Initially copy and adapt more ViewModel code from Compose Multiplatform

The added code in the "common" module is temporarily commented out to see whether it's necessary. Under such a condition, an exception is thrown with the message "No ViewModelStoreOwner was provided via LocalViewModelStoreOwner" on JS DOM in an internal app but not in the demo.

common/build.gradle.kts

@@ -56,6 +56,14 @@ kotlin {
                 // see: https://github.com/varabyte/kobweb/blob/main/frontend/kobweb-compose/build.gradle.kts
                 api("com.varabyte.kobweb:kobweb-compose:${DependencyVersions.kobweb}")
                 implementation("com.huanshankeji:compose-html-common:${DependencyVersions.huanshankejiComposeHtml}")
+
+                // TODO not used yet
+                /*
+                The UI module depends on the lifecycle module to use `androidx.lifecycle.ViewModelStoreOwner`.
+                See https://github.com/JetBrains/compose-multiplatform-core/blob/jb-main/compose/ui/ui/build.gradle#L87.
+                This is actually only needed for JS DOM.
+                 */
+                //implementation(cpnProject(project, ":lifecycle-viewmodel"))
             }
         }
     }

common/src/jsMain/kotlin/com/huanshankeji/compose/ui/platform/DefaultViewModelOwnerStore.kt

@@ -0,0 +1,25 @@
+package com.huanshankeji.compose.ui.platform
+
+/*
+// copied and adapted from "DefaultViewModelOwnerStore.skiko.kt" in `androidx.compose.ui.platform`
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.InternalComposeApi
+import androidx.compose.runtime.staticCompositionLocalOf
+import androidx.lifecycle.ViewModelStoreOwner
+
+/**
+ * Internal helper to provide [ViewModelStoreOwner] from Compose UI module.
+ * In applications please use [androidx.lifecycle.viewmodel.compose.LocalViewModelStoreOwner].
+ *
+ * @hide
+ */
+internal val LocalInternalViewModelStoreOwner = staticCompositionLocalOf<ViewModelStoreOwner?> {
+    null
+}
+
+@InternalComposeApi
+@Composable
+fun findComposeDefaultViewModelStoreOwner(): ViewModelStoreOwner? =
+    LocalInternalViewModelStoreOwner.current
+*/

common/src/jsMain/kotlin/com/huanshankeji/compose/ui/window/ComposeWindow.js.kt

@@ -0,0 +1,28 @@
+package com.huanshankeji.compose.ui.window
+
+/*
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.Composition
+import androidx.compose.runtime.CompositionLocalProvider
+import com.huanshankeji.compose.ui.platform.LocalInternalViewModelStoreOwner
+import org.jetbrains.compose.web.dom.DOMScope
+import org.jetbrains.compose.web.renderComposableInBody
+import org.w3c.dom.HTMLBodyElement
+
+// TODO not used yet so made private
+private fun renderComposableInBodyWithLifecycle(
+    content: @Composable DOMScope<HTMLBodyElement>.() -> Unit
+): Composition =
+    renderComposableInBody {
+        // copied and adapted from `ComposeWindow` in "ComposeWindow.web.kt" in `androidx.compose.ui.window`
+        // also see `ComposeViewport` on Wasm JS
+        CompositionLocalProvider(
+            //LocalSystemTheme provides systemThemeObserver.currentSystemTheme.value, // TODO add back if needed one day
+            //LocalLifecycleOwner provides this, // TODO
+            LocalInternalViewModelStoreOwner provides TODO(),
+            content = {
+                content()
+            }
+        )
+    }
+*/

lifecycle-viewmodel/src/commonMain/kotlin/ViewModel.kt

@@ -1,13 +1,56 @@
 package com.huanshankeji.androidx.lifecycle.viewmodel.compose
 
 import androidx.compose.runtime.Composable
+import androidx.lifecycle.HasDefaultViewModelProviderFactory
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.ViewModelStoreOwner
 import androidx.lifecycle.viewmodel.CreationExtras
+import kotlin.reflect.KClass
 
