State Encapsulation Finished

# Conflicts:
#	demo/maps/src/jvmMain/kotlin/Main.kt
#	maps-kt-compose/src/jvmMain/kotlin/center/sciprog/maps/compose/MapViewJvm.kt

README.md

@@ -1 +1,13 @@
-This repository is a work-in-progress implementation of Map-with-markers component for Compose-Multiplatform
+This repository is a work-in-progress implementation of Map-with-markers component for Compose-Multiplatform
+
+## [maps-kt-core](maps-kt-core)
+A multiplatform coordinates representation and conversion.
+
+## [maps-kt-compose](maps-kt-compose)
+A compose multiplatform (currently desktop only, contributions of android target are welcome) implementation of a map component, features and builder.
+
+## [maps-kt-scheme](maps-kt-scheme)
+An alternative component used for the same functionality on 2D schemes. Not all features from maps could be ported because it requires some code duplication (ideas for common API are welcome).
+
+## [demo](demo)
+Demonstration projects for different features

demo/maps/build.gradle.kts

@@ -33,7 +33,7 @@ compose.desktop {
         mainClass = "MainKt"
         nativeDistributions {
             targetFormats(TargetFormat.Dmg, TargetFormat.Msi, TargetFormat.Deb)
-            packageName = "maps-kt-compose"
+            packageName = "maps-compose-demo"
             packageVersion = "1.0.0"
         }
     }

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

@@ -0,0 +1,6 @@
+import kotlin.math.PI
+
+fun Double.toDegrees() = this * 180 / PI
+
+fun Double.toRadians() = this * PI / 180
+

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

@@ -0,0 +1,148 @@
+// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+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.ui.geometry.Offset
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.PointMode
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.application
+import center.sciprog.maps.compose.*
+import center.sciprog.maps.coordinates.*
+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.math.PI
+import kotlin.random.Random
+
+private fun GeodeticMapCoordinates.toShortString(): String =
+    "${(latitude * 180.0 / PI).toString().take(6)}:${(longitude * 180.0 / PI).toString().take(6)}"
+
+
+@Composable
+@Preview
+fun App() {
+    MaterialTheme {
+        //create a view point
+        val viewPoint = remember {
+            MapViewPoint(
+                GeodeticMapCoordinates.ofDegrees(55.7558, 37.6173),
+                8.0
+            )
+        }
+
+        val scope = rememberCoroutineScope()
+        val mapTileProvider = remember {
+            OpenStreetMapTileProvider(
+                client = HttpClient(CIO),
+                cacheDirectory = Path.of("mapCache")
+            )
+        }
+
+        var centerCoordinates by remember { mutableStateOf<GeodeticMapCoordinates?>(null) }
+
+
+        val pointOne = 55.568548 to 37.568604
+        var pointTwo by remember { mutableStateOf(55.929444 to 37.518434) }
+        val pointThree = 60.929444 to 37.518434
+
+        val state = MapViewState(
+            mapTileProvider = mapTileProvider,
+            initialViewPoint = { viewPoint },
+        ) {
+            image(pointOne, Icons.Filled.Home)
+
+            points(
+                points = listOf(
+                    55.742465 to 37.615812,
+                    55.742713 to 37.616370,
+                    55.742815 to 37.616659,
+                    55.742320 to 37.617132,
+                    55.742086 to 37.616566,
+                    55.741715 to 37.616716
+                ),
+                pointMode = PointMode.Polygon
+            )
+
+            //remember feature Id
+            val circleId: FeatureId = circle(
+                centerCoordinates = pointTwo,
+            )
+
+            draw(
+                position = pointThree,
+                getBoundingBox = {
+                    GmcBox.withCenter(
+                        center = GeodeticMapCoordinates.ofDegrees(
+                            pointThree.first,
+                            pointThree.second
+                        ),
+                        height = Distance(0.001),
+                        width = Distance(0.001)
+                    )
+                }
+            ) {
+                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, Distance(10.0), 0f, PI)
+
+            line(pointOne, pointTwo, id = "line")
+            text(pointOne, "Home", font = { size = 32f })
+
+            centerCoordinates?.let {
+                group(id = "center") {
+                    circle(center = it, color = Color.Blue, size = 1f)
+                    text(position = it, it.toShortString(), color = Color.Blue)
+                }
+            }
+
+            scope.launch {
+                while (isActive) {
+                    delay(200)
+                    //Overwrite a feature with new color
+                    circle(
+                        pointTwo,
+                        id = circleId,
+                        color = Color(Random.nextFloat(), Random.nextFloat(), Random.nextFloat())
+                    )
+                }
+            }
+        }
+
+        val config = MapViewConfig(
+            onViewChange = { centerCoordinates = focus },
+            onDrag = { start, end ->
+                val markerRadius = 5f
+                val startPosition = with(state) { start.focus.toOffset(this@MapViewConfig) }
+                val markerLocation = with(state) {
+                    GeodeticMapCoordinates.ofDegrees(pointTwo.first, pointTwo.second).toOffset(this@MapViewConfig)
+                }
+                if (startPosition.x in (markerLocation.x - markerRadius)..(markerLocation.x + markerRadius) &&
+                    startPosition.y in (markerLocation.y - markerRadius)..(markerLocation.y + markerRadius)
+                ) {
+                    pointTwo = pointTwo.first + (end.focus.latitude - start.focus.latitude).toDegrees() to
+                            pointTwo.second + (end.focus.longitude - start.focus.longitude).toDegrees()
+                    false// returning false, because when we are dragging circle we don't want to drag map
+                } else true
+            }
+        )
+
+        MapView(
+            mapViewState = state,
+            mapViewConfig = config
+        )
+    }
+}
+
+fun main() = application {
+    Window(onCloseRequest = ::exitApplication) {
+        App()
+    }
+}

demo/scheme/build.gradle.kts

@@ -0,0 +1,39 @@
+import org.jetbrains.compose.compose
+import org.jetbrains.compose.desktop.application.dsl.TargetFormat
+
+plugins {
+    kotlin("multiplatform")
+    id("org.jetbrains.compose")
+}
+
+val ktorVersion: String by rootProject.extra
+
+kotlin {
+    jvm {
+        compilations.all {
+            kotlinOptions.jvmTarget = "11"
+        }
+        withJava()
+    }
+    sourceSets {
+        val jvmMain by getting {
+            dependencies {
+                implementation(projects.mapsKtScheme)
+                implementation(compose.desktop.currentOs)
+                implementation("ch.qos.logback:logback-classic:1.2.11")
+            }
+        }
+        val jvmTest by getting
+    }
+}
+
+compose.desktop {
+    application {
+        mainClass = "MainKt"
+        nativeDistributions {
+            targetFormats(TargetFormat.Dmg, TargetFormat.Msi, TargetFormat.Deb)
+            packageName = "scheme-compose-demo"
+            packageVersion = "1.0.0"
+        }
+    }
+}

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

@@ -0,0 +1,47 @@
+// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+import androidx.compose.desktop.ui.tooling.preview.Preview
+import androidx.compose.material.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.application
+import center.sciprog.maps.scheme.*
+
+@Composable
+@Preview
+fun App() {
+    MaterialTheme {
+        //create a view point
+        val viewPoint = remember {
+            SchemeViewPoint(
+                SchemeCoordinates(0f, 0f),
+                1f
+            )
+        }
+
+
+        SchemeView(
+            viewPoint,
+            config = SchemeViewConfig(
+                inferViewBoxFromFeatures = true,
+                onClick = {
+                    println("${focus.x}, ${focus.y}")
+                }
+            )
+        ) {
+            background(painterResource("middle-earth.jpg"))
+            circle(410.52737 to 868.7676, color = Color.Blue)
+            text(410.52737 to 868.7676,"Shire", color = Color.Blue)
+            circle(1132.0881 to 394.99127, color = Color.Red)
+            text(1132.0881 to 394.99127, "Ordruin",color = Color.Red)
+        }
+    }
+}
+
+fun main() = application {
+    Window(onCloseRequest = ::exitApplication) {
+        App()
+    }
+}

demo/src/jvmMain/kotlin/Main.kt

@@ -1,107 +0,0 @@
-// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
-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.ui.geometry.Offset
-import androidx.compose.ui.geometry.Size
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.window.Window
-import androidx.compose.ui.window.application
-import centre.sciprog.maps.GeodeticMapCoordinates
-import centre.sciprog.maps.MapViewPoint
-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.math.PI
-import kotlin.random.Random
-
-private fun GeodeticMapCoordinates.toShortString(): String =
-    "${(latitude * 180.0 / PI).toString().take(6)}:${(longitude * 180.0 / PI).toString().take(6)}"
-
-
-@Composable
-@Preview
-fun App() {
-    MaterialTheme {
-        //create a view point
-        val viewPoint = remember {
-            MapViewPoint(
-                GeodeticMapCoordinates.ofDegrees(55.7558, 37.6173),
-                8.0
-            )
-        }
-
-        val scope = rememberCoroutineScope()
-        val mapTileProvider = remember {
-            OpenStreetMapTileProvider(
-                client = HttpClient(CIO),
-                cacheDirectory = Path.of("mapCache")
-            )
-        }
-
-        var centerCoordinates by remember { mutableStateOf<GeodeticMapCoordinates?>(null) }
-
-
-        MapView(
-            mapTileProvider = mapTileProvider,
-            initialViewPoint = viewPoint,
-            config = MapViewConfig(
-                inferViewBoxFromFeatures = true,
-                onViewChange = { centerCoordinates = focus }
-            )
-        ) {
-            val pointOne = 55.568548 to 37.568604
-            val pointTwo = 55.929444 to 37.518434
-            val pointThree = 60.929444 to 37.518434
-
-            image(pointOne, Icons.Filled.Home)
-
-            //remember feature Id
-            val circleId: FeatureId = circle(
-                centerCoordinates = pointTwo,
-            )
-
-            custom(position = pointThree) {
-                drawRect(
-                    color = Color.Red,
-                    topLeft = Offset(-10f, -10f),
-                    size = Size(20f, 20f)
-                )
-            }
-
-            line(pointOne, pointTwo)
-            text(pointOne, "Home")
-
-            centerCoordinates?.let {
-                group(id = "center") {
-                    circle(center = it, color = Color.Blue, size = 1f)
-                    text(position = it, it.toShortString(), color = Color.Blue)
-                }
-            }
-
-            scope.launch {
-                while (isActive) {
-                    delay(200)
-                    //Overwrite a feature with new color
-                    circle(
-                        pointTwo,
-                        id = circleId,
-                        color = Color(Random.nextFloat(), Random.nextFloat(), Random.nextFloat())
-                    )
-                }
-            }
-        }
-    }
-}
-
-fun main() = application {
-    Window(onCloseRequest = ::exitApplication) {
-        App()
-    }
-}

maps-kt-compose/build.gradle.kts

@@ -1,5 +1,4 @@
 import org.jetbrains.compose.compose
-import org.jetbrains.compose.desktop.application.dsl.TargetFormat
 
 plugins {
     kotlin("multiplatform")
@@ -10,17 +9,19 @@ plugins {
 val ktorVersion: String by rootProject.extra
 
 kotlin {
+    explicitApi = org.jetbrains.kotlin.gradle.dsl.ExplicitApiMode.Warning
     jvm {
         compilations.all {
             kotlinOptions.jvmTarget = "11"
         }
     }
     sourceSets {
-        commonMain{
-            dependencies{
+        commonMain {
+            dependencies {
                 api(projects.mapsKtCore)
                 api(compose.foundation)
                 api("io.ktor:ktor-client-core:$ktorVersion")
+                api("io.github.microutils:kotlin-logging:2.1.23")
             }
         }
         val jvmMain by getting

