Fix state restoration when switching between inner and outer screens.

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

@@ -7,15 +7,19 @@ package org.thoughtcrime.securesms.components.webrtc.v2
 
 import androidx.compose.material3.BottomSheetScaffoldState
 import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.SheetState
 import androidx.compose.material3.SheetValue
 import androidx.compose.material3.rememberBottomSheetScaffoldState
-import androidx.compose.material3.rememberStandardBottomSheetState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableLongStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.saveable.Saver
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.Density
 
 /**
  * Collects and manages state objects for manipulating the call screen UI programatically.
@@ -41,9 +45,11 @@ class CallScreenController private constructor(
           scaffoldState.bottomSheetState.show()
         }
       }
+
       Event.SHOW_CALL_INFO -> {
         scaffoldState.bottomSheetState.expand()
       }
+
       Event.RESTART_HIDE_CONTROLS_TIMER -> {
         restartTimerRequests += 1
       }
@@ -61,7 +67,7 @@ class CallScreenController private constructor(
       }
 
       val scaffoldState = rememberBottomSheetScaffoldState(
-        bottomSheetState = rememberStandardBottomSheetState(
+        bottomSheetState = rememberCallScreenSheetState(
           confirmValueChange = valueChangeOperation,
           skipHiddenState = skip
         )
@@ -84,3 +90,64 @@ class CallScreenController private constructor(
     RESTART_HIDE_CONTROLS_TIMER
   }
 }
+
+/**
+ * Replaces `rememberStandardBottomSheetState` as it appeared to have a bug when the skipHiddenState value would
+ * change before restore.
+ */
+@Composable
+@ExperimentalMaterial3Api
+private fun rememberCallScreenSheetState(
+  confirmValueChange: (SheetValue) -> Boolean = { true },
+  initialValue: SheetValue = SheetValue.PartiallyExpanded,
+  skipHiddenState: Boolean = false
+): SheetState {
+  val density = LocalDensity.current
+  return rememberSaveable(
+    confirmValueChange,
+    skipHiddenState,
+    saver = saveSheetState(
+      confirmValueChange = confirmValueChange,
+      density = density,
+      skipHiddenState = skipHiddenState
+    )
+  ) {
+    SheetState(
+      skipPartiallyExpanded = false,
+      density = density,
+      initialValue = initialValue,
+      confirmValueChange = confirmValueChange,
+      skipHiddenState = skipHiddenState
+    )
+  }
+}
+
+/**
+ * Because we have a dynamic value for `skipHiddenState` we want to make sure we appropriately
+ * set the SheetValue on restore to avoid a crash.
+ */
+@ExperimentalMaterial3Api
+private fun saveSheetState(
+  confirmValueChange: (SheetValue) -> Boolean,
+  density: Density,
+  skipHiddenState: Boolean
+): Saver<SheetState, SheetValue> {
+  return Saver(
+    save = { it.currentValue },
+    restore = { savedValue ->
+      val value = if (savedValue == SheetValue.Hidden && skipHiddenState) {
+        SheetValue.PartiallyExpanded
+      } else {
+        savedValue
+      }
+
+      SheetState(
+        skipPartiallyExpanded = false,
+        density = density,
+        initialValue = value,
+        confirmValueChange = confirmValueChange,
+        skipHiddenState = skipHiddenState
+      )
+    }
+  )
+}