 // https://www.jetbrains.com/help/kotlin-multiplatform-dev/compose-viewmodel.html
 
+// copied and adapted from "ViewModel.kt" in `androidx.lifecycle.viewmodel.compose`
+
+
+// `expect` can be removed if `expect object LocalViewModelStoreOwner` is added.
+@PublishedApi
+@Composable
+internal expect fun defaultViewModelStoreOwner(): ViewModelStoreOwner
+
+@PublishedApi
+internal fun ViewModelStoreOwner.defaultCreationExtras(): CreationExtras =
+    if (this is HasDefaultViewModelProviderFactory) {
+        this.defaultViewModelCreationExtras
+    } else {
+        CreationExtras.Empty
+    }
+
+
+@Composable
+expect fun <VM : ViewModel> viewModel(
+    modelClass: KClass<VM>,
+    viewModelStoreOwner: ViewModelStoreOwner = defaultViewModelStoreOwner(),
+    key: String? = null,
+    factory: ViewModelProvider.Factory? = null,
+    extras: CreationExtras = viewModelStoreOwner.defaultCreationExtras()
+): VM
+
 @Composable
 expect inline fun <reified VM : ViewModel> viewModel(
+    viewModelStoreOwner: ViewModelStoreOwner = defaultViewModelStoreOwner(),
     key: String? = null,
     noinline initializer: CreationExtras.() -> VM
 ): VM
+
+@Deprecated(
+    "Use the one with a `viewModelStoreOwner` parameter instead. " +
+            "This function might be removed in the future. " +
+            "Make sure you call this function with named arguments please so your source still compile when this is removed."
+)
+@Composable
+inline fun <reified VM : ViewModel> viewModel(
+    key: String? = null,
+    noinline initializer: CreationExtras.() -> VM
+): VM =
+    viewModel(defaultViewModelStoreOwner(), key, initializer)

lifecycle-viewmodel/src/composeUiMain/kotlin/ViewModel.composeUi.kt

@@ -2,9 +2,33 @@ package com.huanshankeji.androidx.lifecycle.viewmodel.compose
 
 import androidx.compose.runtime.Composable
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.ViewModelStoreOwner
 import androidx.lifecycle.viewmodel.CreationExtras
-import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.lifecycle.viewmodel.compose.LocalViewModelStoreOwner
+import kotlin.reflect.KClass
+import androidx.lifecycle.viewmodel.compose.viewModel as composeUiViewModel
 
+// copied and adapted from "ViewModel.kt" in `androidx.lifecycle.viewmodel.compose`
+@PublishedApi
 @Composable
-actual inline fun <reified VM : ViewModel> viewModel(key: String?, noinline initializer: CreationExtras.() -> VM): VM =
-    viewModel(key = key, initializer = initializer)
+internal actual fun defaultViewModelStoreOwner(): ViewModelStoreOwner =
+    checkNotNull(LocalViewModelStoreOwner.current) {
+        "No ViewModelStoreOwner was provided via LocalViewModelStoreOwner"
+    }
+
+@Composable
+actual fun <VM : ViewModel> viewModel(
+    modelClass: KClass<VM>,
+    viewModelStoreOwner: ViewModelStoreOwner,
+    key: String?,
+    factory: ViewModelProvider.Factory?,
+    extras: CreationExtras
+): VM =
+    composeUiViewModel(modelClass, viewModelStoreOwner, key, factory, extras)
+
+@Composable
+actual inline fun <reified VM : ViewModel> viewModel(
+    viewModelStoreOwner: ViewModelStoreOwner, key: String?, noinline initializer: CreationExtras.() -> VM
+): VM =
+    composeUiViewModel(viewModelStoreOwner, key, initializer)

