Add TianDiTu

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapNightOverlay.kt

@@ -1,152 +0,0 @@
-/*
- * Look4Sat. Amateur radio satellite tracker and pass predictor.
- * Copyright (C) 2019-2026 Arty Bishop and contributors.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-package com.rtbishop.look4sat.feature.map
-
-import android.graphics.Canvas
-import android.graphics.Color
-import android.graphics.Paint
-import android.graphics.RectF
-import org.osmdroid.views.MapView
-import org.osmdroid.views.overlay.Overlay
-import kotlin.math.cos
-import kotlin.math.sin
-
-/**
- * Custom osmdroid overlay that shades the night side of the globe.
- *
- * Works entirely in screen-pixel space: for each vertical strip on screen it
- * asks osmdroid for the geographic coordinate, then tests whether that point is
- * in the night half-sphere relative to the sub-solar point.  Because the
- * computation happens during draw() the result is always correct regardless
- * of zoom level or map scroll position — no polygon winding issues possible.
- *
- * A point (latRad, lonRad) is in night when the angle to the sub-solar point
- * exceeds 90°, i.e. the dot product of the two unit vectors is negative:
- *   dot = sin(lat)*sin(sunLat) + cos(lat)*cos(sunLat)*cos(lon - sunLon) < 0
- *
- * Performance: we sample one column per [stepPx] pixels (default 4) and draw
- * filled vertical rectangles.  On a 1080-wide screen this means ~270 trig
- * evaluations per row, which is imperceptible.
- */
-class MapNightOverlay : Overlay() {
-
-    /** Sub-solar latitude in degrees. */
-    var sunLatDeg: Double = 0.0
-
-    /** Sub-solar longitude in degrees. */
-    var sunLonDeg: Double = 0.0
-
-    private val nightPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
-        style = Paint.Style.FILL
-        color = Color.argb(75, 0, 0, 0)
-    }
-
-    private val rect = RectF()
-
-    override fun draw(canvas: Canvas, mapView: MapView, shadow: Boolean) {
-        if (shadow) return
-
-        val proj = mapView.projection
-        val sunLatRad = Math.toRadians(sunLatDeg)
-        val sunLonRad = Math.toRadians(sunLonDeg)
-        val sinSunLat = sin(sunLatRad)
-        val cosSunLat = cos(sunLatRad)
-
-        val w = mapView.width
-        val h = mapView.height
-        val stepPx = 4 // sample every N pixels — balance quality vs CPU
-
-        // We scan column by column. For each column we determine the longitude,
-        // then find the latitude range that is in night and shade it.
-        // Since longitude is constant along a vertical strip and the day/night
-        // boundary at a given longitude is at most two latitudes, we can do a
-        // scan-line fill efficiently.
-
-        var x = 0
-        while (x < w) {
-            // Get the geographic coordinate at the top and bottom of this column.
-            val geoTop = proj.fromPixels(x, 0) ?: run { x += stepPx; continue }
-            val geoBot = proj.fromPixels(x, h - 1) ?: run { x += stepPx; continue }
-
-            val lonRad = Math.toRadians(geoTop.longitude)
-            val cosLonDiff = cos(lonRad - sunLonRad)
-
-            // Top pixel geographic lat
-            val latTopRad = Math.toRadians(geoTop.latitude)
-            // Bottom pixel geographic lat (osmdroid: y=0 is top of screen, higher y = lower lat)
-            val latBotRad = Math.toRadians(geoBot.latitude)
-
-            // dot(sunVec, pointVec) < 0 → night
-            // dot = sin(lat)*sinSunLat + cos(lat)*cosSunLat*cosLonDiff
-            val dotTop = sin(latTopRad) * sinSunLat + cos(latTopRad) * cosSunLat * cosLonDiff
-            val dotBot = sin(latBotRad) * sinSunLat + cos(latBotRad) * cosSunLat * cosLonDiff
-
-            when {
-                dotTop < 0 && dotBot < 0 -> {
-                    // Entire column is night — shade from top to bottom
-                    rect.set(x.toFloat(), 0f, (x + stepPx).toFloat(), h.toFloat())
-                    canvas.drawRect(rect, nightPaint)
-                }
-
-                dotTop >= 0 && dotBot >= 0 -> {
-                    // Entire column is day — nothing to draw
-                }
-
-                else -> {
-                    // Terminator crosses this column — find the crossing pixel by binary search
-                    val crossY = findCrossingY(proj, x, 0, h - 1, sinSunLat, cosSunLat, cosLonDiff)
-                    if (dotTop < 0) {
-                        // Night at top, day at bottom
-                        rect.set(x.toFloat(), 0f, (x + stepPx).toFloat(), crossY.toFloat())
-                        canvas.drawRect(rect, nightPaint)
-                    } else {
-                        // Day at top, night at bottom
-                        rect.set(x.toFloat(), crossY.toFloat(), (x + stepPx).toFloat(), h.toFloat())
-                        canvas.drawRect(rect, nightPaint)
-                    }
-                }
-            }
-            x += stepPx
-        }
-    }
-
-    /**
-     * Binary-search for the pixel row where the day/night boundary crosses column [x].
-     * [yTop] is in day, [yBot] is in night (or vice versa).
-     */
-    private fun findCrossingY(
-        proj: org.osmdroid.views.Projection,
-        x: Int,
-        yTop: Int,
-        yBot: Int,
-        sinSunLat: Double,
-        cosSunLat: Double,
-        cosLonDiff: Double
-    ): Int {
-        var lo = yTop
-        var hi = yBot
-        while (hi - lo > 1) {
-            val mid = (lo + hi) / 2
-            val geo = proj.fromPixels(x, mid) ?: return mid
-            val latRad = Math.toRadians(geo.latitude)
-            val dot = sin(latRad) * sinSunLat + cos(latRad) * cosSunLat * cosLonDiff
-            if (dot < 0) hi = mid else lo = mid
-        }
-        return (lo + hi) / 2
-    }
-}

