Full refacor of map state and arguments

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

@@ -2,8 +2,9 @@ import androidx.compose.desktop.ui.tooling.preview.Preview
 import androidx.compose.material.MaterialTheme
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Home
-import androidx.compose.runtime.*
+import androidx.compose.runtime.Composable
-import androidx.compose.ui.geometry.Offset
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.PointMode
 import androidx.compose.ui.unit.DpSize
@@ -17,6 +18,10 @@ import center.sciprog.maps.geojson.geoJson
 import io.ktor.client.HttpClient
 import io.ktor.client.engine.cio.CIO
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.filterNotNull
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
 import java.net.URL
 import java.nio.file.Path
 import kotlin.math.PI
@@ -32,6 +37,7 @@ fun App() {
     MaterialTheme {
 
         val scope = rememberCoroutineScope()
+
         val mapTileProvider = remember {
             OpenStreetMapTileProvider(
                 client = HttpClient(CIO),
@@ -39,7 +45,7 @@ fun App() {
             )
         }
 
-        var centerCoordinates by remember { mutableStateOf<Gmc?>(null) }
+        val centerCoordinates = MutableStateFlow<Gmc?>(null)
 
 
         val pointOne = 55.568548 to 37.568604
@@ -48,17 +54,9 @@ fun App() {
 
         MapView(
             mapTileProvider = mapTileProvider,
-//            initialViewPoint = MapViewPoint(
-//                GeodeticMapCoordinates.ofDegrees(55.7558, 37.6173),
-//                8.0
-//            ),
-//            initialRectangle = GmcRectangle.square(
-//                GeodeticMapCoordinates.ofDegrees(55.7558, 37.6173),
-//                50.kilometers,
-//                50.kilometers
-//            ),
             config = ViewConfig(
-                onViewChange = { centerCoordinates = focus },
+                onViewChange = { centerCoordinates.value = focus },
+                onClick = { _, viewPoint -> println(viewPoint) }
             )
         ) {
 
@@ -95,22 +93,22 @@ fun App() {
                 it.copy(color = Color(Random.nextFloat(), Random.nextFloat(), Random.nextFloat()))
             }
 
-            draw(position = pointThree) {
+//            draw(position = pointThree) {
-                drawLine(start = Offset(-10f, -10f), end = Offset(10f, 10f), color = Color.Red)
+//                drawLine(start = Offset(-10f, -10f), end = Offset(10f, 10f), color = Color.Red)
-                drawLine(start = Offset(-10f, 10f), end = Offset(10f, -10f), color = Color.Red)
+//                drawLine(start = Offset(-10f, 10f), end = Offset(10f, -10f), color = Color.Red)
-            }
+//            }
 
             arc(pointOne, 10.0.kilometers, (PI / 4).radians, -Angle.pi / 2)
 
             line(pointOne, pointTwo, id = "line")
             text(pointOne, "Home", font = { size = 32f })
 
-            centerCoordinates?.let {
+            centerCoordinates.filterNotNull().onEach {
                 group(id = "center") {
                     circle(center = it, color = Color.Blue, id = "circle", size = 1.dp)
                     text(position = it, it.toShortString(), id = "text", color = Color.Blue)
                 }
-            }
+            }.launchIn(scope)
         }
     }
 }

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

@@ -79,15 +79,20 @@ fun App() {
                 )
             }
         ) {
-            SchemeView(
+            val mapState: XYViewScope = rememberMapState(
-                initialViewPoint = initialViewPoint,
+                ViewConfig(
-                featuresState = schemeFeaturesState,
+                    onClick = {_, click ->
-                config = ViewConfig(
+                        println("${click.focus.x}, ${click.focus.y}")
-                    onClick = {
-                        println("${focus.x}, ${focus.y}")
                     },
                     onViewChange = { viewPoint = this }
                 ),
+                schemeFeaturesState.features.values,
+                initialViewPoint = initialViewPoint,
+            )
+
+            SchemeView(
+                mapState,
+                schemeFeaturesState,
             )
         }
 

maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/MapTileProvider.kt

@@ -21,9 +21,9 @@ public interface MapTileProvider {
 
     public val tileSize: Int get() = DEFAULT_TILE_SIZE
 
-    public fun toIndex(d: Double): Int = floor(d / tileSize).toInt()
+    public fun toIndex(d: Float): Int = floor(d / tileSize).toInt()
 
-    public fun toCoordinate(i: Int): Double = (i * tileSize).toDouble()
+    public fun toCoordinate(i: Int): Float = (i * tileSize).toFloat()
 
     public companion object {
         public const val DEFAULT_TILE_SIZE: Int = 256

maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/MapView.kt

@@ -2,42 +2,19 @@ package center.sciprog.maps.compose
 
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.key
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.unit.DpSize
-import androidx.compose.ui.unit.dp
 import center.sciprog.maps.coordinates.Gmc
 import center.sciprog.maps.features.*
-import kotlin.math.PI
-import kotlin.math.log2
-import kotlin.math.min
 
 
 @Composable
 public expect fun MapView(
-    mapTileProvider: MapTileProvider,
+    mapState: MapViewScope,
-    initialViewPoint: MapViewPoint,
     featuresState: FeatureCollection<Gmc>,
-    config: ViewConfig<Gmc> = ViewConfig(),
     modifier: Modifier = Modifier.fillMaxSize(),
 )
 
