Save state for screen models, so that data would remain after process death

Signed-off-by: MrBoom <[email protected]>

Author: MrBoomDeveloper

buildSrc/src/main/kotlin/com/mrboomdev/awery/gradle/util/PropertyUtils.kt

@@ -0,0 +1,5 @@
+package com.mrboomdev.awery.gradle.util
+
+import org.gradle.api.provider.ListProperty
+
+operator fun <T> ListProperty<T>.plusAssign(list: List<T>) = addAll(list)

shared/build.gradle.kts

@@ -7,6 +7,7 @@ import com.mrboomdev.awery.gradle.ProjectVersion.getGitCommitHash
 import com.mrboomdev.awery.gradle.generatedConfigurationsDirectory
 import com.mrboomdev.awery.gradle.settings.GenerateSettingsTask
 import com.mrboomdev.awery.gradle.settings.generatedSettingsDirectory
+import com.mrboomdev.awery.gradle.util.plusAssign
 import org.jetbrains.kotlin.gradle.ExperimentalKotlinGradlePluginApi
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
@@ -64,6 +65,10 @@ kotlin {
 	}
 
 	sourceSets {
+		all {
+			languageSettings.optIn("androidx.lifecycle.viewmodel.compose.SavedStateHandleSaveableApi")
+		}
+		
 		commonMain {
 			for((_, generatedDirectory) in generations) {
 				kotlin.srcDir(generatedDirectory.dir("kotlin"))

shared/src/androidMain/kotlin/com/mrboomdev/awery/ui/utils/ScreenModels.android.kt

@@ -0,0 +1,63 @@
+package com.mrboomdev.awery.ui.utils
+
+import android.content.ContextWrapper
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.remember
+import androidx.compose.ui.platform.LocalContext
+import androidx.lifecycle.SavedStateHandle
+import androidx.savedstate.SavedStateRegistryOwner
+import cafe.adriel.voyager.core.lifecycle.ScreenLifecycleStore
+import cafe.adriel.voyager.core.model.ScreenModel
+import cafe.adriel.voyager.core.model.ScreenModelStore
+import cafe.adriel.voyager.core.screen.Screen
+import kotlin.reflect.KClass
+
+@Composable
+actual fun <T: ScreenModel> Screen.screenModel(
+	clazz: KClass<T>,
+	tag: String?,
+	factory: (SavedStateHandle) -> T
+): T {
+	var context = LocalContext.current
+		
+	while(context !is SavedStateRegistryOwner) {
+		if(context is ContextWrapper) {
+			context = context.baseContext
+		} else {
+			throw UnsupportedOperationException("Activity does not extend SavedStateRegistryOwner!")
+		}
+	}
+	
+	val savedStateRegistryOwner: SavedStateRegistryOwner = context
+	val registry = savedStateRegistryOwner.savedStateRegistry
+	
+	val savedStateKey = "screenModel;;;$key;;;savedState"
+	val rememberKey = "$key:${clazz.qualifiedName}:${tag ?: "default"}"
+	
+	@SuppressWarnings("RestrictedApi")
+	val savedStateHandle = SavedStateHandle.createHandle(
+		registry.consumeRestoredStateForKey(savedStateKey), null
+	).apply {
+		DisposableEffect(rememberKey) {
+			registry.registerSavedStateProvider(savedStateKey, savedStateProvider())
+			
+			onDispose { 
+				registry.unregisterSavedStateProvider(savedStateKey)
+			}
+		}
+	}
+	
+	val screenModelStore = remember(this) {
+		ScreenLifecycleStore.get(this) { ScreenModelStore }
+	}
+
+	@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+	return remember(rememberKey) {
+		screenModelStore.lastScreenModelKey.value = rememberKey
+		@Suppress("UNCHECKED_CAST")
+		screenModelStore.screenModels.getOrPut(rememberKey) { 
+			factory(savedStateHandle) 
+		} as T
+	}
+}

