й

# Conflicts:
#	maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/MapFeature.kt
#	maps-kt-compose/src/jvmMain/kotlin/center/sciprog/maps/compose/MapTextFeature.kt

.gitignore

@@ -1,6 +1,6 @@
 build/
 .gradle/
 .idea/
-*.iml
+/*.iml
 
 mapCache/

.space.kts

@@ -0,0 +1,45 @@
+import kotlin.io.path.readText
+
+job("Build") {
+    gradlew("openjdk:11", "build")
+}
+
+job("Publish") {
+    startOn {
+        gitPush { enabled = false }
+    }
+    container("openjdk:11") {
+        env["SPACE_USER"] = Secrets("space_user")
+        env["SPACE_TOKEN"] = Secrets("space_token")
+        kotlinScript { api ->
+
+            val spaceUser = System.getenv("SPACE_USER")
+            val spaceToken = System.getenv("SPACE_TOKEN")
+
+            // write version to the build directory
+            api.gradlew("version")
+
+            //read version from build file
+            val version = java.nio.file.Path.of("build/project-version.txt").readText()
+
+            val revisionSuffix = if (version.endsWith("SNAPSHOT")) {
+                "-" + api.gitRevision().take(7)
+            } else {
+                ""
+            }
+
+            api.space().projects.automation.deployments.start(
+                project = api.projectIdentifier(),
+                targetIdentifier = TargetIdentifier.Key("maps-kt"),
+                version = version+revisionSuffix,
+                // automatically update deployment status based on a status of a job
+                syncWithAutomationJob = true
+            )
+            api.gradlew(
+                "publishAllPublicationsToSpaceRepository",
+                "-Ppublishing.space.user=\"$spaceUser\"",
+                "-Ppublishing.space.token=\"$spaceToken\"",
+            )
+        }
+    }
+}

LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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+   See the License for the specific language governing permissions and
+   limitations under the License.

README.md

@@ -0,0 +1,13 @@
+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

build.gradle.kts

@@ -1,58 +1,90 @@
-import org.jetbrains.compose.compose
-import org.jetbrains.compose.desktop.application.dsl.TargetFormat
-
 plugins {
-    kotlin("multiplatform")
-    id("org.jetbrains.compose")
-    `maven-publish`
-}
-
-group = "center.sciptog"
-version = "1.0-SNAPSHOT"
-
-repositories {
-    google()
-    mavenCentral()
-    maven("https://maven.pkg.jetbrains.space/public/p/compose/dev")
+    base
 }
 
 val ktorVersion by extra("2.0.3")
 
-kotlin {
-    jvm {
-        compilations.all {
-            kotlinOptions.jvmTarget = "11"
-        }
-        withJava()
-    }
-    sourceSets {
-        commonMain{
-            dependencies{
-                api(compose.runtime)
-                api(compose.foundation)
-                api(compose.material)
-                api("io.ktor:ktor-client-core:$ktorVersion")
-                implementation("io.ktor:ktor-client-cio:$ktorVersion")
-                implementation("io.github.microutils:kotlin-logging:2.1.23")
-            }
-        }
-        val jvmMain by getting {
-            dependencies {
-                implementation(compose.desktop.currentOs)
-                implementation("ch.qos.logback:logback-classic:1.2.11")
-            }
-        }
-        val jvmTest by getting
+allprojects {
+    group = "center.sciprog"
+    version = "0.1.0-SNAPSHOT"
+}
+
+tasks.create("version") {
+    group = "publishing"
+    val versionFile = project.buildDir.resolve("project-version.txt")
+    outputs.file(versionFile)
+    doLast {
+        versionFile.createNewFile()
+        versionFile.writeText(project.version.toString())
+        println(project.version)
     }
 }
 
-compose.desktop {
-    application {
-        mainClass = "MainKt"
-        nativeDistributions {
-            targetFormats(TargetFormat.Dmg, TargetFormat.Msi, TargetFormat.Deb)
-            packageName = "maps-kt-compose"
-            packageVersion = "1.0.0"
+subprojects {
+    repositories {
+        google()
+        mavenCentral()
+        maven("https://maven.pkg.jetbrains.space/public/p/compose/dev")
+    }
+
+    plugins.withId("maven-publish") {
+
+        configure<PublishingExtension> {
+            val vcs = "https://github.com/mipt-npm/maps-kt"
+
+            // Process each publication we have in this project
+            publications {
+                withType<MavenPublication> {
+                    pom {
+                        name.set(project.name)
+                        description.set(project.description)
+                        url.set(vcs)
+
+                        licenses {
+                            license {
+                                name.set("The Apache Software License, Version 2.0")
+                                url.set("https://www.apache.org/licenses/LICENSE-2.0.txt")
+                                distribution.set("repo")
+                            }
+                        }
+
+                        developers {
+                            developer {
+                                id.set("SPC")
+                                name.set("Scientific programming centre")
+                                organization.set("MIPT")
+                                organizationUrl.set("https://sciprog.center/")
+                            }
+                        }
+
+                        scm {
+                            url.set(vcs)
+                            tag.set(project.version.toString())
+                        }
+                    }
+                }
+            }
+
+            val spaceRepo = "https://maven.pkg.jetbrains.space/mipt-npm/p/sci/maven"
+            val spaceUser: String? = project.findProperty("publishing.space.user") as? String
+            val spaceToken: String? = project.findProperty("publishing.space.token") as? String
+
+            if (spaceUser != null && spaceToken != null) {
+                project.logger.info("Adding mipt-npm Space publishing to project [${project.name}]")
+
+                repositories.maven {
+                    name = "space"
+                    url = uri(spaceRepo)
+
+                    credentials {
+                        username = spaceUser
+                        password = spaceToken
+                    }
+                }
+            }
         }
     }
 }
+
+
+

demo/maps/build.gradle.kts

@@ -0,0 +1,40 @@
+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.mapsKtCompose)
+                implementation(compose.desktop.currentOs)
+                implementation("io.ktor:ktor-client-cio:$ktorVersion")
+                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 = "maps-compose-demo"
+            packageVersion = "1.0.0"
+        }
+    }
+}

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

@@ -0,0 +1,128 @@
+// 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.unit.DpSize
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.application
+import center.sciprog.maps.compose.*
+import center.sciprog.maps.coordinates.Distance
+import center.sciprog.maps.coordinates.GeodeticMapCoordinates
+import center.sciprog.maps.coordinates.MapViewPoint
+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 =
+    "${(latitude.degrees.value).toString().take(6)}:${(longitude.degrees.value).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
+        val pointTwo = 55.929444 to 37.518434
+        val pointThree = 60.929444 to 37.518434
+
+        val dragPoint = 55.744 to 37.614
+
+        MapView(
+            mapTileProvider = mapTileProvider,
+            initialViewPoint = viewPoint,
+            config = MapViewConfig(
+                inferViewBoxFromFeatures = true,
+                onViewChange = { centerCoordinates = focus },
+            )
+        ) {
+
+            image(pointOne, Icons.Filled.Home)
+
+            rectangle(dragPoint, id = "dragMe", size = DpSize(10.dp, 10.dp)).draggable()
+
+            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) {
+                drawLine(start = Offset(-10f, -10f), end = Offset(10f, 10f), color = Color.Red)
+                drawLine(start = Offset(-10f, 10f), end = Offset(10f, -10f), color = Color.Red)
+            }
+
+            circle(pointThree, layer = -1, color = Color.Blue)
+
+            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())
+                    )
+                }
+            }
+        }
+    }
+}
+
+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 +1,67 @@
+// 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.runtime.rememberCoroutineScope
+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.*
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+
+@Composable
+@Preview
+fun App() {
+    MaterialTheme {
+        //create a view point
+        val viewPoint = remember {
+            SchemeViewPoint(
+                SchemeCoordinates(0f, 0f),
+                1f
+            )
+        }
+        val scope = rememberCoroutineScope()
+
+
+        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)
+
+            val hobbitId = circle(410.52737 to 868.7676)
+
+            scope.launch {
+                var t = 0.0
+                while (isActive) {
+                    val x = 410.52737 + t * (1132.0881 - 410.52737)
+                    val y = 868.7676 + t * (394.99127 - 868.7676)
+                    circle(x to y, color = Color.Green, id = hobbitId)
+                    delay(100)
+                    t += 0.005
+                    if (t >= 1.0) t = 0.0
+                }
+            }
+
+        }
+    }
+}
+
+fun main() = application {
+    Window(onCloseRequest = ::exitApplication) {
+        App()
+    }
+}

gradle.properties

@@ -1,4 +1,5 @@
 kotlin.code.style=official
 kotlin.version=1.6.10
+compose.version=1.1.1
 agp.version=4.2.2
-compose.version=1.1.1
+android.useAndroidX=true

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.3-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

maps-kt-compose/build.gradle.kts

@@ -0,0 +1,30 @@
+import org.jetbrains.compose.compose
+
+plugins {
+    kotlin("multiplatform")
+    id("org.jetbrains.compose")
+    `maven-publish`
+}
+
+val ktorVersion: String by rootProject.extra
+
+kotlin {
+    explicitApi = org.jetbrains.kotlin.gradle.dsl.ExplicitApiMode.Warning
+    jvm {
+        compilations.all {
+            kotlinOptions.jvmTarget = "11"
+        }
+    }
+    sourceSets {
+        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
+        val jvmTest by getting
+    }
+}

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

@@ -0,0 +1,42 @@
+package center.sciprog.maps.compose
+
+import kotlin.jvm.Synchronized
+
+
+internal class LruCache<K, V>(
+    private var capacity: Int,
+) {
+    private val cache = linkedMapOf<K, V>()
+
+    @Synchronized
+    fun put(key: K, value: V){
+        if (cache.size >= capacity) {
+            cache.remove(cache.iterator().next().key)
+        }
+        cache[key] = value
+    }
+
+    operator fun get(key: K): V? {
+        val value = cache[key]
+        if (value != null) {
+            cache.remove(key)
+            cache[key] = value
+        }
+        return value
+    }
+
+    @Synchronized
+    fun remove(key: K) {
+        cache.remove(key)
+    }
+
+    @Synchronized
+    fun getOrPut(key: K, factory: () -> V): V = get(key) ?: factory().also { put(key, it) }
+
+    @Synchronized
+    fun reset(newCapacity: Int? = null) {
+        cache.clear()
+        capacity = newCapacity ?: capacity
+    }
+
+}

