Issue #553: Add AndroidX ViewModel integration as separate module

demos/appyx-navigation/android/build.gradle.kts

@@ -45,6 +45,7 @@ dependencies {
     implementation(project(":appyx-interactions:appyx-interactions"))
     implementation(project(":appyx-components:stable:backstack:backstack"))
     implementation(project(":appyx-components:experimental:cards:cards"))
+    implementation(project(":utils:viewmodel-android"))
 
     implementation(libs.androidx.activity.compose)
     implementation(libs.androidx.appcompat)

demos/appyx-navigation/android/src/main/AndroidManifest.xml

@@ -8,7 +8,7 @@
         android:supportsRtl="true"
         android:theme="@style/Theme.Appyx">
         <activity
-            android:name="com.bumble.appyx.navigation.MainActivity"
+            android:name="com.bumble.appyx.navigation.node.viewModel.ViewModelExampleActivity"
             android:exported="true"
             android:theme="@style/Theme.Appyx.Starting">
             <intent-filter>

demos/appyx-navigation/android/src/main/kotlin/com/bumble/appyx/navigation/MainActivity.kt

@@ -12,17 +12,17 @@ import androidx.compose.ui.platform.LocalLifecycleOwner
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.ExperimentalUnitApi
 import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
-import com.bumble.appyx.navigation.integration.NodeActivity
 import com.bumble.appyx.navigation.integration.NodeHost
 import com.bumble.appyx.navigation.modality.BuildContext
 import com.bumble.appyx.navigation.node.container.ContainerNode
 import com.bumble.appyx.navigation.platform.AndroidLifecycle
 import com.bumble.appyx.navigation.ui.AppyxSampleAppTheme
+import com.bumble.appyx.utils.viewmodel.integration.ViewModelNodeActivity
 
 @ExperimentalUnitApi
 @ExperimentalAnimationApi
 @ExperimentalComposeUiApi
-class MainActivity : NodeActivity() {
+class MainActivity : ViewModelNodeActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         installSplashScreen()

demos/appyx-navigation/android/src/main/kotlin/com/bumble/appyx/navigation/node/viewModel/ViewModelExample.kt

@@ -0,0 +1,36 @@
+package com.bumble.appyx.navigation.node.viewModel
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.viewmodel.CreationExtras
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.getAndUpdate
+
+class ViewModelExample(startCounterValue: Int = 0) : ViewModel() {
+    private val _uiState = MutableStateFlow(UiState(startCounterValue))
+    val uiState: StateFlow<UiState> = _uiState
+
+    fun incrementCounter() {
+        _uiState.getAndUpdate { value ->
+            UiState(value.counter + 1)
+        }
+    }
+
+    companion object {
+        object StartCounterKey : CreationExtras.Key<Int>
+
+        val Factory: ViewModelProvider.Factory = viewModelFactory {
+            initializer {
+                val startCounterValue = this[StartCounterKey] ?: 0
+                ViewModelExample(
+                    startCounterValue
+                )
+            }
+        }
+    }
+}
+
+data class UiState(val counter: Int)

demos/appyx-navigation/android/src/main/kotlin/com/bumble/appyx/navigation/node/viewModel/ViewModelExampleActivity.kt

@@ -0,0 +1,39 @@
+package com.bumble.appyx.navigation.node.viewModel
+
+import android.os.Bundle
+import androidx.activity.compose.setContent
+import androidx.compose.animation.ExperimentalAnimationApi
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.platform.LocalLifecycleOwner
+import androidx.compose.ui.unit.ExperimentalUnitApi
+import androidx.core.splashscreen.SplashScreen.Companion.installSplashScreen
+import com.bumble.appyx.navigation.integration.NodeHost
+import com.bumble.appyx.navigation.platform.AndroidLifecycle
+import com.bumble.appyx.navigation.ui.AppyxSampleAppTheme
+import com.bumble.appyx.utils.viewmodel.integration.ViewModelNodeActivity
+
+@ExperimentalUnitApi
+@ExperimentalAnimationApi
+@ExperimentalComposeUiApi
+class ViewModelExampleActivity : ViewModelNodeActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        installSplashScreen()
+        super.onCreate(savedInstanceState)
+        setContent {
+            AppyxSampleAppTheme {
+                Surface(color = MaterialTheme.colorScheme.background) {
+                    NodeHost(
+                        lifecycle = AndroidLifecycle(LocalLifecycleOwner.current.lifecycle),
+                        integrationPoint = appyxV2IntegrationPoint,
+                    ) {
+                        ViewModelExampleNode(it)
+                    }
+                }
+            }
+        }
+    }
+
+}

demos/appyx-navigation/android/src/main/kotlin/com/bumble/appyx/navigation/node/viewModel/ViewModelExampleNode.kt