-internal val defaultCanvasSize = DpSize(512.dp, 512.dp)
-
-public fun Rectangle<Gmc>.computeViewPoint(
-    mapTileProvider: MapTileProvider,
-    canvasSize: DpSize = defaultCanvasSize,
-): MapViewPoint {
-    val zoom = log2(
-        min(
-            canvasSize.width.value / longitudeDelta.radians.value,
-            canvasSize.height.value / latitudeDelta.radians.value
-        ) * PI / mapTileProvider.tileSize
-    )
-    return MapViewPoint(center, zoom.toFloat())
-}
-
 /**
  * A builder for a Map with static features.
  */
@@ -50,20 +27,22 @@ public fun MapView(
     config: ViewConfig<Gmc> = ViewConfig(),
     modifier: Modifier = Modifier.fillMaxSize(),
 ) {
-    val featuresState = key(featureMap) {
+
-        FeatureCollection.build(GmcCoordinateSpace) {
+    val featuresState = remember(featureMap) {
+        FeatureCollection.build(WebMercatorSpace) {
             featureMap.forEach { feature(it.key.id, it.value) }
         }
     }
 
-    val viewPointOverride: MapViewPoint = remember(initialViewPoint, initialRectangle) {
+    val mapState: MapViewScope = rememberMapState(
-        initialViewPoint
+        mapTileProvider,
-            ?: initialRectangle?.computeViewPoint(mapTileProvider)
+        config,
-            ?: featureMap.values.computeBoundingBox(GmcCoordinateSpace, 1f)?.computeViewPoint(mapTileProvider)
+        featuresState.features.values,
-            ?: MapViewPoint.globe
+        initialViewPoint = initialViewPoint,
-    }
+        initialRectangle = initialRectangle,
+    )
 
-    MapView(mapTileProvider, viewPointOverride, featuresState, config, modifier)
+    MapView(mapState, featuresState, modifier)
 }
 
 /**
@@ -82,15 +61,15 @@ public fun MapView(
     modifier: Modifier = Modifier.fillMaxSize(),
     buildFeatures: FeatureCollection<Gmc>.() -> Unit = {},
 ) {
-    val featureState = FeatureCollection.remember(GmcCoordinateSpace, buildFeatures)
 
-    val viewPointOverride: MapViewPoint = remember(initialViewPoint, initialRectangle) {
+    val featureState = FeatureCollection.remember(WebMercatorSpace, buildFeatures)
-        initialViewPoint
+    val mapState: MapViewScope = rememberMapState(
-            ?: initialRectangle?.computeViewPoint(mapTileProvider)
+        mapTileProvider,
-            ?: featureState.features.values.computeBoundingBox(GmcCoordinateSpace, 1f)
+        config,
-                ?.computeViewPoint(mapTileProvider)
+        featureState.features.values,
-            ?: MapViewPoint.globe
+        initialViewPoint = initialViewPoint,
-    }
+        initialRectangle = initialRectangle,
+    )
 
     val featureDrag: DragHandle<Gmc> = DragHandle.withPrimaryButton { event, start, end ->
         featureState.forEachWithAttribute(DraggableAttribute) { _, handle ->
@@ -107,16 +86,18 @@ public fun MapView(
         DragResult(end)
     }
 
+    val featureClick: ClickHandle<Gmc> = ClickHandle.withPrimaryButton { event, click ->
+        featureState.forEachWithAttribute(SelectableAttribute) { _, handle ->
+            @Suppress("UNCHECKED_CAST")
+            (handle as ClickHandle<Gmc>).handle(event, click)
+            config.onClick?.handle(event, click)
+        }
+    }
 
     val newConfig = config.copy(
-        dragHandle = DragHandle.combine(featureDrag, config.dragHandle)
+        dragHandle = config.dragHandle?.let { DragHandle.combine(featureDrag, it) } ?: featureDrag,
+        onClick = featureClick
     )
 
-    MapView(
+    MapView(mapState, featureState, modifier)
-        mapTileProvider = mapTileProvider,
-        initialViewPoint = viewPointOverride,
-        featuresState = featureState,
-        config = newConfig,
-        modifier = modifier,
-    )
 }

maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/MapViewPoint.kt

@@ -11,7 +11,7 @@ public data class MapViewPoint(
     override val focus: GeodeticMapCoordinates,
     override val zoom: Float,
 ) : ViewPoint<Gmc>{
-    val scaleFactor: Double by lazy { WebMercatorProjection.scaleFactor(zoom) }
+    val scaleFactor: Float by lazy { WebMercatorProjection.scaleFactor(zoom) }
 
     public companion object{
         public val globe: MapViewPoint = MapViewPoint(GeodeticMapCoordinates(0.0.radians, 0.0.radians), 1f)

maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/MapViewScope.kt

@@ -2,29 +2,30 @@ package center.sciprog.maps.compose
 
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
-import androidx.compose.ui.unit.*
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpOffset
+import androidx.compose.ui.unit.DpRect
+import androidx.compose.ui.unit.dp
 import center.sciprog.maps.coordinates.*
 import center.sciprog.maps.features.*
 import kotlin.math.*
 
-internal class MapViewState internal constructor(
+public class MapViewScope internal constructor(
+    public val mapTileProvider: MapTileProvider,
     config: ViewConfig<Gmc>,
-    canvasSize: DpSize,
+) : CoordinateViewScope<Gmc>(config) {
-    viewPoint: ViewPoint<Gmc>,
+    override val space: CoordinateSpace<Gmc> get() = WebMercatorSpace
-    val tileSize: Int,
-) : CoordinateViewState<Gmc>(config, canvasSize, viewPoint) {
-    override val space: CoordinateSpace<Gmc> get() = GmcCoordinateSpace
 