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

@@ -0,0 +1,186 @@
+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.*
+import kotlin.math.floor
+
+public interface MapFeature {
+    public val zoomRange: IntRange
+    public fun getBoundingBox(zoom: Double): GmcRectangle?
+    public val layer: Int
+}
+
+public interface DraggableMapFeature : MapFeature {
+    public fun withCoordinates(newCoordinates: GeodeticMapCoordinates): MapFeature
+}
+
+public fun Iterable<MapFeature>.computeBoundingBox(zoom: Double): GmcRectangle? =
+    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,
+    override val layer: Int
+) : MapFeature {
+    override val zoomRange: IntRange get() = defaultZoomRange
+
+    override fun getBoundingBox(zoom: Double): GmcRectangle? = selector(floor(zoom).toInt()).getBoundingBox(zoom)
+}
+
+public class MapDrawFeature(
+    public val position: GeodeticMapCoordinates,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val drawFeature: DrawScope.() -> Unit,
+    override val layer: Int
+) : DraggableMapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle {
+        //TODO add box computation
+        return GmcRectangle(position, position)
+    }
+
+    override fun withCoordinates(newCoordinates: GeodeticMapCoordinates): MapFeature =
+        MapDrawFeature(newCoordinates, zoomRange, drawFeature, layer)
+}
+
+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,
+    override val layer: Int
+) : MapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle {
+        return GmcRectangle(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,
+    override val layer: Int
+) : DraggableMapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle {
+        val scale = WebMercatorProjection.scaleFactor(zoom)
+        return GmcRectangle.square(center, (size / scale).radians, (size / scale).radians)
+    }
+
+    override fun withCoordinates(newCoordinates: GeodeticMapCoordinates): MapFeature =
+        MapCircleFeature(newCoordinates, zoomRange, size, color, layer)
+}
+
+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,
+    override val layer: Int
+) : DraggableMapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle {
+        val scale = WebMercatorProjection.scaleFactor(zoom)
+        return GmcRectangle.square(center, (size.height.value / scale).radians, (size.width.value / scale).radians)
+    }
+
+    override fun withCoordinates(newCoordinates: GeodeticMapCoordinates): MapFeature =
+        MapRectangleFeature(newCoordinates, zoomRange, size, color, layer)
+}
+
+public class MapLineFeature(
+    public val a: GeodeticMapCoordinates,
+    public val b: GeodeticMapCoordinates,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val color: Color = Color.Red,
+    override val layer: Int
+) : MapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle = GmcRectangle(a, b)
+}
+
+public class MapArcFeature(
+    public val oval: GmcRectangle,
+    public val startAngle: Float,
+    public val endAngle: Float,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val color: Color = Color.Red,
+    override val layer: Int
+) : MapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle = oval
+}
+
+public class MapBitmapImageFeature(
+    public val position: GeodeticMapCoordinates,
+    public val image: ImageBitmap,
+    public val size: IntSize = IntSize(15, 15),
+    override val zoomRange: IntRange = defaultZoomRange,
+    override val layer: Int
+) : DraggableMapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle = GmcRectangle(position, position)
+
+    override fun withCoordinates(newCoordinates: GeodeticMapCoordinates): MapFeature =
+        MapBitmapImageFeature(newCoordinates, image, size, zoomRange, layer)
+}
+
+public class MapVectorImageFeature(
+    public val position: GeodeticMapCoordinates,
+    public val painter: Painter,
+    public val size: DpSize,
+    override val zoomRange: IntRange = defaultZoomRange,
+    override val layer: Int
+) : DraggableMapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle = GmcRectangle(position, position)
+
+    override fun withCoordinates(newCoordinates: GeodeticMapCoordinates): MapFeature =
+        MapVectorImageFeature(newCoordinates, painter, size, zoomRange, layer)
+}
+
+@Composable
+public fun MapVectorImageFeature(
+    position: GeodeticMapCoordinates,
+    image: ImageVector,
+    size: DpSize = DpSize(20.dp, 20.dp),
+    zoomRange: IntRange = defaultZoomRange,
+    layer: Int
+): MapVectorImageFeature = MapVectorImageFeature(position, rememberVectorPainter(image), size, zoomRange, layer)
+
+/**
+ * A group of other features
+ */
+public class MapFeatureGroup(
+    public val children: Map<FeatureId, MapFeature>,
+    override val zoomRange: IntRange = defaultZoomRange,
+    override val layer: Int
+) : MapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle? =
+        children.values.mapNotNull { it.getBoundingBox(zoom) }.wrapAll()
+}
+
+public class MapTextFeature(
+    public val position: GeodeticMapCoordinates,
+    public val text: String,
+    override val zoomRange: IntRange = defaultZoomRange,
+    public val color: Color,
+    public val fontConfig: MapTextFeatureFont.() -> Unit,
+    override val layer: Int
+) : DraggableMapFeature {
+    override fun getBoundingBox(zoom: Double): GmcRectangle = GmcRectangle(position, position)
+
+    override fun withCoordinates(newCoordinates: GeodeticMapCoordinates): MapFeature =
+        MapTextFeature(newCoordinates, text, zoomRange, color, fontConfig, layer)
+}

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

@@ -0,0 +1,204 @@
+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.GmcRectangle
+
+public typealias FeatureId = String
+
+public interface MapFeatureAttributeKey<T>
+
+
+public class MapFeatureAttributeSet(private val map: Map<MapFeatureAttributeKey<*>, *>) {
+    public operator fun <T> get(key: MapFeatureAttributeKey<*>): T? = map[key]?.let {
+        @Suppress("UNCHECKED_CAST")
+        it as T
+    }
+}
+
+public interface MapFeatureBuilder {
+    public fun addFeature(id: FeatureId?, feature: MapFeature): FeatureId
+
+    public fun <T> setAttribute(id: FeatureId, key: MapFeatureAttributeKey<T>, value: T)
+
+    public val features: MutableMap<FeatureId, MapFeature>
+
+    public fun attributes(): Map<FeatureId, MapFeatureAttributeSet>
+
+    //TODO use context receiver for that
+    public fun FeatureId.draggable(enabled: Boolean = true) {
+        setAttribute(this, DraggableAttribute, enabled)
+    }
+}
+
+internal class MapFeatureBuilderImpl(
+    override val features: SnapshotStateMap<FeatureId, MapFeature>,
+) : MapFeatureBuilder {
+
+    private val attributes = SnapshotStateMap<FeatureId, SnapshotStateMap<MapFeatureAttributeKey<out Any?>, in Any?>>()
+
+
+    private fun generateID(feature: MapFeature): FeatureId = "@feature[${feature.hashCode().toUInt()}]"
+
+    override fun addFeature(id: FeatureId?, feature: MapFeature): FeatureId {
+        val safeId = id ?: generateID(feature)
+        features[id ?: generateID(feature)] = feature
+        return safeId
+    }
+
+    override fun <T> setAttribute(id: FeatureId, key: MapFeatureAttributeKey<T>, value: T) {
+        attributes.getOrPut(id) { SnapshotStateMap() }[key] = value
+    }
+
+    override fun attributes(): Map<FeatureId, MapFeatureAttributeSet> =
+        attributes.mapValues { MapFeatureAttributeSet(it.value) }
+
+}
+
+public fun MapFeatureBuilder.circle(
+    center: GeodeticMapCoordinates,
+    zoomRange: IntRange = defaultZoomRange,
+    size: Float = 5f,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(
+    id, MapCircleFeature(center, zoomRange, size, color, layer)
+)
+
+public fun MapFeatureBuilder.circle(
+    centerCoordinates: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    size: Float = 5f,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(
+    id, MapCircleFeature(centerCoordinates.toCoordinates(), zoomRange, size, color, layer)
+)
+
+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,
+    layer: Int = 0
+): FeatureId = addFeature(
+    id, MapRectangleFeature(centerCoordinates.toCoordinates(), zoomRange, size, color, layer)
+)
+
+public fun MapFeatureBuilder.draw(
+    position: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    id: FeatureId? = null,
+    layer: Int = 0,
+    drawFeature: DrawScope.() -> Unit
+): FeatureId = addFeature(id, MapDrawFeature(position.toCoordinates(), zoomRange, drawFeature, layer))
+
+public fun MapFeatureBuilder.line(
+    aCoordinates: Pair<Double, Double>,
+    bCoordinates: Pair<Double, Double>,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(
+    id,
+    MapLineFeature(aCoordinates.toCoordinates(), bCoordinates.toCoordinates(), zoomRange, color, layer)
+)
+
+public fun MapFeatureBuilder.arc(
+    oval: GmcRectangle,
+    startAngle: Number,
+    endAngle: Number,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(
+    id,
+    MapArcFeature(oval, startAngle.toFloat(), endAngle.toFloat(), zoomRange, color, layer)
+)
+
+public fun MapFeatureBuilder.arc(
+    center: Pair<Double, Double>,
+    radius: Distance,
+    startAngle: Number,
+    endAngle: Number,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(
+    id,
+    MapArcFeature(
+        GmcRectangle.square(center.toCoordinates(), radius, radius),
+        startAngle.toFloat(),
+        endAngle.toFloat(),
+        zoomRange,
+        color,
+        layer
+    )
+)
+
+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,
+    layer: Int = 0
+): FeatureId =
+    addFeature(id, MapPointsFeature(points.map { it.toCoordinates() }, zoomRange, stroke, color, pointMode, layer))
+
+@Composable
+public fun MapFeatureBuilder.image(
+    position: Pair<Double, Double>,
+    image: ImageVector,
+    size: DpSize = DpSize(20.dp, 20.dp),
+    zoomRange: IntRange = defaultZoomRange,
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(id, MapVectorImageFeature(position.toCoordinates(), image, size, zoomRange, layer))
+
+public fun MapFeatureBuilder.group(
+    zoomRange: IntRange = defaultZoomRange,
+    id: FeatureId? = null,
+    layer: Int = 0,
+    builder: MapFeatureBuilder.() -> Unit
+): FeatureId {
+    val map = MapFeatureBuilderImpl(mutableStateMapOf()).apply(builder).features
+    val feature = MapFeatureGroup(map, zoomRange, layer)
+    return addFeature(id, feature)
+}
+
+public fun MapFeatureBuilder.text(
+    position: GeodeticMapCoordinates,
+    text: String,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    font: MapTextFeatureFont.() -> Unit = { size = 16f },
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(id, MapTextFeature(position, text, zoomRange, color, font, layer))
+
+public fun MapFeatureBuilder.text(
+    position: Pair<Double, Double>,
+    text: String,
+    zoomRange: IntRange = defaultZoomRange,
+    color: Color = Color.Red,
+    font: MapTextFeatureFont.() -> Unit = { size = 16f },
+    id: FeatureId? = null,
+    layer: Int = 0
+): FeatureId = addFeature(id, MapTextFeature(position.toCoordinates(), text, zoomRange, color, font, layer))