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapScreen.kt

@@ -60,6 +60,7 @@ import androidx.lifecycle.LifecycleEventObserver
 import androidx.lifecycle.compose.LocalLifecycleOwner
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
+import com.rtbishop.look4sat.core.domain.model.MapSource
 import com.rtbishop.look4sat.core.domain.predict.GeoPos
 import com.rtbishop.look4sat.core.domain.predict.OrbitalObject
 import com.rtbishop.look4sat.core.domain.predict.OrbitalPos
@@ -71,37 +72,56 @@ import com.rtbishop.look4sat.core.presentation.TimerRow
 import com.rtbishop.look4sat.core.presentation.TopBar
 import com.rtbishop.look4sat.core.presentation.isVerticalLayout
 import com.rtbishop.look4sat.core.presentation.layoutPadding
+import org.osmdroid.config.Configuration
+import org.osmdroid.tileprovider.MapTileProviderBasic
+import org.osmdroid.tileprovider.tilesource.OnlineTileSourceBase
+import org.osmdroid.tileprovider.tilesource.TileSourceFactory
 import org.osmdroid.tileprovider.tilesource.XYTileSource
 import org.osmdroid.util.GeoPoint
+import org.osmdroid.util.MapTileIndex
 import org.osmdroid.views.CustomZoomButtonsController
 import org.osmdroid.views.MapView
 import org.osmdroid.views.overlay.FolderOverlay
 import org.osmdroid.views.overlay.Marker
 import org.osmdroid.views.overlay.Polyline
+import org.osmdroid.views.overlay.TilesOverlay
+import java.io.File
+import java.net.URLEncoder
 
