android: Animated switch between chat and chatList

apps/android/app/src/main/java/chat/simplex/app/MainActivity.kt

@@ -327,13 +327,14 @@ fun MainPage(
           else {
             showAdvertiseLAAlert = true
             val stopped = chatModel.chatRunning.value == false
-            if (chatModel.chatId.value == null) {
-              if (chatModel.sharedContent.value == null)
-                ChatListView(chatModel, setPerformLA, stopped)
-              else
-                ShareListView(chatModel, stopped)
+            AnimateScreensNullable(chatModel.chatId) { current ->
+              if (current == null) {
+                if (chatModel.sharedContent.value == null)
+                  ChatListView(chatModel, setPerformLA, stopped)
+                else
+                  ShareListView(chatModel, stopped)
+              } else ChatView(chatModel)
             }
-            else ChatView(chatModel)
           }
         }
       }

apps/android/app/src/main/java/chat/simplex/app/views/chatlist/ChatListView.kt

@@ -15,7 +15,6 @@ import androidx.compose.runtime.*
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.Path
 import androidx.compose.ui.platform.LocalUriHandler

apps/android/app/src/main/java/chat/simplex/app/views/helpers/AnimationUtils.kt

@@ -0,0 +1,65 @@
+package chat.simplex.app.views.helpers
+
+import androidx.compose.animation.*
+import androidx.compose.animation.core.FastOutSlowInEasing
+import androidx.compose.animation.core.tween
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.MutableState
+
+@OptIn(ExperimentalAnimationApi::class)
+@Composable
+fun <S: Comparable<S>> AnimateScreens(
+  targetState: MutableState<S>,
+  content: @Composable AnimatedVisibilityScope.(targetState: S) -> Unit
+) {
+  AnimatedContent(
+    targetState = targetState.value,
+    transitionSpec = {
+      when {
+        targetState.value > initialState -> fromEndToStartTransition()
+        else -> fromStartToEndTransition()
+      }.using(SizeTransform(clip = false))
+    },
+    content = content
+  )
+}
+
+@OptIn(ExperimentalAnimationApi::class)
+@Composable
+fun <S> AnimateScreensNullable(
+  targetState: MutableState<S>,
+  content: @Composable AnimatedVisibilityScope.(targetState: S) -> Unit
+) {
+  AnimatedContent(
+    targetState = targetState.value,
+    transitionSpec = {
+      when {
+        targetState.value != null -> fromEndToStartTransition()
+        else -> fromStartToEndTransition()
+      }.using(SizeTransform(clip = false))
+    },
+    content = content
+  )
+}
+
+@OptIn(ExperimentalAnimationApi::class)
+private fun fromStartToEndTransition() =
+  slideInHorizontally(
+    initialOffsetX = { fullWidth -> -fullWidth },
+    animationSpec = animationSpec()
+  ) with slideOutHorizontally(
+    targetOffsetX = { fullWidth -> fullWidth },
+    animationSpec = animationSpec()
+  )
+
+@OptIn(ExperimentalAnimationApi::class)
+private fun fromEndToStartTransition() =
+  slideInHorizontally(
+    initialOffsetX = { fullWidth -> fullWidth },
+    animationSpec = animationSpec()
+  ) with slideOutHorizontally(
+    targetOffsetX = { fullWidth -> -fullWidth },
+    animationSpec = animationSpec()
+  )
+
+private fun <T> animationSpec() = tween<T>(durationMillis = 250, easing = FastOutSlowInEasing)

apps/android/app/src/main/java/chat/simplex/app/views/helpers/ModalView.kt

@@ -69,15 +69,7 @@ class ModalManager {
   @OptIn(ExperimentalAnimationApi::class)
   @Composable
   fun showInView() {
-    AnimatedContent(targetState = modalCount.value,
-      transitionSpec = {
-        if (targetState > initialState) {
-          fromEndToStartTransition()
-        } else {
-          fromStartToEndTransition()
-        }.using(SizeTransform(clip = false))
-      }
-    ) {
+    AnimateScreens(modalCount) {
       modalViews.getOrNull(it - 1)?.invoke(::closeModal)
       // This is needed because if we delete from modalViews immediately on request, animation will be bad
       if (toRemove.isNotEmpty() && it == modalCount.value && transition.currentState == EnterExitState.Visible && !transition.isRunning) {
@@ -86,30 +78,6 @@ class ModalManager {
     }
   }
 
-  @OptIn(ExperimentalAnimationApi::class)
-  private fun fromStartToEndTransition() =
-    slideInHorizontally(
-      initialOffsetX = { fullWidth -> -fullWidth },
-      animationSpec = animationSpec()
-    ) with slideOutHorizontally(
-      targetOffsetX = { fullWidth -> fullWidth },
-      animationSpec = animationSpec()
-    )
-
-  @OptIn(ExperimentalAnimationApi::class)
-  private fun fromEndToStartTransition() =
-    slideInHorizontally(
-      initialOffsetX = { fullWidth -> fullWidth },
-      animationSpec = animationSpec()
-    ) with slideOutHorizontally(
-      targetOffsetX = { fullWidth -> -fullWidth },
-      animationSpec = animationSpec()
-    )
-
-private fun <T> animationSpec() = tween<T>(durationMillis = 250, easing = FastOutSlowInEasing)
-//  private fun <T> animationSpecFromStart() = tween<T>(durationMillis = 150, easing = FastOutLinearInEasing)
-//  private fun <T> animationSpecFromEnd() = tween<T>(durationMillis = 100, easing = FastOutSlowInEasing)
-
   companion object {
     val shared = ModalManager()
   }