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

@@ -1,4 +1,4 @@
-package centre.sciprog.maps.compose
+package center.sciprog.maps.compose
 
 import kotlin.jvm.Synchronized
 

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

@@ -0,0 +1,133 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.PointMode
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.painter.Painter
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.graphics.vector.rememberVectorPainter
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.dp
+import center.sciprog.maps.coordinates.GeodeticMapCoordinates
+import center.sciprog.maps.coordinates.GmcBox
+import center.sciprog.maps.coordinates.wrapAll
+
+public interface MapFeature {
+    public val zoomRange: IntRange
+    public fun getBoundingBox(zoom: Int): GmcBox?
+}
+
+public fun Iterable<MapFeature>.computeBoundingBox(zoom: Int): GmcBox? =
+    mapNotNull { it.getBoundingBox(zoom) }.wrapAll()
+
+internal fun Pair<Double, Double>.toCoordinates() = GeodeticMapCoordinates.ofDegrees(first, second)
+
+internal val defaultZoomRange = 1..18
+
+/**
+ * A feature that decides what to show depending on the zoom value (it could change size of shape)
+ */
+public class MapFeatureSelector(
+    public val selector: (zoom: Int) -> MapFeature,
+) : MapFeature {
+    override val zoomRange: IntRange get() = defaultZoomRange
+
+    override fun getBoundingBox(zoom: Int): GmcBox? = selector(zoom).getBoundingBox(zoom)
+}
+
+public class MapDrawFeature(
+    public val position: GeodeticMapCoordinates,
+    override val zoomRange: IntRange = defaultZoomRange,
+    private val computeBoundingBox: (zoom: Int) -> GmcBox,
+    public val drawFeature: DrawScope.() -> Unit,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = computeBoundingBox(zoom)
+}
+
+public class MapPointsFeature(
+    public val points: List<GeodeticMapCoordinates>,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val stroke: Float = 2f,
+    public val color: Color = Color.Red,
+    public val pointMode: PointMode = PointMode.Points
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox {
+        return GmcBox(points.first(), points.last())
+    }
+}
+
+public class MapCircleFeature(
+    public val center: GeodeticMapCoordinates,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val size: Float = 5f,
+    public val color: Color = Color.Red,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(center, center)
+}
+
+public class MapRectangleFeature(
+    public val center: GeodeticMapCoordinates,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val size: DpSize = DpSize(5.dp, 5.dp),
+    public val color: Color = Color.Red,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(center, center)
+}
+
+public class MapLineFeature(
+    public val a: GeodeticMapCoordinates,
+    public val b: GeodeticMapCoordinates,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val color: Color = Color.Red,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(a, b)
+}
+
+public class MapArcFeature(
+    public val oval: GmcBox,
+    public val startAngle: Float,
+    public val endAngle: Float,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val color: Color = Color.Red,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = oval
+}
+
+public class MapBitmapImageFeature(
+    public val position: GeodeticMapCoordinates,
+    public val image: ImageBitmap,
+    public val size: IntSize = IntSize(15, 15),
+    override val zoomRange: IntRange = defaultZoomRange,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(position, position)
+}
+
+public class MapVectorImageFeature(
+    public val position: GeodeticMapCoordinates,
+    public val painter: Painter,
+    public val size: DpSize,
+    override val zoomRange: IntRange = defaultZoomRange,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(position, position)
+}
+
+@Composable
+public fun MapVectorImageFeature(
+    position: GeodeticMapCoordinates,
+    image: ImageVector,
+    size: DpSize = DpSize(20.dp, 20.dp),
+    zoomRange: IntRange = defaultZoomRange,
+): MapVectorImageFeature = MapVectorImageFeature(position, rememberVectorPainter(image), size, zoomRange)
+
+/**
+ * A group of other features
+ */
+public class MapFeatureGroup(
+    public val children: Map<FeatureId, MapFeature>,
+    override val zoomRange: IntRange = defaultZoomRange,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox? = children.values.mapNotNull { it.getBoundingBox(zoom) }.wrapAll()
+}

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

@@ -0,0 +1,157 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateMapOf
+import androidx.compose.runtime.snapshots.SnapshotStateMap
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.PointMode
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import center.sciprog.maps.coordinates.Distance
+import center.sciprog.maps.coordinates.GeodeticMapCoordinates
+import center.sciprog.maps.coordinates.GmcBox
+
+public typealias FeatureId = String
+
+public interface MapFeatureBuilder {
+    public fun addFeature(id: FeatureId?, feature: MapFeature): FeatureId
+
+    public fun build(): SnapshotStateMap<FeatureId, MapFeature>
+}
+
+internal class MapFeatureBuilderImpl(initialFeatures: Map<FeatureId, MapFeature>) : MapFeatureBuilder {
+
+    private val content: SnapshotStateMap<FeatureId, MapFeature> = mutableStateMapOf<FeatureId, MapFeature>().apply {
+        putAll(initialFeatures)
+    }
+
+    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
+}
+
+public fun MapFeatureBuilder.circle(
+    center: GeodeticMapCoordinates,
+    zoomRange: IntRange = defaultZoomRange,
+    size: Float = 5f,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+): FeatureId = addFeature(
+    id, MapCircleFeature(center, zoomRange, size, color)
+)
+
+public fun MapFeatureBuilder.circle(
+    centerCoordinates: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    size: Float = 5f,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+): FeatureId = addFeature(
+    id, MapCircleFeature(centerCoordinates.toCoordinates(), zoomRange, size, color)
+)
+
+public fun MapFeatureBuilder.rectangle(
+    centerCoordinates: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    size: DpSize = DpSize(5.dp, 5.dp),
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+): FeatureId = addFeature(
+    id, MapRectangleFeature(centerCoordinates.toCoordinates(), zoomRange, size, color)
+)
+
+public fun MapFeatureBuilder.draw(
+    position: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    id: FeatureId? = null,
+    getBoundingBox: (Int) -> GmcBox,
+    drawFeature: DrawScope.() -> Unit,
+): FeatureId = addFeature(id, MapDrawFeature(position.toCoordinates(), zoomRange, getBoundingBox, drawFeature))
+
+public fun MapFeatureBuilder.line(
+    aCoordinates: Pair<Double, Double>,
+    bCoordinates: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+): FeatureId = addFeature(
+    id,
+    MapLineFeature(aCoordinates.toCoordinates(), bCoordinates.toCoordinates(), zoomRange, color)
+)
+
+public fun MapFeatureBuilder.arc(
+    oval: GmcBox,
+    startAngle: Number,
+    endAngle: Number,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+): FeatureId = addFeature(
+    id,
+    MapArcFeature(oval, startAngle.toFloat(), endAngle.toFloat(), zoomRange, color)
+)
+
+public fun MapFeatureBuilder.arc(
+    center: Pair<Double, Double>,
+    radius: Distance,
+    startAngle: Number,
+    endAngle: Number,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+): FeatureId = addFeature(
+    id,
+    MapArcFeature(
+        GmcBox.withCenter(center.toCoordinates(), radius, radius),
+        startAngle.toFloat(),
+        endAngle.toFloat(),
+        zoomRange,
+        color
+    )
+)
+
+public fun MapFeatureBuilder.points(
+    points: List<Pair<Double, Double>>,
+    zoomRange: IntRange = defaultZoomRange,
+    stroke: Float = 2f,
+    color: Color = Color.Red,
+    pointMode: PointMode = PointMode.Points,
+    id: FeatureId? = null
+): FeatureId = addFeature(id, MapPointsFeature(points.map { it.toCoordinates() }, zoomRange, stroke, color, pointMode))
+
+@Composable
+public fun MapFeatureBuilder.image(
+    position: Pair<Double, Double>,
+    image: ImageVector,
+    size: DpSize = DpSize(20.dp, 20.dp),
+    zoomRange: IntRange = defaultZoomRange,
+    id: FeatureId? = null,
+): FeatureId = addFeature(id, MapVectorImageFeature(position.toCoordinates(), image, size, zoomRange))
+
+public fun MapFeatureBuilder.group(
+    zoomRange: IntRange = defaultZoomRange,
+    id: FeatureId? = null,
+    builder: MapFeatureBuilder.() -> Unit,
+): FeatureId {
+    val map = MapFeatureBuilderImpl(emptyMap()).apply(builder).build()
+    val feature = MapFeatureGroup(map, zoomRange)
+    return addFeature(id, feature)
+}
+
+public fun MapFeatureBuilder.featureSelector(
+    id: FeatureId? = null,
+    onSelect: MapFeatureBuilder.(zoom: Int) -> MapFeature
+): FeatureId = addFeature(
+    id = id,
+    feature = MapFeatureSelector(
+        selector = { onSelect(this, it) }
+    )
+)

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

@@ -0,0 +1,40 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.NativeCanvas
+import center.sciprog.maps.coordinates.GeodeticMapCoordinates
+import center.sciprog.maps.coordinates.GmcBox
+
+public expect class Font constructor() {
+    public var size: Float
+}
+
+public expect fun NativeCanvas.drawString(text: String, x: Float, y: Float, font: Font, color: Color)
+
+public class MapTextFeature(
+    public val position: GeodeticMapCoordinates,
+    public val text: String,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val color: Color,
+    public val fontConfig: Font.() -> Unit,
+) : MapFeature {
+    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(position, position)
+}
+
+public fun MapFeatureBuilder.text(
+    position: GeodeticMapCoordinates,
+    text: String,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    font: Font.() -> Unit = { size = 16f },
+    id: FeatureId? = null,
+): FeatureId = addFeature(id, MapTextFeature(position, text, zoomRange, color, font))
+
+public fun MapFeatureBuilder.text(
+    position: Pair<Double, Double>,
+    text: String,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    font: Font.() -> Unit = { size = 16f },
+    id: FeatureId? = null,
+): FeatureId = addFeature(id, MapTextFeature(position.toCoordinates(), text, zoomRange, color, font))

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

@@ -0,0 +1,31 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.ui.graphics.ImageBitmap
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Deferred
+import kotlin.math.floor
+
+public data class TileId(
+    val zoom: Int,
+    val i: Int,
+    val j: Int,
+)
+
+public data class MapTile(
+    val id: TileId,
+    val image: ImageBitmap,
+)
+
+public interface MapTileProvider {
+    public fun CoroutineScope.loadTileAsync(tileId: TileId): Deferred<MapTile>
+
+    public val tileSize: Int get() = DEFAULT_TILE_SIZE
+
+    public fun toIndex(d: Double): Int = floor(d / tileSize).toInt()
+
+    public fun toCoordinate(i: Int): Double = (i * tileSize).toDouble()
+
+    public companion object {
+        public const val DEFAULT_TILE_SIZE: Int = 256
+    }
+}