-    val scaleFactor: Double
+    public val scaleFactor: Float
-        get() = WebMercatorProjection.scaleFactor(viewPoint.zoom)
+        get() = WebMercatorProjection.scaleFactor(zoom)
 
-    val intZoom: Int get() = floor(zoom).toInt()
+    public val intZoom: Int get() = floor(zoom).toInt()
 
-    val centerCoordinates: WebMercatorCoordinates
+    public val centerCoordinates: WebMercatorCoordinates
         get() = WebMercatorProjection.toMercator(viewPoint.focus, intZoom)
 
-    val tileScale: Float
+    public val tileScale: Float
-        get() = 2f.pow(viewPoint.zoom - floor(viewPoint.zoom))
+        get() = 2f.pow(zoom - floor(zoom))
 
     /*
      * Convert screen independent offset to GMC, adjusting for fractional zoom
@@ -41,8 +42,8 @@ internal class MapViewState internal constructor(
     override fun Gmc.toDpOffset(): DpOffset {
         val mercator = WebMercatorProjection.toMercator(this, intZoom)
         return DpOffset(
-            (canvasSize.width / 2 + (mercator.x.dp - centerCoordinates.x.dp) * tileScale.toFloat()),
+            (canvasSize.width / 2 + (mercator.x.dp - centerCoordinates.x.dp) * tileScale),
-            (canvasSize.height / 2 + (mercator.y.dp - centerCoordinates.y.dp) * tileScale.toFloat())
+            (canvasSize.height / 2 + (mercator.y.dp - centerCoordinates.y.dp) * tileScale)
         )
     }
 
@@ -52,12 +53,12 @@ internal class MapViewState internal constructor(
         return DpRect(topLeft.x, topLeft.y, bottomRight.x, bottomRight.y)
     }
 
-    override fun viewPointFor(rectangle: Rectangle<Gmc>): ViewPoint<Gmc> {
+    override fun computeViewPoint(rectangle: Rectangle<Gmc>): ViewPoint<Gmc> {
         val zoom = log2(
             min(
                 canvasSize.width.value / rectangle.longitudeDelta.radians.value,
                 canvasSize.height.value / rectangle.latitudeDelta.radians.value
-            ) * PI / tileSize
+            ) * PI / mapTileProvider.tileSize
         )
         return MapViewPoint(rectangle.center, zoom.toFloat())
     }
@@ -78,10 +79,21 @@ internal class MapViewState internal constructor(
 
 @Composable
 internal fun rememberMapState(
+    mapTileProvider: MapTileProvider,
     config: ViewConfig<Gmc>,
-    canvasSize: DpSize,
+    features: Collection<Feature<Gmc>> = emptyList(),
-    viewPoint: ViewPoint<Gmc>,
+    initialViewPoint: MapViewPoint? = null,
-    tileSize: Int,
+    initialRectangle: Rectangle<Gmc>? = null,
-): MapViewState = remember {
+): MapViewScope = remember {
-    MapViewState(config, canvasSize, viewPoint, tileSize)
+    MapViewScope(mapTileProvider, config).also { mapState->
+        if (initialViewPoint != null) {
+            mapState.viewPoint = initialViewPoint
+        } else if (initialRectangle != null) {
+            mapState.viewPoint = mapState.computeViewPoint(initialRectangle)
+        } else {
+            features.computeBoundingBox(WebMercatorSpace, 1f)?.let {
+                mapState.viewPoint = mapState.computeViewPoint(it)
+            }
+        }
+    }
 }

maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/WebMercatorSpace.kt

@@ -1,13 +1,21 @@
 package center.sciprog.maps.compose
 
+import androidx.compose.ui.unit.DpOffset
 import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
 import center.sciprog.maps.coordinates.*
 import center.sciprog.maps.features.CoordinateSpace
 import center.sciprog.maps.features.Rectangle
 import center.sciprog.maps.features.ViewPoint
+import kotlin.math.floor
 import kotlin.math.pow
 
-public object GmcCoordinateSpace : CoordinateSpace<Gmc> {
+public object WebMercatorSpace : CoordinateSpace<Gmc> {
+
+    private fun intZoom(zoom: Float): Int = floor(zoom).toInt()
+    private fun tileScale(zoom: Float): Float = 2f.pow(zoom - floor(zoom))
+
+
     override fun Rectangle(first: Gmc, second: Gmc): Rectangle<Gmc> = GmcRectangle(first, second)
 
     override fun Rectangle(center: Gmc, zoom: Float, size: DpSize): Rectangle<Gmc> {
@@ -15,6 +23,8 @@ public object GmcCoordinateSpace : CoordinateSpace<Gmc> {
         return Rectangle(center, (size.width.value / scale).radians, (size.height.value / scale).radians)
     }
 