 // Overlay indices
-private const val OVERLAY_STATION = 0
-private const val OVERLAY_TRACK = 1
-private const val OVERLAY_FOOTPRINT = 2
-private const val OVERLAY_POSITIONS = 3
-private const val OVERLAY_TERMINATOR = 4
+private const val OVERLAY_TDT_LABELS = 0
+private const val OVERLAY_STATION = 1
+private const val OVERLAY_TRACK = 2
+private const val OVERLAY_FOOTPRINT = 3
+private const val OVERLAY_POSITIONS = 4
 private const val OVERLAY_SUN = 5
 private const val OVERLAY_MOON = 6
 private const val OVERLAY_COUNT = 7
 
 private val minLat = MapView.getTileSystem().minLatitude
 private val maxLat = MapView.getTileSystem().maxLatitude
+private val offlineTileSource = XYTileSource("tiles", 0, 6, 256, ".webp", emptyArray<String>())
+private const val OFFLINE_MAX_ZOOM = 7.0
+private const val OSM_MAX_ZOOM = 19.0
+private const val TIANDITU_MAX_ZOOM = 18.0
+private const val TILE_CACHE_MAX_BYTES = 1024L * 1024L * 1024L
+private const val TILE_CACHE_TRIM_BYTES = 900L * 1024L * 1024L
+private const val TILE_REFRESH_DELAY_MS = 250L
+private const val TILE_SOURCE_OSM = "osm"
+private const val TILE_USER_AGENT = "Look4Sat-CNMap"
 private val trackPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
-    strokeWidth = 3f
+    strokeWidth = 4f
     style = Paint.Style.STROKE
-    color = Color.RED
+    color = "#1565C0".toColorInt()
     strokeCap = Paint.Cap.ROUND
     strokeJoin = Paint.Join.ROUND
 }
-private val footprintPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
-    strokeWidth = 3f
-    style = Paint.Style.FILL_AND_STROKE
-    color = "#FFE082".toColorInt()
+private val footprintOutlinePaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+    strokeWidth = 4f
+    style = Paint.Style.STROKE
+    color = "#00897B".toColorInt()
+    strokeCap = Paint.Cap.ROUND
+    strokeJoin = Paint.Join.ROUND
 }
 private val textPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
     textSize = 36f
@@ -134,11 +154,17 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
     val rotateMod = Modifier.rotate(180f)
     val timeString = uiState.mapData?.aosTime ?: "00:00:00"
     val isTimeAos = uiState.mapData?.isTimeAos ?: true
+    val usesTianditu = tiandituLayers(uiState.mapSource) != null && uiState.tiandituKey.isNotBlank()
+    val copyrightResId = if (usesTianditu) R.string.map_copyright_tianditu
+    else R.string.map_copyright_osm
 
     LaunchedEffect(uiState.track) {
         val firstPos = uiState.track?.firstOrNull()?.firstOrNull() ?: return@LaunchedEffect
         mapView.controller.animateTo(GeoPoint(firstPos.latitude, firstPos.longitude))
     }
+    LaunchedEffect(uiState.mapSource, uiState.tiandituKey) {
+        configureTileSources(mapView, uiState.mapSource, uiState.tiandituKey)
+    }
     Column(modifier = Modifier.layoutPadding(), verticalArrangement = Arrangement.spacedBy(6.dp)) {
         val isVertical = isVerticalLayout()
         if (isVertical) {
@@ -163,13 +189,12 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
                     uiState.track?.let { setSatelliteTrack(it, view) }
                     uiState.footprint?.let { setFootprint(it, view) }
                     uiState.positions?.let { setPositions(it, view) { item -> onAction(MapAction.SelectItem(item)) } }
-                    setTerminator(uiState.sunLatDeg, uiState.sunLonDeg, view)
                     setSubSolarPoint(uiState.sunLatDeg, uiState.sunLonDeg, view)
                     setMoonPosition(uiState.moonLatDeg, uiState.moonLonDeg, view)
                     view.invalidate()
                 }
                 uiState.mapData?.let { mapData ->
-                    if (isVertical) MapDataCard(mapData) else MapDataCards(mapData)
+                    if (isVertical) MapDataCard(mapData, copyrightResId) else MapDataCards(mapData, copyrightResId)
                 }
             }
         }
@@ -178,11 +203,11 @@ private fun MapScreen(uiState: MapState, onAction: (MapAction) -> Unit, mapView:
 