lifecycle-viewmodel/src/jsMain/kotlin/LocalViewModelStoreOwner.kt

@@ -0,0 +1,26 @@
+package com.huanshankeji.androidx.lifecycle.viewmodel.compose
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.ProvidedValue
+import androidx.compose.runtime.compositionLocalOf
+import androidx.lifecycle.ViewModelStoreOwner
+
+// copied and adapted from "LocalViewModelStoreOwner.kt" and "LocalViewModelStoreOwner.jb.kt" in `androidx.lifecycle.viewmodel.compose`
+
+object LocalViewModelStoreOwner {
+    private val LocalViewModelStoreOwner =
+        compositionLocalOf<ViewModelStoreOwner?> { null }
+    val current: ViewModelStoreOwner?
+        @Composable
+        get() = LocalViewModelStoreOwner.current ?: findViewTreeViewModelStoreOwner()
+
+    infix fun provides(viewModelStoreOwner: ViewModelStoreOwner):
+            ProvidedValue<ViewModelStoreOwner?> {
+        return LocalViewModelStoreOwner.provides(viewModelStoreOwner)
+    }
+}
+
+@Composable
+internal fun findViewTreeViewModelStoreOwner(): ViewModelStoreOwner? =
+    // TODO
+    null //findComposeDefaultViewModelStoreOwner()

lifecycle-viewmodel/src/jsMain/kotlin/ViewModel.js.kt

@@ -1,10 +1,74 @@
 package com.huanshankeji.androidx.lifecycle.viewmodel.compose
 
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.remember
+import androidx.lifecycle.HasDefaultViewModelProviderFactory
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.ViewModelStoreOwner
 import androidx.lifecycle.viewmodel.CreationExtras
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
+import kotlin.reflect.KClass
+
+// copied and adapted from "ViewModel.kt" in `androidx.lifecycle.viewmodel.compose`
+
+
+
+@PublishedApi
+@Composable
+internal actual fun defaultViewModelStoreOwner(): ViewModelStoreOwner =
+    checkNotNull(LocalViewModelStoreOwner.current) {
+        "No ViewModelStoreOwner was provided via LocalViewModelStoreOwner"
+    }
+
 
 @Composable
-actual inline fun <reified VM : ViewModel> viewModel(key: String?, noinline initializer: CreationExtras.() -> VM): VM =
+actual fun <VM : ViewModel> viewModel(
+    modelClass: KClass<VM>,
+    viewModelStoreOwner: ViewModelStoreOwner,
+    key: String?,
+    factory: ViewModelProvider.Factory?,
+    extras: CreationExtras
+): VM = viewModelStoreOwner.get(modelClass, key, factory, extras)
+
+@Composable
+actual inline fun <reified VM : ViewModel> viewModel(
+    viewModelStoreOwner: ViewModelStoreOwner,
+    key: String?,
+    noinline initializer: CreationExtras.() -> VM
+): VM = viewModel(
+    VM::class,
+    viewModelStoreOwner,
+    key,
+    viewModelFactory { initializer(initializer) },
+    viewModelStoreOwner.defaultCreationExtras()
+)
+
+// TODO remove
+/*
+@Composable
+actual inline fun <reified VM : ViewModel> viewModel(
+    viewModelStoreOwner: ViewModelStoreOwner, key: String?, noinline initializer: CreationExtras.() -> VM
+): VM =
     remember(key) { CreationExtras.Empty.initializer() }
+*/
+
+internal fun <VM : ViewModel> ViewModelStoreOwner.get(
+    modelClass: KClass<VM>,
+    key: String?,
+    factory: ViewModelProvider.Factory?,
+    extras: CreationExtras
+): VM {
+    val provider = if (factory != null) {
+        ViewModelProvider.create(this.viewModelStore, factory, extras)
+    } else if (this is HasDefaultViewModelProviderFactory) {
+        ViewModelProvider.create(this.viewModelStore, this.defaultViewModelProviderFactory, extras)
+    } else {
+        ViewModelProvider.create(this)
+    }
+    return if (key != null) {
+        provider[key, modelClass]
+    } else {
+        provider[modelClass]
+    }
+}