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

@@ -0,0 +1,5 @@
+package center.sciprog.maps.compose
+
+public expect class MapTextFeatureFont {
+    public var size: Float
+}

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 +1,155 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.*
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.input.pointer.PointerEvent
+import androidx.compose.ui.input.pointer.isPrimaryPressed
+import androidx.compose.ui.unit.DpSize
+import center.sciprog.maps.coordinates.*
+import kotlin.math.PI
+import kotlin.math.log2
+import kotlin.math.min
+
+
+public fun interface DragHandle {
+    /**
+     * @param event - qualifiers of the event used for drag
+     * @param start - is a point where drag begins, end is a point where drag ends
+     * @param end - end point of the drag
+     *
+     * @return true if default event processors should be used after this one
+     */
+    public fun handle(event: PointerEvent, start: MapViewPoint, end: MapViewPoint): Boolean
+
+    public companion object {
+        public val BYPASS: DragHandle = DragHandle { _, _, _ -> true }
+
+        /**
+         * Process only events with primary button pressed
+         */
+        public fun withPrimaryButton(
+            block: (event: PointerEvent, start: MapViewPoint, end: MapViewPoint) -> Boolean,
+        ): DragHandle = DragHandle { event, start, end ->
+            if (event.buttons.isPrimaryPressed) {
+                block(event, start, end)
+            } else {
+                false
+            }
+        }
+
+        /**
+         * Combine several handles into one
+         */
+        public fun combine(vararg handles: DragHandle): DragHandle = DragHandle { event, start, end ->
+            handles.forEach {
+                if (!it.handle(event, start, end)) return@DragHandle false
+            }
+            return@DragHandle true
+        }
+    }
+}
+
+//TODO consider replacing by modifier
+/**
+ */
+public data class MapViewConfig(
+    val zoomSpeed: Double = 1.0 / 3.0,
+    val inferViewBoxFromFeatures: Boolean = false,
+    val onClick: MapViewPoint.(PointerEvent) -> Unit = {},
+    val dragHandle: DragHandle = DragHandle.BYPASS,
+    val onViewChange: MapViewPoint.() -> Unit = {},
+    val onSelect: (GmcRectangle) -> Unit = {},
+    val zoomOnSelect: Boolean = true,
+    val resetViewPoint: Boolean = false,
+)
+
+@Composable
+public expect fun MapView(
+    mapTileProvider: MapTileProvider,
+    computeViewPoint: (canvasSize: DpSize) -> MapViewPoint,
+    features: Map<FeatureId, MapFeature>,
+    config: MapViewConfig = MapViewConfig(),
+    modifier: Modifier = Modifier.fillMaxSize(),
+)
+
+private fun prepareConfig(initialConfig: MapViewConfig, featureBuilder: MapFeatureBuilder): MapViewConfig {
+    val draggableFeatureIds: Set<FeatureId> = featureBuilder.attributes().filterValues {
+        it[DraggableAttribute] ?: false
+    }.keys
+
+    val features = featureBuilder.features
+
+    val featureDrag = DragHandle.withPrimaryButton { _, start, end ->
+        val zoom = start.zoom
+        draggableFeatureIds.forEach { id ->
+            val feature = features[id] as? DraggableMapFeature ?: return@forEach
+            //val border = WebMercatorProjection.scaleFactor(zoom)
+            val boundingBox = feature.getBoundingBox(zoom) ?: return@forEach
+            if (start.focus in boundingBox) {
+                features[id] = feature.withCoordinates(end.focus)
+                return@withPrimaryButton false
+            }
+        }
+        return@withPrimaryButton true
+    }
+    return initialConfig.copy(
+        dragHandle = DragHandle.combine(featureDrag, initialConfig.dragHandle),
+    )
+}
+
+@Composable
+public fun MapView(
+    mapTileProvider: MapTileProvider,
+    initialViewPoint: MapViewPoint,
+    config: MapViewConfig = MapViewConfig(),
+    modifier: Modifier = Modifier.fillMaxSize(),
+    buildFeatures: @Composable (MapFeatureBuilder.() -> Unit) = {},
+) {
+    val featuresBuilder = MapFeatureBuilderImpl(mutableStateMapOf())
+    featuresBuilder.buildFeatures()
+    val features = remember { featuresBuilder.features }
+
+    val newConfig = remember(features) {
+        prepareConfig(config, featuresBuilder)
+    }
+
+    MapView(
+        mapTileProvider,
+        { initialViewPoint },
+        features,
+        newConfig,
+        modifier
+    )
+}
+
+internal fun GmcRectangle.computeViewPoint(
+    mapTileProvider: MapTileProvider,
+): (canvasSize: DpSize) -> MapViewPoint = { canvasSize ->
+    val zoom = log2(
+        min(
+            canvasSize.width.value / longitudeDelta.radians.value,
+            canvasSize.height.value / latitudeDelta.radians.value
+        ) * PI / mapTileProvider.tileSize
+    )
+    MapViewPoint(center, zoom)
+}
+//
+//@Composable
+//public fun MapView(
+//    mapTileProvider: MapTileProvider,
+//    box: GmcRectangle,
+//    config: MapViewConfig = MapViewConfig(),
+//    modifier: Modifier = Modifier.fillMaxSize(),
+//    buildFeatures: @Composable (MapFeatureBuilder.() -> Unit) = {},
+//) {
+//    val builder by derivedStateOf { MapFeatureBuilderImpl().apply(buildFeatures) }
+//
+//    MapView(
+//        mapTileProvider,
+//        box.computeViewPoint(mapTileProvider),
+//        builder.features,
+//        prepareConfig(config, builder),
+//        modifier
+//    )
+//}

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

@@ -0,0 +1,3 @@
+package center.sciprog.maps.compose
+
+public object DraggableAttribute: MapFeatureAttributeKey<Boolean>

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

@@ -0,0 +1,5 @@
+package center.sciprog.maps.compose
+
+import org.jetbrains.skia.Font
+
+public actual typealias MapTextFeatureFont = Font

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

@@ -0,0 +1,371 @@
+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.runtime.snapshots.SnapshotStateMap
+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 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(
+        (focus.latitude + (deltaY / scaleFactor).radians).coerceIn(
+            -MercatorProjection.MAXIMUM_LATITUDE,
+            MercatorProjection.MAXIMUM_LATITUDE
+        ),
+        focus.longitude + (deltaX / scaleFactor).radians
+    )
+    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(
+    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 viewPointInternal: MapViewPoint? by remember {
+        mutableStateOf(null)
+    }
+
+    if (config.resetViewPoint) {
+        viewPointInternal = null
+    }
+
+    val viewPoint: MapViewPoint by derivedStateOf {
+        viewPointInternal ?: if (config.inferViewBoxFromFeatures) {
+            features.values.computeBoundingBox(1.0)?.let { box ->
+                val zoom = log2(
+                    min(
+                        canvasSize.width.value / box.longitudeDelta.radians.value,
+                        canvasSize.height.value / box.latitudeDelta.radians.value
+                    ) * PI / mapTileProvider.tileSize
+                )
+                MapViewPoint(box.center, zoom)
+            } ?: computeViewPoint(canvasSize)
+        } else {
+            computeViewPoint(canvasSize)
+        }
+    }
+
+    val zoom: Int by derivedStateOf {
+        require(viewPoint.zoom in 1.0..18.0) { "Zoom value of ${viewPoint.zoom} is not valid" }
+        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 ->
+                    val dragStart = change.position
+                    val dpPos = DpOffset(dragStart.x.toDp(), dragStart.y.toDp())
+
+                    //start selection
+                    if (event.buttons.isPrimaryPressed && event.keyboardModifiers.isShiftPressed) {
+                        selectRect = Rect(change.position, change.position)
+                    }
+
+                    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())
+
+                        //apply drag handle and check if it prohibits the drag even propagation
+                        if (
+                            !config.dragHandle.handle(
+                                event,
+                                MapViewPoint(dpStart.toGeodetic(), viewPoint.zoom),
+                                MapViewPoint(dpEnd.toGeodetic(), viewPoint.zoom)
+                            )
+                        ) {
+                            //clear selection just in case
+                            selectRect = null
+                            return@drag
+                        }
+
+                        if (event.buttons.isPrimaryPressed) {
+                            //Evaluating selection frame
+                            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)
+                                )
+                                return@drag
+                            }
+
+                            config.onClick(MapViewPoint(dpPos.toGeodetic(), viewPoint.zoom), event)
+
+                            val newViewPoint = viewPoint.move(
+                                -dragAmount.x.toDp().value / tileScale,
+                                +dragAmount.y.toDp().value / tileScale
+                            )
+                            config.onViewChange(newViewPoint)
+                            viewPointInternal = newViewPoint
+                        }
+                    }
+
+                    // evaluate selection
+                    selectRect?.let { rect ->
+                        //Use selection override if it is defined
+                        val gmcBox = GmcRectangle(
+                            rect.topLeft.toDpOffset().toGeodetic(),
+                            rect.bottomRight.toDpOffset().toGeodetic()
+                        )
+                        config.onSelect(gmcBox)
+                        if (config.zoomOnSelect) {
+                            val newViewPoint = gmcBox.computeViewPoint(mapTileProvider).invoke(canvasSize)
+
+                            config.onViewChange(newViewPoint)
+                            viewPointInternal = newViewPoint
+                        }
+                        selectRect = null
+                    }
+                }
+            }
+        }
+    }.onPointerEvent(PointerEventType.Scroll) {
+        val change = it.changes.first()
+        val (xPos, yPos) = change.position
+        //compute invariant point of translation
+        val invariant = DpOffset(xPos.toDp(), yPos.toDp()).toGeodetic()
+        val newViewPoint = viewPoint.zoom(-change.scrollDelta.y.toDouble() * config.zoomSpeed, invariant)
+        config.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)
+                    try {
+                        //start all
+                        val deferred = loadTileAsync(id)
+                        //wait asynchronously for it to finish
+                        launch {
+                            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 MapRectangleFeature -> drawRect(
+                    feature.color,
+                    topLeft = feature.center.toOffset() - Offset(
+                        feature.size.width.toPx() / 2,
+                        feature.size.height.toPx() / 2
+                    ),
+                    size = feature.size.toSize()
+                )
+
+                is MapLineFeature -> drawLine(feature.color, feature.a.toOffset(), feature.b.toOffset())
+                is MapArcFeature -> {
+                    val topLeft = feature.oval.topLeft.toOffset()
+                    val bottomRight = feature.oval.bottomRight.toOffset()
+
+                    val path = Path().apply {
+                        addArcRad(Rect(topLeft, bottomRight), feature.startAngle, feature.endAngle - feature.startAngle)
+                    }
+
+                    drawPath(path, color = feature.color, style = Stroke())
+
+                }
+
+                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(feature.fontConfig),
+                        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)
+                    }
+                }
+
+                is MapPointsFeature -> {
+                    val points = feature.points.map { it.toOffset() }
+                    drawPoints(
+                        points = points,
+                        color = feature.color,
+                        strokeWidth = feature.stroke,
+                        pointMode = feature.pointMode
+                    )
+                }
+
+                else -> {
+                    logger.error { "Unrecognized feature type: ${feature::class}" }
+                }
+            }
+        }
+
+        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 }.sortedBy { it.layer }.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

