feat: compose saved state handle

Added support to use composeValueManager inside an AAC ViewModel and restore values using SavedStateHandle

compose/android/src/dev/programadorthi/state/compose/ComposeValueManagerSavedStateHandle.kt

@@ -0,0 +1,56 @@
+package dev.programadorthi.state.compose
+
+import androidx.compose.runtime.SnapshotMutationPolicy
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.saveable.Saver
+import androidx.compose.runtime.saveable.SaverScope
+import androidx.lifecycle.SavedStateHandle
+import dev.programadorthi.state.core.ValueManager
+
+internal class ComposeValueManagerSavedStateHandle<T>(
+    private val valueManager: ValueManager<T>,
+    private val policy: SnapshotMutationPolicy<T>,
+    private val savedStateHandle: SavedStateHandle,
+    stateRestorationKey: String,
+    saver: Saver<T, out Any>,
+) : SaverScope, ValueManager<T> by valueManager {
+
+    private val valueManagerSaver = ValueManagerSaver(saver) { valueManager }
+    private val state = mutableStateOf(valueManager.value, policy)
+    private val key = "$KEY:$stateRestorationKey"
+    private val canBeSaved: Boolean
+
+    init {
+        val restoredValue = savedStateHandle.remove<Any>(key)
+
+        // By default SaveStateHandle throw exceptions when can't save the value in a Bundle
+        savedStateHandle[key] = valueManager.value
+        canBeSaved = true
+
+        valueManager.collect { newValue ->
+            state.value = newValue
+            savedStateHandle[key] = with(valueManagerSaver) {
+                save(valueManager)
+            }
+        }
+
+        if (restoredValue != null) {
+            valueManagerSaver.restore(restoredValue)
+        }
+    }
+
+    override var value: T
+        get() = state.value
+        set(value) {
+            val current = state.value
+            if (policy.equivalent(current, value).not()) {
+                valueManager.value = value
+            }
+        }
+
+    override fun canBeSaved(value: Any): Boolean = canBeSaved
+
+    private companion object {
+        private const val KEY = "dev.programadorthi.state.compose.ComposeValueManagerState.android"
+    }
+}

compose/android/src/dev/programadorthi/state/compose/ValueManagerAsState.android.kt

@@ -0,0 +1,70 @@
+package dev.programadorthi.state.compose
+
+import androidx.compose.runtime.SnapshotMutationPolicy
+import androidx.compose.runtime.saveable.Saver
+import androidx.compose.runtime.saveable.autoSaver
+import androidx.compose.runtime.structuralEqualityPolicy
+import androidx.lifecycle.SavedStateHandle
+import dev.programadorthi.state.core.ValueManager
+import dev.programadorthi.state.core.extension.basicValueManager
+import kotlin.properties.PropertyDelegateProvider
+import kotlin.properties.ReadWriteProperty
+import kotlin.reflect.KProperty
+
+public fun <T> composeValueManager(
+    initialValue: T,
+    stateRestorationKey: String,
+    savedStateHandle: SavedStateHandle,
+    policy: SnapshotMutationPolicy<T> = structuralEqualityPolicy(),
+    saver: Saver<T, out Any> = autoSaver(),
+): ValueManager<T> = ComposeValueManagerSavedStateHandle(
+    valueManager = basicValueManager(initialValue),
+    policy = policy,
+    savedStateHandle = savedStateHandle,
+    stateRestorationKey = stateRestorationKey,
+    saver = saver,
+)
+
+public fun <T> composeValueManager(
+    initialValue: T,
+    savedStateHandle: SavedStateHandle,
+    policy: SnapshotMutationPolicy<T> = structuralEqualityPolicy(),
+    saver: Saver<T, out Any> = autoSaver(),
+): ComposeValueManager<T> = basicValueManager(initialValue).asState(
+    savedStateHandle = savedStateHandle,
+    policy = policy,
+    saver = saver,
+)
+
+public fun <T> ValueManager<T>.asState(
+    savedStateHandle: SavedStateHandle,
+    policy: SnapshotMutationPolicy<T> = structuralEqualityPolicy(),
+    saver: Saver<T, out Any> = autoSaver(),
+): ComposeValueManager<T> = PropertyDelegateProvider { _, property ->
+    val state = asState(
+        stateRestorationKey = property.name,
+        savedStateHandle = savedStateHandle,
+        policy = policy,
+        saver = saver,
+    )
+    object : ReadWriteProperty<Any?, T> {
+        override fun getValue(thisRef: Any?, property: KProperty<*>): T = state.value
+
+        override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) {
+            state.value = value
+        }
+    }
+}
+
+public fun <T> ValueManager<T>.asState(
+    stateRestorationKey: String,
+    savedStateHandle: SavedStateHandle,
+    policy: SnapshotMutationPolicy<T> = structuralEqualityPolicy(),
+    saver: Saver<T, out Any> = autoSaver(),
+): ValueManager<T> = ComposeValueManagerSavedStateHandle(
+    valueManager = this,
+    policy = policy,
+    savedStateHandle = savedStateHandle,
+    stateRestorationKey = stateRestorationKey,
+    saver = saver,
+)