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

@@ -0,0 +1,89 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.DpSize
+import center.sciprog.maps.coordinates.*
+import kotlin.math.PI
+import kotlin.math.log2
+import kotlin.math.min
+
+
+//TODO consider replacing by modifier
+/**
+ * @param onDrag - returns true if you want to drag a map and false, if you want to make map stationary.
+ *          start - is a point where drag begins, end is a point where drag ends
+ */
+public data class MapViewConfig(
+    val zoomSpeed: Double = 1.0 / 3.0,
+    val onClick: MapViewPoint.() -> Unit = {},
+    val onDrag: Density.(start: MapViewPoint, end: MapViewPoint) -> Boolean = { _, _ -> true },
+    val onViewChange: MapViewPoint.() -> Unit = {},
+    val onSelect: (GmcBox) -> Unit = {},
+    val zoomOnSelect: Boolean = true,
+    val resetViewPoint: Boolean = false
+)
+
+@Composable
+public expect fun MapView(
+    modifier: Modifier = Modifier,
+    mapViewState: MapViewState,
+    mapViewConfig: MapViewConfig,
+)
+
+@Composable
+public fun MapView(
+    mapTileProvider: MapTileProvider,
+    initialViewPoint: MapViewPoint,
+    features: Map<FeatureId, MapFeature> = emptyMap(),
+    config: MapViewConfig = MapViewConfig(),
+    modifier: Modifier = Modifier.fillMaxSize(),
+    buildFeatures: @Composable (MapFeatureBuilder.() -> Unit) = {},
+) {
+    val featuresBuilder = MapFeatureBuilderImpl(features)
+    featuresBuilder.buildFeatures()
+    MapView(
+        mapViewState = MapViewState(
+            mapTileProvider = mapTileProvider,
+            initialViewPoint = { initialViewPoint },
+            features = featuresBuilder.build(),
+        ),
+        mapViewConfig = config,
+        modifier = modifier
+    )
+}
+
+internal fun GmcBox.computeViewPoint(mapTileProvider: MapTileProvider): (canvasSize: DpSize) -> MapViewPoint =
+    { canvasSize ->
+        val zoom = log2(
+            min(
+                canvasSize.width.value / width,
+                canvasSize.height.value / height
+            ) * PI / mapTileProvider.tileSize
+        )
+        MapViewPoint(center, zoom)
+    }
+
+@Composable
+public fun MapView(
+    mapTileProvider: MapTileProvider,
+    box: GmcBox,
+    features: Map<FeatureId, MapFeature> = emptyMap(),
+    config: MapViewConfig = MapViewConfig(),
+    modifier: Modifier = Modifier.fillMaxSize(),
+    buildFeatures: @Composable (MapFeatureBuilder.() -> Unit) = {},
+) {
+    val featuresBuilder = MapFeatureBuilderImpl(features)
+    featuresBuilder.buildFeatures()
+    MapView(
+        mapViewState = MapViewState(
+            mapTileProvider = mapTileProvider,
+            features = featuresBuilder.build(),
+            initialViewPoint = box.computeViewPoint(mapTileProvider),
+        ),
+        modifier = modifier,
+        mapViewConfig = config,
+    )
+}

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

@@ -0,0 +1,181 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.runtime.*
+import androidx.compose.runtime.snapshots.SnapshotStateList
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.graphics.Path
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.drawscope.Stroke
+import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
+import androidx.compose.ui.graphics.drawscope.translate
+import androidx.compose.ui.graphics.nativeCanvas
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.DpOffset
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import center.sciprog.maps.coordinates.*
+import mu.KotlinLogging
+import kotlin.math.*
+
+@Composable
+public fun MapViewState(
+    initialViewPoint: (canvasSize: DpSize) -> MapViewPoint,
+    mapTileProvider: MapTileProvider,
+    features: Map<FeatureId, MapFeature> = emptyMap(),
+    inferViewBoxFromFeatures: Boolean = false,
+    buildFeatures: @Composable (MapFeatureBuilder.() -> Unit) = {},
+): MapViewState {
+    val featuresBuilder = MapFeatureBuilderImpl(features)
+    featuresBuilder.buildFeatures()
+    return MapViewState(
+        initialViewPoint = initialViewPoint,
+        mapTileProvider = mapTileProvider,
+        features = featuresBuilder.build(),
+        inferViewBoxFromFeatures = inferViewBoxFromFeatures
+    )
+}
+
+public class MapViewState(
+    public val initialViewPoint: (canvasSize: DpSize) -> MapViewPoint,
+    public val mapTileProvider: MapTileProvider,
+    public val features: Map<FeatureId, MapFeature> = emptyMap(),
+    inferViewBoxFromFeatures: Boolean = false,
+) {
+    public var canvasSize: DpSize by mutableStateOf(DpSize(512.dp, 512.dp))
+    public var viewPointInternal: MapViewPoint? by mutableStateOf(null)
+    public val viewPoint: MapViewPoint by derivedStateOf {
+        viewPointInternal ?: if (inferViewBoxFromFeatures) {
+            features.values.computeBoundingBox(1)?.let { box ->
+                val zoom = log2(
+                    min(
+                        canvasSize.width.value / box.width,
+                        canvasSize.height.value / box.height
+                    ) * PI / mapTileProvider.tileSize
+                )
+                MapViewPoint(box.center, zoom)
+            } ?: initialViewPoint(canvasSize)
+        } else {
+            initialViewPoint(canvasSize)
+        }
+    }
+    public val zoom: Int by derivedStateOf { floor(viewPoint.zoom).toInt() }
+
+    public val tileScale: Double by derivedStateOf { 2.0.pow(viewPoint.zoom - zoom) }
+
+    public val mapTiles: SnapshotStateList<MapTile> = mutableStateListOf()
+
+    public val centerCoordinates: WebMercatorCoordinates by derivedStateOf {
+        WebMercatorProjection.toMercator(
+            viewPoint.focus,
+            zoom
+        )
+    }
+
+    public fun DpOffset.toMercator(): WebMercatorCoordinates = WebMercatorCoordinates(
+        zoom,
+        (x - canvasSize.width / 2).value / tileScale + centerCoordinates.x,
+        (y - canvasSize.height / 2).value / tileScale + centerCoordinates.y,
+    )
+
+    /*
+     * Convert screen independent offset to GMC, adjusting for fractional zoom
+     */
+    public fun DpOffset.toGeodetic(): GeodeticMapCoordinates =
+        with(this@MapViewState) { WebMercatorProjection.toGeodetic(toMercator()) }
+
+    // Selection rectangle. If null - no selection
+    public var selectRect: Rect? by mutableStateOf(null)
+
+    public fun WebMercatorCoordinates.toOffset(density: Density): Offset =
+        with(density) {
+            with(this@MapViewState) {
+                Offset(
+                    (canvasSize.width / 2 + (x.dp - centerCoordinates.x.dp) * tileScale.toFloat()).toPx(),
+                    (canvasSize.height / 2 + (y.dp - centerCoordinates.y.dp) * tileScale.toFloat()).toPx()
+                )
+            }
+        }
+
+    //Convert GMC to offset in pixels (not DP), adjusting for zoom
+    public fun GeodeticMapCoordinates.toOffset(density: Density): Offset =
+        WebMercatorProjection.toMercator(this, zoom).toOffset(density)
+
+    private val logger = KotlinLogging.logger("MapViewState")
+
+    public fun DrawScope.drawFeature(zoom: Int, feature: MapFeature) {
+        when (feature) {
+            is MapFeatureSelector -> drawFeature(zoom, feature.selector(zoom))
+            is MapCircleFeature -> drawCircle(
+                feature.color,
+                feature.size,
+                center = feature.center.toOffset(this@drawFeature)
+            )
+            is MapRectangleFeature -> drawRect(
+                feature.color,
+                topLeft = feature.center.toOffset(this@drawFeature) - Offset(
+                    feature.size.width.toPx() / 2,
+                    feature.size.height.toPx() / 2
+                ),
+                size = feature.size.toSize()
+            )
+            is MapLineFeature -> drawLine(
+                feature.color,
+                feature.a.toOffset(this@drawFeature),
+                feature.b.toOffset(this@drawFeature)
+            )
+            is MapArcFeature -> {
+                val topLeft = feature.oval.topLeft.toOffset(this@drawFeature)
+                val bottomRight = feature.oval.bottomRight.toOffset(this@drawFeature)
+
+                val path = Path().apply {
+                    addArcRad(Rect(topLeft, bottomRight), feature.startAngle, feature.endAngle - feature.startAngle)
+                }
+
+                drawPath(path, color = feature.color, style = Stroke())
+
+            }
+            is MapBitmapImageFeature -> drawImage(
+                image = feature.image,
+                topLeft = feature.position.toOffset(this@drawFeature)
+            )
+            is MapVectorImageFeature -> {
+                val offset = feature.position.toOffset(this@drawFeature)
+                val size = feature.size.toSize()
+                translate(offset.x - size.width / 2, offset.y - size.height / 2) {
+                    with(feature.painter) {
+                        draw(size)
+                    }
+                }
+            }
+            is MapTextFeature -> drawIntoCanvas { canvas ->
+                val offset = feature.position.toOffset(this@drawFeature)
+                canvas.nativeCanvas.drawString(
+                    feature.text,
+                    offset.x + 5,
+                    offset.y - 5,
+                    Font().apply(feature.fontConfig),
+                    feature.color
+                )
+            }
+            is MapDrawFeature -> {
+                val offset = feature.position.toOffset(this)
+                translate(offset.x, offset.y) {
+                    feature.drawFeature(this)
+                }
+            }
+            is MapFeatureGroup -> {
+                feature.children.values.forEach {
+                    drawFeature(zoom, it)
+                }
+            }
+            else -> {
+                logger.error { "Unrecognized feature type: ${feature::class}" }
+            }
+        }
+    }
+}
+
+
+
+

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

@@ -1,106 +0,0 @@
-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.graphics.Color
-import androidx.compose.ui.graphics.drawscope.DrawScope
-import androidx.compose.ui.graphics.vector.ImageVector
-import androidx.compose.ui.unit.DpSize
-import androidx.compose.ui.unit.dp
-import centre.sciprog.maps.GeodeticMapCoordinates
-
-typealias FeatureId = String
-
-interface FeatureBuilder {
-    fun addFeature(id: FeatureId?, feature: MapFeature): FeatureId
-
-    fun build(): SnapshotStateMap<FeatureId, MapFeature>
-}
-
-internal class MapFeatureBuilder(initialFeatures: Map<FeatureId, MapFeature>) : FeatureBuilder {
-
-    private val content: SnapshotStateMap<FeatureId, MapFeature> = mutableStateMapOf<FeatureId, MapFeature>().apply {
-        putAll(initialFeatures)
-    }
-
-    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(
-    center: GeodeticMapCoordinates,
-    zoomRange: IntRange = defaultZoomRange,
-    size: Float = 5f,
-    color: Color = Color.Red,
-    id: FeatureId? = null,
-) = addFeature(
-    id, MapCircleFeature(center, zoomRange, size, color)
-)
-
-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.custom(
-    position: Pair<Double, Double>,
-    zoomRange: IntRange = defaultZoomRange,
-    id: FeatureId? = null,
-    drawFeature: DrawScope.() -> Unit,
-) = addFeature(id, MapDrawFeature(position.toCoordinates(), zoomRange, drawFeature))
-
-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: GeodeticMapCoordinates,
-    text: String,
-    zoomRange: IntRange = defaultZoomRange,
-    color: Color = Color.Red,
-    id: FeatureId? = null,
-) = addFeature(id, MapTextFeature(position, text, 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: DpSize = DpSize(20.dp, 20.dp),
-    zoomRange: IntRange = defaultZoomRange,
-    id: FeatureId? = null,
-) = addFeature(id, MapVectorImageFeature(position.toCoordinates(), image, size, zoomRange))
-
-fun FeatureBuilder.group(
-    zoomRange: IntRange = defaultZoomRange,
-    id: FeatureId? = null,
-    builder: FeatureBuilder.() -> Unit,
-): FeatureId {
-    val map = MapFeatureBuilder(emptyMap()).apply(builder).build()
-    val feature = MapFeatureGroup(map, zoomRange)
-    return addFeature(id, feature)
-}