@@ -0,0 +1,97 @@
+package center.sciprog.maps.compose
+
+import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.graphics.toComposeImageBitmap
+import io.ktor.client.HttpClient
+import io.ktor.client.request.get
+import io.ktor.client.statement.readBytes
+import io.ktor.utils.io.CancellationException
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Deferred
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.async
+import kotlinx.coroutines.sync.Semaphore
+import kotlinx.coroutines.sync.withPermit
+import mu.KotlinLogging
+import org.jetbrains.skia.Image
+import java.net.URL
+import java.nio.file.Path
+import kotlin.io.path.*
+
+/**
+ * A [MapTileProvider] based on Open Street Map API. With in-memory and file cache
+ */
+public class OpenStreetMapTileProvider(
+    private val client: HttpClient,
+    private val cacheDirectory: Path,
+    parallelism: Int = 4,
+    cacheCapacity: Int = 200,
+) : MapTileProvider {
+    private val semaphore = Semaphore(parallelism)
+    private val cache = LruCache<TileId, Deferred<ImageBitmap>>(cacheCapacity)
+
+    private fun TileId.osmUrl() = URL("https://tile.openstreetmap.org/${zoom}/${i}/${j}.png")
+
+    private fun TileId.cacheFilePath() = cacheDirectory.resolve("${zoom}/${i}/${j}.png")
+
+    /**
+     * Download and cache the tile image
+     */
+    private fun CoroutineScope.downloadImageAsync(id: TileId): Deferred<ImageBitmap> = async(Dispatchers.IO) {
+
+        id.cacheFilePath()?.let { path ->
+            if (path.exists()) {
+                try {
+                    return@async Image.makeFromEncoded(path.readBytes()).toComposeImageBitmap()
+                } catch (ex: Exception) {
+                    logger.debug { "Failed to load image from $path" }
+                    path.deleteIfExists()
+                }
+            }
+        }
+
+        //semaphore works only for actual download
+        semaphore.withPermit {
+            val url = id.osmUrl()
+            val byteArray = client.get(url).readBytes()
+            logger.debug { "Finished downloading map tile with id $id from $url" }
+            id.cacheFilePath()?.let { path ->
+                logger.debug { "Caching map tile $id to $path" }
+
+                path.parent.createDirectories()
+                path.writeBytes(byteArray)
+            }
+
+            Image.makeFromEncoded(byteArray).toComposeImageBitmap()
+        }
+    }
+
+    override fun CoroutineScope.loadTileAsync(
+        tileId: TileId,
+    ): Deferred<MapTile> {
+
+        //start image download
+        val imageDeferred = cache.getOrPut(tileId) {
+            downloadImageAsync(tileId)
+        }
+
+        //collect the result asynchronously
+        return async {
+            val image: ImageBitmap = try {
+                imageDeferred.await()
+            } catch (ex: Exception) {
+                cache.remove(tileId)
+                if (ex !is CancellationException) {
+                    logger.error(ex) { "Failed to load tile image with id=$tileId" }
+                }
+                throw ex
+            }
+            MapTile(tileId, image)
+        }
+    }
+
+
+    public companion object {
+        private val logger = KotlinLogging.logger("OpenStreetMapCache")
+    }
+}

maps-kt-core/build.gradle.kts

@@ -0,0 +1,26 @@
+plugins {
+    kotlin("multiplatform")
+    `maven-publish`
+}
+
+val ktorVersion: String by rootProject.extra
+
+kotlin {
+    explicitApi = org.jetbrains.kotlin.gradle.dsl.ExplicitApiMode.Warning
+    jvm {
+        compilations.all {
+            kotlinOptions.jvmTarget = "11"
+        }
+    }
+    js(IR) {
+        browser()
+    }
+
+    sourceSets{
+        commonTest{
+            dependencies{
+                implementation(kotlin("test"))
+            }
+        }
+    }
+}

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

@@ -0,0 +1,18 @@
+package center.sciprog.maps.coordinates
+
+import kotlin.jvm.JvmInline
+
+@JvmInline
+public value class Distance(public val kilometers: Double) : Comparable<Distance> {
+    override fun compareTo(other: Distance): Int = this.kilometers.compareTo(other.kilometers)
+}
+
+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/GeoEllipsoid.kt

@@ -0,0 +1,73 @@
+package center.sciprog.maps.coordinates
+
+import kotlin.math.acos
+import kotlin.math.pow
+import kotlin.math.sqrt
+
+
+public class GeoEllipsoid(public val equatorRadius: Distance, public val polarRadius: Distance) {
+
+    /**
+     * Flattening https://en.wikipedia.org/wiki/Flattening
+     */
+    public val f: Double = (equatorRadius.kilometers - polarRadius.kilometers) / equatorRadius.kilometers
+
+    /**
+     * Inverse flattening
+     */
+    public val inverseF: Double = equatorRadius.kilometers / (equatorRadius.kilometers - polarRadius.kilometers)
+
+    public val eSquared: Double = 2 * f - f * f
+
+    public companion object {
+
+        public val WGS84: GeoEllipsoid = GeoEllipsoid(
+            equatorRadius = Distance(6378.137),
+            polarRadius = Distance(6356.752314245)
+        )
+
+        public val GRS80: GeoEllipsoid = GeoEllipsoid(
+            equatorRadius = Distance(6378.137),
+            polarRadius = Distance(6356.752314140)
+        )
+
+        public val sphere: GeoEllipsoid = GeoEllipsoid(
+            equatorRadius = Distance(6378.137),
+            polarRadius = Distance(6378.137)
+        )
+
+//        /**
+//         * https://en.wikipedia.org/wiki/Great-circle_distance
+//         */
+//        public fun greatCircleAngleBetween(r1: GMC, r2: GMC): Radians = acos(
+//            sin(r1.latitude) * sin(r2.latitude) + cos(r1.latitude) * cos(r2.latitude) * cos(r1.longitude - r2.longitude)
+//        ).radians
+    }
+}
+
+/**
+ * A radius of circle normal to the axis of the ellipsoid at given latitude
+ */
+internal fun GeoEllipsoid.reducedRadius(latitude: Angle): Distance {
+    val reducedLatitudeTan = (1 - f) * tan(latitude)
+    return equatorRadius / sqrt(1.0 + reducedLatitudeTan.pow(2))
+}
+//
+//
+///**
+// * Compute distance between two map points using giv
+// * https://en.wikipedia.org/wiki/Geographical_distance#Lambert's_formula_for_long_lines
+// */
+//public fun GeoEllipsoid.lambertDistanceBetween(r1: GMC, r2: GMC): Distance {
+//    val s = greatCircleAngleBetween(r1, r2)
+//
+//    val b1: Double = (1 - f) * tan(r1.latitude)
+//    val b2: Double = (1 - f) * tan(r2.latitude)
+//    val p = (b1 + b2) / 2
+//    val q = (b2 - b1) / 2
+//
+//    val x = (s.value - sin(s)) * sin(p).pow(2) * cos(q).pow(2) / cos(s / 2).pow(2)
+//    val y = (s.value + sin(s)) * cos(p).pow(2) * sin(q).pow(2) / sin(s / 2).pow(2)
+//
+//    return equatorRadius * (s.value - f / 2 * (x + y))
+//}

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

@@ -1,11 +1,19 @@
-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(
+    public val latitude: Angle,
+    longitude: Angle,
+) {
+    public val longitude: Radians = longitude.radians.value.rem(PI / 2).radians
+
+    init {
+        require(latitude.radians.value in (-PI / 2)..(PI / 2)) { "Latitude $latitude is not in (-PI/2)..(PI/2)" }
+    }
 
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
@@ -26,23 +34,23 @@ public class GeodeticMapCoordinates private constructor(public val latitude: Dou
     }
 
     override fun toString(): String {
-        return "GeodeticCoordinates(latitude=${latitude / PI * 180} deg, longitude=${longitude / PI * 180} deg)"
+        return "GMC(latitude=${latitude.degrees.value} deg, longitude=${longitude.degrees.value} deg)"
     }
 
 
     public companion object {
-        public fun ofRadians(latitude: Double, longitude: Double): GeodeticMapCoordinates {
-            require(latitude in (-PI/2)..(PI/2)) { "Latitude $latitude is not in (-PI/2)..(PI/2)" }
-            return GeodeticMapCoordinates(latitude, longitude.rem(PI / 2))
-        }
+        public fun ofRadians(latitude: Double, longitude: Double): GeodeticMapCoordinates =
+            GeodeticMapCoordinates(latitude.radians, longitude.radians)
 
