StringBuilder.printGroup(id: String, group: FeatureGroup<*>, prefix: String) {
         appendLine("${prefix}* [group] $id")
-        group.featureMap.forEach { (id, feature) ->
+        group.features.forEach { (id, feature) ->
             if (feature is FeatureGroup<*>) {
                 printGroup(id, feature, "  ")
             } else {

maps-kt-features/src/commonMain/kotlin/space/kscience/maps/features/compositeFeatures.kt

@@ -4,7 +4,7 @@ import space.kscience.attributes.Attributes
 import kotlin.jvm.JvmName
 
 
-public fun <T : Any> FeatureGroup<T>.draggableLine(
+public fun <T : Any> FeatureBuilder<T>.draggableLine(
     aId: FeatureRef<T, MarkerFeature<T>>,
     bId: FeatureRef<T, MarkerFeature<T>>,
     id: String? = null,
@@ -39,7 +39,7 @@ public fun <T : Any> FeatureGroup<T>.draggableLine(
     return drawLine()
 }
 
-public fun <T : Any> FeatureGroup<T>.draggableMultiLine(
+public fun <T : Any> FeatureBuilder<T>.draggableMultiLine(
     points: List<FeatureRef<T, MarkerFeature<T>>>,
     id: String? = null,
 ): FeatureRef<T, MultiLineFeature<T>> {
@@ -71,7 +71,7 @@ public fun <T : Any> FeatureGroup<T>.draggableMultiLine(
 }
 
 @JvmName("draggableMultiLineFromPoints")
-public fun <T : Any> FeatureGroup<T>.draggableMultiLine(
+public fun <T : Any> FeatureBuilder<T>.draggableMultiLine(
     points: List<T>,
     id: String? = null,
 ): FeatureRef<T, MultiLineFeature<T>> {

maps-kt-features/src/commonMain/kotlin/space/kscience/maps/features/drawFeature.kt

@@ -94,7 +94,7 @@ public fun <T : Any> FeatureDrawScope<T>.drawFeature(
         }
 
         is FeatureGroup -> {
-            feature.featureMap.values.forEach {
+            feature.features.values.forEach {
                 drawFeature(
                     it.withAttributes {
                         feature.attributes + this

maps-kt-features/src/commonMain/kotlin/space/kscience/maps/features/mapFeatureAttributes.kt

@@ -55,7 +55,7 @@ public fun <T : Any, F : Feature<T>> FeatureRef<T, F>.modifyAttributes(
     modification: AttributesBuilder<F>.() -> Unit,
 ): FeatureRef<T, F> {
     @Suppress("UNCHECKED_CAST")
-    parent.feature(
+    store.feature(
         id,
         resolve().withAttributes { modified(modification) } as F
     )
@@ -67,7 +67,7 @@ public fun <T : Any, F : Feature<T>, V> FeatureRef<T, F>.modifyAttribute(
     value: V,
 ): FeatureRef<T, F> {
     @Suppress("UNCHECKED_CAST")
-    parent.feature(id, resolve().withAttributes { withAttribute(key, value) } as F)
+    store.feature(id, resolve().withAttributes { withAttribute(key, value) } as F)
     return this
 }
 
@@ -80,10 +80,10 @@ public fun <T : Any, F : Feature<T>, V> FeatureRef<T, F>.modifyAttribute(
 public fun <T : Any, F : DraggableFeature<T>> FeatureRef<T, F>.draggable(
     constraint: ((T) -> T)? = null,
     listener: (PointerEvent.(from: ViewPoint<T>, to: ViewPoint<T>) -> Unit)? = null,
-): FeatureRef<T, F> = with(parent) {
+): FeatureRef<T, F> = with(store) {
     if (attributes[DraggableAttribute] == null) {
         val handle = DragHandle.withPrimaryButton<Any> { event, start, end ->
-            val feature = featureMap[id] as? DraggableFeature<T> ?: return@withPrimaryButton DragResult(end)
+            val feature = features[id] as? DraggableFeature<T> ?: return@withPrimaryButton DragResult(end)
             start as ViewPoint<T>
             end as ViewPoint<T>
             if (start in feature) {

maps-kt-geojson/src/commonMain/kotlin/space/kscience/maps/geojson/geoJsonToMap.kt