 // region Map data composables
 @Composable
-private fun MapDataCard(data: MapData) {
+private fun MapDataCard(data: MapData, copyrightResId: Int) {
     val textColor = MaterialTheme.colorScheme.primary
     val cardColors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.surfaceContainerLowest)
     Column(horizontalAlignment = Alignment.CenterHorizontally) {
-        Text(text = stringResource(R.string.map_copyright), fontSize = 14.sp)
+        Text(text = stringResource(copyrightResId), fontSize = 14.sp)
         Card(colors = cardColors) {
             Column(modifier = Modifier.padding(horizontal = 8.dp, vertical = 4.dp)) {
                 MapDataRow(
@@ -220,7 +245,7 @@ private fun MapDataRow(
 }
 
 @Composable
-private fun MapDataCards(data: MapData) {
+private fun MapDataCards(data: MapData, copyrightResId: Int) {
     val cardColors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.surfaceContainerLowest)
     val paddingMod = Modifier
         .padding(horizontal = 8.dp, vertical = 4.dp)
@@ -246,7 +271,7 @@ private fun MapDataCards(data: MapData) {
             }
         }
         Text(
-            text = stringResource(R.string.map_copyright),
+            text = stringResource(copyrightResId),
             fontSize = 14.sp,
             modifier = Modifier.align(Alignment.BottomCenter)
         )
@@ -260,6 +285,114 @@ private fun MapDataCards(data: MapData) {
 }
 // endregion
 
+// region Tile sources
+private var configuredTileMapView: MapView? = null
+private var configuredTileSource: String? = null
+
+private fun configureTileSources(mapView: MapView, mapSource: String, tiandituKey: String) {
+    val key = tiandituKey.trim()
+    val layers = tiandituLayers(mapSource)
+    val tileSourceKey = if (layers == null || key.isBlank()) {
+        TILE_SOURCE_OSM
+    } else {
+        "tianditu:${layers.base}:${layers.label}:$key"
+    }
+    if (configuredTileMapView === mapView && configuredTileSource == tileSourceKey) {
+        requestTileRefresh(mapView)
+        return
+    }
+    configuredTileMapView = mapView
+    configuredTileSource = tileSourceKey
+
+    if (layers == null || key.isBlank()) {
+        mapView.setUseDataConnection(true)
+        mapView.setTileProvider(MapTileProviderBasic(mapView.context, TileSourceFactory.MAPNIK))
+        mapView.maxZoomLevel = OSM_MAX_ZOOM
+        mapView.overlayManager.tilesOverlay.applyTileOverlayDefaults()
+        mapView.overlays[OVERLAY_TDT_LABELS] = FolderOverlay()
+        requestTileRefresh(mapView)
+        return
+    }
+    mapView.setUseDataConnection(true)
+    mapView.setTileProvider(MapTileProviderBasic(mapView.context, TiandituTileSource(layer = layers.base, key = key)))
+    mapView.maxZoomLevel = TIANDITU_MAX_ZOOM
+    mapView.overlayManager.tilesOverlay.applyTileOverlayDefaults()
+    mapView.overlays[OVERLAY_TDT_LABELS] = TilesOverlay(
+        MapTileProviderBasic(mapView.context, TiandituTileSource(layer = layers.label, key = key)),
+        mapView.context
+    ).apply {
+        applyTileOverlayDefaults()
+        setUseDataConnection(true)
+    }
+    requestTileRefresh(mapView)
+}
+
+private data class TiandituLayers(val base: String, val label: String)
+
+private fun tiandituLayers(mapSource: String): TiandituLayers? = when (MapSource.normalize(mapSource)) {
+    MapSource.TIANDITU_VECTOR -> TiandituLayers(base = "vec", label = "cva")
+    MapSource.TIANDITU_IMAGE -> TiandituLayers(base = "img", label = "cia")
+    else -> null
+}
+
+private fun TilesOverlay.applyTileOverlayDefaults() {
+    setColorFilter(null)
+    setLoadingBackgroundColor(Color.TRANSPARENT)
+    setLoadingLineColor(Color.TRANSPARENT)
+}
+
+private fun requestTileRefresh(mapView: MapView) {
+    mapView.post {
+        mapView.requestLayout()
+        mapView.invalidate()
+        mapView.postInvalidate()
+    }
+    mapView.postDelayed({
+        mapView.invalidate()
+        mapView.postInvalidate()
+    }, TILE_REFRESH_DELAY_MS)
+}
+
+private fun buildTiandituWmtsUrl(
+    baseUrl: String,
+    layer: String,
+    zoom: Int,
+    row: Int,
+    col: Int,
+    encodedKey: String
+): String = "$baseUrl?SERVICE=WMTS&REQUEST=GetTile&VERSION=1.0.0&LAYER=$layer" +
+    "&STYLE=default&TILEMATRIXSET=w&FORMAT=tiles&TILEMATRIX=$zoom&TILEROW=$row&TILECOL=$col&tk=$encodedKey"
+
+private class TiandituTileSource(
+    private val layer: String,
+    private val key: String
+) : OnlineTileSourceBase(
+    "tianditu-wmts-https-$layer",
+    1,
+    18,
+    256,
+    ".png",
+    Array(8) { index -> "https://t$index.tianditu.gov.cn/${layer}_w/wmts" },
+    "Tianditu"
+) {
+    private val encodedKey = URLEncoder.encode(key, Charsets.UTF_8.name())
+
+    override fun getTileURLString(pMapTileIndex: Long): String {
+        val zoom = MapTileIndex.getZoom(pMapTileIndex)
+        val row = MapTileIndex.getY(pMapTileIndex)
+        val col = MapTileIndex.getX(pMapTileIndex)
+        return buildTiandituWmtsUrl(
+            baseUrl = getBaseUrl(),
+            layer = layer,
+            zoom = zoom,
+            row = row,
+            col = col,
+            encodedKey = encodedKey
+        )
+    }
+}
+// endregion
+
 // region Map overlay helpers
 private fun setStationPosition(stationPos: GeoPos, mapView: MapView) {
     try {
@@ -282,6 +415,8 @@ private fun setStationPosition(stationPos: GeoPos, mapView: MapView) {
 /** Pool of reusable Marker objects keyed by satellite name, to avoid re-creation every frame */
 private val markerPool = HashMap<String, Marker>()
 private var lastMapView: MapView? = null
+private var lastSatelliteTrack: List<List<GeoPos>>? = null
+private var satelliteTrackOverlay: FolderOverlay? = null
 
