Add pixel map implementation

demo/maps/build.gradle.kts

@@ -8,10 +8,8 @@ plugins {
 val ktorVersion: String by rootProject.extra
 
 kotlin {
+    jvmToolchain(11)
     jvm {
-        compilations.all {
-            kotlinOptions.jvmTarget = "11"
-        }
         withJava()
     }
     sourceSets {

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

@@ -123,6 +123,21 @@ fun App() {
             line(pointOne, pointTwo, id = "line")
             text(pointOne, "Home", font = { size = 32f })
 
+            pixelMap(
+                space.Rectangle(
+                    Gmc(latitude = 55.58461879539754.degrees, longitude = 37.8746197303493.degrees),
+                    Gmc(latitude = 55.442792937592415.degrees, longitude = 38.132240805463844.degrees)
+                ),
+                0.005.degrees,
+                0.005.degrees
+            ) { gmc ->
+                Color(
+                    red = ((gmc.latitude + Angle.piDiv2).degrees*10 % 1f).toFloat(),
+                    green = ((gmc.longitude + Angle.pi).degrees*10 % 1f).toFloat(),
+                    blue = 0f
+                ).copy(alpha = 0.3f)
+            }
+
             centerCoordinates.filterNotNull().onEach {
                 group(id = "center") {
                     circle(center = it, id = "circle", size = 1.dp).color(Color.Blue)

maps-kt-compose/build.gradle.kts

@@ -4,14 +4,10 @@ plugins {
     `maven-publish`
 }
 
-
 kotlin {
     explicitApi = org.jetbrains.kotlin.gradle.dsl.ExplicitApiMode.Warning
-    jvm {
+    jvmToolchain(11)
-        compilations.all {
+    jvm()
-            kotlinOptions.jvmTarget = space.kscience.gradle.KScienceVersions.JVM_TARGET.toString()
-        }
-    }
     sourceSets {
         commonMain {
             dependencies {

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

@@ -26,7 +26,7 @@ public class MapViewScope internal constructor(
     public val intZoom: Int get() = floor(zoom).toInt()
 
     public val centerCoordinates: WebMercatorCoordinates
-        get() = WebMercatorProjection.toMercator(viewPoint.focus, intZoom)
+        get() = WebMercatorProjection.toMercator(viewPoint.focus, intZoom) ?: WebMercatorCoordinates(intZoom, 0f, 0f)
 
     public val tileScale: Float
         get() = 2f.pow(zoom - floor(zoom))
@@ -44,7 +44,7 @@ public class MapViewScope internal constructor(
     }
 
     override fun Gmc.toDpOffset(): DpOffset {
-        val mercator = WebMercatorProjection.toMercator(this, intZoom)
+        val mercator = WebMercatorProjection.toMercator(this, intZoom) ?: WebMercatorCoordinates(intZoom, 0f, 0f)
         return DpOffset(
             (canvasSize.width / 2 + (mercator.x.dp - centerCoordinates.x.dp) * tileScale),
             (canvasSize.height / 2 + (mercator.y.dp - centerCoordinates.y.dp) * tileScale)

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

@@ -77,8 +77,8 @@ public object WebMercatorSpace : CoordinateSpace<Gmc> {
 
     override fun Gmc.offsetTo(b: Gmc, zoom: Float): DpOffset {
         val intZoom = intZoom(zoom)
-        val mercatorA = WebMercatorProjection.toMercator(this, intZoom)
+        val mercatorA = WebMercatorProjection.toMercator(this, intZoom) ?: WebMercatorCoordinates(intZoom, 0f, 0f)
-        val mercatorB = WebMercatorProjection.toMercator(b, intZoom)
+        val mercatorB = WebMercatorProjection.toMercator(b, intZoom) ?: WebMercatorCoordinates(intZoom, 0f, 0f)
         val tileScale = tileScale(zoom)
         return DpOffset(
             (mercatorA.x - mercatorB.x).dp * tileScale,

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

@@ -1,5 +1,6 @@
 package center.sciprog.maps.compose
 
+import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.drawscope.DrawScope
 import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.unit.Dp
@@ -11,6 +12,12 @@ import center.sciprog.maps.coordinates.Gmc
 import center.sciprog.maps.coordinates.GmcCurve
 import center.sciprog.maps.features.*
 import space.kscience.kmath.geometry.Angle
+import space.kscience.kmath.nd.BufferND
+import space.kscience.kmath.nd.ShapeND
+import space.kscience.kmath.nd.Strides
+import space.kscience.kmath.nd.as2D
+import space.kscience.kmath.structures.Buffer
+import kotlin.math.ceil
 