@@ -12,7 +12,7 @@ import space.kscience.maps.features.*
 /**
  * Add a single Json geometry to a feature builder
  */
-public fun FeatureGroup<Gmc>.geoJsonGeometry(
+public fun FeatureBuilder<Gmc>.geoJsonGeometry(
     geometry: GeoJsonGeometry,
     id: String? = null,
 ): FeatureRef<Gmc, Feature<Gmc>> = when (geometry) {
@@ -50,11 +50,11 @@ public fun FeatureGroup<Gmc>.geoJsonGeometry(
     }
 }
 
-public fun FeatureGroup<Gmc>.geoJsonFeature(
+public fun FeatureBuilder<Gmc>.geoJsonFeature(
     geoJson: GeoJsonFeature,
     id: String? = null,
 ): FeatureRef<Gmc, Feature<Gmc>> {
-    val geometry = geoJson.geometry ?: return group {}
+    val geometry = geoJson.geometry ?: return group(null) {}
     val idOverride = id ?: geoJson.getProperty("id")?.jsonPrimitive?.contentOrNull
 
     return geoJsonGeometry(geometry, idOverride).modifyAttributes {
@@ -72,7 +72,7 @@ public fun FeatureGroup<Gmc>.geoJsonFeature(
     }
 }
 
-public fun FeatureGroup<Gmc>.geoJson(
+public fun FeatureBuilder<Gmc>.geoJson(
     geoJson: GeoJson,
     id: String? = null,
 ): FeatureRef<Gmc, Feature<Gmc>> = when (geoJson) {

maps-kt-geojson/src/jvmMain/kotlin/space/kscience/maps/geojson/geoJsonFeatureJvm.kt

@@ -4,14 +4,14 @@ import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.jsonObject
 import space.kscience.maps.coordinates.Gmc
 import space.kscience.maps.features.Feature
-import space.kscience.maps.features.FeatureGroup
+import space.kscience.maps.features.FeatureBuilder
 import space.kscience.maps.features.FeatureRef
 import java.net.URL
 
 /**
  * Add geojson features from url
  */
-public fun FeatureGroup<Gmc>.geoJson(
+public fun FeatureBuilder<Gmc>.geoJson(
     geoJsonUrl: URL,
     id: String? = null,
 ): FeatureRef<Gmc, Feature<Gmc>> {

maps-kt-scheme/src/commonMain/kotlin/space/kscience/maps/scheme/SchemeView.kt

@@ -15,10 +15,10 @@ private val logger = KotlinLogging.logger("SchemeView")
 @Composable
 public fun SchemeView(
     state: XYCanvasState,
-    features: FeatureGroup<XY>,
+    featureStore: FeatureStore<XY>,
     modifier: Modifier = Modifier.fillMaxSize(),
 ): Unit {
-    FeatureCanvas(state, features, modifier = modifier.canvasControls(state, features))
+    FeatureCanvas(state, featureStore.featureFlow, modifier = modifier.canvasControls(state, featureStore))
 }
 
 
@@ -38,7 +38,7 @@ public fun Rectangle<XY>.computeViewPoint(
  */
 @Composable
 public fun SchemeView(
-    features: FeatureGroup<XY>,
+    features: FeatureStore<XY>,
     initialViewPoint: ViewPoint<XY>? = null,
     initialRectangle: Rectangle<XY>? = null,
     config: ViewConfig<XY> = ViewConfig(),
@@ -67,14 +67,13 @@ public fun SchemeView(
     initialRectangle: Rectangle<XY>? = null,
     config: ViewConfig<XY> = ViewConfig(),
     modifier: Modifier = Modifier.fillMaxSize(),
-    buildFeatures: FeatureGroup<XY>.() -> Unit = {},
+    buildFeatures: FeatureStore<XY>.() -> Unit = {},
 ) {
-    val featureState = FeatureGroup.remember(XYCoordinateSpace, buildFeatures)
+    val featureState = FeatureStore.remember(XYCoordinateSpace, buildFeatures)
     val mapState: XYCanvasState = XYCanvasState.remember(
         config,
         initialViewPoint = initialViewPoint,
-        initialRectangle = initialRectangle ?: featureState.features.computeBoundingBox(
+        initialRectangle = initialRectangle ?: featureState.getBoundingBox(
-            XYCoordinateSpace,
             Float.MAX_VALUE
         ),
     )

maps-kt-scheme/src/commonMain/kotlin/space/kscience/maps/scheme/schemeFeatures.kt