 private fun setPositions(
     posMap: Map<OrbitalObject, GeoPos>,
@@ -294,8 +429,9 @@ private fun setPositions(
             lastMapView = mapView
             markerPool.clear()
             iconCache.evictAll()
-            footprintPolyline = null
-            footprintPoints = null
+            lastSatelliteTrack = null
+            satelliteTrackOverlay = null
+            footprintOverlay = null
         }
         // Reuse the existing FolderOverlay — creating a new one and replacing it
         // causes osmdroid to detach shared Marker objects, making them invisible.
@@ -357,6 +493,10 @@ private fun getCachedTextIcon(name: String, mapView: MapView): Drawable {
 }
 
 private fun setSatelliteTrack(satTrack: List<List<GeoPos>>, mapView: MapView) {
+    val cachedOverlay = satelliteTrackOverlay
+    if (lastSatelliteTrack === satTrack && cachedOverlay != null && mapView.overlays[OVERLAY_TRACK] === cachedOverlay) {
+        return
+    }
     val trackOverlay = FolderOverlay()
     try {
         satTrack.forEach { track ->
@@ -366,61 +506,76 @@ private fun setSatelliteTrack(satTrack: List<List<GeoPos>>, mapView: MapView) {
                 trackOverlay.add(this)
             }
         }
+        lastSatelliteTrack = satTrack
+        satelliteTrackOverlay = trackOverlay
         mapView.overlays[OVERLAY_TRACK] = trackOverlay
     } catch (e: Exception) {
         println(e)
     }
 }
 