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

@@ -1,110 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.geometry.Offset
-import androidx.compose.ui.geometry.Size
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.ImageBitmap
-import androidx.compose.ui.graphics.drawscope.DrawScope
-import androidx.compose.ui.graphics.painter.Painter
-import androidx.compose.ui.graphics.vector.ImageVector
-import androidx.compose.ui.graphics.vector.rememberVectorPainter
-import androidx.compose.ui.unit.DpSize
-import androidx.compose.ui.unit.IntSize
-import androidx.compose.ui.unit.dp
-import centre.sciprog.maps.GeodeticMapCoordinates
-import centre.sciprog.maps.GmcBox
-import centre.sciprog.maps.wrapAll
-
-//TODO replace zoom range with zoom-based representation change
-sealed class MapFeature(val zoomRange: IntRange) {
-    abstract fun getBoundingBox(zoom: Int): GmcBox?
-}
-
-fun Iterable<MapFeature>.computeBoundingBox(zoom: Int): GmcBox? =
-    mapNotNull { it.getBoundingBox(zoom) }.wrapAll()
-
-internal fun Pair<Double, Double>.toCoordinates() = GeodeticMapCoordinates.ofDegrees(first, second)
-
-internal val defaultZoomRange = 1..18
-
-/**
- * A feature that decides what to show depending on the zoom value (it could change size of shape)
- */
-class MapFeatureSelector(val selector: (zoom: Int) -> MapFeature) : MapFeature(defaultZoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox? = selector(zoom).getBoundingBox(zoom)
-}
-
-class MapDrawFeature(
-    val position: GeodeticMapCoordinates,
-    zoomRange: IntRange = defaultZoomRange,
-    val drawFeature: DrawScope.() -> Unit,
-) : MapFeature(zoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox {
-        //TODO add box computation
-        return GmcBox(position, position)
-    }
-}
-
-class MapCircleFeature(
-    val center: GeodeticMapCoordinates,
-    zoomRange: IntRange = defaultZoomRange,
-    val size: Float = 5f,
-    val color: Color = Color.Red,
-) : MapFeature(zoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(center, center)
-}
-
-class MapLineFeature(
-    val a: GeodeticMapCoordinates,
-    val b: GeodeticMapCoordinates,
-    zoomRange: IntRange = defaultZoomRange,
-    val color: Color = Color.Red,
-) : MapFeature(zoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(a, b)
-}
-
-class MapTextFeature(
-    val position: GeodeticMapCoordinates,
-    val text: String,
-    zoomRange: IntRange = defaultZoomRange,
-    val color: Color = Color.Red,
-) : MapFeature(zoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(position, position)
-}
-
-class MapBitmapImageFeature(
-    val position: GeodeticMapCoordinates,
-    val image: ImageBitmap,
-    val size: IntSize = IntSize(15, 15),
-    zoomRange: IntRange = defaultZoomRange,
-) : MapFeature(zoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(position, position)
-}
-
-class MapVectorImageFeature(
-    val position: GeodeticMapCoordinates,
-    val painter: Painter,
-    val size: DpSize,
-    zoomRange: IntRange = defaultZoomRange,
-) : MapFeature(zoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox = GmcBox(position, position)
-}
-
-@Composable
-fun MapVectorImageFeature(
-    position: GeodeticMapCoordinates,
-    image: ImageVector,
-    size: DpSize = DpSize(20.dp, 20.dp),
-    zoomRange: IntRange = defaultZoomRange,
-): MapVectorImageFeature = MapVectorImageFeature(position, rememberVectorPainter(image), size, zoomRange)
-
-/**
- * A group of other features
- */
-class MapFeatureGroup(
-    val children: Map<FeatureId, MapFeature>,
-    zoomRange: IntRange = defaultZoomRange,
-) : MapFeature(zoomRange) {
-    override fun getBoundingBox(zoom: Int): GmcBox? = children.values.mapNotNull { it.getBoundingBox(zoom) }.wrapAll()
-}

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

@@ -1,31 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.ui.graphics.ImageBitmap
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.Deferred
-import kotlin.math.floor
-
-data class TileId(
-    val zoom: Int,
-    val i: Int,
-    val j: Int,
-)
-
-data class MapTile(
-    val id: TileId,
-    val image: ImageBitmap,
-)
-
-interface MapTileProvider {
-    fun CoroutineScope.loadTileAsync(tileId: TileId): Deferred<MapTile>
-
-    val tileSize: Int get() = DEFAULT_TILE_SIZE
-
-    fun toIndex(d: Double): Int = floor(d / tileSize).toInt()
-
-    fun toCoordinate(i: Int): Double = (i * tileSize).toDouble()
-
-    companion object {
-        const val DEFAULT_TILE_SIZE = 256
-    }
-}

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

@@ -1,80 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.unit.DpSize
-import centre.sciprog.maps.*
-import kotlin.math.PI
-import kotlin.math.log2
-import kotlin.math.min
-
-
-//TODO consider replacing by modifier
-data class MapViewConfig(
-    val zoomSpeed: Double = 1.0 / 3.0,
-    val inferViewBoxFromFeatures: Boolean = false,
-    val onClick: MapViewPoint.() -> Unit = {},
-    val onViewChange: MapViewPoint.() -> Unit = {},
-    val onSelect: (GmcBox) -> Unit = {},
-    val zoomOnSelect: Boolean = true
-)
-
-@Composable
-expect fun MapView(
-    mapTileProvider: MapTileProvider,
-    computeViewPoint: (canvasSize: DpSize) -> MapViewPoint,
-    features: Map<FeatureId, MapFeature>,
-    config: MapViewConfig = MapViewConfig(),
-    modifier: Modifier = Modifier.fillMaxSize(),
-)
-
-@Composable
-fun MapView(
-    mapTileProvider: MapTileProvider,
-    initialViewPoint: MapViewPoint,
-    features: Map<FeatureId, MapFeature> = emptyMap(),
-    config: MapViewConfig = MapViewConfig(),
-    modifier: Modifier = Modifier.fillMaxSize(),
-    buildFeatures: @Composable (FeatureBuilder.() -> Unit) = {},
-) {
-    val featuresBuilder = MapFeatureBuilder(features)
-    featuresBuilder.buildFeatures()
-    MapView(
-        mapTileProvider,
-        { initialViewPoint },
-        featuresBuilder.build(),
-        config,
-        modifier
-    )
-}
-
-internal fun GmcBox.getComputeViewPoint(mapTileProvider: MapTileProvider): (canvasSize: DpSize) -> MapViewPoint = { canvasSize ->
-    val zoom = log2(
-        min(
-            canvasSize.width.value / width,
-            canvasSize.height.value / height
-        ) * PI / mapTileProvider.tileSize
-    )
-    MapViewPoint(center, zoom)
-}
-
-@Composable
-fun MapView(
-    mapTileProvider: MapTileProvider,
-    box: GmcBox,
-    features: Map<FeatureId, MapFeature> = emptyMap(),
-    config: MapViewConfig = MapViewConfig(),
-    modifier: Modifier = Modifier.fillMaxSize(),
-    buildFeatures: @Composable (FeatureBuilder.() -> Unit) = {},
-) {
-    val featuresBuilder = MapFeatureBuilder(features)
-    featuresBuilder.buildFeatures()
-    MapView(
-        mapTileProvider,
-        box.getComputeViewPoint(mapTileProvider),
-        featuresBuilder.build(),
-        config,
-        modifier
-    )
-}

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

@@ -0,0 +1,23 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.NativeCanvas
+import androidx.compose.ui.graphics.toArgb
+import org.jetbrains.skia.Paint
+
+public actual typealias Font = org.jetbrains.skia.Font
+
+public actual fun NativeCanvas.drawString(
+    text: String,
+    x: Float,
+    y: Float,
+    font: Font,
+    color: Color
+) {
+    drawString(text, x, y, font, color.toPaint())
+}
+
+private fun Color.toPaint(): Paint = Paint().apply {
+    isAntiAlias = true
+    color = toArgb()
+}

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

@@ -0,0 +1,213 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.gestures.drag
+import androidx.compose.foundation.gestures.forEachGesture
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.*
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.graphics.*
+import androidx.compose.ui.graphics.drawscope.*
+import androidx.compose.ui.input.pointer.*
+import androidx.compose.ui.unit.*
+import center.sciprog.maps.coordinates.*
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.launch
+import mu.KotlinLogging
+import kotlin.math.*
+
+
+
+
+private fun IntRange.intersect(other: IntRange) = max(first, other.first)..min(last, other.last)
+
+internal fun MapViewPoint.move(deltaX: Double, deltaY: Double): MapViewPoint {
+    val newCoordinates = GeodeticMapCoordinates.ofRadians(
+        (focus.latitude + deltaY / scaleFactor).coerceIn(
+            -MercatorProjection.MAXIMUM_LATITUDE,
+            MercatorProjection.MAXIMUM_LATITUDE
+        ),
+        focus.longitude + deltaX / scaleFactor
+    )
+    return MapViewPoint(newCoordinates, zoom)
+}
+
+private val logger = KotlinLogging.logger("MapView")
+
+/**
+ * A component that renders map and provides basic map manipulation capabilities
+ */
+
+@Composable
+public actual fun MapView(
+    modifier: Modifier,
+    mapViewState: MapViewState,
+    mapViewConfig: MapViewConfig,
+) {
+    with(mapViewState) {
+        @OptIn(ExperimentalComposeUiApi::class)
+        val canvasModifier = modifier.pointerInput(Unit) {
+            forEachGesture {
+                awaitPointerEventScope {
+                    fun Offset.toDpOffset() = DpOffset(x.toDp(), y.toDp())
+
+                    val event: PointerEvent = awaitPointerEvent()
+                    event.changes.forEach { change ->
+                        if (event.buttons.isPrimaryPressed) {
+                            //Evaluating selection frame
+                            if (event.keyboardModifiers.isShiftPressed) {
+                                selectRect = Rect(change.position, change.position)
+                                drag(change.id) { dragChange ->
+                                    selectRect?.let { rect ->
+                                        val offset = dragChange.position
+                                        selectRect = Rect(
+                                            min(offset.x, rect.left),
+                                            min(offset.y, rect.top),
+                                            max(offset.x, rect.right),
+                                            max(offset.y, rect.bottom)
+                                        )
+                                    }
+                                }
+                                selectRect?.let { rect ->
+                                    //Use selection override if it is defined
+                                    val gmcBox = GmcBox(
+                                            rect.topLeft.toDpOffset().toGeodetic(),
+                                            rect.bottomRight.toDpOffset().toGeodetic()
+                                        )
+
+                                    mapViewConfig.onSelect(gmcBox)
+                                    if (mapViewConfig.zoomOnSelect) {
+                                        val newViewPoint = gmcBox.computeViewPoint(mapTileProvider).invoke(canvasSize)
+
+                                        mapViewConfig.onViewChange(newViewPoint)
+                                        viewPointInternal = newViewPoint
+                                    }
+                                    selectRect = null
+                                }
+                            } else {
+                                val dragStart = change.position
+                                val dpPos = DpOffset(dragStart.x.toDp(), dragStart.y.toDp())
+                                mapViewConfig.onClick(
+                                    MapViewPoint(
+                                         dpPos.toGeodetic() ,
+                                        viewPoint.zoom
+                                    )
+                                )
+                                drag(change.id) { dragChange ->
+                                    val dragAmount = dragChange.position - dragChange.previousPosition
+                                    val dpStart =
+                                        DpOffset(
+                                            dragChange.previousPosition.x.toDp(),
+                                            dragChange.previousPosition.y.toDp()
+                                        )
+                                    val dpEnd = DpOffset(dragChange.position.x.toDp(), dragChange.position.y.toDp())
+                                    if (!mapViewConfig.onDrag(
+                                            this,
+                                            MapViewPoint(dpStart.toGeodetic(), viewPoint.zoom),
+                                            MapViewPoint(dpEnd.toGeodetic(), viewPoint.zoom)
+                                        )
+                                    ) return@drag
+                                    val newViewPoint = viewPoint.move(
+                                        -dragAmount.x.toDp().value / tileScale,
+                                        +dragAmount.y.toDp().value / tileScale
+                                    )
+                                    mapViewConfig.onViewChange(newViewPoint)
+                                    viewPointInternal = newViewPoint
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }.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()).toGeodetic()
+            val newViewPoint = viewPoint.zoom(-change.scrollDelta.y.toDouble() * mapViewConfig.zoomSpeed, invariant)
+            mapViewConfig.onViewChange(newViewPoint)
+            viewPointInternal = newViewPoint
+        }.fillMaxSize()
+
+
+        // Load tiles asynchronously
+        LaunchedEffect(viewPoint, canvasSize) {
+            with(mapTileProvider) {
+                val indexRange = 0 until 2.0.pow(zoom).toInt()
+
+                val left = centerCoordinates.x - canvasSize.width.value / 2 / tileScale
+                val right = centerCoordinates.x + canvasSize.width.value / 2 / tileScale
+                val horizontalIndices: IntRange = (toIndex(left)..toIndex(right)).intersect(indexRange)
+
+                val top = (centerCoordinates.y + canvasSize.height.value / 2 / tileScale)
+                val bottom = (centerCoordinates.y - canvasSize.height.value / 2 / tileScale)
+                val verticalIndices: IntRange = (toIndex(bottom)..toIndex(top)).intersect(indexRange)
+
+                mapTiles.clear()
+
+                for (j in verticalIndices) {
+                    for (i in horizontalIndices) {
+                        val id = TileId(zoom, i, j)
+                        //start all
+                        val deferred = loadTileAsync(id)
+                        //wait asynchronously for it to finish
+                        launch {
+                            try {
+                                mapTiles += deferred.await()
+                            } catch (ex: Exception) {
+                                if (ex !is CancellationException) {
+                                    //displaying the error is maps responsibility
+                                    logger.error(ex) { "Failed to load tile with id=$id" }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+
+        Canvas(canvasModifier) {
+        if (mapViewState.canvasSize != size.toDpSize()) {
+            mapViewState.canvasSize = size.toDpSize()
+                logger.debug { "Recalculate canvas. Size: $size" }
+            }
+            clipRect {
+                val tileSize = IntSize(
+                    ceil((mapTileProvider.tileSize.dp * tileScale.toFloat()).toPx()).toInt(),
+                    ceil((mapTileProvider.tileSize.dp * tileScale.toFloat()).toPx()).toInt()
+                )
+                mapTiles.forEach { (id, image) ->
+                    //converting back from tile index to screen offset
+                    val offset = IntOffset(
+                        (canvasSize.width / 2 + (mapTileProvider.toCoordinate(id.i).dp - centerCoordinates.x.dp) * tileScale.toFloat()).roundToPx(),
+                        (canvasSize.height / 2 + (mapTileProvider.toCoordinate(id.j).dp - centerCoordinates.y.dp) * tileScale.toFloat()).roundToPx()
+                    )
+                    drawImage(
+                        image = image,
+                        dstOffset = offset,
+                        dstSize = tileSize
+                    )
+                }
+                features.values.filter { zoom in it.zoomRange }.forEach { feature ->
+                    drawFeature(zoom, feature)
+                }
+            }
+            selectRect?.let { rect ->
+                drawRect(
+                    color = Color.Blue,
+                    topLeft = rect.topLeft,
+                    size = rect.size,
+                    alpha = 0.5f,
+                    style = Stroke(
+                        width = 2f,
+                        pathEffect = PathEffect.dashPathEffect(floatArrayOf(10f, 10f), 0f)
+                    )
+                )
+            }
+        }
+    }
+}