@@ -0,0 +1,68 @@
+package com.bumble.appyx.navigation.node.viewModel
+
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.Button
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import com.bumble.appyx.interactions.core.state.MutableSavedStateMap
+import com.bumble.appyx.navigation.modality.BuildContext
+import com.bumble.appyx.utils.viewmodel.node.ViewModelNode
+import com.bumble.appyx.utils.viewmodel.node.viewModels
+
+class ViewModelExampleNode(
+    buildContext: BuildContext,
+    private val startCounterValue: Int = (buildContext.savedStateMap?.getValue("startCounterValue") as? Int) ?: 10
+) : ViewModelNode(buildContext) {
+
+    private val viewModel: ViewModelExample by viewModels(
+        factoryProducer = {
+            viewModelFactory {
+                initializer {
+                    ViewModelExample(
+                        startCounterValue
+                    )
+                }
+            }
+        }
+    )
+
+    override fun onSaveInstanceState(state: MutableSavedStateMap) {
+        state["startCounterValue"] = viewModel.uiState.value.counter
+        super.onSaveInstanceState(state)
+    }
+
+
+    @Composable
+    @Override
+    override fun View(modifier: Modifier) {
+        val uiState by viewModel.uiState.collectAsState(initial = UiState(0))
+
+        Column(
+            modifier = modifier.fillMaxSize(),
+            verticalArrangement = Arrangement.spacedBy(24.dp)
+        ) {
+            Text(
+                modifier = Modifier.align(Alignment.CenterHorizontally),
+                text = "Counter: ${uiState.counter}",
+                fontSize = 45.sp
+            )
+
+            Button(
+                modifier = Modifier.align(Alignment.CenterHorizontally),
+                onClick = { viewModel.incrementCounter() }
+            ) {
+                Text("Increment")
+            }
+        }
+    }
+}

gradle/libs.versions.toml

@@ -26,13 +26,17 @@ uuid = "9.0.0"
 
 [libraries]
 androidx-activity-compose = "androidx.activity:activity-compose:1.7.2"
+androidx-activity = "androidx.activity:activity:1.7.2"
 androidx-appcompat = "androidx.appcompat:appcompat:1.3.1"
 androidx-arch-core-testing = "androidx.arch.core:core-testing:2.1.0"
 androidx-core = "androidx.core:core-ktx:1.9.0"
+androidx-core-core = "androidx.core:core:1.9.0"
 androidx-core-splashscreen = "androidx.core:core-splashscreen:1.0.0"
 androidx-lifecycle-common = { module = "androidx.lifecycle:lifecycle-common", version.ref = "androidx-lifecycle" }
 androidx-lifecycle-java8 = { module = "androidx.lifecycle:lifecycle-common-java8", version.ref = "androidx-lifecycle" }
 androidx-lifecycle-runtime = { module = "androidx.lifecycle:lifecycle-runtime-ktx", version.ref = "androidx-lifecycle" }
+androidx-lifecycle-viewmodel = { module = "androidx.lifecycle:lifecycle-viewmodel", version.ref = "androidx-lifecycle" }
+androidx-lifecycle-viewmodel-compose = { group = "androidx.lifecycle", name = "lifecycle-viewmodel-compose", version = "androidx-lifecycle" }
 androidx-navigation-compose = { module = "androidx.navigation:navigation-compose", version.ref = "androidx-navigation-compose" }
 androidx-test-espresso-core = "androidx.test.espresso:espresso-core:3.5.1"
 androidx-test-junit = "androidx.test.ext:junit:1.1.3"

settings.gradle.kts

@@ -82,6 +82,7 @@ include(
     ":utils:testing-ui-activity",
     ":utils:testing-unit-common",
     ":utils:multiplatform",
+    ":utils:viewmodel-android",
 )
 
 // do not remove this. Otherwise all multiplatform modules will produce clashing artifacts

utils/viewmodel-android/build.gradle.kts

@@ -0,0 +1,29 @@
+plugins {
+    id("com.bumble.appyx.android.library")
+    id("appyx-publish-android")
+}
+
+publishingPlugin {
+    artifactId = "utils-node-viewmodel"
+}
+
+appyx {
+    namespace.set("com.bumble.appyx.utils.viewmodel")
+
+    buildFeatures {
+        compose.set(true)
+    }
+}
+
+dependencies {
+    api(project(":appyx-navigation:appyx-navigation"))
+    api(project(":appyx-interactions:appyx-interactions"))
+    api(libs.androidx.activity)
+    api(libs.androidx.appcompat)
+    api(libs.androidx.lifecycle.viewmodel)
+    implementation(libs.androidx.lifecycle.viewmodel.compose)
+    debugApi(libs.compose.runtime)
+    implementation(libs.androidx.core.core)
+    implementation(libs.androidx.lifecycle.common)
+    releaseImplementation(libs.compose.runtime)
+}

utils/viewmodel-android/lint-baseline.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<issues format="6" by="lint 7.1.3" type="baseline" client="gradle" dependencies="false"
+    name="AGP (7.1.3)" variant="all" version="7.1.3">
+
+</issues>

utils/viewmodel-android/src/main/AndroidManifest.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest />

utils/viewmodel-android/src/main/kotlin/com/bumble/appyx/utils/viewmodel/integration/ActivityIntegrationPointWithViewModelStoreProvider.kt