compose/build.gradle.kts

@@ -1,6 +1,7 @@
 plugins {
     kotlin("multiplatform")
     id("org.jetbrains.compose")
+    id("com.android.library")
     id("com.vanniktech.maven.publish")
 }
 
@@ -9,6 +10,10 @@ applyBasicSetup()
 darwinTargetsFramework()
 
 kotlin {
+    androidTarget {
+        publishLibraryVariants("release")
+    }
+
     sourceSets {
         commonMain {
             dependencies {
@@ -23,5 +28,40 @@ kotlin {
                 implementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.8.0")
             }
         }
+        androidMain {
+            dependencies {
+                implementation("androidx.activity:activity-ktx:1.8.2")
+                implementation("androidx.fragment:fragment-ktx:1.6.2")
+            }
+        }
+    }
+}
+
+android {
+    namespace = "dev.programadorthi.state.compose"
+    compileSdk = 34
+
+    defaultConfig {
+        minSdk = 23
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_1_8
+        targetCompatibility = JavaVersion.VERSION_1_8
+    }
+
+    buildTypes {
+        getByName("release") {
+            isMinifyEnabled = false
+        }
     }
+
+    packaging {
+        resources {
+            excludes += "/META-INF/{AL2.0,LGPL2.1}"
+        }
+    }
+
+    sourceSets["main"].manifest.srcFile("src/AndroidManifest.xml")
+    sourceSets["main"].res.srcDirs("src/res")
 }

compose/common/src/dev/programadorthi/state/compose/ComposeValueManagerState.kt

@@ -18,6 +18,7 @@ internal class ComposeValueManagerState<T>(
 
     private val valueManagerSaver = ValueManagerSaver(saver) { valueManager }
     private val state = mutableStateOf(valueManager.value, policy)
+    private val key = "$KEY:$stateRestorationKey"
 
     private var entry: SaveableStateRegistry.Entry? = null
 
@@ -55,17 +56,17 @@ internal class ComposeValueManagerState<T>(
     }
 
     private fun tryRestoreAndRegister() {
-        val keyToRestore = stateRestorationKey.takeIf { it.isNullOrBlank().not() } ?: return
+        if (stateRestorationKey.isNullOrBlank()) return
         val registry = stateRegistry ?: return
-        registry.consumeRestored(keyToRestore)?.let { consumed ->
+        registry.consumeRestored(key)?.let { consumed ->
             valueManagerSaver.restore(consumed)
         }
 
         register()
     }
 
     private fun register() {
-        val keyToRestore = stateRestorationKey.takeIf { it.isNullOrBlank().not() } ?: return
+        if (stateRestorationKey.isNullOrBlank()) return
         val registry = stateRegistry ?: return
 
         val saveable = {
@@ -77,7 +78,11 @@ internal class ComposeValueManagerState<T>(
             "$value cannot be saved using the current SaveableStateRegistry"
         }
         if (registry.canBeSaved(toSave)) {
-            entry = registry.registerProvider(keyToRestore, saveable)
+            entry = registry.registerProvider(key, saveable)
         }
     }
+
+    private companion object {
+        private const val KEY = "dev.programadorthi.state.compose.ComposeValueManagerState"
+    }
 }

core/android/src/dev/programadorthi/state/core/AndroidValueManager.kt

@@ -13,6 +13,10 @@ import kotlin.properties.PropertyDelegateProvider
 import kotlin.properties.ReadWriteProperty
 import kotlin.reflect.KProperty
 