 
 internal fun FeatureGroup<Gmc>.coordinatesOf(pair: Pair<Number, Number>) =
@@ -114,3 +121,36 @@ public fun FeatureGroup<Gmc>.text(
     id,
     TextFeature(space, coordinatesOf(position), text, fontConfig = font)
 )
+
+public fun <T> BufferND(shape: ShapeND, initializer: (IntArray) -> T): BufferND<T> {
+    val strides = Strides(shape)
+    return BufferND(strides, Buffer.boxing(strides.linearSize) { initializer(strides.index(it)) })
+}
+
+public fun FeatureGroup<Gmc>.pixelMap(
+    rectangle: Rectangle<Gmc>,
+    latitudeDelta: Angle,
+    longitudeDelta: Angle,
+    id: String? = null,
+    builder: (Gmc) -> Color?,
+): FeatureRef<Gmc, PixelMapFeature<Gmc>> {
+    val shape = ShapeND(
+        ceil(rectangle.longitudeDelta / latitudeDelta).toInt(),
+        ceil(rectangle.latitudeDelta / longitudeDelta).toInt()
+    )
+
+    return feature(
+        id,
+        PixelMapFeature(
+            space,
+            rectangle,
+            BufferND(shape) { (i, j) ->
+                val longitude = rectangle.left + longitudeDelta * i
+                val latitude = rectangle.bottom + latitudeDelta * j
+                builder(
+                    Gmc(latitude, longitude)
+                )
+            }.as2D()
+        )
+    )
+}

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

@@ -55,7 +55,7 @@ public class GeodeticMapCoordinates(
             longitude: Angle,
             elevation: Distance? = null,
         ): GeodeticMapCoordinates = GeodeticMapCoordinates(
-            latitude, longitude.normalized(Angle.zero), elevation
+            latitude.coerceIn(-Angle.piDiv2..Angle.piDiv2), longitude.normalized(Angle.zero), elevation
         )
 
         public fun ofRadians(

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

@@ -27,9 +27,11 @@ public object WebMercatorProjection {
 
     /**
      * https://en.wikipedia.org/wiki/Web_Mercator_projection#Formulas
+     *
+     * return null if gmc is outside of possible coordinate scope for WebMercator
      */
-    public fun toMercator(gmc: GeodeticMapCoordinates, zoom: Int): WebMercatorCoordinates {
+    public fun toMercator(gmc: GeodeticMapCoordinates, zoom: Int): WebMercatorCoordinates? {
-        require(abs(gmc.latitude) <= MercatorProjection.MAXIMUM_LATITUDE) { "Latitude exceeds the maximum latitude for mercator coordinates" }
+        if (abs(gmc.latitude) > MercatorProjection.MAXIMUM_LATITUDE) return null
 
         val scaleFactor = scaleFactor(zoom.toFloat())
         return WebMercatorCoordinates(

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

@@ -20,6 +20,7 @@ import androidx.compose.ui.unit.dp
 import center.sciprog.attributes.Attributes
 import center.sciprog.attributes.NameAttribute
 import space.kscience.kmath.geometry.Angle
+import space.kscience.kmath.nd.Structure2D
 
 public typealias FloatRange = ClosedFloatingPointRange<Float>
 
@@ -332,3 +333,26 @@ public data class TextFeature<T : Any>(
 
     override fun withAttributes(modify: (Attributes) -> Attributes): Feature<T> = copy(attributes = modify(attributes))
 }
+
+/**
+ * A pixel map representation on the map/scheme.
+ * [rectangle] describes the boundary of the pixel map.
+ * [pixelMap] contained indexed color of pixels. Minimal indices correspond to bottom-left corner of the rectangle.
+ * Maximal indices - top-right.
+ */
+public data class PixelMapFeature<T : Any>(
+    override val space: CoordinateSpace<T>,
+    val rectangle: Rectangle<T>,
+    val pixelMap: Structure2D<Color?>,
+    override val attributes: Attributes = Attributes.EMPTY,
+) : Feature<T> {
+
+    init {
+        require(pixelMap.shape[0] > 0) { "Empty dimensions in pixel map are not allowed" }
+        require(pixelMap.shape[1] > 0) { "Empty dimensions in pixel map are not allowed" }
+    }
+
+    override fun getBoundingBox(zoom: Float): Rectangle<T> = rectangle
+
+    override fun withAttributes(modify: Attributes.() -> Attributes): Feature<T> = copy(attributes = modify(attributes))
+}

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

@@ -12,6 +12,7 @@ import center.sciprog.attributes.plus
 import org.jetbrains.skia.Font
 import org.jetbrains.skia.Paint
 import space.kscience.kmath.geometry.degrees
+import space.kscience.kmath.misc.PerformancePitfall
 
 
 internal fun Color.toPaint(): Paint = Paint().apply {
@@ -168,6 +169,31 @@ public fun <T : Any> DrawScope.drawFeature(
             }
         }
 
+        is PixelMapFeature -> {
+            val rect = feature.rectangle.toDpRect().toRect()
+            val xStep = rect.size.width / feature.pixelMap.shape[0]
+            val yStep = rect.size.height / feature.pixelMap.shape[1]
+            val pixelSize = Size(xStep, yStep)
+            //TODO add re-clasterization for small pixel scales
+            val offset = rect.topLeft
+            translate(offset.x, offset.y) {
+                @OptIn(PerformancePitfall::class)
+                feature.pixelMap.elements().forEach { (index, color: Color?) ->
+                    val (i, j) = index
+                    if (color != null) {
+                        drawRect(
+                            color,
+                            topLeft = Offset(
+                                x = i * xStep,
+                                y = rect.height - j * yStep
+                            ),
+                            size = pixelSize
+                        )
+                    }
+                }
+            }
+        }
+
         else -> {
             //logger.error { "Unrecognized feature type: ${feature::class}" }
         }