-/** Reusable footprint Polyline — created once, points updated in-place each frame */
-private var footprintPolyline: Polyline? = null
-private var footprintPoints: ArrayList<GeoPoint>? = null
+/** Reusable footprint overlay - split at the date line so wrapped maps don't drop the circle. */
+private var footprintOverlay: FolderOverlay? = null
 
 private fun setFootprint(orbitalPos: OrbitalPos, mapView: MapView) {
     try {
         val rangeCircle = orbitalPos.getRangeCircle()
-        var pts = footprintPoints
-        if (pts == null || pts.size != rangeCircle.size) {
-            pts = ArrayList(rangeCircle.size)
-            for (gp in rangeCircle) pts.add(GeoPoint(gp.latitude, gp.longitude))
-            footprintPoints = pts
-        } else {
-            for (i in rangeCircle.indices) {
-                pts[i].latitude = rangeCircle[i].latitude
-                pts[i].longitude = rangeCircle[i].longitude
+        val overlay = footprintOverlay ?: FolderOverlay().also { footprintOverlay = it }
+        overlay.items.clear()
+        splitClosedPathOnDateLine(rangeCircle).forEach { segment ->
+            if (segment.size > 1) {
+                overlay.add(
+                    Polyline().apply {
+                        setPoints(segment.map { GeoPoint(it.latitude, it.longitude) })
+                        outlinePaint.set(footprintOutlinePaint)
+                    }
+                )
             }
         }
-        val polyline = footprintPolyline ?: Polyline().apply {
-            outlinePaint.set(footprintPaint)
-            footprintPolyline = this
-        }
-        polyline.setPoints(pts)
-        mapView.overlays[OVERLAY_FOOTPRINT] = polyline
+        mapView.overlays[OVERLAY_FOOTPRINT] = overlay
     } catch (e: Exception) {
         println(e)
     }
 }
 
-/**
- * Update the NightOverlay with the current sub-solar position.
- * The overlay is created once and kept in OVERLAY_TERMINATOR; only its
- * sunLatDeg/sunLonDeg fields are updated each tick so osmdroid redraws it.
- */
-private fun setTerminator(sunLatDeg: Double, sunLonDeg: Double, mapView: MapView) {
-    try {
-        val overlay = mapView.overlays[OVERLAY_TERMINATOR]
-        if (overlay is MapNightOverlay) {
-            overlay.sunLatDeg = sunLatDeg
-            overlay.sunLonDeg = sunLonDeg
-        } else {
-            mapView.overlays[OVERLAY_TERMINATOR] = MapNightOverlay().apply {
-                this.sunLatDeg = sunLatDeg
-                this.sunLonDeg = sunLonDeg
+private fun splitClosedPathOnDateLine(points: List<GeoPos>): List<List<GeoPos>> {
+    if (points.isEmpty()) return emptyList()
+    val segments = mutableListOf<List<GeoPos>>()
+    val segment = mutableListOf<GeoPos>()
+    var previous = points.first()
+    segment.add(previous)
+    (points.drop(1) + points.first()).forEach { current ->
+        when {
+            previous.longitude < -170.0 && current.longitude > 170.0 -> {
+                val edgeLatitude = getDateLineLatitude(previous, current, -180.0)
+                segment.add(GeoPos(edgeLatitude, -180.0))
+                segments.add(segment.toList())
+                segment.clear()
+                segment.add(GeoPos(edgeLatitude, 180.0))
+            }
+            previous.longitude > 170.0 && current.longitude < -170.0 -> {
+                val edgeLatitude = getDateLineLatitude(previous, current, 180.0)
+                segment.add(GeoPos(edgeLatitude, 180.0))
+                segments.add(segment.toList())
+                segment.clear()
+                segment.add(GeoPos(edgeLatitude, -180.0))
             }
         }
-    } catch (e: Exception) {
-        println(e)
+        segment.add(current)
+        previous = current
     }
+    if (segment.size > 1) segments.add(segment)
+    return segments
+}
+
+private fun getDateLineLatitude(previous: GeoPos, current: GeoPos, edgeLongitude: Double): Double {
+    val currentLongitude = when {
+        previous.longitude < -170.0 && current.longitude > 170.0 -> current.longitude - 360.0
+        previous.longitude > 170.0 && current.longitude < -170.0 -> current.longitude + 360.0
+        else -> current.longitude
+    }
+    val fraction = (edgeLongitude - previous.longitude) / (currentLongitude - previous.longitude)
+    return previous.latitude + (current.latitude - previous.latitude) * fraction
 }
 