@@ -15,7 +15,7 @@ import kotlin.math.ceil
 
 internal fun Pair<Number, Number>.toCoordinates(): XY = XY(first.toFloat(), second.toFloat())
 
-public fun FeatureGroup<XY>.background(
+public fun FeatureBuilder<XY>.background(
     width: Float,
     height: Float,
     offset: XY = XY(0f, 0f),
@@ -37,26 +37,26 @@ public fun FeatureGroup<XY>.background(
     )
 }
 
-public fun FeatureGroup<XY>.circle(
+public fun FeatureBuilder<XY>.circle(
     centerCoordinates: Pair<Number, Number>,
     size: Dp = 5.dp,
     id: String? = null,
 ): FeatureRef<XY, CircleFeature<XY>> = circle(centerCoordinates.toCoordinates(), size, id = id)
 
-public fun FeatureGroup<XY>.draw(
+public fun FeatureBuilder<XY>.draw(
     position: Pair<Number, Number>,
     id: String? = null,
     draw: DrawScope.() -> Unit,
 ): FeatureRef<XY, DrawFeature<XY>> = draw(position.toCoordinates(), id = id, draw = draw)
 
-public fun FeatureGroup<XY>.line(
+public fun FeatureBuilder<XY>.line(
     aCoordinates: Pair<Number, Number>,
     bCoordinates: Pair<Number, Number>,
     id: String? = null,
 ): FeatureRef<XY, LineFeature<XY>> = line(aCoordinates.toCoordinates(), bCoordinates.toCoordinates(), id = id)
 
 
-public fun FeatureGroup<XY>.arc(
+public fun FeatureBuilder<XY>.arc(
     center: Pair<Double, Double>,
     radius: Float,
     startAngle: Angle,
@@ -69,7 +69,7 @@ public fun FeatureGroup<XY>.arc(
     id = id
 )
 
-public fun FeatureGroup<XY>.image(
+public fun FeatureBuilder<XY>.image(
     position: Pair<Number, Number>,
     image: ImageVector,
     size: DpSize = DpSize(image.defaultWidth, image.defaultHeight),
@@ -77,13 +77,13 @@ public fun FeatureGroup<XY>.image(
 ): FeatureRef<XY, VectorIconFeature<XY>> =
     icon(position.toCoordinates(), image, size = size, id = id)
 
-public fun FeatureGroup<XY>.text(
+public fun FeatureBuilder<XY>.text(
     position: Pair<Number, Number>,
     text: String,
     id: String? = null,
 ): FeatureRef<XY, TextFeature<XY>> = text(position.toCoordinates(), text, id = id)
 
-public fun FeatureGroup<XY>.pixelMap(
+public fun FeatureBuilder<XY>.pixelMap(
     rectangle: Rectangle<XY>,
     xSize: Float,
     ySize: Float,
@@ -108,7 +108,7 @@ public fun FeatureGroup<XY>.pixelMap(
     )
 )
 
-public fun FeatureGroup<XY>.rectanglePolygon(
+public fun FeatureBuilder<XY>.rectanglePolygon(
     left: Number, right: Number,
     bottom: Number, top: Number,
     attributes: Attributes = Attributes.EMPTY,
@@ -123,7 +123,7 @@ public fun FeatureGroup<XY>.rectanglePolygon(
     attributes, id
 )
 
-public fun FeatureGroup<XY>.rectanglePolygon(
+public fun FeatureBuilder<XY>.rectanglePolygon(
     rectangle: Rectangle<XY>,
     attributes: Attributes = Attributes.EMPTY,
     id: String? = null,

maps-kt-scheme/src/jvmMain/kotlin/space/kscience/maps/svg/exportToSvg.kt

@@ -17,11 +17,9 @@ public class FeatureStateSnapshot<T : Any>(
 )
 
 @Composable
-public fun <T : Any> FeatureGroup<T>.snapshot(): FeatureStateSnapshot<T> = FeatureStateSnapshot(
+public fun <T : Any> FeatureSet<T>.snapshot(): FeatureStateSnapshot<T> = FeatureStateSnapshot(
-    featureMap,
+    features,
-    features.flatMap {
+    features.values.filterIsInstance<PainterFeature<T>>().associateWith { it.getPainter() }
-        if (it is FeatureGroup) it.features else listOf(it)
-    }.filterIsInstance<PainterFeature<T>>().associateWith { it.getPainter() }
 )