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

@@ -1,4 +1,4 @@
-package centre.sciprog.maps.compose
+package center.sciprog.maps.compose
 
 import androidx.compose.ui.graphics.ImageBitmap
 import androidx.compose.ui.graphics.toComposeImageBitmap
@@ -21,7 +21,7 @@ import kotlin.io.path.*
 /**
  * A [MapTileProvider] based on Open Street Map API. With in-memory and file cache
  */
-class OpenStreetMapTileProvider(
+public class OpenStreetMapTileProvider(
     private val client: HttpClient,
     private val cacheDirectory: Path,
     parallelism: Int = 1,
@@ -93,7 +93,7 @@ class OpenStreetMapTileProvider(
     }
 
 
-    companion object {
+    public companion object {
         private val logger = KotlinLogging.logger("OpenStreetMapCache")
     }
 }

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

@@ -1,299 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.foundation.Canvas
-import androidx.compose.foundation.gestures.drag
-import androidx.compose.foundation.gestures.forEachGesture
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.runtime.*
-import androidx.compose.ui.ExperimentalComposeUiApi
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.geometry.Offset
-import androidx.compose.ui.geometry.Rect
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.PathEffect
-import androidx.compose.ui.graphics.drawscope.*
-import androidx.compose.ui.graphics.nativeCanvas
-import androidx.compose.ui.graphics.toArgb
-import androidx.compose.ui.input.pointer.*
-import androidx.compose.ui.unit.*
-import centre.sciprog.maps.*
-import io.ktor.utils.io.CancellationException
-import kotlinx.coroutines.launch
-import mu.KotlinLogging
-import org.jetbrains.skia.Font
-import org.jetbrains.skia.Paint
-import kotlin.math.*
-
-
-private fun Color.toPaint(): Paint = Paint().apply {
-    isAntiAlias = true
-    color = toArgb()
-}
-
-private fun IntRange.intersect(other: IntRange) = max(first, other.first)..min(last, other.last)
-
-internal fun MapViewPoint.move(deltaX: Double, deltaY: Double): MapViewPoint {
-    val newCoordinates = GeodeticMapCoordinates.ofRadians(
-        (focus.latitude + deltaY / scaleFactor).coerceIn(
-            -MercatorProjection.MAXIMUM_LATITUDE,
-            MercatorProjection.MAXIMUM_LATITUDE
-        ),
-        focus.longitude + deltaX / scaleFactor
-    )
-    return MapViewPoint(newCoordinates, zoom)
-}
-
-private val logger = KotlinLogging.logger("MapView")
-
-/**
- * A component that renders map and provides basic map manipulation capabilities
- */
-
-@Composable
-actual fun MapView(
-    mapTileProvider: MapTileProvider,
-    computeViewPoint: (canvasSize: DpSize) -> MapViewPoint,
-    features: Map<FeatureId, MapFeature>,
-    config: MapViewConfig,
-    modifier: Modifier,
-) {
-    var canvasSize by remember { mutableStateOf(DpSize(512.dp, 512.dp)) }
-
-    var viewPointOverride: MapViewPoint? by remember {
-        mutableStateOf(
-            if (config.inferViewBoxFromFeatures) {
-                features.values.computeBoundingBox(1)?.let { box ->
-                    val zoom = log2(
-                        min(
-                            canvasSize.width.value / box.width,
-                            canvasSize.height.value / box.height
-                        ) * PI / mapTileProvider.tileSize
-                    )
-                    MapViewPoint(box.center, zoom)
-                }
-            } else {
-                null
-            }
-        )
-    }
-
-    val viewPoint by derivedStateOf { viewPointOverride ?: computeViewPoint(canvasSize) }
-
-    val zoom: Int by derivedStateOf { floor(viewPoint.zoom).toInt() }
-
-    val tileScale: Double by derivedStateOf { 2.0.pow(viewPoint.zoom - zoom) }
-
-    val mapTiles = remember { mutableStateListOf<MapTile>() }
-
-    val centerCoordinates by derivedStateOf { WebMercatorProjection.toMercator(viewPoint.focus, zoom) }
-
-    fun DpOffset.toMercator(): WebMercatorCoordinates = WebMercatorCoordinates(
-        zoom,
-        (x - canvasSize.width / 2).value / tileScale + centerCoordinates.x,
-        (y - canvasSize.height / 2).value / tileScale + centerCoordinates.y,
-    )
-
-    /*
-     * Convert screen independent offset to GMC, adjusting for fractional zoom
-     */
-    fun DpOffset.toGeodetic() = WebMercatorProjection.toGeodetic(toMercator())
-
-    // Selection rectangle. If null - no selection
-    var selectRect by remember { mutableStateOf<Rect?>(null) }
-
-    @OptIn(ExperimentalComposeUiApi::class)
-    val canvasModifier = modifier.pointerInput(Unit) {
-        forEachGesture {
-            awaitPointerEventScope {
-                fun Offset.toDpOffset() = DpOffset(x.toDp(), y.toDp())
-
-                val event: PointerEvent = awaitPointerEvent()
-                event.changes.forEach { change ->
-                    if (event.buttons.isPrimaryPressed) {
-                        //Evaluating selection frame
-                        if (event.keyboardModifiers.isShiftPressed) {
-                            selectRect = Rect(change.position, change.position)
-                            drag(change.id) { dragChange ->
-                                selectRect?.let { rect ->
-                                    val offset = dragChange.position
-                                    selectRect = Rect(
-                                        min(offset.x, rect.left),
-                                        min(offset.y, rect.top),
-                                        max(offset.x, rect.right),
-                                        max(offset.y, rect.bottom)
-                                    )
-                                }
-                            }
-                            selectRect?.let { rect ->
-                                //Use selection override if it is defined
-                                val gmcBox = GmcBox(
-                                    rect.topLeft.toDpOffset().toGeodetic(),
-                                    rect.bottomRight.toDpOffset().toGeodetic()
-                                )
-                                config.onSelect(gmcBox)
-                                if(config.zoomOnSelect) {
-                                    val newViewPoint = gmcBox.getComputeViewPoint(mapTileProvider).invoke(canvasSize)
-
-                                    config.onViewChange(newViewPoint)
-                                    viewPointOverride = newViewPoint
-                                }
-                                selectRect = null
-                            }
-                        } else {
-                            val dragStart = change.position
-                            val dpPos = DpOffset(dragStart.x.toDp(), dragStart.y.toDp())
-                            config.onClick(MapViewPoint(dpPos.toGeodetic(), viewPoint.zoom))
-                            drag(change.id) { dragChange ->
-                                val dragAmount = dragChange.position - dragChange.previousPosition
-                                val newViewPoint = viewPoint.move(
-                                    -dragAmount.x.toDp().value / tileScale,
-                                    +dragAmount.y.toDp().value / tileScale
-                                )
-                                config.onViewChange(newViewPoint)
-                                viewPointOverride = newViewPoint
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }.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()).toGeodetic()
-        val newViewPoint = viewPoint.zoom(-change.scrollDelta.y.toDouble() * config.zoomSpeed, invariant)
-        config.onViewChange(newViewPoint)
-        viewPointOverride = newViewPoint
-    }.fillMaxSize()
-
-
-    // Load tiles asynchronously
-    LaunchedEffect(viewPoint, canvasSize) {
-        with(mapTileProvider) {
-            val indexRange = 0 until 2.0.pow(zoom).toInt()
-
-            val left = centerCoordinates.x - canvasSize.width.value / 2 / tileScale
-            val right = centerCoordinates.x + canvasSize.width.value / 2 / tileScale
-            val horizontalIndices: IntRange = (toIndex(left)..toIndex(right)).intersect(indexRange)
-
-            val top = (centerCoordinates.y + canvasSize.height.value / 2 / tileScale)
-            val bottom = (centerCoordinates.y - canvasSize.height.value / 2 / tileScale)
-            val verticalIndices: IntRange = (toIndex(bottom)..toIndex(top)).intersect(indexRange)
-
-            mapTiles.clear()
-
-            for (j in verticalIndices) {
-                for (i in horizontalIndices) {
-                    val id = TileId(zoom, i, j)
-                    //start all
-                    val deferred = loadTileAsync(id)
-                    //wait asynchronously for it to finish
-                    launch {
-                        try {
-                            mapTiles += deferred.await()
-                        } catch (ex: Exception) {
-                            if (ex !is CancellationException) {
-                                //displaying the error is maps responsibility
-                                logger.error(ex) { "Failed to load tile with id=$id" }
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-
-    Canvas(canvasModifier) {
-        fun WebMercatorCoordinates.toOffset(): Offset = Offset(
-            (canvasSize.width / 2 + (x.dp - centerCoordinates.x.dp) * tileScale.toFloat()).toPx(),
-            (canvasSize.height / 2 + (y.dp - centerCoordinates.y.dp) * tileScale.toFloat()).toPx()
-        )
-
-        //Convert GMC to offset in pixels (not DP), adjusting for zoom
-        fun GeodeticMapCoordinates.toOffset(): Offset = WebMercatorProjection.toMercator(this, zoom).toOffset()
-
-
-        fun DrawScope.drawFeature(zoom: Int, feature: MapFeature) {
-            when (feature) {
-                is MapFeatureSelector -> drawFeature(zoom, feature.selector(zoom))
-                is MapCircleFeature -> drawCircle(
-                    feature.color,
-                    feature.size,
-                    center = feature.center.toOffset()
-                )
-                is MapLineFeature -> drawLine(feature.color, feature.a.toOffset(), feature.b.toOffset())
-                is MapBitmapImageFeature -> drawImage(feature.image, feature.position.toOffset())
-                is MapVectorImageFeature -> {
-                    val offset = feature.position.toOffset()
-                    val size = feature.size.toSize()
-                    translate(offset.x - size.width / 2, offset.y - size.height / 2) {
-                        with(feature.painter) {
-                            draw(size)
-                        }
-                    }
-                }
-                is MapTextFeature -> drawIntoCanvas { canvas ->
-                    val offset = feature.position.toOffset()
-                    canvas.nativeCanvas.drawString(
-                        feature.text,
-                        offset.x + 5,
-                        offset.y - 5,
-                        Font().apply { size = 16f },
-                        feature.color.toPaint()
-                    )
-                }
-                is MapDrawFeature -> {
-                    val offset = feature.position.toOffset()
-                    translate(offset.x, offset.y) {
-                        feature.drawFeature(this)
-                    }
-                }
-                is MapFeatureGroup -> {
-                    feature.children.values.forEach {
-                        drawFeature(zoom, it)
-                    }
-                }
-            }
-        }
-
-        if (canvasSize != size.toDpSize()) {
-            canvasSize = size.toDpSize()
-            logger.debug { "Recalculate canvas. Size: $size" }
-        }
-        clipRect {
-            val tileSize = IntSize(
-                ceil((mapTileProvider.tileSize.dp * tileScale.toFloat()).toPx()).toInt(),
-                ceil((mapTileProvider.tileSize.dp * tileScale.toFloat()).toPx()).toInt()
-            )
-            mapTiles.forEach { (id, image) ->
-                //converting back from tile index to screen offset
-                val offset = IntOffset(
-                    (canvasSize.width / 2 + (mapTileProvider.toCoordinate(id.i).dp - centerCoordinates.x.dp) * tileScale.toFloat()).roundToPx(),
-                    (canvasSize.height / 2 + (mapTileProvider.toCoordinate(id.j).dp - centerCoordinates.y.dp) * tileScale.toFloat()).roundToPx()
-                )
-                drawImage(
-                    image = image,
-                    dstOffset = offset,
-                    dstSize = tileSize
-                )
-            }
-            features.values.filter { zoom in it.zoomRange }.forEach { feature ->
-                drawFeature(zoom, feature)
-            }
-        }
-        selectRect?.let { rect ->
-            drawRect(
-                color = Color.Blue,
-                topLeft = rect.topLeft,
-                size = rect.size,
-                alpha = 0.5f,
-                style = Stroke(
-                    width = 2f,
-                    pathEffect = PathEffect.dashPathEffect(floatArrayOf(10f, 10f), 0f)
-                )
-            )
-        }
-    }
-}

