Implement OnConnectionLost, show a dialog on the main netplay screen forcing the user to exit

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/Netplay.kt

@@ -47,6 +47,9 @@ object Netplay {
     private val _stopGame = Channel<Unit>(Channel.CONFLATED)
     val stopGame = _stopGame.receiveAsFlow()
 
+    private val _connectionLost = Channel<Unit>(Channel.CONFLATED)
+    val connectionLost = _connectionLost.receiveAsFlow()
+
     private val _connectionErrors = Channel<String>(Channel.BUFFERED)
     val connectionErrors = _connectionErrors.receiveAsFlow()
 
@@ -63,7 +66,7 @@ object Netplay {
     val players = _players.asSharedFlow().distinctUntilChanged()
 
     private val _chatMessages = MutableSharedFlow<String>(
-        replay = 1,
+        extraBufferCapacity = 32,
         onBufferOverflow = BufferOverflow.DROP_OLDEST
     )
     val chatMessages = _chatMessages.asSharedFlow()
@@ -180,6 +183,12 @@ object Netplay {
         _stopGame.trySend(Unit)
     }
 
+    @Keep
+    @JvmStatic
+    fun onConnectionLost() {
+        _connectionLost.trySend(Unit)
+    }
+
     @JvmStatic
     fun onConnectionError(message: String) {
         _connectionErrors.trySend(message)

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/model/NetplayViewModel.kt

@@ -25,6 +25,8 @@ class NetplayViewModel : ViewModel() {
     private val _goBack = Channel<Unit>(CONFLATED)
     val goBack = _goBack.receiveAsFlow()
 
+    val connectionLost = Netplay.connectionLost
+
     val players = Netplay.players
         .stateIn(viewModelScope, SharingStarted.WhileSubscribed(), emptyList())
 

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayActivity.kt

@@ -44,6 +44,7 @@ class NetplayActivity : AppCompatActivity(), ThemeProvider {
             DolphinTheme {
                 NetplayScreen(
                     onBackClicked = { finish() },
+                    connectionLost = viewModel.connectionLost,
                     messages = viewModel.messages.collectAsState().value,
                     onSendMessage = viewModel::sendMessage,
                     game = viewModel.game.collectAsState().value,

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/netplay/ui/NetplayScreen.kt

@@ -28,6 +28,7 @@ import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
 import androidx.compose.material.icons.filled.Add
 import androidx.compose.material.icons.filled.Remove
+import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Button
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.HorizontalDivider
@@ -43,6 +44,7 @@ import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.material3.rememberModalBottomSheetState
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
@@ -63,6 +65,8 @@ import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.emptyFlow
 import org.dolphinemu.dolphinemu.R
 import org.dolphinemu.dolphinemu.features.netplay.model.NetplayMessage
 import org.dolphinemu.dolphinemu.features.netplay.model.Player
@@ -75,6 +79,7 @@ import org.dolphinemu.dolphinemu.ui.theme.PreviewTheme
 @Composable
 fun NetplayScreen(
     onBackClicked: () -> Unit,
+    connectionLost: Flow<Unit>,
     messages: List<NetplayMessage>,
     onSendMessage: (String) -> Unit,
     game: String,
@@ -126,6 +131,22 @@ fun NetplayScreen(
                 modifier = modifier
             )
         }
+
+        var showConnectionLostDialog by remember { mutableStateOf(false) }
+        LaunchedEffect(Unit) {
+            connectionLost.collect { showConnectionLostDialog = true }
+        }
+        if (showConnectionLostDialog) {
+            AlertDialog(
+                text = { Text(stringResource(R.string.netplay_connection_lost)) },
+                confirmButton = {
+                    TextButton(onClick = onBackClicked) {
+                        Text(stringResource(R.string.ok))
+                    }
+                },
+                onDismissRequest = onBackClicked,
+            )
+        }
     }
 }
 
@@ -246,7 +267,7 @@ private fun PlayersAndSettings(
                     .fillMaxWidth()
             )
         }
-        
+
         if (hostInputAuthorityEnabled) {
             MenuSpacer()
 
@@ -539,6 +560,7 @@ private fun LandscapeNetplayScreenDarkPreview() {
 private fun PreviewNetplayScreen() {
     NetplayScreen(
         onBackClicked = {},
+        connectionLost = emptyFlow(),
         players = listOf(
             Player(
                 pid = 1,

Source/Android/app/src/main/res/values/strings.xml

@@ -1008,4 +1008,5 @@ It can efficiently compress both junk data and encrypted Wii data.
     <string name="netplay_players_ping">Ping</string>
     <string name="netplay_players_mapping">Mapping</string>
     <string name="netplay_max_buffer">Max buffer</string>
+    <string name="netplay_connection_lost">Netplay connection lost</string>
 </resources>