Add "fake" chat list bitmap to fake transition.

app/src/main/java/org/thoughtcrime/securesms/window/AppScaffold.kt

@@ -221,6 +221,7 @@ enum class WindowSizeClass(
 @Composable
 fun AppScaffold(
   navigator: AppScaffoldNavigator<Any>,
+  modifier: Modifier = Modifier,
   topBarContent: @Composable () -> Unit = {},
   primaryContent: @Composable () -> Unit = {},
   secondaryContent: @Composable () -> Unit,
@@ -242,7 +243,8 @@ fun AppScaffold(
       navRailContent = navRailContent,
       bottomNavContent = bottomNavContent,
       windowSizeClass = windowSizeClass,
-      contentWindowInsets = contentWindowInsets
+      contentWindowInsets = contentWindowInsets,
+      modifier = modifier
     )
 
     return
@@ -255,7 +257,8 @@ fun AppScaffold(
     containerColor = Color.Transparent,
     contentWindowInsets = contentWindowInsets,
     topBar = topBarContent,
-    snackbarHost = snackbarHost
+    snackbarHost = snackbarHost,
+    modifier = modifier
   ) { paddingValues ->
     NavigableListDetailPaneScaffold(
       navigator = navigator,
@@ -353,13 +356,15 @@ private fun ListAndNavigation(
   bottomNavContent: @Composable () -> Unit,
   snackbarHost: @Composable () -> Unit = {},
   windowSizeClass: WindowSizeClass,
-  contentWindowInsets: WindowInsets
+  contentWindowInsets: WindowInsets,
+  modifier: Modifier = Modifier
 ) {
   Scaffold(
     containerColor = Color.Transparent,
     topBar = topBarContent,
     contentWindowInsets = contentWindowInsets,
-    snackbarHost = snackbarHost
+    snackbarHost = snackbarHost,
+    modifier = modifier
   ) { paddingValues ->
     Row(
       modifier = Modifier

app/src/main/java/org/thoughtcrime/securesms/window/AppScaffoldAnimationState.kt

@@ -5,6 +5,8 @@
 
 package org.thoughtcrime.securesms.window
 
+import androidx.compose.animation.core.CubicBezierEasing
+import androidx.compose.animation.core.tween
 import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
@@ -18,6 +20,16 @@ import androidx.compose.ui.graphics.Shape
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 
+/**
+ * Default animation settings for app-scaffold animations.
+ */
+object AppScaffoldAnimationDefaults {
+  val TweenEasing = CubicBezierEasing(0.4f, 0.0f, 0.2f, 1f)
+  val InitAnimationOffset = 48.dp
+
+  fun <T> tween() = tween<T>(durationMillis = 200, easing = TweenEasing)
+}
+
 /**
  * Produces modifier that can be composed into another modifier chain.
  * This object allows us to store "latest state" as we transition.
@@ -47,17 +59,31 @@ data class AppScaffoldAnimationState(
  * Allows for the customization of the AppScaffold Animators.
  */
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)
-abstract class AppScaffoldAnimationStateFactory {
+class AppScaffoldAnimationStateFactory(
+  val enabledStates: Set<AppScaffoldNavigator.NavigationState> = AppScaffoldNavigator.NavigationState.entries.toSet()
+) {
 
-  object Default : AppScaffoldAnimationStateFactory()
+  companion object {
+    val Default = AppScaffoldAnimationStateFactory()
 
-  protected var latestListSeekState: AppScaffoldAnimationState = AppScaffoldAnimationState(AppScaffoldNavigator.NavigationState.SEEK)
-  protected var latestDetailSeekState: AppScaffoldAnimationState = AppScaffoldAnimationState(AppScaffoldNavigator.NavigationState.SEEK)
+    private val EMPTY_STATE = AppScaffoldAnimationState(
+      navigationState = AppScaffoldNavigator.NavigationState.ENTER,
+      alpha = 1f
+    )
+  }
+
+  private var latestListSeekState: AppScaffoldAnimationState = AppScaffoldAnimationState(AppScaffoldNavigator.NavigationState.SEEK)
+  private var latestDetailSeekState: AppScaffoldAnimationState = AppScaffoldAnimationState(AppScaffoldNavigator.NavigationState.SEEK)
 
   @Composable
   fun ThreePaneScaffoldPaneScope.getListAnimationState(navigationState: AppScaffoldNavigator.NavigationState): AppScaffoldAnimationState {
+    if (navigationState !in enabledStates) {
+      return EMPTY_STATE
+    }
+
     return when (navigationState) {
-      AppScaffoldNavigator.NavigationState.INIT -> defaultListInitAnimationState()
+      AppScaffoldNavigator.NavigationState.ENTER -> defaultListInitAnimationState()
+      AppScaffoldNavigator.NavigationState.EXIT -> defaultListInitAnimationState()
       AppScaffoldNavigator.NavigationState.SEEK -> defaultListSeekAnimationState().also {
         latestListSeekState = it
       }
@@ -67,8 +93,13 @@ abstract class AppScaffoldAnimationStateFactory {
 
