pref(BackHandler): 导航到其他页面时当前页不处理返回

app/src/main/java/com/huanchengfly/tieba/post/MainActivityV2.kt

@@ -31,6 +31,8 @@ import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.State
 import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.compositionLocalOf
+import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.staticCompositionLocalOf
 import androidx.compose.ui.Alignment
@@ -41,6 +43,7 @@ import androidx.core.content.ContextCompat
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
 import androidx.lifecycle.flowWithLifecycle
 import androidx.lifecycle.lifecycleScope
+import androidx.navigation.NavController
 import androidx.navigation.plusAssign
 import androidx.window.layout.FoldingFeature
 import androidx.window.layout.WindowInfoTracker
@@ -75,6 +78,8 @@ import com.ramcosta.composedestinations.DestinationsNavHost
 import com.ramcosta.composedestinations.animations.defaults.RootNavGraphDefaultAnimations
 import com.ramcosta.composedestinations.animations.rememberAnimatedNavHostEngine
 import com.ramcosta.composedestinations.navigation.dependency
+import com.ramcosta.composedestinations.spec.DestinationSpec
+import com.ramcosta.composedestinations.utils.currentDestinationAsState
 import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.channels.BufferOverflow
@@ -93,6 +98,9 @@ val LocalNotificationCountFlow =
     staticCompositionLocalOf<Flow<Int>> { throw IllegalStateException("not allowed here!") }
 val LocalDevicePosture =
     staticCompositionLocalOf<State<DevicePosture>> { throw IllegalStateException("not allowed here!") }
+val LocalNavController =
+    staticCompositionLocalOf<NavController> { throw IllegalStateException("not allowed here!") }
+val LocalDestination = compositionLocalOf<DestinationSpec<*>?> { null }
 
 @OptIn(ExperimentalMaterialApi::class, ExperimentalMaterialNavigationApi::class)
 @Composable
@@ -294,18 +302,26 @@ class MainActivityV2 : BaseComposeActivity() {
                         skipHalfExpanded = true
                     )
                 navController.navigatorProvider += bottomSheetNavigator
-                ModalBottomSheetLayout(
-                    bottomSheetNavigator = bottomSheetNavigator,
-                    sheetShape = RoundedCornerShape(topStart = 12.dp, topEnd = 12.dp)
+
+                val currentDestination by navController.currentDestinationAsState()
+
+                CompositionLocalProvider(
+                    LocalNavController provides navController,
+                    LocalDestination provides currentDestination
                 ) {
-                    DestinationsNavHost(
-                        navController = navController,
-                        navGraph = NavGraphs.root,
-                        engine = engine,
-                        dependenciesContainerBuilder = {
-                            dependency(MainPageDestination) { this@MainActivityV2 }
-                        }
-                    )
+                    ModalBottomSheetLayout(
+                        bottomSheetNavigator = bottomSheetNavigator,
+                        sheetShape = RoundedCornerShape(topStart = 12.dp, topEnd = 12.dp)
+                    ) {
+                        DestinationsNavHost(
+                            navController = navController,
+                            navGraph = NavGraphs.root,
+                            engine = engine,
+                            dependenciesContainerBuilder = {
+                                dependency(MainPageDestination) { this@MainActivityV2 }
+                            }
+                        )
+                    }
                 }
             }
         }

app/src/main/java/com/huanchengfly/tieba/post/ui/page/thread/ThreadPage.kt

@@ -1,6 +1,5 @@
 package com.huanchengfly.tieba.post.ui.page.thread
 
-import androidx.activity.compose.BackHandler
 import androidx.compose.animation.animateColorAsState
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.background
@@ -114,6 +113,7 @@ import com.huanchengfly.tieba.post.ui.common.theme.compose.ExtendedTheme
 import com.huanchengfly.tieba.post.ui.page.ProvideNavigator
 import com.huanchengfly.tieba.post.ui.page.destinations.ForumPageDestination
 import com.huanchengfly.tieba.post.ui.page.destinations.SubPostsSheetPageDestination
+import com.huanchengfly.tieba.post.ui.page.destinations.ThreadPageDestination
 import com.huanchengfly.tieba.post.ui.widgets.compose.Avatar
 import com.huanchengfly.tieba.post.ui.widgets.compose.BackNavigationIcon
 import com.huanchengfly.tieba.post.ui.widgets.compose.Button
@@ -124,6 +124,7 @@ import com.huanchengfly.tieba.post.ui.widgets.compose.HorizontalDivider
 import com.huanchengfly.tieba.post.ui.widgets.compose.LazyLoad
 import com.huanchengfly.tieba.post.ui.widgets.compose.ListMenuItem
 import com.huanchengfly.tieba.post.ui.widgets.compose.LoadMoreLayout
+import com.huanchengfly.tieba.post.ui.widgets.compose.MyBackHandler
 import com.huanchengfly.tieba.post.ui.widgets.compose.MyScaffold
 import com.huanchengfly.tieba.post.ui.widgets.compose.PromptDialog
 import com.huanchengfly.tieba.post.ui.widgets.compose.Sizes
@@ -545,7 +546,10 @@ fun ThreadPage(
         }
     }
 
-    BackHandler(enabled = bottomSheetState.isVisible) {
+    MyBackHandler(
+        enabled = bottomSheetState.isVisible,
+        currentScreen = ThreadPageDestination
+    ) {
         closeBottomSheet()
     }
 
@@ -594,7 +598,10 @@ fun ThreadPage(
     ) {
         Text(text = stringResource(R.string.message_update_collect_mark, readFloorBeforeBack))
     }
-    BackHandler(enabled = isCollected && !bottomSheetState.isVisible) {
+    MyBackHandler(
+        enabled = isCollected && !bottomSheetState.isVisible,
+        currentScreen = ThreadPageDestination
+    ) {
         readFloorBeforeBack = getLastVisibilityPost()?.get { floor } ?: 0
         if (readFloorBeforeBack != 0) {
             updateCollectMarkDialogState.show()

app/src/main/java/com/huanchengfly/tieba/post/ui/widgets/compose/BackHandler.kt

@@ -0,0 +1,20 @@
+package com.huanchengfly.tieba.post.ui.widgets.compose
+
+import androidx.activity.compose.BackHandler
+import androidx.compose.runtime.Composable
+import com.huanchengfly.tieba.post.LocalDestination
+import com.ramcosta.composedestinations.spec.DestinationSpec
+
+@Composable
+fun MyBackHandler(
+    enabled: Boolean,
+    currentScreen: DestinationSpec<*>? = null,
+    onBack: () -> Unit,
+) {
+    val currentDestination = LocalDestination.current
+
+    val shouldEnable =
+        enabled && (currentScreen == null || currentDestination?.baseRoute == currentScreen.baseRoute)
+
+    BackHandler(enabled = shouldEnable, onBack = onBack)
+}