-        public fun ofDegrees(latitude: Double, longitude: Double): GeodeticMapCoordinates {
-            require(latitude in (-90.0)..(90.0)) { "Latitude $latitude is not in -90..90" }
-            return GeodeticMapCoordinates(latitude * PI / 180, (longitude.rem(180) * PI / 180))
-        }
+        public fun ofDegrees(latitude: Double, longitude: Double): GeodeticMapCoordinates =
+            GeodeticMapCoordinates(latitude.degrees.radians, longitude.degrees.radians)
     }
 }
 
+/**
+ * Short name for GeodeticMapCoordinates
+ */
+public typealias Gmc = GeodeticMapCoordinates
 
 //public interface GeoToScreenConversion {
 //    public fun getScreenX(gmc: GeodeticMapCoordinates): Double

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

@@ -0,0 +1,350 @@
+package center.sciprog.maps.coordinates
+
+import center.sciprog.maps.coordinates.Angle.Companion.pi
+import center.sciprog.maps.coordinates.Angle.Companion.piDiv2
+import center.sciprog.maps.coordinates.Angle.Companion.zero
+import kotlin.math.*
+
+/**
+ * A directed straight (geodetic) segment on a spheroid with given start, direction, end point and distance.
+ * @param forward coordinate of a start point with forward direction
+ * @param backward coordinate of an end point with backward direction
+ */
+public class GmcCurve internal constructor(
+    public val forward: GmcPose,
+    public val backward: GmcPose,
+    public val distance: Distance,
+)
+
+public fun GmcCurve.reversed(): GmcCurve = GmcCurve(backward, forward, distance)
+
+/**
+ * Compute a curve alongside a meridian
+ */
+public fun GeoEllipsoid.meridianCurve(
+    longitude: Angle,
+    fromLatitude: Angle,
+    toLatitude: Angle,
+    step: Radians = 0.015.radians,
+): GmcCurve {
+    require(fromLatitude in (-piDiv2)..(piDiv2)) { "Latitude must be in (-90, 90) degrees range" }
+    require(toLatitude in (-piDiv2)..(piDiv2)) { "Latitude must be in (-90, 90) degrees range" }
+
+    fun smallDistance(from: Radians, to: Radians): Distance = equatorRadius *
+            (1 - eSquared) *
+            (1 - eSquared * sin(from).pow(2)).pow(-1.5) *
+            abs((from - to).value)
+
+    val up = toLatitude > fromLatitude
+
+    val integrateFrom: Radians
+    val integrateTo: Radians
+
+    if (up) {
+        integrateFrom = fromLatitude.radians
+        integrateTo = toLatitude.radians
+    } else {
+        integrateTo = fromLatitude.radians
+        integrateFrom = toLatitude.radians
+    }
+
+    var current = integrateFrom
+    var s = Distance(0.0)
+    while (current < integrateTo) {
+        val next = minOf(current + step, integrateTo)
+        s += smallDistance(current, next)
+        current = next
+    }
+
+    return GmcCurve(
+        forward = GmcPose(Gmc(fromLatitude, longitude), if (up) zero else pi),
+        backward = GmcPose(Gmc(toLatitude, longitude), if (up) pi else zero),
+        distance = s
+    )
+}
+
+/**
+ * Compute a curve alongside a parallel
+ */
+public fun GeoEllipsoid.parallelCurve(latitude: Angle, fromLongitude: Angle, toLongitude: Angle): GmcCurve {
+    require(latitude in (-piDiv2)..(piDiv2)) { "Latitude must be in (-90, 90) degrees range" }
+    val right = toLongitude > fromLongitude
+    return GmcCurve(
+        forward = GmcPose(Gmc(latitude, fromLongitude), if (right) piDiv2.radians else -piDiv2.radians),
+        backward = GmcPose(Gmc(latitude, toLongitude), if (right) -piDiv2.radians else piDiv2.radians),
+        distance = reducedRadius(latitude) * abs((fromLongitude - toLongitude).radians.value)
+    )
+}
+
+
+/**
+ * Taken from https://github.com/mgavaghan/geodesy
+ * https://github.com/mgavaghan/geodesy/blob/ab1c6969dc964ff34929911f055b27525909ef3f/src/main/java/org/gavaghan/geodesy/GeodeticCalculator.java#L58
+ *
+ * Calculate the destination and final bearing after traveling a specified
+ * distance, and a specified starting bearing, for an initial location. This
+ * is the solution to the direct geodetic problem.
+ *
+ * @param start starting location
+ * @return solution to the direct geodetic problem
+ */
+@Suppress("SpellCheckingInspection", "LocalVariableName")
+public fun GeoEllipsoid.curveInDirection(
+    start: GmcPose,
+    distance: Distance,
+    precision: Double = 1e-6,
+): GmcCurve {
+    val a: Distance = equatorRadius
+    val b: Distance = polarRadius
+    val aSquared: Double = a.kilometers.pow(2)
+    val bSquared: Double = b.kilometers.pow(2)
+    val phi1 = start.latitude
+    val alpha1 = start.bearing
+    val cosAlpha1: Double = cos(alpha1)
+    val sinAlpha1: Double = sin(alpha1)
+    val tanU1: Double = (1.0 - f) * tan(phi1)
+    val cosU1: Double = 1.0 / sqrt(1.0 + tanU1 * tanU1)
+    val sinU1 = tanU1 * cosU1
+
+    // eq. 1
+    val sigma1: Radians = atan2(tanU1, cosAlpha1).radians
+
+    // eq. 2
+    val sinAlpha: Double = cosU1 * sinAlpha1
+    val sin2Alpha = sinAlpha * sinAlpha
+    val cos2Alpha = 1 - sin2Alpha
+    val uSquared = cos2Alpha * (aSquared - bSquared) / bSquared
+
+    // eq. 3
+    val A: Double = 1 + uSquared / 16384 * (4096 + uSquared * (-768 + uSquared * (320 - 175 * uSquared)))
+
+    // eq. 4
+    val B: Double = uSquared / 1024 * (256 + uSquared * (-128 + uSquared * (74 - 47 * uSquared)))
+
+    // iterate until there is a negligible change in sigma
+    val sOverbA: Radians = (distance / b / A).radians
+    var sigma: Radians = sOverbA
+    var sinSigma: Double
+    var prevSigma: Radians = sOverbA
+    var sigmaM2: Radians
+    var cosSigmaM2: Double
+    var cos2SigmaM2: Double
+    while (!prevSigma.value.isNaN()) {
+        // eq. 5
+        sigmaM2 = sigma1 * 2.0 + sigma
+        cosSigmaM2 = cos(sigmaM2)
+        cos2SigmaM2 = cosSigmaM2 * cosSigmaM2
+        sinSigma = sin(sigma)
+//        val cosSigma: Double = cos(sigma)
+
+        // eq. 6
+        val deltaSigma = B * sinSigma *
+                (cosSigmaM2 + B / 4.0 * (cos(sigma) * (-1 + 2 * cos2SigmaM2) -
+                        B / 6.0 * cosSigmaM2 * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM2)))
+
+        // eq. 7
+        sigma = sOverbA + deltaSigma.radians
+
+        // break after converging to tolerance
+        if (abs((sigma - prevSigma).value) < precision) break
+        prevSigma = sigma
+    }
+    sigmaM2 = sigma1 * 2.0 + sigma
+    cosSigmaM2 = cos(sigmaM2)
+    cos2SigmaM2 = cosSigmaM2 * cosSigmaM2
+    val cosSigma: Double = cos(sigma)
+    sinSigma = sin(sigma)
+
+    // eq. 8
+    val phi2: Radians = atan2(
+        sinU1 * cosSigma + cosU1 * sinSigma * cosAlpha1,
+        (1.0 - f) * sqrt(
+            sin2Alpha + (sinU1 * sinSigma - cosU1 * cosSigma * cosAlpha1).pow(2)
+        )
+    ).radians
+
+    // eq. 9
+    // This fixes the pole crossing defect spotted by Matt Feemster. When a
+    // path passes a pole and essentially crosses a line of latitude twice -
+    // once in each direction - the longitude calculation got messed up.
+    //
+    // Using atan2 instead of atan fixes the defect. The change is in the
+    // next 3 lines.
+    //
+    // double tanLambda = sinSigma * sinAlpha1 / (cosU1 * cosSigma - sinU1 *
+    // sinSigma * cosAlpha1);
+    // double lambda = Math.atan(tanLambda);
+    val lambda: Double = atan2(
+        sinSigma * sinAlpha1,
+        cosU1 * cosSigma - sinU1 * sinSigma * cosAlpha1
+    )
+
+    // eq. 10
+    val C = f / 16 * cos2Alpha * (4 + f * (4 - 3 * cos2Alpha))
+
+    // eq. 11
+    val L = lambda - (1 - C) * f * sinAlpha *
+            (sigma.value + C * sinSigma * (cosSigmaM2 + C * cosSigma * (-1 + 2 * cos2SigmaM2)))
+
+    val endPoint = Gmc(phi2, L.radians)
+
+    // eq. 12
+
+    return GmcCurve(
+        start,
+        GmcPose(
+            endPoint,
+            atan2(sinAlpha, -sinU1 * sinSigma + cosU1 * cosSigma * cosAlpha1).radians
+        ),
+        distance
+    )
+}
+
+/**
+ * Taken from https://github.com/mgavaghan/geodesy
+ *
+ * Calculate the geodetic curve between two points on a specified reference
+ * ellipsoid. This is the solution to the inverse geodetic problem.
+ *
+ * @receiver reference ellipsoid to use
+ * @param start starting coordinates
+ * @param end ending coordinates
+ * @return solution to the inverse geodetic problem
+ */
+@Suppress("SpellCheckingInspection", "LocalVariableName")
+public fun GeoEllipsoid.curveBetween(start: Gmc, end: Gmc, precision: Double = 1e-6): GmcCurve {
+    //
+    // All equation numbers refer back to Vincenty's publication:
+    // See http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf
+    //
+
+    // get constants
+    val a = equatorRadius
+    val b = polarRadius
+
+    // get parameters as radians
+    val phi1 = start.latitude
+    val lambda1 = start.longitude
+    val phi2 = end.latitude
+    val lambda2 = end.longitude
+
+    // calculations
+    val a2 = a.kilometers * a.kilometers
+    val b2 = b.kilometers * b.kilometers
+    val a2b2b2 = (a2 - b2) / b2
+    val omega: Radians = lambda2 - lambda1
+    val tanphi1: Double = tan(phi1)
+    val tanU1 = (1.0 - f) * tanphi1
+    val U1: Double = atan(tanU1)
+    val sinU1: Double = sin(U1)
+    val cosU1: Double = cos(U1)
+    val tanphi2: Double = tan(phi2)
+    val tanU2 = (1.0 - f) * tanphi2
+    val U2: Double = atan(tanU2)
+    val sinU2: Double = sin(U2)
+    val cosU2: Double = cos(U2)
+    val sinU1sinU2 = sinU1 * sinU2
+    val cosU1sinU2 = cosU1 * sinU2
+    val sinU1cosU2 = sinU1 * cosU2
+    val cosU1cosU2 = cosU1 * cosU2
+
+    // eq. 13
+    var lambda = omega
+
+    // intermediates we'll need to compute 's'
+    var A = 0.0
+
+    var sigma = 0.0
+    var deltasigma = 0.0
+    var lambda0: Radians
+    var converged = false
+    for (i in 0..19) {
+        lambda0 = lambda
+        val sinlambda: Double = sin(lambda)
+        val coslambda: Double = cos(lambda)
+
+        // eq. 14
+        val sin2sigma =
+            cosU2 * sinlambda * cosU2 * sinlambda + (cosU1sinU2 - sinU1cosU2 * coslambda) * (cosU1sinU2 - sinU1cosU2 * coslambda)
+        val sinsigma: Double = sqrt(sin2sigma)
+
+        // eq. 15
+        val cossigma = sinU1sinU2 + cosU1cosU2 * coslambda
+
+        // eq. 16
+        sigma = atan2(sinsigma, cossigma)
+
+        // eq. 17 Careful! sin2sigma might be almost 0!
+        val sinalpha = if (sin2sigma == 0.0) 0.0 else cosU1cosU2 * sinlambda / sinsigma
+        val alpha: Double = asin(sinalpha)
+        val cosalpha: Double = cos(alpha)
+        val cos2alpha = cosalpha * cosalpha
+
+        // eq. 18 Careful! cos2alpha might be almost 0!
+        val cos2sigmam = if (cos2alpha == 0.0) 0.0 else cossigma - 2 * sinU1sinU2 / cos2alpha
+        val u2 = cos2alpha * a2b2b2
+        val cos2sigmam2 = cos2sigmam * cos2sigmam
+
+        // eq. 3
+        A = 1.0 + u2 / 16384 * (4096 + u2 * (-768 + u2 * (320 - 175 * u2)))
+
+        // eq. 4
+        val B = u2 / 1024 * (256 + u2 * (-128 + u2 * (74 - 47 * u2)))
+
+        // eq. 6
+        deltasigma =
+            B * sinsigma * (cos2sigmam + B / 4 * (cossigma * (-1 + 2 * cos2sigmam2) - B / 6 * cos2sigmam * (-3 + 4 * sin2sigma) * (-3 + 4 * cos2sigmam2)))
+
+        // eq. 10
+        val C = f / 16 * cos2alpha * (4 + f * (4 - 3 * cos2alpha))
+
+        // eq. 11 (modified)
+        lambda = omega + (
+                (1 - C) * f * sinalpha *
+                        (sigma + C * sinsigma * (cos2sigmam + C * cossigma * (-1 + 2 * cos2sigmam2)))
+                ).radians
+
+        // see how much improvement we got
+        val change: Double = abs((lambda - lambda0) / lambda)
+        if (i > 1 && change < precision) {
+            converged = true
+            break
+        }
+    }
+
+    // eq. 19
+    val s: Distance = b * A * (sigma - deltasigma)
+    val alpha1: Radians
+    val alpha2: Radians
+
+    // didn't converge? must be N/S
+    if (!converged) {
+        if (phi1 > phi2) {
+            alpha1 = pi.radians
+            alpha2 = 0.0.radians
+        } else if (phi1 < phi2) {
+            alpha1 = 0.0.radians
+            alpha2 = pi.radians
+        } else {
+            alpha1 = Double.NaN.radians
+            alpha2 = Double.NaN.radians
+        }
+    } else {
+        // eq. 20
+        alpha1 = atan2(
+            cosU2 * sin(lambda),
+            cosU1sinU2 - sinU1cosU2 * cos(lambda)
+        ).radians
+
+        // eq. 21
+        alpha2 = atan2(
+            cosU1 * sin(lambda),
+            -sinU1cosU2 + cosU1sinU2 * cos(lambda)
+        ).radians + pi
+    }
+    return GmcCurve(
+        GmcPose(start, alpha1),
+        GmcPose(end, alpha2),
+        s
+    )
+}

