WIP: MapScreen.kt changes

app/src/main/kotlin/org/db3/airmq/features/map/MapScreen.kt

@@ -2,6 +2,7 @@ package org.db3.airmq.features.map
 
 import android.graphics.Bitmap
 import android.graphics.Canvas
+import android.graphics.Point
 import android.graphics.drawable.BitmapDrawable
 import android.os.Handler
 import android.os.Looper
@@ -22,8 +23,14 @@ import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableFloatStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
@@ -63,6 +70,8 @@ import org.osmdroid.views.overlay.Marker
 import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.ModalBottomSheet
+import androidx.compose.material3.SheetState
+import androidx.compose.material3.SheetValue
 import androidx.compose.material3.rememberModalBottomSheetState
 import androidx.core.graphics.createBitmap
 import androidx.core.graphics.drawable.toDrawable
@@ -98,6 +107,29 @@ fun MapScreen(
     )
 }
 
+/**
+ * Bottom-sheet height fraction for map camera padding (0 = none, 0.5 = half screen).
+ * Uses [SheetState] so the map reacts as soon as open/close *animations* start, not only when
+ * values settle: closing uses target Hidden while still expanded; opening must not keep 0 inset
+ * while both values are still Hidden (that delayed the camera until the sheet finished opening).
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+private fun mapSheetFractionForDevicePanel(
+    devicePanelPresent: Boolean,
+    sheetState: SheetState
+): Float {
+    if (!devicePanelPresent) return 0f
+    return when {
+        sheetState.currentValue == SheetValue.Expanded &&
+            sheetState.targetValue == SheetValue.Expanded -> 0.5f
+        sheetState.targetValue == SheetValue.Hidden &&
+            sheetState.currentValue == SheetValue.Expanded -> 0f
+        sheetState.targetValue == SheetValue.Expanded &&
+            sheetState.currentValue == SheetValue.Hidden -> 0.5f
+        else -> 0.5f
+    }
+}
+
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 private fun MapScreenContent(
@@ -106,10 +138,22 @@ private fun MapScreenContent(
     showMap: Boolean
 ) {
     val context = LocalContext.current
+    val modalBottomSheetState = rememberModalBottomSheetState(skipPartiallyExpanded = true)
     val centerOnMarker = uiState.selectedMarkerId?.let { id ->
         uiState.items.find { it.id == id }
     }
-    val sheetHeightFraction = if (uiState.devicePanelState != null) 0.5f else 0f
+    // Map padding tracks sheet motion: interpolate with SheetState.progress during open/close so the
+    // camera offset stays in sync with the panel animation (not only after VM/sheet settle).
+    val mapSheetHeightFraction = mapSheetFractionForDevicePanel(
+        devicePanelPresent = uiState.devicePanelState != null,
+        sheetState = modalBottomSheetState
+    )
+
+    LaunchedEffect(uiState.devicePanelState?.id) {
+        if (uiState.devicePanelState != null) {
+            modalBottomSheetState.show()
+        }
+    }
 
     Box(modifier = Modifier.fillMaxSize()) {
         if (showMap) {
@@ -117,7 +161,7 @@ private fun MapScreenContent(
                 items = uiState.items,
                 onMarkerClick = { onEvent(Event.MarkerClicked(it)) },
                 centerOnMarker = centerOnMarker,
-                sheetHeightFraction = sheetHeightFraction,
+                sheetHeightFraction = mapSheetHeightFraction,
                 clusterEnabled = true,
                 modifier = Modifier.fillMaxSize()
             )
@@ -165,10 +209,9 @@ private fun MapScreenContent(
         }
 
         uiState.devicePanelState?.let { panelData ->
-            val sheetState = rememberModalBottomSheetState(skipPartiallyExpanded = true)
             ModalBottomSheet(
                 onDismissRequest = { onEvent(Event.DevicePanelClosed) },
-                sheetState = sheetState
+                sheetState = modalBottomSheetState
             ) {
                 MapDevicePanelContent(
                     data = panelData,
@@ -200,6 +243,22 @@ private const val MapClusterDebounceMs = 150L
 private const val MapClusterDistanceDp = 48f
 private const val MapClusterZoomPaddingPx = 64
 