+    override val defaultViewPoint: ViewPoint<Gmc> = MapViewPoint.globe
+
     override fun ViewPoint(center: Gmc, zoom: Float): ViewPoint<Gmc> = MapViewPoint(center, zoom)
 
     override fun ViewPoint<Gmc>.moveBy(delta: Gmc): ViewPoint<Gmc> {
@@ -29,7 +39,7 @@ public object GmcCoordinateSpace : CoordinateSpace<Gmc> {
     }
 
     override fun ViewPoint<Gmc>.zoomBy(zoomDelta: Float, invariant: Gmc): ViewPoint<Gmc> = if (invariant == focus) {
-        ViewPoint(focus, (zoom + zoomDelta).coerceIn(2f, 18f) )
+        ViewPoint(focus, (zoom + zoomDelta).coerceIn(2f, 18f))
     } else {
         val difScale = (1 - 2f.pow(-zoomDelta))
         val newCenter = GeodeticMapCoordinates(
@@ -61,6 +71,17 @@ public object GmcCoordinateSpace : CoordinateSpace<Gmc> {
         val maxLong = maxOf { it.longitude }
         return GmcRectangle(GeodeticMapCoordinates(minLat, minLong), GeodeticMapCoordinates(maxLat, maxLong))
     }
+
+    override fun Gmc.offsetTo(b: Gmc, zoom: Float): DpOffset {
+        val intZoom = intZoom(zoom)
+        val mercatorA = WebMercatorProjection.toMercator(this, intZoom)
+        val mercatorB = WebMercatorProjection.toMercator(b, intZoom)
+        val tileScale = tileScale(zoom)
+        return DpOffset(
+            (mercatorA.x - mercatorB.x).dp * tileScale,
+            (mercatorA.y - mercatorB.y).dp * tileScale
+        )
+    }
 }
 
 /**

maps-kt-compose/src/jvmMain/kotlin/center/sciprog/maps/compose/MapViewJvm.kt

@@ -15,7 +15,10 @@ import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.IntSize
 import androidx.compose.ui.unit.dp
 import center.sciprog.maps.coordinates.Gmc
-import center.sciprog.maps.features.*
+import center.sciprog.maps.features.FeatureCollection
+import center.sciprog.maps.features.PainterFeature
+import center.sciprog.maps.features.drawFeature
+import center.sciprog.maps.features.z
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.supervisorScope
 import mu.KotlinLogging
@@ -40,21 +43,10 @@ private val logger = KotlinLogging.logger("MapView")
  */
 @Composable
 public actual fun MapView(
-    mapTileProvider: MapTileProvider,
+    mapState: MapViewScope,
-    initialViewPoint: MapViewPoint,
     featuresState: FeatureCollection<Gmc>,
-    config: ViewConfig<Gmc>,
     modifier: Modifier,
-): Unit = key(initialViewPoint) {
+): Unit = with(mapState) {
-
-    val state = rememberMapState(
-        config,
-        defaultCanvasSize,
-        initialViewPoint,
-        mapTileProvider.tileSize
-    )
-
-    with(state) {
 
     val mapTiles = remember(mapTileProvider) { mutableStateListOf<MapTile>() }
 
@@ -101,7 +93,7 @@ public actual fun MapView(
         featuresState.features.values.filterIsInstance<PainterFeature<Gmc>>().associateWith { it.getPainter() }
     }
 
-        Canvas(modifier = modifier.mapControls(state).fillMaxSize()) {
+    Canvas(modifier = modifier.mapControls(mapState).fillMaxSize()) {
 
         if (canvasSize != size.toDpSize()) {
             logger.debug { "Recalculate canvas. Size: $size" }
@@ -127,8 +119,9 @@ public actual fun MapView(
                 )
             }
 
-                featuresState.features.values.filter { viewPoint.zoom in it.zoomRange }.sortedBy { it.z }.forEach { feature ->
+            featuresState.features.values.filter { viewPoint.zoom in it.zoomRange }.sortedBy { it.z }
-                    drawFeature(state, painterCache, feature)
+                .forEach { feature ->
+                    drawFeature(mapState, painterCache, feature)
                 }
         }
 
@@ -146,5 +139,5 @@ public actual fun MapView(
             )
         }
     }
-    }
 }
+

maps-kt-core/src/commonMain/kotlin/center/sciprog/maps/coordinates/WebMercatorProjection.kt

@@ -7,14 +7,14 @@ package center.sciprog.maps.coordinates
 
 import kotlin.math.*
 
-public data class WebMercatorCoordinates(val zoom: Int, val x: Double, val y: Double)
+public data class WebMercatorCoordinates(val zoom: Int, val x: Float, val y: Float)
 
 public object WebMercatorProjection {
 
     /**
      * Compute radians to projection coordinates ratio for given [zoom] factor
      */
-    public fun scaleFactor(zoom: Float): Double = 256.0 / 2 / PI * 2f.pow(zoom)
+    public fun scaleFactor(zoom: Float): Float = (256.0 / 2 / PI * 2f.pow(zoom)).toFloat()
 
     public fun toGeodetic(mercator: WebMercatorCoordinates): GeodeticMapCoordinates {
         val scaleFactor = scaleFactor(mercator.zoom.toFloat())
@@ -32,8 +32,8 @@ public object WebMercatorProjection {
         val scaleFactor = scaleFactor(zoom.toFloat())
         return WebMercatorCoordinates(
             zoom = zoom,
-            x = scaleFactor * (gmc.longitude.radians.value + PI),
+            x = scaleFactor * (gmc.longitude.radians.value + PI).toFloat(),
-            y = scaleFactor * (PI - ln(tan(PI / 4 + gmc.latitude.radians.value / 2)))
+            y = scaleFactor * (PI - ln(tan(PI / 4 + gmc.latitude.radians.value / 2))).toFloat()
         )
     }
 