+private const val KEY = "dev.programadorthi.state.core.AndroidValueManagerState"
+
+private fun String.compoundKey(): String = "$KEY:$this"
+
 public typealias AndroidValueManager<T> = PropertyDelegateProvider<Any?, ReadWriteProperty<Any?, T>>
 
 public fun <T> androidValueManager(
@@ -32,7 +36,7 @@ public fun <T> androidValueManager(
     )
     val state = AndroidValueManagerState(
         valueManager = valueManager,
-        stateRestorationKey = stateRestorationKey,
+        stateRestorationKey = stateRestorationKey.compoundKey(),
         savedStateHandle = savedStateHandle,
         saver = saver,
     )
@@ -162,15 +166,16 @@ private fun <T> ViewModelStoreOwner.ownerValueManager(
         changeHandler = changeHandler,
         errorHandler = errorHandler,
     )
+    val key = stateRestorationKey.compoundKey()
     val provider = ViewModelProvider(
         owner = this,
         factory = AndroidValueManagerStateFactory(
-            stateRestorationKey = stateRestorationKey,
+            stateRestorationKey = key,
             valueManager = valueManager,
             saver = saver,
         )
     )
-    val state = provider[stateRestorationKey, AndroidValueManagerState::class.java]
+    val state = provider[key, AndroidValueManagerState::class.java]
     @Suppress("UNCHECKED_CAST")
     state as AndroidValueManagerState<T>
     state.valueManager

samples/compose/norris-facts/android/build.gradle.kts

@@ -33,4 +33,5 @@ dependencies {
     implementation("androidx.activity:activity-compose:1.8.2")
     implementation("androidx.appcompat:appcompat:1.6.1")
     implementation("androidx.core:core-ktx:1.12.0")
+    implementation("androidx.lifecycle:lifecycle-viewmodel-compose:2.6.1")
 }

samples/compose/norris-facts/android/src/main/AndroidManifest.xml

@@ -4,14 +4,17 @@
     <uses-permission android:name="android.permission.INTERNET" />
 
     <application
-            android:allowBackup="false"
-            android:supportsRtl="true"
-            android:theme="@style/Theme.AppCompat.Light.NoActionBar">
-            <activity android:name=".MainActivity" android:exported="true">
+        android:allowBackup="false"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.AppCompat.Light.NoActionBar">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true">
             <intent-filter>
-                <action android:name="android.intent.action.MAIN"/>
-                <category android:name="android.intent.category.LAUNCHER"/>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <activity android:name=".ComposeActivity" android:exported="false" />
     </application>
 </manifest>

samples/compose/norris-facts/android/src/main/java/dev/programadorthi/android/ComposeActivity.kt

@@ -0,0 +1,48 @@
+package dev.programadorthi.android
+
+import android.os.Bundle
+import androidx.activity.compose.setContent
+import androidx.appcompat.app.AppCompatActivity
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.material.Button
+import androidx.compose.material.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.dp
+import androidx.lifecycle.viewmodel.compose.viewModel
+
+class ComposeActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContent {
+            Content()
+        }
+    }
+
+    @Composable
+    private fun Content(
+        viewModel: ComposeViewModel = viewModel()
+    ) {
+        Column(
+            modifier = Modifier.fillMaxSize(),
+            verticalArrangement = Arrangement.Center,
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Text("Counter: ${viewModel.state}")
+            Spacer(modifier = Modifier.height(16.dp))
+            Button(onClick = viewModel::decrement) {
+                Text("Decrement")
+            }
+            Spacer(modifier = Modifier.height(16.dp))
+            Button(onClick = viewModel::increment) {
+                Text("Increment")
+            }
+        }
+    }
+}

samples/compose/norris-facts/android/src/main/java/dev/programadorthi/android/ComposeViewModel.kt

@@ -0,0 +1,21 @@
+package dev.programadorthi.android
+
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.ViewModel
+import dev.programadorthi.state.compose.composeValueManager
+
+class ComposeViewModel(savedStateHandle: SavedStateHandle) : ViewModel() {
+
+    private var composeState by composeValueManager(0, savedStateHandle)
+
+    val state: Int
+        get() = composeState
+
+    fun increment() {
+        composeState++
+    }
+
+    fun decrement() {
+        composeState--
+    }
+}