 /** Place an ic_sun icon marker at the sub-solar point. */
@@ -482,40 +637,62 @@ private fun setMoonPosition(moonLatDeg: Double, moonLonDeg: Double, mapView: Map
 // region MapView lifecycle
 @Composable
 private fun rememberMapViewWithLifecycle(): MapView {
-    val tileSource = XYTileSource("tiles", 0, 6, 256, ".webp", emptyArray<String>())
     val context = LocalContext.current
     val isVertical = isVerticalLayout()
     val mapView = remember {
+        configureOsmdroidCache(context)
         MapView(context).apply {
             setMultiTouchControls(true)
             setUseDataConnection(false)
-            setTileSource(tileSource)
+            setTileSource(offlineTileSource)
             minZoomLevel = getMinZoom(resources.displayMetrics.heightPixels, isVertical)
-            maxZoomLevel = 7.0
+            maxZoomLevel = OFFLINE_MAX_ZOOM
             controller.setCenter(GeoPoint(48.8575, 6.3514))
             controller.setZoom(minZoomLevel + 2)
             zoomController.setVisibility(CustomZoomButtonsController.Visibility.NEVER)
             overlayManager.tilesOverlay.loadingBackgroundColor = Color.TRANSPARENT
             overlayManager.tilesOverlay.loadingLineColor = Color.TRANSPARENT
             overlayManager.tilesOverlay.setColorFilter(createColorFilter())
+            setHorizontalMapRepetitionEnabled(true)
+            setVerticalMapRepetitionEnabled(false)
             setScrollableAreaLimitLatitude(maxLat, minLat, 0)
             overlays.addAll(Array(OVERLAY_COUNT) { FolderOverlay() })
+            addOnFirstLayoutListener { _, _, _, _, _ -> requestTileRefresh(this) }
         }
     }
     val lifecycleObserver = rememberMapViewLifecycleObserver(mapView)
     val lifecycle = LocalLifecycleOwner.current.lifecycle
     DisposableEffect(lifecycle) {
         lifecycle.addObserver(lifecycleObserver)
+        if (lifecycle.currentState.isAtLeast(Lifecycle.State.STARTED)) {
+            mapView.onResume()
+            requestTileRefresh(mapView)
+        }
         onDispose { lifecycle.removeObserver(lifecycleObserver) }
     }
     return mapView
 }
 
+private fun configureOsmdroidCache(context: android.content.Context) {
+    val cacheRoot = File(context.filesDir, "osmdroid")
+    val tileCache = File(cacheRoot, "tiles")
+    Configuration.getInstance().apply {
+        setUserAgentValue(TILE_USER_AGENT)
+        setOsmdroidBasePath(cacheRoot)
+        setOsmdroidTileCache(tileCache)
+        setTileFileSystemCacheMaxBytes(TILE_CACHE_MAX_BYTES)
+        setTileFileSystemCacheTrimBytes(TILE_CACHE_TRIM_BYTES)
+    }
+}
+
 @Composable
 private fun rememberMapViewLifecycleObserver(mapView: MapView) = remember(mapView) {
     LifecycleEventObserver { _, event ->
         when (event) {
-            Lifecycle.Event.ON_RESUME -> mapView.onResume()
+            Lifecycle.Event.ON_RESUME -> {
+                mapView.onResume()
+                requestTileRefresh(mapView)
+            }
             Lifecycle.Event.ON_PAUSE -> mapView.onPause()
             else -> {}
         }