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/AttributeMap.kt

@@ -5,7 +5,11 @@ import androidx.compose.ui.graphics.Color
 
 public object ZAttribute : Feature.Attribute<Float>
 
-public object SelectableAttribute : Feature.Attribute<(FeatureId<*>, SelectableFeature<*>) -> Unit>
+public object DraggableAttribute : Feature.Attribute<DragHandle<Any>>
+
+public object DragListenerAttribute : Feature.Attribute<Set<(begin: Any, end: Any) -> Unit>>
+
+public object SelectableAttribute : Feature.Attribute<ClickHandle<Any>>
 
 public object VisibleAttribute : Feature.Attribute<Boolean>
 

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/CoordinateSpace.kt

@@ -1,6 +1,11 @@
 package center.sciprog.maps.features
 
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpOffset
 import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import kotlin.math.abs
+import kotlin.math.sqrt
 
 
 public interface Area<T : Any> {
@@ -31,6 +36,11 @@ public interface CoordinateSpace<T : Any> {
      */
     public fun Rectangle(center: T, zoom: Float, size: DpSize): Rectangle<T>
 
+    /**
+     * A view point used by default
+     */
+    public val defaultViewPoint: ViewPoint<T>
+
     /**
      * Create a [ViewPoint] associated with this coordinate space.
      */
@@ -52,6 +62,20 @@ public interface CoordinateSpace<T : Any> {
 
     public fun Collection<T>.wrapPoints(): Rectangle<T>?
 
+    public fun T.offsetTo(b: T, zoom: Float): DpOffset
+
+    public fun T.distanceTo(b: T, zoom: Float): Dp {
+        val offset = offsetTo(b, zoom)
+        return sqrt(offset.x.value * offset.x.value + offset.y.value * offset.y.value).dp
+    }
+
+    public fun T.distanceToLine(a: T, b: T, zoom: Float): Dp {
+        val d12 = a.offsetTo(b, zoom)
+        val d01 = offsetTo(a, zoom)
+        val distanceVale = abs(d12.x.value * d01.y.value - d12.y.value * d01.x.value) / a.distanceTo(b, zoom).value
+
+        return distanceVale.dp
+    }
 }
 
 public fun <T : Any> CoordinateSpace<T>.Rectangle(viewPoint: ViewPoint<T>, size: DpSize): Rectangle<T> =

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/CoordinateViewScope.kt

@@ -6,32 +6,43 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.unit.*
+import kotlin.math.pow
+import kotlin.math.sqrt
 
-public abstract class CoordinateViewState<T : Any>(
+private fun distanceBetween(a: DpOffset, b: DpOffset): Dp = sqrt((b.x - a.x).value.pow(2) + (b.y - a.y).value.pow(2)).dp
+
+public abstract class CoordinateViewScope<T : Any>(
     public val config: ViewConfig<T>,
-    canvasSize: DpSize,
-    viewPoint: ViewPoint<T>,
 ) {
 
     public abstract val space: CoordinateSpace<T>
 
-    public var canvasSize: DpSize by mutableStateOf(canvasSize)
+    protected var canvasSizeState: MutableState<DpSize?> = mutableStateOf(null)
-    protected var viewPointState: MutableState<ViewPoint<T>> = mutableStateOf(viewPoint)
+    protected var viewPointState: MutableState<ViewPoint<T>?> = mutableStateOf(null)
+
+    public var canvasSize: DpSize
+        get() = canvasSizeState.value ?: DpSize(512.dp, 512.dp)
+        set(value) {
+            canvasSizeState.value = value
+        }
 
     public var viewPoint: ViewPoint<T>
-        get() = viewPointState.value
+        get() = viewPointState.value ?: space.defaultViewPoint
         set(value) {
-            config.onViewChange(value)
             viewPointState.value = value
         }
 
     public val zoom: Float get() = viewPoint.zoom
 
+
+    // Selection rectangle. If null - no selection
+    public var selectRect: DpRect? by mutableStateOf(null)
+
     public abstract fun DpOffset.toCoordinates(): T
 
     public abstract fun T.toDpOffset(): DpOffset
 
-    public fun T.toOffset(density: Density): Offset = with(density){
+    public fun T.toOffset(density: Density): Offset = with(density) {
         val dpOffset = this@toOffset.toDpOffset()
         Offset(dpOffset.x.toPx(), dpOffset.y.toPx())
     }
@@ -40,10 +51,7 @@ public abstract class CoordinateViewState<T : Any>(
 
     public abstract fun ViewPoint<T>.moveBy(x: Dp, y: Dp): ViewPoint<T>
 
-    public abstract fun viewPointFor(rectangle: Rectangle<T>): ViewPoint<T>
+    public abstract fun computeViewPoint(rectangle: Rectangle<T>): ViewPoint<T>
-
-    // Selection rectangle. If null - no selection
-    public var selectRect: DpRect? by mutableStateOf(null)
 }
 
 

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/DraggableAttribute.kt

@@ -1,6 +0,0 @@
-package center.sciprog.maps.features
-
-
-public object DraggableAttribute : Feature.Attribute<DragHandle<Any>>
-
-public object DragListenerAttribute : Feature.Attribute<Set<(begin: Any, end: Any) -> Unit>>

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Feature.kt

@@ -29,14 +29,14 @@ public interface Feature<T : Any> {
     public fun getBoundingBox(zoom: Float): Rectangle<T>?
 }
 
-public interface PainterFeature<T:Any>: Feature<T> {
+public interface PainterFeature<T : Any> : Feature<T> {
     @Composable
     public fun getPainter(): Painter
 }
 
 public interface SelectableFeature<T : Any> : Feature<T> {
-    public operator fun contains(point: ViewPoint<T>): Boolean = getBoundingBox(point.zoom)?.let {
+    public fun contains(point: T, zoom: Float): Boolean = getBoundingBox(zoom)?.let {
-        point.focus in it
+        point in it
     } ?: false
 }
 