maps-kt-core/build.gradle.kts

@@ -6,21 +6,13 @@ plugins {
 val ktorVersion: String by rootProject.extra
 
 kotlin {
+    explicitApi = org.jetbrains.kotlin.gradle.dsl.ExplicitApiMode.Warning
     jvm {
         compilations.all {
             kotlinOptions.jvmTarget = "11"
         }
     }
-    js(IR){
+    js(IR) {
         browser()
     }
-    sourceSets {
-        commonMain{
-            dependencies{
-                api("io.github.microutils:kotlin-logging:2.1.23")
-            }
-        }
-        val jvmMain by getting
-        val jvmTest by getting
-    }
 }

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

@@ -0,0 +1,17 @@
+package center.sciprog.maps.coordinates
+
+import kotlin.jvm.JvmInline
+
+@JvmInline
+public value class Distance(public val kilometers: Double)
+
+public operator fun Distance.div(other: Distance): Double = kilometers / other.kilometers
+
+public operator fun Distance.plus(other: Distance): Distance = Distance(kilometers + other.kilometers)
+public operator fun Distance.minus(other: Distance): Distance = Distance(kilometers - other.kilometers)
+
+public operator fun Distance.times(number: Number): Distance = Distance(kilometers * number.toDouble())
+public operator fun Distance.div(number: Number): Distance = Distance(kilometers / number.toDouble())
+
+
+public val Distance.meters: Double get() = kilometers * 1000

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

@@ -0,0 +1,14 @@
+package center.sciprog.maps.coordinates
+
+public class Ellipsoid(public val equatorRadius: Distance, public val polarRadius: Distance) {
+    public companion object {
+        public val WGS84: Ellipsoid = Ellipsoid(
+            equatorRadius = Distance(6378.137),
+            polarRadius = Distance(6356.7523142)
+        )
+    }
+}
+
+public val Ellipsoid.f: Double get() = (equatorRadius.kilometers - polarRadius.kilometers) / equatorRadius.kilometers
+
+public val Ellipsoid.inverseF: Double get() = equatorRadius.kilometers / (equatorRadius.kilometers - polarRadius.kilometers)

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

@@ -1,11 +1,14 @@
-package centre.sciprog.maps
+package center.sciprog.maps.coordinates
 
 import kotlin.math.PI
 
 /**
  * Geodetic coordinated
  */
-public class GeodeticMapCoordinates private constructor(public val latitude: Double, public val longitude: Double) {
+public class GeodeticMapCoordinates private constructor(
+    public val latitude: Double,
+    public val longitude: Double,
+){
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
@@ -43,9 +46,6 @@ public class GeodeticMapCoordinates private constructor(public val latitude: Dou
     }
 }
 
-internal typealias Gmc = GeodeticMapCoordinates
-
-
 //public interface GeoToScreenConversion {
 //    public fun getScreenX(gmc: GeodeticMapCoordinates): Double
 //    public fun getScreenY(gmc: GeodeticMapCoordinates): Double

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

@@ -0,0 +1,77 @@
+package center.sciprog.maps.coordinates
+
+import kotlin.math.abs
+import kotlin.math.cos
+import kotlin.math.max
+import kotlin.math.min
+
+public data class GmcBox(
+    public val a: GeodeticMapCoordinates,
+    public val b: GeodeticMapCoordinates,
+) {
+    public companion object {
+        public fun withCenter(
+            center: GeodeticMapCoordinates,
+            width: Distance,
+            height: Distance,
+            ellipsoid: Ellipsoid = Ellipsoid.WGS84,
+        ): GmcBox {
+            val r = ellipsoid.equatorRadius * cos(center.latitude)
+            val a = GeodeticMapCoordinates.ofRadians(
+                center.latitude - height / ellipsoid.polarRadius / 2,
+                center.longitude - width / r / 2
+            )
+            val b = GeodeticMapCoordinates.ofRadians(
+                center.latitude + height / ellipsoid.polarRadius / 2,
+                center.longitude + width / r / 2
+            )
+            return GmcBox(a, b)
+        }
+    }
+}
+
+public val GmcBox.center: GeodeticMapCoordinates
+    get() = GeodeticMapCoordinates.ofRadians(
+        (a.latitude + b.latitude) / 2,
+        (a.longitude + b.longitude) / 2
+    )
+
+/**
+ * Minimum longitude
+ */
+public val GmcBox.left: Double get() = min(a.longitude, b.longitude)
+
+/**
+ * maximum longitude
+ */
+public val GmcBox.right: Double get() = max(a.longitude, b.longitude)
+
+/**
+ * Maximum latitude
+ */
+public val GmcBox.top: Double get() = max(a.latitude, b.latitude)
+
+/**
+ * Minimum latitude
+ */
+public val GmcBox.bottom: Double get() = min(a.latitude, b.latitude)
+
+//TODO take curvature into account
+public val GmcBox.width: Double get() = abs(a.longitude - b.longitude)
+public val GmcBox.height: Double get() = abs(a.latitude - b.latitude)
+
+public val GmcBox.topLeft: GeodeticMapCoordinates get() = GeodeticMapCoordinates.ofRadians(top, left)
+public val GmcBox.bottomRight: GeodeticMapCoordinates get() = GeodeticMapCoordinates.ofRadians(bottom, right)
+
+/**
+ * Compute a minimal bounding box including all given boxes. Return null if collection is empty
+ */
+public fun Collection<GmcBox>.wrapAll(): GmcBox? {
+    if (isEmpty()) return null
+    //TODO optimize computation
+    val minLat = minOf { it.bottom }
+    val maxLat = maxOf { it.top }
+    val minLong = minOf { it.left }
+    val maxLong = maxOf { it.right }
+    return GmcBox(GeodeticMapCoordinates.ofRadians(minLat, minLong), GeodeticMapCoordinates.ofRadians(maxLat, maxLong))
+}

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

@@ -1,18 +1,18 @@
-package centre.sciprog.maps
+package center.sciprog.maps.coordinates
 
 import kotlin.math.pow
 
 /**
  * Observable position on the map. Includes observation coordinate and [zoom] factor
  */
-data class MapViewPoint(
+public data class MapViewPoint(
     val focus: GeodeticMapCoordinates,
     val zoom: Double,
 ) {
-    val scaleFactor by lazy { WebMercatorProjection.scaleFactor(zoom) }
+    val scaleFactor: Double by lazy { WebMercatorProjection.scaleFactor(zoom) }
 }
 
-fun MapViewPoint.move(delta: GeodeticMapCoordinates): MapViewPoint {
+public fun MapViewPoint.move(delta: GeodeticMapCoordinates): MapViewPoint {
     val newCoordinates = GeodeticMapCoordinates.ofRadians(
         (focus.latitude + delta.latitude).coerceIn(
             -MercatorProjection.MAXIMUM_LATITUDE,
@@ -23,7 +23,7 @@ fun MapViewPoint.move(delta: GeodeticMapCoordinates): MapViewPoint {
     return MapViewPoint(newCoordinates, zoom)
 }
 
-fun MapViewPoint.zoom(
+public fun MapViewPoint.zoom(
     zoomDelta: Double,
     invariant: GeodeticMapCoordinates = focus,
 ): MapViewPoint = if (invariant == focus) {