   @Composable
   fun ThreePaneScaffoldPaneScope.getDetailAnimationState(navigationState: AppScaffoldNavigator.NavigationState): AppScaffoldAnimationState {
+    if (navigationState !in enabledStates) {
+      return EMPTY_STATE
+    }
+
     return when (navigationState) {
-      AppScaffoldNavigator.NavigationState.INIT -> defaultDetailInitAnimationState()
+      AppScaffoldNavigator.NavigationState.ENTER -> defaultDetailInitAnimationState()
+      AppScaffoldNavigator.NavigationState.EXIT -> defaultDetailInitAnimationState()
       AppScaffoldNavigator.NavigationState.SEEK -> defaultDetailSeekAnimationState().also {
         latestDetailSeekState = it
       }

app/src/main/java/org/thoughtcrime/securesms/window/AppScaffoldAnimators.kt

@@ -5,14 +5,12 @@
 
 package org.thoughtcrime.securesms.window
 
-import androidx.compose.animation.core.CubicBezierEasing
 import androidx.compose.animation.core.FiniteAnimationSpec
 import androidx.compose.animation.core.Spring
 import androidx.compose.animation.core.Transition
 import androidx.compose.animation.core.animateDp
 import androidx.compose.animation.core.animateFloat
 import androidx.compose.animation.core.spring
-import androidx.compose.animation.core.tween
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
 import androidx.compose.material3.adaptive.layout.PaneAdaptedValue
@@ -38,12 +36,10 @@ fun <T> appScaffoldSeekSpring(): FiniteAnimationSpec<T> = spring(
   stiffness = SEEK_STIFFNESS
 )
 
-private val easing = CubicBezierEasing(0.4f, 0.0f, 0.2f, 1f)
-
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)
 @Composable
 fun ThreePaneScaffoldPaneScope.animateDp(
-  transitionSpec: @Composable Transition.Segment<*>.() -> FiniteAnimationSpec<Dp> = { tween(durationMillis = 200, easing = easing) },
+  transitionSpec: @Composable Transition.Segment<*>.() -> FiniteAnimationSpec<Dp> = { AppScaffoldAnimationDefaults.tween() },
   targetWhenHiding: () -> Dp = { 0.dp },
   targetWhenShowing: () -> Dp
 ): State<Dp> {
@@ -63,7 +59,7 @@ fun ThreePaneScaffoldPaneScope.animateDp(
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)
 @Composable
 fun ThreePaneScaffoldPaneScope.animateFloat(
-  transitionSpec: @Composable Transition.Segment<*>.() -> FiniteAnimationSpec<Float> = { tween(durationMillis = 200, easing = easing) },
+  transitionSpec: @Composable Transition.Segment<*>.() -> FiniteAnimationSpec<Float> = { AppScaffoldAnimationDefaults.tween() },
   targetWhenHiding: () -> Float = { 0f },
   targetWhenShowing: () -> Float
 ): State<Float> {
@@ -85,7 +81,7 @@ fun ThreePaneScaffoldPaneScope.animateFloat(
 fun ThreePaneScaffoldPaneScope.defaultListInitAnimationState(): AppScaffoldAnimationState {
   val offset by animateDp(
     targetWhenHiding = {
-      (-48).dp
+      -AppScaffoldAnimationDefaults.InitAnimationOffset
     },
     targetWhenShowing = {
       0.dp
@@ -97,7 +93,7 @@ fun ThreePaneScaffoldPaneScope.defaultListInitAnimationState(): AppScaffoldAnima
   }
 
   return AppScaffoldAnimationState(
-    AppScaffoldNavigator.NavigationState.INIT,
+    AppScaffoldNavigator.NavigationState.ENTER,
     alpha = alpha,
     offset = offset
   )
@@ -169,7 +165,7 @@ fun ThreePaneScaffoldPaneScope.defaultListReleaseAnimationState(from: AppScaffol
 fun ThreePaneScaffoldPaneScope.defaultDetailInitAnimationState(): AppScaffoldAnimationState {
   val offset by animateDp(
     targetWhenHiding = {
-      48.dp
+      AppScaffoldAnimationDefaults.InitAnimationOffset
     },
     targetWhenShowing = {
       0.dp
@@ -181,7 +177,7 @@ fun ThreePaneScaffoldPaneScope.defaultDetailInitAnimationState(): AppScaffoldAni
   }
 
   return AppScaffoldAnimationState(
-    navigationState = AppScaffoldNavigator.NavigationState.INIT,
+    navigationState = AppScaffoldNavigator.NavigationState.ENTER,
     alpha = alpha,
     offset = offset
   )

app/src/main/java/org/thoughtcrime/securesms/window/AppScaffoldNavigator.kt

@@ -31,11 +31,11 @@ import org.thoughtcrime.securesms.keyvalue.SignalStore
 @OptIn(ExperimentalMaterial3AdaptiveApi::class)
 open class AppScaffoldNavigator<T> @RememberInComposition constructor(private val delegate: ThreePaneScaffoldNavigator<T>) : ThreePaneScaffoldNavigator<T> by delegate {
 
-  var state: NavigationState by mutableStateOf(NavigationState.INIT)
+  var state: NavigationState by mutableStateOf(NavigationState.ENTER)
     private set
 
   override suspend fun navigateTo(pane: ThreePaneScaffoldRole, contentKey: T?) {
-    state = NavigationState.INIT
+    state = NavigationState.ENTER
     return delegate.navigateTo(pane, contentKey)
   }
 
@@ -44,6 +44,10 @@ open class AppScaffoldNavigator<T> @RememberInComposition constructor(private va
       state = NavigationState.RELEASE
     }
 
+    if (state == NavigationState.ENTER) {
+      state = NavigationState.EXIT
+    }
+
     return delegate.navigateBack(backNavigationBehavior)
   }
 
@@ -60,11 +64,14 @@ open class AppScaffoldNavigator<T> @RememberInComposition constructor(private va
    */
   enum class NavigationState {
     /**
-     * We've navigated to a new pane. This animation is used for both immediate
-     * pane entry and exit (such as tapping a back button instead of using a
-     * gesture)
+     * We've navigated to a new pane.
      */
-    INIT,
+    ENTER,
+
+    /**
+     * We've navigated back from a pane without using seek.
+     */
+    EXIT,
 
     /**
      * The user is performing a back gesture seek action.