enhancement: back to home; closes #345 (#358)

androidApp/build.gradle.kts

@@ -68,6 +68,8 @@ dependencies {
     implementation(libs.koin.android)
     implementation(libs.coil)
     implementation(libs.coil.gif)
+    implementation(libs.voyager.navigator)
+    implementation(libs.voyager.tab)
 
     implementation(projects.shared)
     implementation(projects.core.utils)

androidApp/src/main/java/com/github/diegoberaldin/raccoonforlemmy/android/MainActivity.kt

@@ -8,7 +8,9 @@ import androidx.activity.compose.setContent
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
 import androidx.lifecycle.lifecycleScope
 import com.github.diegoberaldin.raccoonforlemmy.MainView
+import com.github.diegoberaldin.raccoonforlemmy.core.navigation.TabNavigationSection
 import com.github.diegoberaldin.raccoonforlemmy.core.navigation.di.getNavigationCoordinator
+import com.github.diegoberaldin.raccoonforlemmy.feature.home.ui.HomeTab
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
@@ -27,8 +29,17 @@ class MainActivity : ComponentActivity() {
         val navigationCoordinator = getNavigationCoordinator()
         val backPressedCallback = object : OnBackPressedCallback(true) {
             override fun handleOnBackPressed() {
-                if (!navigationCoordinator.exitMessageVisible.value) {
-                    navigationCoordinator.setExitMessageVisible(true)
+                if (navigationCoordinator.currentSection.value == TabNavigationSection.Home) {
+                    // asks for confirmation
+                    if (!navigationCoordinator.exitMessageVisible.value) {
+                        navigationCoordinator.setExitMessageVisible(true)
+                    }
+                } else {
+                    // goes back to home
+                    with(navigationCoordinator) {
+                        changeTab(HomeTab)
+                        setCurrentSection(TabNavigationSection.Home)
+                    }
                 }
             }
         }

core/navigation/src/commonMain/kotlin/com/github/diegoberaldin/raccoonforlemmy/core/navigation/DefaultNavigationCoordinator.kt

@@ -4,6 +4,8 @@ import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
 import cafe.adriel.voyager.core.screen.Screen
 import cafe.adriel.voyager.navigator.Navigator
 import cafe.adriel.voyager.navigator.bottomSheet.BottomSheetNavigator
+import cafe.adriel.voyager.navigator.tab.Tab
+import cafe.adriel.voyager.navigator.tab.TabNavigator
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.SupervisorJob
@@ -13,6 +15,7 @@ import kotlinx.coroutines.ensureActive
 import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.debounce
+import kotlinx.coroutines.flow.getAndUpdate
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.flow.receiveAsFlow
@@ -28,6 +31,7 @@ private sealed interface NavigationEvent {
 @OptIn(FlowPreview::class)
 internal class DefaultNavigationCoordinator : NavigationCoordinator {
 
+    override val currentSection = MutableStateFlow<TabNavigationSection?>(null)
     override val onDoubleTabSelection = MutableSharedFlow<TabNavigationSection>()
     override val deepLinkUrl = MutableSharedFlow<String>()
     override val inboxUnread = MutableStateFlow(0)
@@ -38,7 +42,7 @@ internal class DefaultNavigationCoordinator : NavigationCoordinator {
     private var connection: NestedScrollConnection? = null
     private var navigator: Navigator? = null
     private var bottomNavigator: BottomSheetNavigator? = null
-    private var currentTab: TabNavigationSection? = null
+    private var tabNavigator: TabNavigator? = null
     private val scope = CoroutineScope(SupervisorJob())
     private var canGoBackCallback: (() -> Boolean)? = null
     private val bottomSheetChannel = Channel<NavigationEvent>()
@@ -93,12 +97,13 @@ internal class DefaultNavigationCoordinator : NavigationCoordinator {
     override fun getBottomBarScrollConnection() = connection
 
     override fun setCurrentSection(section: TabNavigationSection) {
-        val oldTab = currentTab
-        currentTab = section
-        if (section == oldTab) {
-            scope.launch {
-                onDoubleTabSelection.emit(section)
+        currentSection.getAndUpdate { oldValue ->
+            if (section == oldValue) {
+                scope.launch {
+                    onDoubleTabSelection.emit(section)
+                }
             }
+            section
         }
     }
 
@@ -157,4 +162,12 @@ internal class DefaultNavigationCoordinator : NavigationCoordinator {
     override fun setBottomSheetGesturesEnabled(value: Boolean) {
         bottomSheetGesturesEnabled.value = value
     }
+
+    override fun setTabNavigator(value: TabNavigator) {
+        tabNavigator = value
+    }
+
+    override fun changeTab(value: Tab) {
+        tabNavigator?.current = value
+    }
 }

core/navigation/src/commonMain/kotlin/com/github/diegoberaldin/raccoonforlemmy/core/navigation/NavigationCoordinator.kt

@@ -5,6 +5,8 @@ import androidx.compose.ui.input.nestedscroll.NestedScrollConnection
 import cafe.adriel.voyager.core.screen.Screen
 import cafe.adriel.voyager.navigator.Navigator
 import cafe.adriel.voyager.navigator.bottomSheet.BottomSheetNavigator
+import cafe.adriel.voyager.navigator.tab.Tab
+import cafe.adriel.voyager.navigator.tab.TabNavigator
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.StateFlow
 
@@ -19,6 +21,7 @@ sealed interface TabNavigationSection {
 @Stable
 interface NavigationCoordinator {
 
+    val currentSection: StateFlow<TabNavigationSection?>
     val onDoubleTabSelection: Flow<TabNavigationSection>
     val inboxUnread: StateFlow<Int>
     val deepLinkUrl: Flow<String?>
@@ -41,4 +44,6 @@ interface NavigationCoordinator {
     fun popScreen()
     fun setExitMessageVisible(value: Boolean)
     fun setBottomSheetGesturesEnabled(value: Boolean)
+    fun setTabNavigator(value: TabNavigator)
+    fun changeTab(value: Tab)
 }

shared/src/commonMain/kotlin/com/github/diegoberaldin/raccoonforlemmy/MainScreen.kt

@@ -110,10 +110,13 @@ internal object MainScreen : Screen {
         }
 
         TabNavigator(HomeTab) { tabNavigator ->
+            navigationCoordinator.setTabNavigator(tabNavigator)
+
             LaunchedEffect(tabNavigator.current) {
                 // when the current tab chanes, reset the bottom bar offset to the default value
                 model.reduce(MainScreenMviModel.Intent.SetBottomBarOffsetHeightPx(0f))
             }
+
             LaunchedEffect(drawerCoordinator) {
                 drawerCoordinator.events.onEach { evt ->
                     when (evt) {
@@ -121,7 +124,10 @@ internal object MainScreen : Screen {
                             if (tabNavigator.current == HomeTab) {
                                 notificationCenter.send(NotificationCenterEvent.ChangeFeedType(evt.value))
                             } else {
-                                tabNavigator.current = HomeTab
+                                with(navigationCoordinator) {
+                                    changeTab(HomeTab)
+                                    setCurrentSection(TabNavigationSection.Home)
+                                }
                                 launch {
                                     // wait for transition to finish
                                     delay(750)