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

@@ -0,0 +1,12 @@
+package center.sciprog.maps.coordinates
+
+/**
+ * A coordinate-bearing pair
+ */
+public data class GmcPose(val coordinates: GeodeticMapCoordinates, val bearing: Angle) {
+    val latitude: Angle get() = coordinates.latitude
+    val longitude: Angle get() = coordinates.longitude
+}
+
+public fun GmcPose.reversed(): GmcPose = copy(bearing = (bearing + Angle.pi).normalized())
+

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

@@ -0,0 +1,116 @@
+package center.sciprog.maps.coordinates
+
+/**
+ * A section of the map between two parallels and two meridians. The figure represents a square in a Mercator projection.
+ * Params are two opposing "corners" of  quasi-square.
+ *
+ * Note that this is a rectangle only on a Mercator projection.
+ */
+public data class GmcRectangle(
+    public val a: GeodeticMapCoordinates,
+    public val b: GeodeticMapCoordinates,
+) {
+    public companion object {
+
+        /**
+         * A quasi-square section.
+         */
+        public fun square(
+            center: GeodeticMapCoordinates,
+            height: Angle,
+            width: Angle,
+        ): GmcRectangle {
+            val a = GeodeticMapCoordinates(
+                center.latitude - (height / 2),
+                center.longitude - (width / 2)
+            )
+            val b = GeodeticMapCoordinates(
+                center.latitude + (height / 2),
+                center.longitude + (width / 2)
+            )
+            return GmcRectangle(a, b)
+        }
+
+        /**
+         * A quasi-square section. Note that latitudinal distance could be imprecise for large distances
+         */
+        public fun square(
+            center: GeodeticMapCoordinates,
+            height: Distance,
+            width: Distance,
+            ellipsoid: GeoEllipsoid = GeoEllipsoid.WGS84,
+        ): GmcRectangle {
+            val reducedRadius = ellipsoid.reducedRadius(center.latitude)
+            return square(center, (height / ellipsoid.polarRadius).radians, (width / reducedRadius).radians)
+        }
+    }
+}
+
+public val GmcRectangle.center: GeodeticMapCoordinates
+    get() = GeodeticMapCoordinates(
+        (a.latitude + b.latitude) / 2,
+        (a.longitude + b.longitude) / 2
+    )
+
+/**
+ * Minimum longitude
+ */
+public val GmcRectangle.left: Angle get() = minOf(a.longitude, b.longitude)
+
+/**
+ * maximum longitude
+ */
+public val GmcRectangle.right: Angle get() = maxOf(a.longitude, b.longitude)
+
+/**
+ * Maximum latitude
+ */
+public val GmcRectangle.top: Angle get() = maxOf(a.latitude, b.latitude)
+
+/**
+ * Minimum latitude
+ */
+public val GmcRectangle.bottom: Angle get() = minOf(a.latitude, b.latitude)
+
+public val GmcRectangle.longitudeDelta: Angle get() = abs(a.longitude - b.longitude)
+public val GmcRectangle.latitudeDelta: Angle get() = abs(a.latitude - b.latitude)
+
+public val GmcRectangle.topLeft: GeodeticMapCoordinates get() = GeodeticMapCoordinates(top, left)
+public val GmcRectangle.bottomRight: GeodeticMapCoordinates get() = GeodeticMapCoordinates(bottom, right)
+
+//public fun GmcRectangle.enlarge(
+//    top: Distance,
+//    bottom: Distance = top,
+//    left: Distance = top,
+//    right: Distance = left,
+//): GmcRectangle {
+//
+//}
+//
+//public fun GmcRectangle.enlarge(
+//    top: Angle,
+//    bottom: Angle = top,
+//    left: Angle = top,
+//    right: Angle = left,
+//): GmcRectangle {
+//
+//}
+
+/**
+ * Check if coordinate is inside the box
+ */
+public operator fun GmcRectangle.contains(coordinate: Gmc): Boolean =
+    coordinate.latitude in (bottom..top) && coordinate.longitude in (left..right)
+
+/**
+ * Compute a minimal bounding box including all given boxes. Return null if collection is empty
+ */
+public fun Collection<GmcRectangle>.wrapAll(): GmcRectangle? {
+    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 GmcRectangle(GeodeticMapCoordinates(minLat, minLong), GeodeticMapCoordinates(maxLat, maxLong))
+}

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

@@ -1,34 +1,19 @@
-package centre.sciprog.maps
+package center.sciprog.maps.coordinates
 
 import kotlin.math.pow
-import kotlin.math.roundToInt
 
 /**
  * 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) }
 }
 
-/**
- *
- */
-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)
-}
-
-fun MapViewPoint.move(delta: GeodeticMapCoordinates): MapViewPoint {
-    val newCoordinates = GeodeticMapCoordinates.ofRadians(
+public fun MapViewPoint.move(delta: GeodeticMapCoordinates): MapViewPoint {
+    val newCoordinates = GeodeticMapCoordinates(
         (focus.latitude + delta.latitude).coerceIn(
             -MercatorProjection.MAXIMUM_LATITUDE,
             MercatorProjection.MAXIMUM_LATITUDE
@@ -38,14 +23,14 @@ 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) {
     copy(zoom = (zoom + zoomDelta).coerceIn(2.0, 18.0))
 } else {
     val difScale = (1 - 2.0.pow(-zoomDelta))
-    val newCenter = GeodeticMapCoordinates.ofRadians(
+    val newCenter = GeodeticMapCoordinates(
         focus.latitude + (invariant.latitude - focus.latitude) * difScale,
         focus.longitude + (invariant.longitude - focus.longitude) * difScale
     )

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

@@ -3,11 +3,14 @@
  * 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.*
+import center.sciprog.maps.coordinates.Angle.Companion.pi
+import kotlin.math.atan
+import kotlin.math.ln
+import kotlin.math.sinh
 