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapState.kt

@@ -26,6 +26,8 @@ data class MapState(
     val mapData: MapData? = null,
     val isLightUi: Boolean = false,
     val isUtc: Boolean = false,
+    val mapSource: String = "",
+    val tiandituKey: String = "",
     val stationPosition: GeoPos? = null,
     val orbitalPass: OrbitalPass,
     val track: List<List<GeoPos>>? = null,

feature/map/src/main/java/com/rtbishop/look4sat/feature/map/MapViewModel.kt

@@ -61,6 +61,8 @@ class MapViewModel(
         MapState(
             isLightUi = settingsRepo.otherSettings.value.stateOfLightTheme,
             isUtc = settingsRepo.otherSettings.value.stateOfUtc,
+            mapSource = settingsRepo.otherSettings.value.mapSource,
+            tiandituKey = settingsRepo.otherSettings.value.tiandituKey,
             orbitalPass = defaultPass
         )
     )
@@ -74,7 +76,13 @@ class MapViewModel(
     init {
         viewModelScope.launch {
             settingsRepo.otherSettings.collectLatest { settings ->
-                _uiState.update { it.copy(isUtc = settings.stateOfUtc) }
+                _uiState.update {
+                    it.copy(
+                        isUtc = settings.stateOfUtc,
+                        mapSource = settings.mapSource,
+                        tiandituKey = settings.tiandituKey
+                    )
+                }
             }
         }
         val (selectedCatNum, _) = satelliteRepo.selectedPass.value
@@ -269,29 +277,45 @@ class MapViewModel(
         val satTracks = mutableListOf<List<GeoPos>>()
         val currentTrack = mutableListOf<GeoPos>()
         val endDate = Date(date.time + (orbitalObject.data.orbitalPeriod * 2.4 * 60000L).toLong())
-        var oldLongitude = 0.0
+        var previousPosition: GeoPos? = null
         satelliteRepo.getTrack(orbitalObject, pos, date.time, endDate.time).forEach { satPos ->
             val currentPosition = satPos.toMapGeoPos()
-            if (oldLongitude < -170.0 && currentPosition.longitude > 170.0) {
+            val previous = previousPosition
+            if (previous != null && previous.longitude < -170.0 && currentPosition.longitude > 170.0) {
                 // adding left terminal position
-                currentTrack.add(GeoPos(currentPosition.latitude, -180.0))
+                val edgeLatitude = getDateLineLatitude(previous, currentPosition)
+                currentTrack.add(GeoPos(edgeLatitude, -180.0))
                 val finishedTrack = mutableListOf<GeoPos>().apply { addAll(currentTrack) }
                 satTracks.add(finishedTrack)
                 currentTrack.clear()
-            } else if (oldLongitude > 170.0 && currentPosition.longitude < -170.0) {
+                currentTrack.add(GeoPos(edgeLatitude, 180.0))
+            } else if (previous != null && previous.longitude > 170.0 && currentPosition.longitude < -170.0) {
                 // adding right terminal position
-                currentTrack.add(GeoPos(currentPosition.latitude, 180.0))
+                val edgeLatitude = getDateLineLatitude(previous, currentPosition)
+                currentTrack.add(GeoPos(edgeLatitude, 180.0))
                 val finishedTrack = mutableListOf<GeoPos>().apply { addAll(currentTrack) }
                 satTracks.add(finishedTrack)
                 currentTrack.clear()
+                currentTrack.add(GeoPos(edgeLatitude, -180.0))
             }
-            oldLongitude = currentPosition.longitude
+            previousPosition = currentPosition
             currentTrack.add(currentPosition)
         }
         satTracks.add(currentTrack)
         _uiState.update { it.copy(track = satTracks) }
     }
 
+    private fun getDateLineLatitude(previous: GeoPos, current: GeoPos): Double {
+        val currentLon = if (previous.longitude < 0.0 && current.longitude > 0.0) {
+            current.longitude - 360.0
+        } else {
+            current.longitude + 360.0
+        }
+        val edgeLon = if (previous.longitude < 0.0) -180.0 else 180.0
+        val fraction = (edgeLon - previous.longitude) / (currentLon - previous.longitude)
+        return previous.latitude + (current.latitude - previous.latitude) * fraction
+    }
+
     companion object {
         /** Number of parallel chunks for satellite position computation */
         private const val PARALLEL_CHUNKS = 4