Auto dark/bright follows the sun at the tablet's own location

Without a light sensor an app may read (the Redmi Pad SE has none), auto is dark while
the sun is more than 4° below the horizon (lib/theme/sun.dart), at Android's coarse
location, polled and kept across restarts. The tablet's own, not the Orin's GNSS: the
tablet has its own GNSS and cellular. Android's dark theme is the last fallback.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

android/app/src/main/AndroidManifest.xml

@@ -3,6 +3,8 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
     <!-- requestNetwork for the USB (NCM) Ethernet link to the Orin -->
     <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>
+    <!-- Where the tablet is, roughly: for the sun (auto dark/bright, lib/theme/sun.dart). -->
+    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
     <application
         android:label="Yukart"
         android:name="${applicationName}"

android/app/src/main/kotlin/dev/yukart/display/MainActivity.kt

@@ -1,15 +1,19 @@
 package dev.yukart.display
 
+import android.Manifest
 import android.content.Context
 import android.content.Intent
+import android.content.pm.PackageManager
 import android.hardware.Sensor
 import android.hardware.SensorEvent
 import android.hardware.SensorEventListener
 import android.hardware.SensorManager
+import android.location.LocationManager
 import android.net.ConnectivityManager
 import android.net.Network
 import android.net.NetworkCapabilities
 import android.net.NetworkRequest
+import android.os.Build
 import android.os.Bundle
 import android.view.WindowManager
 import io.flutter.embedding.android.FlutterActivity
@@ -29,6 +33,7 @@ import io.flutter.plugin.common.MethodChannel
  *
  * Also the light sensor, for auto dark/bright (lib/theme/light.dart): lux on `yukart/light`
  * while Dart listens, where the device lets apps read one (the Redmi Pad SE does not).
+ * And, for the sun instead, the tablet's own rough location on `yukart/location`.
  *
  * Also a development hook: `am start -n dev.yukart.display/.MainActivity --es linktest [dl:|bi:]<label>[@<host>]`
  * runs the link test (lib/linktest.dart) without touching the screen.
@@ -39,6 +44,7 @@ class MainActivity : FlutterActivity() {
     private var ethernet: Network? = null
     private var wantBinding = false
     private var pendingLinkTest: String? = null
+    private var askedLocation = false
 
     private val callback = object : ConnectivityManager.NetworkCallback() {
         override fun onAvailable(network: Network) {
@@ -90,10 +96,38 @@ class MainActivity : FlutterActivity() {
             .build()
         cm.requestNetwork(request, callback)
 
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "yukart/location").setMethodCallHandler { call, result ->
+            if (call.method == "last") result.success(lastLocation()) else result.notImplemented()
+        }
+
         EventChannel(flutterEngine.dartExecutor.binaryMessenger, "yukart/light")
             .setStreamHandler(LightStream(getSystemService(Context.SENSOR_SERVICE) as SensorManager))
     }
 
+    /**
+     * [lat, lon] of the newest location Android has (other apps' fixes included), or null.
+     * Asks for coarse location the first time; with none known, asks for one, which the
+     * next call sees.
+     */
+    private fun lastLocation(): List<Double>? {
+        if (checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
+            if (!askedLocation) {
+                askedLocation = true
+                requestPermissions(arrayOf(Manifest.permission.ACCESS_COARSE_LOCATION), 1)
+            }
+            return null
+        }
+        val lm = getSystemService(Context.LOCATION_SERVICE) as LocationManager
+        val enabled = lm.getProviders(true)
+        val best = enabled.mapNotNull { runCatching { lm.getLastKnownLocation(it) }.getOrNull() }.maxByOrNull { it.time }
+        if (best == null && Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
+            listOf("fused", LocationManager.NETWORK_PROVIDER, LocationManager.GPS_PROVIDER)
+                .firstOrNull { it in enabled }
+                ?.let { runCatching { lm.getCurrentLocation(it, null, mainExecutor) {} } }
+        }
+        return best?.let { listOf(it.latitude, it.longitude) }
+    }
+
     /** Lux from the default light sensor while listened to; an error at once without one, or when refused. */
     private class LightStream(private val sm: SensorManager) : EventChannel.StreamHandler {
         private var listener: SensorEventListener? = null