shared/src/commonMain/kotlin/com/mrboomdev/awery/ui/routes/SearchRoute.kt

@@ -36,14 +36,16 @@ import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.viewmodel.compose.saveable
 import cafe.adriel.voyager.core.model.ScreenModel
-import cafe.adriel.voyager.core.model.rememberScreenModel
 import cafe.adriel.voyager.navigator.LocalNavigator
 import cafe.adriel.voyager.navigator.currentOrThrow
 import com.mrboomdev.awery.ext.data.Setting
 import com.mrboomdev.awery.generated.*
 import com.mrboomdev.awery.sources.ExtensionsManager
 import com.mrboomdev.awery.ui.utils.LocalToaster
+import com.mrboomdev.awery.ui.utils.screenModel
 import kotlinx.serialization.Contextual
 import kotlinx.serialization.Serializable
 import org.jetbrains.compose.resources.painterResource
@@ -61,12 +63,12 @@ open class DefaultSearchRoute(
 	@Composable
 	override fun Content() {
 		val navigation = LocalNavigator.currentOrThrow
-		val model = rememberScreenModel { SearchModel() }
+		val screenModel = screenModel { SearchModel(it) }
 		val queryFocusRequested = remember { FocusRequester() }
 
 		val foundSources by remember { derivedStateOf {
 			ExtensionsManager.allSources.filter { source ->
-				model.query.text.trim().let { text ->
+				screenModel.query.text.trim().let { text ->
 					source.context.name?.contains(text) == true || source.context.id.contains(text)
 				}
 			}.sortedBy { it.context.name ?: it.context.id }
@@ -103,7 +105,7 @@ open class DefaultSearchRoute(
 						.padding(4.dp)
 						.fillMaxWidth(),
 
-					state = model.query,
+					state = screenModel.query,
 					lineLimits = TextFieldLineLimits.SingleLine,
 					cursorBrush = SolidColor(MaterialTheme.colorScheme.onSurface),
 
@@ -168,6 +170,6 @@ open class DefaultSearchRoute(
 	}
 }
 
-private class SearchModel: ScreenModel {
-	val query = TextFieldState()
+private class SearchModel(savedState: SavedStateHandle): ScreenModel {
+	val query by savedState.saveable(saver = TextFieldState.Saver) { TextFieldState() }
 }

shared/src/commonMain/kotlin/com/mrboomdev/awery/ui/screens/SplashScreen.kt

@@ -188,7 +188,7 @@ fun SplashScreen(
 					}
 				}
 
-				LoadingStatus.Finished -> stringResource(Res.string.status_finished)
+				LoadingStatus.Finished -> ""
 			}
 		)
 	}

shared/src/commonMain/kotlin/com/mrboomdev/awery/ui/utils/ScreenModels.kt

@@ -0,0 +1,23 @@
+package com.mrboomdev.awery.ui.utils
+
+import androidx.compose.runtime.Composable
+import androidx.lifecycle.SavedStateHandle
+import cafe.adriel.voyager.core.model.ScreenModel
+import cafe.adriel.voyager.core.screen.Screen
+import kotlin.reflect.KClass
+
+@Composable
+inline fun <reified T: ScreenModel> Screen.screenModel(
+	tag: String? = null,
+	noinline factory: (SavedStateHandle) -> T
+) = screenModel(T::class, tag, factory)
+
+/**
+ * This function allows us to use an [SavedStateHandle] to restore state after an process death :)
+ */
+@Composable
+expect fun <T: ScreenModel> Screen.screenModel(
+	clazz: KClass<T>,
+	tag: String? = null,
+	factory: (SavedStateHandle) -> T
+): T

shared/src/desktopMain/kotlin/com/mrboomdev/awery/ui/utils/ScreenModels.desktop.kt

@@ -0,0 +1,31 @@
+package com.mrboomdev.awery.ui.utils
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.lifecycle.SavedStateHandle
+import cafe.adriel.voyager.core.lifecycle.ScreenLifecycleStore
+import cafe.adriel.voyager.core.model.ScreenModel
+import cafe.adriel.voyager.core.model.ScreenModelStore
+import cafe.adriel.voyager.core.screen.Screen
+import kotlin.reflect.KClass
+
+// On desktop system don't kill your app, so we may just use a regular rememberScreenModel
+@Composable
+actual fun <T: ScreenModel> Screen.screenModel(
+	clazz: KClass<T>,
+	tag: String?,
+	factory: (SavedStateHandle) -> T
+): T {
+	val screenModelStore = remember(this) {
+		ScreenLifecycleStore.get(this) { ScreenModelStore }
+	}
+	
+	val rememberKey = "$key:${clazz.qualifiedName}:${tag ?: "default"}"
+	
+	@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+	return remember(rememberKey) {
+		screenModelStore.lastScreenModelKey.value = rememberKey
+		@Suppress("UNCHECKED_CAST")
+		screenModelStore.screenModels.getOrPut(rememberKey) { factory(SavedStateHandle()) } as T
+	}
+}