-public data class MercatorCoordinates(val x: Double, val y: Double)
+public data class MercatorCoordinates(val x: Distance, val y: Distance)
 
 /**
  * @param baseLongitude the longitude offset in radians
@@ -15,21 +18,21 @@ public data class MercatorCoordinates(val x: Double, val y: Double)
  * @param correctedRadius optional radius correction to account for ellipsoid model
  */
 public open class MercatorProjection(
-    public val baseLongitude: Double = 0.0,
-    protected val radius: Double = DEFAULT_EARTH_RADIUS,
-    private val correctedRadius: ((GeodeticMapCoordinates) -> Double)? = null,
+    public val baseLongitude: Angle = Angle.zero,
+    protected val radius: Distance = DEFAULT_EARTH_RADIUS,
+    private val correctedRadius: ((GeodeticMapCoordinates) -> Distance)? = null,
 ) {
 
     public fun toGeodetic(mc: MercatorCoordinates): GeodeticMapCoordinates {
         val res = GeodeticMapCoordinates.ofRadians(
             atan(sinh(mc.y / radius)),
-            baseLongitude + mc.x / radius,
+            baseLongitude.radians.value + (mc.x / radius),
         )
         return if (correctedRadius != null) {
             val r = correctedRadius.invoke(res)
             GeodeticMapCoordinates.ofRadians(
                 atan(sinh(mc.y / r)),
-                baseLongitude + mc.x / r,
+                baseLongitude.radians.value + mc.x / r,
             )
         } else {
             res
@@ -41,15 +44,15 @@ public open class MercatorProjection(
      */
     public fun toMercator(gmc: GeodeticMapCoordinates): MercatorCoordinates {
         require(abs(gmc.latitude) <= MAXIMUM_LATITUDE) { "Latitude exceeds the maximum latitude for mercator coordinates" }
-        val r = correctedRadius?.invoke(gmc) ?: radius
+        val r: Distance = correctedRadius?.invoke(gmc) ?: radius
         return MercatorCoordinates(
-            x = r * (gmc.longitude - baseLongitude),
-            y = r * ln(tan(PI / 4 + gmc.latitude / 2))
+            x = r * (gmc.longitude - baseLongitude).radians.value,
+            y = r * ln(tan(pi / 4 + gmc.latitude / 2))
         )
     }
 
-    public companion object : MercatorProjection(0.0, 6378137.0) {
-        public const val MAXIMUM_LATITUDE: Double = 85.05113
-        public val DEFAULT_EARTH_RADIUS: Double = radius
+    public companion object : MercatorProjection(Angle.zero, Distance(6378.137)) {
+        public val MAXIMUM_LATITUDE: Angle = 85.05113.degrees
+        public val DEFAULT_EARTH_RADIUS: Distance = radius
     }
 }

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

@@ -3,18 +3,18 @@
  * 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.*
 
 public data class WebMercatorCoordinates(val zoom: Int, val x: Double, val y: Double)
 
-public object WebMercatorProjection  {
+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())
@@ -32,8 +32,8 @@ public object WebMercatorProjection  {
         val scaleFactor = scaleFactor(zoom.toDouble())
         return WebMercatorCoordinates(
             zoom = zoom,
-            x = scaleFactor * (gmc.longitude + PI),
-            y = scaleFactor * (PI - ln(tan(PI / 4 + gmc.latitude / 2)))
+            x = scaleFactor * (gmc.longitude.radians.value + PI),
+            y = scaleFactor * (PI - ln(tan(PI / 4 + gmc.latitude.radians.value / 2)))
         )
     }
 

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

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2018-2021 KMath contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package center.sciprog.maps.coordinates
+
+import kotlin.jvm.JvmInline
+import kotlin.math.PI
+
+// Taken from KMath dev version, to be used directly in the future
+
+
+public sealed interface Angle : Comparable<Angle> {
+    public val radians: Radians
+    public val degrees: Degrees
+
+    public operator fun plus(other: Angle): Angle
+    public operator fun minus(other: Angle): Angle
+
+    public operator fun times(other: Number): Angle
+    public operator fun div(other: Number): Angle
+    public operator fun div(other: Angle): Double
+    public operator fun unaryMinus(): Angle
+
+    public companion object {
+        public val zero: Angle = 0.radians
+        public val pi: Angle = PI.radians
+        public val piTimes2: Angle = (2 * PI).radians
+        public val piDiv2: Angle = (PI / 2).radians
+    }
+}
+
+/**
+ * Type safe radians
+ */
+@JvmInline
+public value class Radians(public val value: Double) : Angle {
+    override val radians: Radians
+        get() = this
+    override val degrees: Degrees
+        get() = Degrees(value * 180 / PI)
+
+    public override fun plus(other: Angle): Radians = Radians(value + other.radians.value)
+    public override fun minus(other: Angle): Radians = Radians(value - other.radians.value)
+
+    public override fun times(other: Number): Radians = Radians(value * other.toDouble())
+    public override fun div(other: Number): Radians = Radians(value / other.toDouble())
+    override fun div(other: Angle): Double = value / other.radians.value
+    public override fun unaryMinus(): Radians = Radians(-value)
+
+    override fun compareTo(other: Angle): Int = value.compareTo(other.radians.value)
+}
+
+public fun sin(angle: Angle): Double = kotlin.math.sin(angle.radians.value)
+public fun cos(angle: Angle): Double = kotlin.math.cos(angle.radians.value)
+public fun tan(angle: Angle): Double = kotlin.math.tan(angle.radians.value)
+
+public val Number.radians: Radians get() = Radians(toDouble())
+
+/**
+ * Type safe degrees
+ */
+@JvmInline
+public value class Degrees(public val value: Double) : Angle {
+    override val radians: Radians
+        get() = Radians(value * PI / 180)
+    override val degrees: Degrees
+        get() = this
+
+    public override fun plus(other: Angle): Degrees = Degrees(value + other.degrees.value)
+    public override fun minus(other: Angle): Degrees = Degrees(value - other.degrees.value)
+
+    public override fun times(other: Number): Degrees = Degrees(value * other.toDouble())
+    public override fun div(other: Number): Degrees = Degrees(value / other.toDouble())
+    override fun div(other: Angle): Double = value / other.degrees.value
+    public override fun unaryMinus(): Degrees = Degrees(-value)
+
+    override fun compareTo(other: Angle): Int = value.compareTo(other.degrees.value)
+}
+
+public val Number.degrees: Degrees get() = Degrees(toDouble())
+
+/**
+ * Normalized angle to (0, 2PI) for radians or (0, 360) for degrees.
+ */
+public fun Angle.normalized(): Angle = when (this) {
+    is Degrees -> (value + 180.0).rem(360.0).degrees
+    is Radians -> (value + PI).rem(PI * 2).radians
+}
+
+public fun abs(angle: Angle): Angle = if (angle < Angle.zero) -angle else angle

maps-kt-core/src/commonTest/kotlin/center/sciprog/maps/coordinates/DistanceTest.kt

@@ -0,0 +1,34 @@
+package center.sciprog.maps.coordinates
+
+import kotlin.test.Ignore
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+internal class DistanceTest {
+    companion object {
+        val moscow = GMC.ofDegrees(55.76058287719673, 37.60358622841869)
+        val spb = GMC.ofDegrees(59.926686023580444, 30.36038109122013)
+    }
+
+    @Test
+    fun ellipsoidParameters() {
+        assertEquals(298.257223563, GeoEllipsoid.WGS84.inverseF, 1e-6)
+    }
+
+    @Test
+    fun curveBetween() {
+        val curve = GeoEllipsoid.WGS84.curveBetween(moscow, spb)
+        val distance = curve.distance
+
+        assertEquals(632.035426877, distance.kilometers, 0.0001)
+    }
+
+    @Test
+    fun curveInDirection() {
+        val curve = GeoEllipsoid.WGS84.curveInDirection(
+            GmcPose(moscow, (-0.6947937116552751).radians), Distance(632.035426877)
+        )
+
+        assertEquals(spb.latitude.radians.value,curve.backward.latitude.radians.value, 0.0001)
+    }
+}

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

@@ -1,4 +1,7 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+rootProject.name = "maps-kt"
+
+enableFeaturePreview("TYPESAFE_PROJECT_ACCESSORS")
+
 pluginManagement {
     repositories {
         google()
@@ -9,9 +12,19 @@ pluginManagement {
 
     plugins {
         kotlin("multiplatform").version(extra["kotlin.version"] as String)
+        kotlin("android").version(extra["kotlin.version"] as String)
+        id("com.android.application").version(extra["agp.version"] as String)
+        id("com.android.library").version(extra["agp.version"] as String)
         id("org.jetbrains.compose").version(extra["compose.version"] as String)
     }
 }
 
-rootProject.name = "maps-kt-compose"
+
+include(
+    ":maps-kt-core",
+    ":maps-kt-compose",
+    ":demo:maps",
+    ":maps-kt-scheme",
+    ":demo:scheme"
+)
 

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

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

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

@@ -1,67 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.geometry.Size
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.graphics.ImageBitmap
-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.IntSize
-import centre.sciprog.maps.GeodeticMapCoordinates
-
-//TODO replace zoom range with zoom-based representation change
-sealed class MapFeature(val zoomRange: IntRange)
-
-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)
-
-class MapCircleFeature(
-    val center: GeodeticMapCoordinates,
-    zoomRange: IntRange = defaultZoomRange,
-    val size: Float = 5f,
-    val color: Color = Color.Red,
-) : MapFeature(zoomRange)
-
-class MapLineFeature(
-    val a: GeodeticMapCoordinates,
-    val b: GeodeticMapCoordinates,
-    zoomRange: IntRange = defaultZoomRange,
-    val color: Color = Color.Red,
-) : MapFeature(zoomRange)
-
-class MapTextFeature(
-    val position: GeodeticMapCoordinates,
-    val text: String,
-    zoomRange: IntRange = defaultZoomRange,
-    val color: Color = Color.Red,
-) : MapFeature(zoomRange)
-
-class MapBitmapImageFeature(
-    val position: GeodeticMapCoordinates,
-    val image: ImageBitmap,
-    val size: IntSize = IntSize(15, 15),
-    zoomRange: IntRange = defaultZoomRange,
-) : MapFeature(zoomRange)
-
-
-class MapVectorImageFeature (
-    val position: GeodeticMapCoordinates,
-    val painter: Painter,
-    val size: Size,
-    zoomRange: IntRange = defaultZoomRange,
-) : MapFeature(zoomRange)
-
-@Composable
-fun MapVectorImageFeature(
-    position: GeodeticMapCoordinates,
-    image: ImageVector,
-    size: Size = Size(20f, 20f),
-    zoomRange: IntRange = defaultZoomRange,
-): MapVectorImageFeature = MapVectorImageFeature(position, rememberVectorPainter(image), size, zoomRange)

