Fix call screen crash when participant count drops during speaker view.

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/v2/CallParticipantsPager.kt

@@ -15,7 +15,6 @@ import androidx.compose.material3.Surface
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Immutable
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.movableContentOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberUpdatedState
@@ -52,67 +51,55 @@ fun CallParticipantsPager(
     callParticipantsPagerState.callParticipants.firstOrNull()?.videoSink
   )
 
-  // Use movableContentOf to preserve CallGrid state when switching between
-  // single participant (no pager) and multiple participants (with pager)
-  val callGridContent = remember {
-    movableContentOf { state: CallParticipantsPagerState, mod: Modifier, aspectRatio: Float? ->
-      CallGrid(
-        items = state.callParticipants,
-        singleParticipantAspectRatio = aspectRatio,
-        modifier = mod,
-        itemKey = { it.callParticipantId }
-      ) { participant, itemModifier ->
-        val longPressModifier = if (!participant.recipient.isSelf && currentOnLongPress.value != null) {
-          var itemWindowOrigin by remember(participant.callParticipantId) { mutableStateOf(Offset.Zero) }
-          itemModifier
-            .onGloballyPositioned { coords -> itemWindowOrigin = coords.positionInRoot() }
-            .pointerInput(participant.callParticipantId) {
-              detectTapGestures(
-                onTap = { currentOnTap.value?.invoke() },
-                onLongPress = { local -> currentOnLongPress.value?.invoke(participant, itemWindowOrigin + local) }
-              )
-            }
-        } else {
-          itemModifier
-        }
+  VerticalPager(
+    state = pagerState,
+    modifier = modifier
+      .displayCutoutPadding()
+      .statusBarsPadding()
+  ) { page ->
+    when (page) {
+      0 -> {
+        CallGrid(
+          items = callParticipantsPagerState.callParticipants,
+          singleParticipantAspectRatio = firstParticipantAR,
+          modifier = Modifier.fillMaxSize(),
+          itemKey = { it.callParticipantId }
+        ) { participant, itemModifier ->
+          val longPressModifier = if (!participant.recipient.isSelf && currentOnLongPress.value != null) {
+            var itemWindowOrigin by remember(participant.callParticipantId) { mutableStateOf(Offset.Zero) }
+            itemModifier
+              .onGloballyPositioned { coords -> itemWindowOrigin = coords.positionInRoot() }
+              .pointerInput(participant.callParticipantId) {
+                detectTapGestures(
+                  onTap = { currentOnTap.value?.invoke() },
+                  onLongPress = { local -> currentOnLongPress.value?.invoke(participant, itemWindowOrigin + local) }
+                )
+              }
+          } else {
+            itemModifier
+          }
 
-        RemoteParticipantContent(
-          participant = participant,
-          renderInPip = state.isRenderInPip,
-          raiseHandAllowed = false,
-          onInfoMoreInfoClick = null,
-          showAudioIndicator = state.callParticipants.size > 1,
-          modifier = longPressModifier
-        )
-      }
-    }
-  }
-
-  if (callParticipantsPagerState.callParticipants.size > 1) {
-    VerticalPager(
-      state = pagerState,
-      modifier = modifier
-        .displayCutoutPadding()
-        .statusBarsPadding()
-    ) { page ->
-      when (page) {
-        0 -> {
-          callGridContent(callParticipantsPagerState, Modifier.fillMaxSize(), firstParticipantAR)
-        }
-
-        1 -> {
           RemoteParticipantContent(
-            participant = callParticipantsPagerState.focusedParticipant,
+            participant = participant,
             renderInPip = callParticipantsPagerState.isRenderInPip,
             raiseHandAllowed = false,
             onInfoMoreInfoClick = null,
-            modifier = Modifier.fillMaxSize()
+            showAudioIndicator = callParticipantsPagerState.callParticipants.size > 1,
+            modifier = longPressModifier
           )
         }
       }
+
+      1 -> {
+        RemoteParticipantContent(
+          participant = callParticipantsPagerState.focusedParticipant,
+          renderInPip = callParticipantsPagerState.isRenderInPip,
+          raiseHandAllowed = false,
+          onInfoMoreInfoClick = null,
+          modifier = Modifier.fillMaxSize()
+        )
+      }
     }
-  } else {
-    callGridContent(callParticipantsPagerState, modifier, firstParticipantAR)
   }
 }
 

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/v2/CallScreen.kt

@@ -104,8 +104,10 @@ fun CallScreen(
   savedLocalParticipantLandscape: Boolean = false,
   callScreenState: CallScreenState,
   callControlsState: CallControlsState,
+  callParticipantsPagerState: CallParticipantsPagerState,
   callScreenController: CallScreenController = CallScreenController.rememberCallScreenController(
     skipHiddenState = callControlsState.skipHiddenState,
+    hasMultipleRemoteParticipants = callParticipantsPagerState.callParticipants.size > 1,
     onControlsToggled = {},
     callControlsState = callControlsState,
     callControlsListener = CallScreenControlsListener.Empty
@@ -113,7 +115,6 @@ fun CallScreen(
   callScreenControlsListener: CallScreenControlsListener = CallScreenControlsListener.Empty,
   callScreenSheetDisplayListener: CallScreenSheetDisplayListener = CallScreenSheetDisplayListener.Empty,
   additionalActionsListener: AdditionalActionsListener = AdditionalActionsListener.Empty,
-  callParticipantsPagerState: CallParticipantsPagerState,
   pendingParticipantsListener: PendingParticipantsListener = PendingParticipantsListener.Empty,
   callParticipantUpdatePopupController: CallParticipantUpdatePopupController,
   overflowParticipants: List<CallParticipant>,

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/v2/CallScreenController.kt

@@ -77,11 +77,13 @@ class CallScreenController private constructor(
     @Composable
     fun rememberCallScreenController(
       skipHiddenState: Boolean,
+      hasMultipleRemoteParticipants: Boolean,
       onControlsToggled: (Boolean) -> Unit,
       callControlsState: CallControlsState,
       callControlsListener: CallScreenControlsListener
     ): CallScreenController {
       val skip by rememberUpdatedState(skipHiddenState)
+      val hasMultipleRemoteParticipantsState = rememberUpdatedState(hasMultipleRemoteParticipants)
       val valueChangeOperation: (SheetValue) -> Boolean = remember {
         {
           !(it == SheetValue.Hidden && skip)
@@ -130,7 +132,7 @@ class CallScreenController private constructor(
 
       val callParticipantsVerticalPagerState = rememberPagerState(
         initialPage = 0,
-        pageCount = { 2 }
+        pageCount = { if (hasMultipleRemoteParticipantsState.value) 2 else 1 }
       )
 
       return remember(scaffoldState, callParticipantsVerticalPagerState, audioOutputPickerController) {

app/src/main/java/org/thoughtcrime/securesms/components/webrtc/v2/ComposeCallScreenMediator.kt

@@ -164,6 +164,7 @@ class ComposeCallScreenMediator(private val activity: WebRtcCallActivity, viewMo
 
       val callScreenController = CallScreenController.rememberCallScreenController(
         skipHiddenState = callControlsState.skipHiddenState,
+        hasMultipleRemoteParticipants = callParticipantsPagerState.callParticipants.size > 1,
         onControlsToggled = onControlsToggled,
         callControlsState = callControlsState,
         callControlsListener = callScreenControlsListener