phone: ask for call permissions on the phone from the car's Phone screen

gearslip/src/main/AndroidManifest.xml

@@ -162,6 +162,12 @@
           activity so Settings can switch off just this (AppSettings.setGearslipEnabled) and leave
           the head unit to Android Auto, without disabling the screen the switch is on.
         -->
+        <activity
+            android:name=".PermissionActivity"
+            android:exported="false"
+            android:excludeFromRecents="true"
+            android:theme="@style/Theme.Gearslip.Invisible" />
+
         <activity-alias
             android:name=".GearslipUsbAccessory"
             android:targetActivity=".GearslipActivity"

gearslip/src/main/java/app/seb3thehacker/gearslip/PermissionActivity.kt

@@ -0,0 +1,49 @@
+package app.seb3thehacker.gearslip
+
+import android.app.Activity
+import android.app.ActivityOptions
+import android.content.Context
+import android.content.Intent
+import android.os.Bundle
+import android.view.Display
+
+/**
+ * Asks for runtime permissions on the phone's own screen, for a car screen that can't show
+ * Android's dialog itself. It has no look of its own: the dialog appears, the answer is given,
+ * and it finishes.
+ */
+class PermissionActivity : Activity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        val wanted = intent.getStringArrayExtra(EXTRA_PERMISSIONS)
+            ?.filter { checkSelfPermission(it) != android.content.pm.PackageManager.PERMISSION_GRANTED }
+            .orEmpty()
+        if (wanted.isEmpty() || savedInstanceState != null) {
+            if (wanted.isEmpty()) finish()
+            return
+        }
+        requestPermissions(wanted.toTypedArray(), REQUEST)
+    }
+
+    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<out String>, grantResults: IntArray) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
+        GearslipLog.i("permissions: ${permissions.zip(grantResults.toList()).joinToString { (p, r) -> "${p.substringAfterLast('.')}=${r == 0}" }}")
+        finish()
+    }
+
+    companion object {
+        private const val EXTRA_PERMISSIONS = "permissions"
+        private const val REQUEST = 1
+
+        /** Shows the permission dialog on the phone, whichever screen [context] belongs to. */
+        fun ask(context: Context, permissions: Array<String>) {
+            val intent = Intent(context, PermissionActivity::class.java)
+                .putExtra(EXTRA_PERMISSIONS, permissions)
+                .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+            val options = ActivityOptions.makeBasic().setLaunchDisplayId(Display.DEFAULT_DISPLAY)
+            runCatching { context.startActivity(intent, options.toBundle()) }
+                .onFailure { GearslipLog.w("permissions: could not ask on the phone: ${it.message}") }
+        }
+    }
+}

gearslip/src/main/java/app/seb3thehacker/gearslip/car/PhoneDialerScreen.kt

@@ -133,7 +133,7 @@ private const val TAB_KEYPAD = 1
 @Composable
 fun PhoneDialerScreen() {
     val context = LocalContext.current
-    val hasPermissions = hasCallPermissions(context)
+    var hasPermissions by remember { mutableStateOf(hasCallPermissions(context)) }
     var tab by remember { mutableStateOf(TAB_CONTACTS) }
 
     Column(Modifier.fillMaxSize().padding(16.dp), verticalArrangement = Arrangement.spacedBy(16.dp)) {
@@ -148,7 +148,7 @@ fun PhoneDialerScreen() {
         }
 
         if (!hasPermissions) {
-            MissingPermission(context)
+            MissingPermission(context) { hasPermissions = true }
             return@Column
         }
 
@@ -159,19 +159,23 @@ fun PhoneDialerScreen() {
 }
 
 @Composable
-private fun MissingPermission(context: Context) {
+private fun MissingPermission(context: Context, onGranted: () -> Unit) {
+    // Android's dialog can't show on the car screen, so it opens on the phone; checking again
+    // every second picks the answer up without the driver having to come back in.
+    androidx.compose.runtime.LaunchedEffect(Unit) {
+        while (!hasCallPermissions(context)) kotlinx.coroutines.delay(1_000)
+        onGranted()
+    }
     Column(verticalArrangement = Arrangement.spacedBy(12.dp)) {
         Text(
-            "Gearslip needs the Phone and Contacts permissions to dial from here. Grant them " +
-                "from the app's settings.",
+            "Gearslip needs the Phone and Contacts permissions to dial from here. Allow them on " +
+                "the phone when you're parked.",
             style = MaterialTheme.typography.bodyLarge,
             color = MaterialTheme.colorScheme.onSurfaceVariant,
         )
         GsButton(tone = GsTone.Tonal, onClick = {
-            context.startActivity(
-                Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS, Uri.fromParts("package", context.packageName, null)),
-            )
-        }) { Text("Open app settings") }
+            app.seb3thehacker.gearslip.PermissionActivity.ask(context, CALL_PERMISSIONS)
+        }) { Text("Ask on the phone") }
     }
 }
 

gearslip/src/main/res/values/themes.xml

@@ -9,4 +9,12 @@
         <item name="android:windowNoTitle">true</item>
         <item name="windowActionBar">false</item>
     </style>
+
+    <!-- For PermissionActivity: only Android's own permission dialog shows, over whatever was there. -->
+    <style name="Theme.Gearslip.Invisible" parent="Theme.Gearslip">
+        <item name="android:windowIsTranslucent">true</item>
+        <item name="android:windowBackground">@android:color/transparent</item>
+        <item name="android:windowAnimationStyle">@null</item>
+        <item name="android:backgroundDimEnabled">false</item>
+    </style>
 </resources>