@@ -0,0 +1,13 @@
+package com.bumble.appyx.utils.viewmodel.integration
+
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import com.bumble.appyx.navigation.integration.ActivityIntegrationPoint
+
+open class ActivityIntegrationPointWithViewModelStoreProvider(
+    activity: ComponentActivity,
+    savedInstanceState: Bundle?,
+) : ActivityIntegrationPoint(activity, savedInstanceState) {
+
+    open val viewModelStoreProvider = ViewModelStoreProvider.getInstance(activity)
+}

utils/viewmodel-android/src/main/kotlin/com/bumble/appyx/utils/viewmodel/integration/ViewModelNodeActivity.kt

@@ -0,0 +1,56 @@
+package com.bumble.appyx.utils.viewmodel.integration
+
+import android.content.Intent
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import com.bumble.appyx.navigation.integrationpoint.IntegrationPointProvider
+
+/**
+ * Helper class for root [Node] integration into projects using [AppCompatActivity].
+ *
+ * See [NodeComponentActivity] for building upon [ComponentActivity].
+ *
+ * Also offers base functionality to satisfy dependencies of Android-related functionality
+ * down the tree via [appyxV2IntegrationPoint]:
+ * - [ActivityStarter]
+ * - [PermissionRequester]
+ *
+ * Feel free to not extend this and use your own integration point - in this case,
+ * don't forget to take a look here what methods needs to be forwarded to the root Node.
+ */
+open class ViewModelNodeActivity : AppCompatActivity(), IntegrationPointProvider {
+
+    override lateinit var appyxV2IntegrationPoint: ActivityIntegrationPointWithViewModelStoreProvider
+        protected set
+
+    protected open fun createIntegrationPoint(savedInstanceState: Bundle?) =
+        ActivityIntegrationPointWithViewModelStoreProvider(
+            activity = this,
+            savedInstanceState = savedInstanceState
+        )
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        appyxV2IntegrationPoint = createIntegrationPoint(savedInstanceState)
+    }
+
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        super.onActivityResult(requestCode, resultCode, data)
+        appyxV2IntegrationPoint.onActivityResult(requestCode, resultCode, data)
+    }
+
+    override fun onRequestPermissionsResult(
+        requestCode: Int,
+        permissions: Array<out String>,
+        grantResults: IntArray
+    ) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
+        appyxV2IntegrationPoint.onRequestPermissionsResult(requestCode, permissions, grantResults)
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        appyxV2IntegrationPoint.onSaveInstanceState(outState)
+    }
+
+}

utils/viewmodel-android/src/main/kotlin/com/bumble/appyx/utils/viewmodel/integration/ViewModelStoreProvider.kt

@@ -0,0 +1,30 @@
+package com.bumble.appyx.utils.viewmodel.integration
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.ViewModelStore
+import androidx.lifecycle.ViewModelStoreOwner
+import androidx.lifecycle.get
+
+open class ViewModelStoreProvider : ViewModel() {
+    private val viewModelStores = mutableMapOf<String, ViewModelStore>()
+    fun clear(nodeId: String) {
+        val viewModelStore = viewModelStores.remove(nodeId)
+        viewModelStore?.clear()
+    }
+
+    override fun onCleared() {
+        super.onCleared()
+        viewModelStores.values.forEach { it.clear() }
+        viewModelStores.clear()
+    }
+
+    fun getViewModelStoreForNode(nodeId: String): ViewModelStore =
+        viewModelStores.getOrPut(nodeId) { ViewModelStore() }
+
+    companion object {
+        fun getInstance(viewModelStoreOwner: ViewModelStoreOwner): ViewModelStoreProvider {
+            return ViewModelProvider(viewModelStoreOwner).get()
+        }
+    }
+}

utils/viewmodel-android/src/main/kotlin/com/bumble/appyx/utils/viewmodel/node/ViewModelNode.kt

@@ -0,0 +1,32 @@
+package com.bumble.appyx.utils.viewmodel.node
+
+import androidx.lifecycle.ViewModelStore
+import androidx.lifecycle.ViewModelStoreOwner
+import com.bumble.appyx.navigation.lifecycle.DefaultPlatformLifecycleObserver
+import com.bumble.appyx.navigation.modality.BuildContext
+import com.bumble.appyx.navigation.node.Node
+import com.bumble.appyx.utils.viewmodel.integration.ActivityIntegrationPointWithViewModelStoreProvider
+
+open class ViewModelNode(
+    buildContext: BuildContext,
+) : Node(buildContext), ViewModelStoreOwner {
+
+    private val nodeViewModelStore by lazy {
+        (integrationPoint as ActivityIntegrationPointWithViewModelStoreProvider).viewModelStoreProvider.getViewModelStoreForNode(
+            id
+        )
+    }
+
+    init {
+        lifecycle.addObserver(object : DefaultPlatformLifecycleObserver {
+            override fun onDestroy() {
+                if (!(integrationPoint as ActivityIntegrationPointWithViewModelStoreProvider).isChangingConfigurations) {
+                    (integrationPoint as ActivityIntegrationPointWithViewModelStoreProvider).viewModelStoreProvider.clear(id)
+                }
+            }
+        })
+    }
+
+    override val viewModelStore: ViewModelStore
+        get() = nodeViewModelStore
+}