@@ -47,7 +47,7 @@ public interface DraggableFeature<T : Any> : SelectableFeature<T> {
 /**
  * A draggable marker feature. Other features could be bound to this one.
  */
-public interface MarkerFeature<T: Any>: DraggableFeature<T>{
+public interface MarkerFeature<T : Any> : DraggableFeature<T> {
     public val center: T
 }
 
@@ -72,7 +72,6 @@ public class FeatureSelector<T : Any>(
     public val selector: (zoom: Float) -> Feature<T>,
 ) : Feature<T> {
 
-
     override fun getBoundingBox(zoom: Float): Rectangle<T>? = selector(zoom).getBoundingBox(zoom)
 }
 
@@ -157,8 +156,8 @@ public class LineFeature<T : Any>(
     override fun getBoundingBox(zoom: Float): Rectangle<T> =
         space.Rectangle(a, b)
 
-    override fun contains(point: ViewPoint<T>): Boolean {
+    override fun contains(point: T, zoom: Float): Boolean = with(space) {
-        return super.contains(point)
+        point in space.Rectangle(a, b) && point.distanceToLine(a, b, zoom).value < 5f
     }
 }
 
@@ -228,17 +227,17 @@ public data class VectorImageFeature<T : Any>(
  *
  * @param rectangle the size of background in scheme size units. The screen units to scheme units ratio equals scale.
  */
-public class ScalableImageFeature<T: Any>(
+public class ScalableImageFeature<T : Any>(
     override val space: CoordinateSpace<T>,
     public val rectangle: Rectangle<T>,
     override val zoomRange: FloatRange,
     override val attributes: AttributeMap = AttributeMap(),
     public val painter: @Composable () -> Painter,
-) : Feature<T>, PainterFeature<T>{
+) : Feature<T>, PainterFeature<T> {
     @Composable
     override fun getPainter(): Painter = painter.invoke()
 
-    override fun getBoundingBox(zoom: Float): Rectangle<T> =rectangle
+    override fun getBoundingBox(zoom: Float): Rectangle<T> = rectangle
 }
 
 

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/FeatureCollection.kt

@@ -119,9 +119,14 @@ public class FeatureCollection<T : Any>(
 
     @Suppress("UNCHECKED_CAST")
     public fun <F : SelectableFeature<T>> FeatureId<F>.selectable(
-        onSelect: (FeatureId<F>, F) -> Unit,
+        onSelect: () -> Unit,
     ) {
-        setAttribute(this, SelectableAttribute) { id, feature -> onSelect(id as FeatureId<F>, feature as F) }
+//        val handle = ClickHandle<Any> { event, click ->
+//            val feature: F = get(this@selectable)
+//            if (feature.contains(this, click.focus))
+//        }
+//
+//        setAttribute(this, SelectableAttribute, handle)
     }
 
 

maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/ViewConfig.kt

@@ -1,12 +1,27 @@
 package center.sciprog.maps.features
 
 import androidx.compose.ui.input.pointer.PointerEvent
+import androidx.compose.ui.input.pointer.isPrimaryPressed
 import androidx.compose.ui.unit.DpSize
 
+public fun interface ClickHandle<T : Any> {
+    public fun handle(event: PointerEvent, click: ViewPoint<T>): Unit
+
+    public companion object {
+        public fun <T : Any> withPrimaryButton(
+            block: (event: PointerEvent, click: ViewPoint<T>) -> Unit,
+        ): ClickHandle<T> = ClickHandle { event, click ->
+            if (event.buttons.isPrimaryPressed) {
+                block(event, click)
+            }
+        }
+    }
+}
+
 public data class ViewConfig<T : Any>(
     val zoomSpeed: Float = 1f / 3f,
-    val onClick: ViewPoint<T>.(PointerEvent) -> Unit = {},
+    val onClick: ClickHandle<T>? = null,
-    val dragHandle: DragHandle<T> = DragHandle.bypass(),
+    val dragHandle: DragHandle<T>? = null,
     val onViewChange: ViewPoint<T>.() -> Unit = {},
     val onSelect: (Rectangle<T>) -> Unit = {},
     val zoomOnSelect: Boolean = true,

maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/compose/mapControls.kt

@@ -1,14 +1,14 @@
 package center.sciprog.maps.compose
 
 import androidx.compose.foundation.gestures.drag
-import androidx.compose.foundation.gestures.forEachGesture
-import androidx.compose.runtime.*
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.input.pointer.*
-import androidx.compose.ui.unit.*
+import androidx.compose.ui.unit.DpOffset
-import center.sciprog.maps.features.CoordinateViewState
+import androidx.compose.ui.unit.DpRect
+import androidx.compose.ui.unit.dp
+import center.sciprog.maps.features.CoordinateViewScope
 import center.sciprog.maps.features.bottomRight
 import center.sciprog.maps.features.topLeft
 import kotlin.math.max
@@ -17,16 +17,37 @@ import kotlin.math.min
 