+/** Extra time after [mapAnimationSpeedMs] so osmdroid ValueAnimator + layout can finish before we read Projection. */
+private const val MapCameraSettleExtraMs = 48L
+
+/**
+ * Waits until [MapView.isAnimating] is false (zoom/pan animation) or [maxWaitMs], then one more frame.
+ */
+private suspend fun MapView.awaitMapAnimationSettled(maxWaitMs: Long = 600L) {
+    val step = 16L
+    var waited = 0L
+    while (isAnimating() && waited < maxWaitMs) {
+        delay(step)
+        waited += step
+    }
+    delay(MapCameraSettleExtraMs)
+}
+
 @Composable
 private fun AirMQMap(
     items: List<MapMarker>,
@@ -216,6 +275,9 @@ private fun AirMQMap(
     val latestOnMarkerClick = rememberUpdatedState(onMarkerClick)
     val latestClusterEnabled = rememberUpdatedState(clusterEnabled)
     val latestCenterOnMarker = rememberUpdatedState(centerOnMarker)
+    val latestSheetHeightFraction = rememberUpdatedState(sheetHeightFraction)
+    /** Tracks sheet inset so we can run a one-shot recenter when the panel fully dismisses (fraction 0). */
+    var previousSheetFraction by remember { mutableFloatStateOf(0f) }
 
     val initialCameraDone = remember { AtomicBoolean(false) }
 
@@ -279,26 +341,55 @@ private fun AirMQMap(
     }
 
     val mapAnimationSpeedMs = 200L
-    LaunchedEffect(centerOnMarker, sheetHeightFraction) {
-        centerOnMarker?.let { marker ->
+    val markerZoomLevel = 15.5
+
+    // Zoom/pan starts as soon as the marker is selected (same time as the bottom sheet), not after it opens.
+    LaunchedEffect(centerOnMarker?.id) {
+        val marker = centerOnMarker ?: return@LaunchedEffect
         val markerGeo = GeoPoint(marker.latitude, marker.longitude)
-            val zoomLevel = 15.5
-            if (sheetHeightFraction > 0f) {
+        mapView.controller.animateTo(markerGeo, markerZoomLevel, mapAnimationSpeedMs)
+        coroutineScope {
+            launch {
+                var waited = 0
+                while (latestSheetHeightFraction.value <= 0f && waited < 500) {
+                    delay(16)
+                    waited += 16
+                }
+                val frac = latestSheetHeightFraction.value
+                if (frac <= 0f) return@launch
+                delay(mapAnimationSpeedMs)
+                mapView.awaitMapAnimationSettled()
                 mapView.post {
                     val height = mapView.height
-                    val width = mapView.width
-                    if (height > 0 && width > 0) {
-                        val sheetHeightPx = (height * sheetHeightFraction).toInt()
-                        val offsetCenterY = height / 2 + sheetHeightPx / 2
+                    if (height <= 0) return@post
+                    val sheetHeightPx = (height * frac).toInt()
+                    val targetY = (height - sheetHeightPx) / 2
                     val projection = mapView.projection
-                        val offsetGeo = projection.fromPixels(width / 2, offsetCenterY)
-                        mapView.controller.animateTo(offsetGeo, zoomLevel, mapAnimationSpeedMs)
+                    val p = Point()
+                    projection.toPixels(markerGeo, p)
+                    mapView.scrollBy(0, p.y - targetY)
                 }
             }
-            } else {
-                mapView.controller.animateTo(markerGeo, zoomLevel, mapAnimationSpeedMs)
         }
     }
+
+    // When the device panel dismisses, recenter on the marker for the full map (no sheet inset).
+    LaunchedEffect(sheetHeightFraction, centerOnMarker?.id) {
+        val marker = centerOnMarker
+        if (marker == null) {
+            previousSheetFraction = sheetHeightFraction
+            return@LaunchedEffect
+        }
+        val wasSheet = previousSheetFraction > 0f
+        val isSheet = sheetHeightFraction > 0f
+        if (wasSheet && !isSheet) {
+            mapView.controller.animateTo(
+                GeoPoint(marker.latitude, marker.longitude),
+                markerZoomLevel,
+                mapAnimationSpeedMs
+            )
+        }
+        previousSheetFraction = sheetHeightFraction
     }
 
     // Overlay rebuild must be keyed off composable inputs: AndroidView's `update` runs without