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

@@ -3,7 +3,7 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package centre.sciprog.maps
+package center.sciprog.maps.coordinates
 
 import kotlin.math.*
 

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

@@ -3,7 +3,7 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package centre.sciprog.maps
+package center.sciprog.maps.coordinates
 
 import kotlin.math.*
 
@@ -14,7 +14,7 @@ public object WebMercatorProjection  {
     /**
      * Compute radians to projection coordinates ratio for given [zoom] factor
      */
-    public fun scaleFactor(zoom: Double) = 256.0 / 2 / PI * 2.0.pow(zoom)
+    public fun scaleFactor(zoom: Double): Double = 256.0 / 2 / PI * 2.0.pow(zoom)
 
     public fun toGeodetic(mercator: WebMercatorCoordinates): GeodeticMapCoordinates {
         val scaleFactor = scaleFactor(mercator.zoom.toDouble())

maps-kt-core/src/commonMain/kotlin/centre/sciprog/maps/GmcBox.kt

@@ -1,39 +0,0 @@
-package centre.sciprog.maps
-
-import kotlin.math.*
-
-class GmcBox(val a: GeodeticMapCoordinates, val b: GeodeticMapCoordinates)
-
-fun GmcBox(latitudes: ClosedFloatingPointRange<Double>, longitudes: ClosedFloatingPointRange<Double>) = GmcBox(
-    GeodeticMapCoordinates.ofRadians(latitudes.start, longitudes.start),
-    GeodeticMapCoordinates.ofRadians(latitudes.endInclusive, longitudes.endInclusive)
-)
-
-val GmcBox.center
-    get() = GeodeticMapCoordinates.ofRadians(
-        (a.latitude + b.latitude) / 2,
-        (a.longitude + b.longitude) / 2
-    )
-
-val GmcBox.left get() = min(a.longitude, b.longitude)
-val GmcBox.right get() = max(a.longitude, b.longitude)
-
-val GmcBox.top get() = max(a.latitude, b.latitude)
-val GmcBox.bottom get() = min(a.latitude, b.latitude)
-
-//TODO take curvature into account
-val GmcBox.width get() = abs(a.longitude - b.longitude)
-val GmcBox.height get() = abs(a.latitude - b.latitude)
-
-/**
- * Compute a minimal bounding box including all given boxes. Return null if collection is empty
- */
-fun Collection<GmcBox>.wrapAll(): GmcBox? {
-    if (isEmpty()) return null
-    //TODO optimize computation
-    val minLat = minOf { it.bottom }
-    val maxLat = maxOf { it.top }
-    val minLong = minOf { it.left }
-    val maxLong = maxOf { it.right }
-    return GmcBox(minLat..maxLat, minLong..maxLong)
-}

maps-kt-scheme/build.gradle.kts

@@ -0,0 +1,30 @@
+import org.jetbrains.compose.compose
+
+
+plugins {
+    kotlin("multiplatform")
+    id("org.jetbrains.compose")
+}
+
+kotlin {
+    jvm {
+        compilations.all {
+            kotlinOptions.jvmTarget = "11"
+        }
+        withJava()
+    }
+    sourceSets {
+        commonMain {
+            dependencies {
+                api("io.github.microutils:kotlin-logging:2.1.23")
+                api(compose.foundation)
+            }
+        }
+        val jvmMain by getting {
+            dependencies {
+                api(compose.desktop.currentOs)
+            }
+        }
+        val jvmTest by getting
+    }
+}

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

@@ -0,0 +1,37 @@
+package center.sciprog.maps.scheme
+
+import kotlin.math.abs
+import kotlin.math.max
+import kotlin.math.min
+
+data class SchemeCoordinates(val x: Float, val y: Float)
+
+data class SchemeCoordinateBox(
+    val a: SchemeCoordinates,
+    val b: SchemeCoordinates,
+)
+
+val SchemeCoordinateBox.top get() = max(a.y, b.y)
+val SchemeCoordinateBox.bottom get() = min(a.y, b.y)
+
+val SchemeCoordinateBox.right get() = max(a.x, b.x)
+val SchemeCoordinateBox.left get() = min(a.x, b.x)
+
+val SchemeCoordinateBox.width get() = abs(a.x - b.x)
+val SchemeCoordinateBox.height get() = abs(a.y - b.y)
+
+val SchemeCoordinateBox.center get() = SchemeCoordinates((a.x + b.x) / 2, (a.y + b.y) / 2)
+
+
+fun Collection<SchemeCoordinateBox>.wrapAll(): SchemeCoordinateBox? {
+    if (isEmpty()) return null
+    val minX = minOf { it.left }
+    val maxX = maxOf { it.right }
+
+    val minY = minOf { it.bottom }
+    val maxY = maxOf { it.top }
+    return SchemeCoordinateBox(
+        SchemeCoordinates(minX, minY),
+        SchemeCoordinates(maxX, maxY)
+    )
+}

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

@@ -0,0 +1,119 @@
+package center.sciprog.maps.scheme
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.drawscope.DrawScope
+import androidx.compose.ui.graphics.painter.Painter
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.graphics.vector.rememberVectorPainter
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.unit.dp
+import center.sciprog.maps.scheme.SchemeFeature.Companion.defaultScaleRange
+
+internal typealias FloatRange = ClosedFloatingPointRange<Float>
+
+sealed class SchemeFeature(val scaleRange: FloatRange) {
+    abstract fun getBoundingBox(scale: Float): SchemeCoordinateBox?
+
+    companion object {
+        val defaultScaleRange = 0f..Float.MAX_VALUE
+    }
+}
+
+
+fun Iterable<SchemeFeature>.computeBoundingBox(scale: Float): SchemeCoordinateBox? =
+    mapNotNull { it.getBoundingBox(scale) }.wrapAll()
+
+
+internal fun Pair<Number, Number>.toCoordinates() = SchemeCoordinates(first.toFloat(), second.toFloat())
+
+/**
+ * A background image that is bound to scheme coordinates and is scaled together with them
+ *
+ * @param position the size of background in scheme size units. The screen units to scheme units ratio equals scale.
+ */
+class SchemeBackgroundFeature(
+    val position: SchemeCoordinateBox,
+    val painter: Painter,
+    scaleRange: FloatRange = defaultScaleRange,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox = position
+}
+
+class SchemeFeatureSelector(val selector: (scale: Float) -> SchemeFeature) : SchemeFeature(defaultScaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox? = selector(scale).getBoundingBox(scale)
+}
+
+class SchemeDrawFeature(
+    val position: SchemeCoordinates,
+    scaleRange: FloatRange = defaultScaleRange,
+    val drawFeature: DrawScope.() -> Unit,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox = SchemeCoordinateBox(position, position)
+}
+
+class SchemeCircleFeature(
+    val center: SchemeCoordinates,
+    scaleRange: FloatRange = defaultScaleRange,
+    val size: Float = 5f,
+    val color: Color = Color.Red,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox = SchemeCoordinateBox(center, center)
+}
+
+class SchemeLineFeature(
+    val a: SchemeCoordinates,
+    val b: SchemeCoordinates,
+    scaleRange: FloatRange = defaultScaleRange,
+    val color: Color = Color.Red,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox = SchemeCoordinateBox(a, b)
+}
+
+class SchemeTextFeature(
+    val position: SchemeCoordinates,
+    val text: String,
+    scaleRange: FloatRange = defaultScaleRange,
+    val color: Color = Color.Red,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox = SchemeCoordinateBox(position, position)
+}
+
+class SchemeBitmapFeature(
+    val position: SchemeCoordinates,
+    val image: ImageBitmap,
+    val size: IntSize = IntSize(15, 15),
+    scaleRange: FloatRange = defaultScaleRange,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox = SchemeCoordinateBox(position, position)
+}
+
+class SchemeImageFeature(
+    val position: SchemeCoordinates,
+    val painter: Painter,
+    val size: DpSize,
+    scaleRange: FloatRange = defaultScaleRange,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox = SchemeCoordinateBox(position, position)
+}
+
+@Composable
+fun SchemeVectorImageFeature(
+    position: SchemeCoordinates,
+    image: ImageVector,
+    size: DpSize = DpSize(20.dp, 20.dp),
+    scaleRange: FloatRange = defaultScaleRange,
+): SchemeImageFeature = SchemeImageFeature(position, rememberVectorPainter(image), size, scaleRange)
+
+/**
+ * A group of other features
+ */
+class SchemeFeatureGroup(
+    val children: Map<FeatureId, SchemeFeature>,
+    scaleRange: FloatRange = defaultScaleRange,
+) : SchemeFeature(scaleRange) {
+    override fun getBoundingBox(scale: Float): SchemeCoordinateBox? =
+        children.values.mapNotNull { it.getBoundingBox(scale) }.wrapAll()
+}

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

@@ -0,0 +1,133 @@
+package center.sciprog.maps.scheme
+
+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.drawscope.DrawScope
+import androidx.compose.ui.graphics.painter.Painter
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import center.sciprog.maps.scheme.SchemeFeature.Companion.defaultScaleRange
+
+typealias FeatureId = String
+
+interface SchemeFeatureBuilder {
+    fun addFeature(id: FeatureId?, feature: SchemeFeature): FeatureId
+
+    fun build(): SnapshotStateMap<FeatureId, SchemeFeature>
+}
+
+internal class SchemeFeatureBuilderImpl(
+    initialFeatures: Map<FeatureId, SchemeFeature>,
+) : SchemeFeatureBuilder {
+
+    private val content: SnapshotStateMap<FeatureId, SchemeFeature> =
+        mutableStateMapOf<FeatureId, SchemeFeature>().apply {
+            putAll(initialFeatures)
+        }
+
+    private fun generateID(feature: SchemeFeature): FeatureId = "@feature[${feature.hashCode().toUInt()}]"
+
+    override fun addFeature(id: FeatureId?, feature: SchemeFeature): FeatureId {
+        val safeId = id ?: generateID(feature)
+        content[id ?: generateID(feature)] = feature
+        return safeId
+    }
+
+    override fun build(): SnapshotStateMap<FeatureId, SchemeFeature> = content
+}
+
+fun SchemeFeatureBuilder.background(
+    painter: Painter,
+    box: SchemeCoordinateBox,
+    id: FeatureId? = null,
+): FeatureId = addFeature(
+    id,
+    SchemeBackgroundFeature(box, painter)
+)
+
+fun SchemeFeatureBuilder.background(
+    painter: Painter,
+    size: Size = painter.intrinsicSize,
+    offset: SchemeCoordinates = SchemeCoordinates(0f, 0f),
+    id: FeatureId? = null,
+): FeatureId {
+    val box = SchemeCoordinateBox(
+        offset,
+        SchemeCoordinates(size.width + offset.x, size.height + offset.y)
+    )
+    return background(painter, box, id)
+}
+
+fun SchemeFeatureBuilder.circle(
+    center: SchemeCoordinates,
+    scaleRange: FloatRange = defaultScaleRange,
+    size: Float = 5f,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(
+    id, SchemeCircleFeature(center, scaleRange, size, color)
+)
+
+fun SchemeFeatureBuilder.circle(
+    centerCoordinates: Pair<Number, Number>,
+    scaleRange: FloatRange = defaultScaleRange,
+    size: Float = 5f,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(
+    id, SchemeCircleFeature(centerCoordinates.toCoordinates(), scaleRange, size, color)
+)
+
+fun SchemeFeatureBuilder.draw(
+    position: Pair<Number, Number>,
+    scaleRange: FloatRange = defaultScaleRange,
+    id: FeatureId? = null,
+    drawFeature: DrawScope.() -> Unit,
+) = addFeature(id, SchemeDrawFeature(position.toCoordinates(), scaleRange, drawFeature))
+
+fun SchemeFeatureBuilder.line(
+    aCoordinates: Pair<Number, Number>,
+    bCoordinates: Pair<Number, Number>,
+    scaleRange: FloatRange = defaultScaleRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(id, SchemeLineFeature(aCoordinates.toCoordinates(), bCoordinates.toCoordinates(), scaleRange, color))
+
+fun SchemeFeatureBuilder.text(
+    position: SchemeCoordinates,
+    text: String,
+    scaleRange: FloatRange = defaultScaleRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(id, SchemeTextFeature(position, text, scaleRange, color))
+
+fun SchemeFeatureBuilder.text(
+    position: Pair<Number, Number>,
+    text: String,
+    scaleRange: FloatRange = defaultScaleRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+) = addFeature(id, SchemeTextFeature(position.toCoordinates(), text, scaleRange, color))
+
+@Composable
+fun SchemeFeatureBuilder.image(
+    position: Pair<Number, Number>,
+    image: ImageVector,
+    size: DpSize = DpSize(20.dp, 20.dp),
+    scaleRange: FloatRange = defaultScaleRange,
+    id: FeatureId? = null,
+) = addFeature(id, SchemeVectorImageFeature(position.toCoordinates(), image, size, scaleRange))
+
+fun SchemeFeatureBuilder.group(
+    scaleRange: FloatRange = defaultScaleRange,
+    id: FeatureId? = null,
+    builder: SchemeFeatureBuilder.() -> Unit,
+): FeatureId {
+    val map = SchemeFeatureBuilderImpl(emptyMap()).apply(builder).build()
+    val feature = SchemeFeatureGroup(map, scaleRange)
+    return addFeature(id, feature)
+}