 @OptIn(ExperimentalComposeUiApi::class)
 public fun <T : Any> Modifier.mapControls(
-    state: CoordinateViewState<T>,
+    state: CoordinateViewScope<T>,
 ): Modifier = with(state) {
     pointerInput(Unit) {
-        forEachGesture {
-            awaitPointerEventScope {
         fun Offset.toDpOffset() = DpOffset(x.toDp(), y.toDp())
-
+        awaitPointerEventScope {
+            while (true) {
+                val event = awaitPointerEvent()
+                if (event.type == PointerEventType.Release ) {
+                    config.onClick?.handle(
+                        event,
+                        space.ViewPoint(event.changes.first().position.toDpOffset().toCoordinates(), zoom)
+                    )
+                }
+            }
+        }
+    }.pointerInput(Unit) {
+        fun Offset.toDpOffset() = DpOffset(x.toDp(), y.toDp())
+        awaitPointerEventScope {
+            while (true) {
                 val event: PointerEvent = awaitPointerEvent()
-
                 event.changes.forEach { change ->
+
+                    if (event.type == PointerEventType.Scroll) {
+                        val (xPos, yPos) = change.position
+                        //compute invariant point of translation
+                        val invariant = DpOffset(xPos.toDp(), yPos.toDp()).toCoordinates()
+                        viewPoint = with(space) {
+                            viewPoint.zoomBy(-change.scrollDelta.y * config.zoomSpeed, invariant)
+                        }
+                        change.consume()
+                    }
                     //val dragStart = change.position
                     //val dpPos = DpOffset(dragStart.x.toDp(), dragStart.y.toDp())
 
@@ -45,12 +66,12 @@ public fun <T : Any> Modifier.mapControls(
 
                         //apply drag handle and check if it prohibits the drag even propagation
                         if (selectionStart == null) {
-                            val dragResult = config.dragHandle.handle(
+                            val dragResult = config.dragHandle?.handle(
                                 event,
-                                space.ViewPoint(dpStart.toCoordinates(), viewPoint.zoom),
+                                space.ViewPoint(dpStart.toCoordinates(), zoom),
-                                space.ViewPoint(dpEnd.toCoordinates(), viewPoint.zoom)
+                                space.ViewPoint(dpEnd.toCoordinates(), zoom)
                             )
-                            if(!dragResult.handleNext) return@drag
+                            if (dragResult?.handleNext == false) return@drag
                         }
 
                         if (event.buttons.isPrimaryPressed) {
@@ -85,20 +106,12 @@ public fun <T : Any> Modifier.mapControls(
                         )
                         config.onSelect(coordinateRect)
                         if (config.zoomOnSelect) {
-                            viewPoint = viewPointFor(coordinateRect)
+                            viewPoint = computeViewPoint(coordinateRect)
                         }
                         selectRect = null
                     }
                 }
             }
         }
-    }.onPointerEvent(PointerEventType.Scroll) {
-        val change = it.changes.first()
-        val (xPos, yPos) = change.position
-        //compute invariant point of translation
-        val invariant = DpOffset(xPos.toDp(), yPos.toDp()).toCoordinates()
-        viewPoint = with(space) {
-            viewPoint.zoomBy(-change.scrollDelta.y * config.zoomSpeed, invariant)
-        }
     }
 }

maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/features/drawFeature.kt

@@ -21,7 +21,7 @@ internal fun Color.toPaint(): Paint = Paint().apply {
 }
 
 public fun <T : Any> DrawScope.drawFeature(
-    state: CoordinateViewState<T>,
+    state: CoordinateViewScope<T>,
     painterCache: Map<PainterFeature<T>, Painter>,
     feature: Feature<T>,
 ): Unit = with(state) {

maps-kt-scheme/src/commonMain/kotlin/center/sciprog/maps/scheme/XYCoordinateSpace.kt

@@ -1,6 +1,8 @@
 package center.sciprog.maps.scheme
 
+import androidx.compose.ui.unit.DpOffset
 import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
 import center.sciprog.maps.features.CoordinateSpace
 import center.sciprog.maps.features.Rectangle
 import center.sciprog.maps.features.ViewPoint
@@ -61,4 +63,11 @@ object XYCoordinateSpace : CoordinateSpace<XY> {
             XY(maxX, maxY)
         )
     }
+
+    override val defaultViewPoint: ViewPoint<XY> = XYViewPoint(XY(0f, 0f), 1f)
+
+    override fun XY.offsetTo(b: XY, zoom: Float): DpOffset = DpOffset(
+        (b.x - x).dp * zoom,
+        (b.y - y).dp * zoom
+    )
 }

maps-kt-scheme/src/commonMain/kotlin/center/sciprog/maps/scheme/XYViewScope.kt

@@ -1,14 +1,17 @@
 package center.sciprog.maps.scheme
 
-import androidx.compose.ui.unit.*
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.unit.Dp
+import androidx.compose.ui.unit.DpOffset
+import androidx.compose.ui.unit.DpRect
+import androidx.compose.ui.unit.dp
 import center.sciprog.maps.features.*
 import kotlin.math.min
 
-class XYViewState(
+class XYViewScope(
     config: ViewConfig<XY>,
-    canvasSize: DpSize,
+) : CoordinateViewScope<XY>(config) {
-    viewPoint: ViewPoint<XY>,
-) : CoordinateViewState<XY>(config, canvasSize, viewPoint) {
     override val space: CoordinateSpace<XY>
         get() = XYCoordinateSpace
 