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

@@ -1,29 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.ui.graphics.ImageBitmap
-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 {
-    suspend fun loadTile(id: TileId): 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
-    }
-}

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

@@ -1,37 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import centre.sciprog.maps.GeodeticMapCoordinates
-import centre.sciprog.maps.MapViewPoint
-
-
-data class MapViewConfig(
-    val zoomSpeed: Double = 1.0 / 3.0,
-)
-
-@Composable
-expect fun MapView(
-    initialViewPoint: MapViewPoint,
-    mapTileProvider: MapTileProvider,
-    features: Map<FeatureId, MapFeature>,
-    onClick: (GeodeticMapCoordinates) -> Unit = {},
-    //TODO consider replacing by modifier
-    config: MapViewConfig = MapViewConfig(),
-    modifier: Modifier = Modifier.fillMaxSize(),
-)
-
-@Composable
-fun MapView(
-    initialViewPoint: MapViewPoint,
-    mapTileProvider: MapTileProvider,
-    onClick: (GeodeticMapCoordinates) -> Unit = {},
-    config: MapViewConfig = MapViewConfig(),
-    modifier: Modifier = Modifier.fillMaxSize(),
-    addFeatures: @Composable() (FeatureBuilder.() -> Unit) = {},
-) {
-    val featuresBuilder = MapFeatureBuilder()
-    featuresBuilder.addFeatures()
-    MapView(initialViewPoint, mapTileProvider, featuresBuilder.build(), onClick, config, modifier)
-}

src/jvmMain/kotlin/Main.kt

@@ -1,71 +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.foundation.layout.Column
-import androidx.compose.material.MaterialTheme
-import androidx.compose.material.Text
-import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.filled.Home
-import androidx.compose.runtime.*
-import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.window.Window
-import androidx.compose.ui.window.application
-import centre.sciprog.maps.GeodeticMapCoordinates
-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.random.Random
-
-@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(scope, HttpClient(CIO), Path.of("mapCache")) }
-
-        var coordinates by remember { mutableStateOf<GeodeticMapCoordinates?>(null) }
-
-        Column {
-            //display click coordinates
-            Text(coordinates?.toString() ?: "")
-            MapView(viewPoint, mapTileProvider, onClick = { gmc: GeodeticMapCoordinates -> coordinates = gmc }) {
-                val pointOne = 55.568548 to 37.568604
-                val pointTwo = 55.929444 to 37.518434
-
-                image(pointOne, Icons.Filled.Home)
-
-                //remember feature Id
-                val circleId: FeatureId = circle(pointTwo)
-
-                line(pointOne, pointTwo)
-                text(pointOne, "Home")
-
-                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()
-    }
-}

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

@@ -1,245 +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 mu.KotlinLogging
-import org.jetbrains.skia.Font
-import org.jetbrains.skia.Paint
-import kotlin.math.ceil
-import kotlin.math.floor
-import kotlin.math.log2
-import kotlin.math.pow
-
-
-private fun Color.toPaint(): Paint = Paint().apply {
-    isAntiAlias = true
-    color = toArgb()
-}
-
-private val logger = KotlinLogging.logger("MapView")
-
-/**
- * A component that renders map and provides basic map manipulation capabilities
- */
-@OptIn(ExperimentalComposeUiApi::class)
-@Composable
-actual fun MapView(
-    initialViewPoint: MapViewPoint,
-    mapTileProvider: MapTileProvider,
-    features: Map<FeatureId, MapFeature>,
-    onClick: (GeodeticMapCoordinates) -> Unit,
-    config: MapViewConfig,
-    modifier: Modifier,
-) {
-
-    var viewPoint by remember { mutableStateOf(initialViewPoint) }
-
-    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>() }
-
-    //var mapRectangle by remember { mutableStateOf(initialRectangle) }
-    var canvasSize by remember { mutableStateOf(DpSize(512.dp, 512.dp)) }
-
-    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) }
-
-    val canvasModifier = modifier.pointerInput(Unit) {
-        forEachGesture {
-            awaitPointerEventScope {
-                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(
-                                        kotlin.math.min(offset.x, rect.left),
-                                        kotlin.math.min(offset.y, rect.top),
-                                        kotlin.math.max(offset.x, rect.right),
-                                        kotlin.math.max(offset.y, rect.bottom)
-                                    )
-                                }
-                            }
-                            selectRect?.let { rect ->
-                                val (centerX, centerY) = rect.center
-                                val centerGmc = DpOffset(centerX.toDp(), centerY.toDp()).toGeodetic()
-
-                                val horizontalZoom: Float = log2(canvasSize.width.toPx() / rect.width)
-                                val verticalZoom: Float = log2(canvasSize.height.toPx() / rect.height)
-
-
-                                viewPoint = MapViewPoint(centerGmc, viewPoint.zoom + kotlin.math.min(verticalZoom, horizontalZoom))
-                                selectRect = null
-                            }
-                        } else {
-                            val dragStart = change.position
-                            val dpPos = DpOffset(dragStart.x.toDp(), dragStart.y.toDp())
-                            onClick(dpPos.toGeodetic())
-                            drag(change.id) { dragChange ->
-                                val dragAmount = dragChange.position - dragChange.previousPosition
-                                viewPoint = viewPoint.move(
-                                    -dragAmount.x.toDp().value / tileScale,
-                                    +dragAmount.y.toDp().value / tileScale
-                                )
-                            }
-                        }
-                    }
-                }
-            }
-        }
-    }.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()
-        viewPoint = viewPoint.zoom(-change.scrollDelta.y.toDouble() * config.zoomSpeed, invariant)
-    }.fillMaxSize()
-
-
-    // Load tiles asynchronously
-    LaunchedEffect(viewPoint, canvasSize) {
-        val left = centerCoordinates.x - canvasSize.width.value / 2 / tileScale
-        val right = centerCoordinates.x + canvasSize.width.value / 2 / tileScale
-        val horizontalIndices = mapTileProvider.toIndex(left)..mapTileProvider.toIndex(right)
-
-        val top = (centerCoordinates.y + canvasSize.height.value / 2 / tileScale)
-        val bottom = (centerCoordinates.y - canvasSize.height.value / 2 / tileScale)
-        val verticalIndices = mapTileProvider.toIndex(bottom)..mapTileProvider.toIndex(top)
-
-        mapTiles.clear()
-
-        val indexRange = 0 until 2.0.pow(zoom).toInt()
-
-        for (j in verticalIndices) {
-            for (i in horizontalIndices) {
-                if (i in indexRange && j in indexRange) {
-                    val tileId = TileId(zoom, i, j)
-                    try {
-                        val tile = mapTileProvider.loadTile(tileId)
-                        mapTiles.add(tile)
-                    } catch (ex: Exception) {
-                        logger.error(ex) { "Failed to load tile $tileId" }
-                    }
-                }
-            }
-        }
-
-    }
-
-    // d
-    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()
-                    translate(offset.x - feature.size.width / 2, offset.y - feature.size.height / 2) {
-                        with(feature.painter) {
-                            draw(feature.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()
-                    )
-                }
-
-            }
-        }
-
-        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)
-                )
-            )
-        }
-    }
-}

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

@@ -1,73 +0,0 @@
-package centre.sciprog.maps.compose
-
-import androidx.compose.ui.graphics.ImageBitmap
-import androidx.compose.ui.graphics.toComposeImageBitmap
-import io.ktor.client.HttpClient
-import io.ktor.client.request.get
-import io.ktor.client.statement.readBytes
-import kotlinx.coroutines.*
-import mu.KotlinLogging
-import org.jetbrains.skia.Image
-import java.net.URL
-import java.nio.file.Path
-import kotlin.io.path.*
-import kotlin.math.pow
-
-/**
- * A [MapTileProvider] based on Open Street Map API. With in-memory and file cache
- */
-public class OpenStreetMapTileProvider(private val scope: CoroutineScope, private val client: HttpClient, private val cacheDirectory: Path): MapTileProvider {
-    private val cache = HashMap<TileId, Deferred<ImageBitmap>>()
-
-    private fun TileId.osmUrl() = URL("https://tile.openstreetmap.org/${zoom}/${i}/${j}.png")
-
-    private fun TileId.cacheFilePath() = cacheDirectory.resolve("${zoom}/${i}/${j}.png")
-
-    /**
-     * Download and cache the tile image
-     */
-    private fun downloadImageAsync(id: TileId) = scope.async(Dispatchers.IO) {
-        id.cacheFilePath()?.let { path ->
-            if (path.exists()) {
-                try {
-                    return@async Image.makeFromEncoded(path.readBytes()).toComposeImageBitmap()
-                } catch (ex: Exception) {
-                    logger.debug { "Failed to load image from $path" }
-                    path.deleteIfExists()
-                }
-            }
-        }
-
-        val url = id.osmUrl()
-        val byteArray = client.get(url).readBytes()
-
-        logger.debug { "Finished downloading map tile with id $id from $url" }
-
-        id.cacheFilePath()?.let { path ->
-            logger.debug { "Caching map tile $id to $path" }
-
-            path.parent.createDirectories()
-            path.writeBytes(byteArray)
-        }
-
-        Image.makeFromEncoded(byteArray).toComposeImageBitmap()
-    }
-
-    override suspend fun loadTile(id: TileId): MapTile {
-        val indexRange = indexRange(id.zoom)
-        if(id.i !in indexRange || id.j !in indexRange){
-            error("Indices (${id.i}, ${id.j}) are not in index range $indexRange for zoom ${id.zoom}")
-        }
-
-        val image = cache.getOrPut(id) {
-            downloadImageAsync(id)
-        }.await()
-
-        return MapTile(id, image)
-    }
-
-    companion object{
-        private val logger = KotlinLogging.logger("OpenStreetMapCache")
-        private fun indexRange(zoom: Int): IntRange = 0 until 2.0.pow(zoom).toInt()
-    }
-}