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

@@ -0,0 +1,23 @@
+package center.sciprog.maps.scheme
+
+import kotlin.math.pow
+
+data class SchemeViewPoint(val focus: SchemeCoordinates, val scale: Float = 1f)
+
+fun SchemeViewPoint.move(deltaX: Float, deltaY: Float): SchemeViewPoint {
+    return copy(focus = SchemeCoordinates(focus.x + deltaX, focus.y + deltaY))
+}
+
+fun SchemeViewPoint.zoom(
+    zoom: Float,
+    invariant: SchemeCoordinates = focus,
+): SchemeViewPoint = if (invariant == focus) {
+    copy(scale = scale * 2f.pow(zoom))
+} else {
+    val difScale =  (1 - 2f.pow(-zoom))
+    val newCenter = SchemeCoordinates(
+        focus.x + (invariant.x - focus.x) * difScale,
+        focus.y + (invariant.y - focus.y) * difScale
+    )
+    SchemeViewPoint(newCenter, scale * 2f.pow(zoom))
+}

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

@@ -0,0 +1,262 @@
+package center.sciprog.maps.scheme
+
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.gestures.drag
+import androidx.compose.foundation.gestures.forEachGesture
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.*
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.geometry.Rect
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.PathEffect
+import androidx.compose.ui.graphics.drawscope.*
+import androidx.compose.ui.graphics.nativeCanvas
+import androidx.compose.ui.graphics.toArgb
+import androidx.compose.ui.input.pointer.*
+import androidx.compose.ui.unit.DpOffset
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.dp
+import mu.KotlinLogging
+import org.jetbrains.skia.Font
+import org.jetbrains.skia.Paint
+import kotlin.math.max
+import kotlin.math.min
+
+
+private fun Color.toPaint(): Paint = Paint().apply {
+    isAntiAlias = true
+    color = toArgb()
+}
+
+private fun IntRange.intersect(other: IntRange) = max(first, other.first)..min(last, other.last)
+
+private val logger = KotlinLogging.logger("SchemeView")
+
+data class SchemeViewConfig(
+    val zoomSpeed: Float = 1f / 3f,
+    val inferViewBoxFromFeatures: Boolean = false,
+    val onClick: SchemeViewPoint.() -> Unit = {},
+    val onViewChange: SchemeViewPoint.() -> Unit = {},
+    val onSelect: (SchemeCoordinateBox) -> Unit = {},
+    val zoomOnSelect: Boolean = true,
+)
+
+@Composable
+public fun SchemeView(
+    computeViewPoint: (canvasSize: DpSize) -> SchemeViewPoint,
+    features: Map<FeatureId, SchemeFeature>,
+    config: SchemeViewConfig = SchemeViewConfig(),
+    modifier: Modifier = Modifier.fillMaxSize(),
+) {
+
+    var canvasSize by remember { mutableStateOf(DpSize(512.dp, 512.dp)) }
+
+    var viewPointInternal: SchemeViewPoint? by remember {
+        mutableStateOf(null)
+    }
+
+    val viewPoint: SchemeViewPoint by derivedStateOf {
+        viewPointInternal ?: if (config.inferViewBoxFromFeatures) {
+            features.values.computeBoundingBox(1f)?.let { box ->
+                val scale = min(
+                    canvasSize.width.value / box.width,
+                    canvasSize.height.value / box.height
+                )
+                SchemeViewPoint(box.center, scale)
+            } ?: computeViewPoint(canvasSize)
+        } else {
+            computeViewPoint(canvasSize)
+        }
+    }
+
+    fun DpOffset.toCoordinates(): SchemeCoordinates = SchemeCoordinates(
+        (x - canvasSize.width / 2).value / viewPoint.scale + viewPoint.focus.x,
+        (canvasSize.height / 2 - y).value / viewPoint.scale + viewPoint.focus.y
+    )
+
+    // Selection rectangle. If null - no selection
+    var selectRect by remember { mutableStateOf<Rect?>(null) }
+
+    @OptIn(ExperimentalComposeUiApi::class)
+    val canvasModifier = modifier.pointerInput(Unit) {
+        forEachGesture {
+            awaitPointerEventScope {
+                fun Offset.toDpOffset() = DpOffset(x.toDp(), y.toDp())
+
+                val event: PointerEvent = awaitPointerEvent()
+                event.changes.forEach { change ->
+                    if (event.buttons.isPrimaryPressed) {
+                        //Evaluating selection frame
+                        if (event.keyboardModifiers.isShiftPressed) {
+                            selectRect = Rect(change.position, change.position)
+                            drag(change.id) { dragChange ->
+                                selectRect?.let { rect ->
+                                    val offset = dragChange.position
+                                    selectRect = Rect(
+                                        min(offset.x, rect.left),
+                                        min(offset.y, rect.top),
+                                        max(offset.x, rect.right),
+                                        max(offset.y, rect.bottom)
+                                    )
+                                }
+                            }
+                            selectRect?.let { rect ->
+                                //Use selection override if it is defined
+                                val box = SchemeCoordinateBox(
+                                    rect.topLeft.toDpOffset().toCoordinates(),
+                                    rect.bottomRight.toDpOffset().toCoordinates()
+                                )
+                                config.onSelect(box)
+                                if (config.zoomOnSelect) {
+                                    val newScale = min(
+                                        canvasSize.width.value / box.width,
+                                        canvasSize.height.value / box.height
+                                    )
+
+                                    val newViewPoint = SchemeViewPoint(box.center, newScale)
+
+                                    config.onViewChange(newViewPoint)
+                                    viewPointInternal = newViewPoint
+                                }
+                                selectRect = null
+                            }
+                        } else {
+                            val dragStart = change.position
+                            val dpPos = DpOffset(dragStart.x.toDp(), dragStart.y.toDp())
+                            config.onClick(SchemeViewPoint(dpPos.toCoordinates(), viewPoint.scale))
+                            drag(change.id) { dragChange ->
+                                val dragAmount = dragChange.position - dragChange.previousPosition
+                                val newViewPoint = viewPoint.move(
+                                    -dragAmount.x.toDp().value / viewPoint.scale,
+                                    dragAmount.y.toDp().value / viewPoint.scale
+                                )
+                                config.onViewChange(newViewPoint)
+                                viewPointInternal = newViewPoint
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }.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()
+        val newViewPoint = viewPoint.zoom(-change.scrollDelta.y * config.zoomSpeed, invariant)
+        config.onViewChange(newViewPoint)
+        viewPointInternal = newViewPoint
+    }.fillMaxSize()
+
+    Canvas(canvasModifier) {
+        fun SchemeCoordinates.toOffset(): Offset = Offset(
+            (canvasSize.width / 2 + (x.dp - viewPoint.focus.x.dp) * viewPoint.scale).toPx(),
+            (canvasSize.height / 2 + (viewPoint.focus.y.dp - y.dp) * viewPoint.scale).toPx()
+        )
+
+
+        fun DrawScope.drawFeature(scale: Float, feature: SchemeFeature) {
+            when (feature) {
+                is SchemeBackgroundFeature -> {
+                    val offset = SchemeCoordinates(feature.position.left, feature.position.top).toOffset()
+
+                    val backgroundSize = DpSize(
+                        (feature.position.width * scale).dp,
+                        (feature.position.height * scale).dp
+                    ).toSize()
+
+                    translate(offset.x, offset.y) {
+                        with(feature.painter) {
+                            draw(backgroundSize)
+                        }
+                    }
+                }
+                is SchemeFeatureSelector -> drawFeature(scale, feature.selector(scale))
+                is SchemeCircleFeature -> drawCircle(
+                    feature.color,
+                    feature.size,
+                    center = feature.center.toOffset()
+                )
+                is SchemeLineFeature -> drawLine(feature.color, feature.a.toOffset(), feature.b.toOffset())
+                is SchemeBitmapFeature -> drawImage(feature.image, feature.position.toOffset())
+                is SchemeImageFeature -> {
+                    val offset = feature.position.toOffset()
+                    val imageSize = feature.size.toSize()
+                    translate(offset.x - imageSize.width / 2, offset.y - imageSize.height / 2) {
+                        with(feature.painter) {
+                            draw(imageSize)
+                        }
+                    }
+                }
+                is SchemeTextFeature -> drawIntoCanvas { canvas ->
+                    val offset = feature.position.toOffset()
+                    canvas.nativeCanvas.drawString(
+                        feature.text,
+                        offset.x + 5,
+                        offset.y - 5,
+                        Font().apply { size = 16f },
+                        feature.color.toPaint()
+                    )
+                }
+                is SchemeDrawFeature -> {
+                    val offset = feature.position.toOffset()
+                    translate(offset.x, offset.y) {
+                        feature.drawFeature(this)
+                    }
+                }
+                is SchemeFeatureGroup -> {
+                    feature.children.values.forEach {
+                        drawFeature(scale, it)
+                    }
+                }
+            }
+        }
+
+        if (canvasSize != size.toDpSize()) {
+            canvasSize = size.toDpSize()
+            logger.debug { "Recalculate canvas. Size: $size" }
+        }
+        clipRect {
+            features.values.filterIsInstance<SchemeBackgroundFeature>().forEach { background ->
+                drawFeature(viewPoint.scale, background)
+            }
+            features.values.filter {
+                it !is SchemeBackgroundFeature && viewPoint.scale in it.scaleRange
+            }.forEach { feature ->
+                drawFeature(viewPoint.scale, feature)
+            }
+        }
+        selectRect?.let { rect ->
+            drawRect(
+                color = Color.Blue,
+                topLeft = rect.topLeft,
+                size = rect.size,
+                alpha = 0.5f,
+                style = Stroke(
+                    width = 2f,
+                    pathEffect = PathEffect.dashPathEffect(floatArrayOf(10f, 10f), 0f)
+                )
+            )
+        }
+    }
+}
+
+@Composable
+fun SchemeView(
+    initialViewPoint: SchemeViewPoint,
+    features: Map<FeatureId, SchemeFeature> = emptyMap(),
+    config: SchemeViewConfig = SchemeViewConfig(),
+    modifier: Modifier = Modifier.fillMaxSize(),
+    buildFeatures: @Composable (SchemeFeatureBuilder.() -> Unit) = {},
+) {
+    val featuresBuilder = SchemeFeatureBuilderImpl(features)
+    featuresBuilder.buildFeatures()
+    SchemeView(
+        { initialViewPoint },
+        featuresBuilder.build(),
+        config,
+        modifier
+    )
+}

settings.gradle.kts

@@ -23,6 +23,8 @@ pluginManagement {
 include(
     ":maps-kt-core",
     ":maps-kt-compose",
-    ":demo"
+    ":demo:maps",
+    ":maps-kt-scheme",
+    ":demo:scheme"
 )