@@ -21,8 +24,7 @@ class XYViewState(
         (canvasSize.width / 2 + (x.dp - viewPoint.focus.x.dp) * viewPoint.zoom),
         (canvasSize.height / 2 + (viewPoint.focus.y.dp - y.dp) * viewPoint.zoom)
     )
-
+    override fun computeViewPoint(rectangle: Rectangle<XY>): ViewPoint<XY> {
-    override fun viewPointFor(rectangle: Rectangle<XY>): ViewPoint<XY> {
         val scale = min(
             canvasSize.width.value / rectangle.width,
             canvasSize.height.value / rectangle.height
@@ -41,5 +43,24 @@ class XYViewState(
         val bottomRight = rightBottom.toDpOffset()
         return DpRect(topLeft.x, topLeft.y, bottomRight.x, bottomRight.y)
     }
-
+}
+
+@Composable
+public fun rememberMapState(
+    config: ViewConfig<XY>,
+    features: Collection<Feature<XY>> = emptyList(),
+    initialViewPoint: ViewPoint<XY>? = null,
+    initialRectangle: Rectangle<XY>? = null,
+): XYViewScope = remember {
+    XYViewScope(config).also { mapState->
+        if (initialViewPoint != null) {
+            mapState.viewPoint = initialViewPoint
+        } else if (initialRectangle != null) {
+            mapState.viewPoint = mapState.computeViewPoint(initialRectangle)
+        } else {
+            features.computeBoundingBox(XYCoordinateSpace, 1f)?.let {
+                mapState.viewPoint = mapState.computeViewPoint(it)
+            }
+        }
+    }
 }

maps-kt-scheme/src/jvmMain/kotlin/center/sciprog/maps/scheme/SchemeView.kt

@@ -4,7 +4,6 @@ import androidx.compose.foundation.Canvas
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.key
-import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.PathEffect
@@ -22,19 +21,10 @@ private val logger = KotlinLogging.logger("SchemeView")
 
 @Composable
 public fun SchemeView(
-    initialViewPoint: ViewPoint<XY>,
+    state: XYViewScope,
     featuresState: FeatureCollection<XY>,
-    config: ViewConfig<XY>,
     modifier: Modifier = Modifier.fillMaxSize(),
-) = key(initialViewPoint) {
+) {
-
-    val state = remember {
-        XYViewState(
-            config,
-            defaultCanvasSize,
-            initialViewPoint,
-        )
-    }
     with(state) {
         val painterCache: Map<PainterFeature<XY>, Painter> = key(featuresState) {
             featuresState.features.values.filterIsInstance<PainterFeature<XY>>().associateWith { it.getPainter() }
@@ -95,20 +85,22 @@ public fun SchemeView(
     config: ViewConfig<XY> = ViewConfig(),
     modifier: Modifier = Modifier.fillMaxSize(),
 ) {
+
+
     val featuresState = key(featureMap) {
         FeatureCollection.build(XYCoordinateSpace) {
             featureMap.forEach { feature(it.key.id, it.value) }
         }
     }
 
-    val viewPointOverride: ViewPoint<XY> = remember(initialViewPoint, initialRectangle) {
+    val state = rememberMapState(
-        initialViewPoint
+        config,
-            ?: initialRectangle?.computeViewPoint()
+        featuresState.features.values,
-            ?: featureMap.values.computeBoundingBox(XYCoordinateSpace, 1f)?.computeViewPoint()
+        initialViewPoint = initialViewPoint,
-            ?: XYViewPoint(XY(0f, 0f), 1f)
+        initialRectangle = initialRectangle,
-    }
+    )
 
-    SchemeView(viewPointOverride, featuresState, config, modifier)
+    SchemeView(state, featuresState, modifier)
 }
 
 /**
@@ -127,37 +119,42 @@ public fun SchemeView(
     buildFeatures: FeatureCollection<XY>.() -> Unit = {},
 ) {
     val featureState = FeatureCollection.remember(XYCoordinateSpace, buildFeatures)
+    val mapState: XYViewScope = rememberMapState(
+        config,
+        featureState.features.values,
+        initialViewPoint = initialViewPoint,
+        initialRectangle = initialRectangle,
+    )
 
-    val viewPointOverride: ViewPoint<XY> = remember(initialViewPoint, initialRectangle) {
+    val featureDrag: DragHandle<XY> = DragHandle.withPrimaryButton { event, start, end ->
-        initialViewPoint
-            ?: initialRectangle?.computeViewPoint()
-            ?: featureState.features.values.computeBoundingBox(XYCoordinateSpace, 1f)?.computeViewPoint()
-            ?: XYViewPoint(XY(0f, 0f), 1f)
-    }
-
-    val featureDrag: DragHandle<XY> =
-        DragHandle.withPrimaryButton { event, start: ViewPoint<XY>, end: ViewPoint<XY> ->
         featureState.forEachWithAttribute(DraggableAttribute) { _, handle ->
-                //TODO add safety
+            @Suppress("UNCHECKED_CAST")
             (handle as DragHandle<XY>)
                 .handle(event, start, end)
                 .takeIf { !it.handleNext }
-                    ?.let { return@withPrimaryButton it }
+                ?.let {
+                    //we expect it already have no bypass
+                    return@withPrimaryButton it
                 }
+        }
+        //bypass
         DragResult(end)
     }
 
+    val featureClick: ClickHandle<XY> = ClickHandle.withPrimaryButton { event, click ->
+        featureState.forEachWithAttribute(SelectableAttribute) { _, handle ->
+            @Suppress("UNCHECKED_CAST")
+            (handle as ClickHandle<XY>).handle(event, click)
+            config.onClick?.handle(event, click)
+        }
+    }
 
     val newConfig = config.copy(
-        dragHandle = DragHandle.combine(featureDrag, config.dragHandle)
+        dragHandle = config.dragHandle?.let { DragHandle.combine(featureDrag, it) } ?: featureDrag,
+        onClick = featureClick
     )
 
-    SchemeView(
+    SchemeView(mapState, featureState, modifier)
-        initialViewPoint = viewPointOverride,
-        featuresState = featureState,
-        config = newConfig,
-        modifier = modifier,
-    )
 }
 
 ///**