BREAKING: Replaces ComposeScreenViewFactory with `ScreenComposableF…

…actory`

`ScreenComposableFactory` replaces `ComposeScreenViewFactory`, and `ComposeScreen` no longer extends `AndroidScreen`. Compose support is now a first class citizen, instead of a hack bolted on to View support.

Unfortunately, `ViewEnvironment.withComposeInteropSupport()` (see below) now must be called near the root of a Workflow app to enable the seamless Compose > Classic > Compose handling that used to be built in to `WorkflowRendering` and `ComposeScreenViewFactory`. This means that call is required for Compose support for built in rendering types like `BodyAndOverlaysScreen` and `BackStackScreen`, which so far are backed only by classic View implementations.

Also introduces:

- `Screen.toComposableFactory()`, used by `WorkflowRendering()` in the same way that `WorkflowViewStub` uses `Screen.toViewFactory()`

- `ScreenComposableFactoryFinder`, a `ViewEnvironment`-based strategy object used by `Screen.toComposableFactory()` the same way that `Screen.toViewFactory()` uses `ScreenViewFactoryFinder`. The default implementation provides Compose bindings for `NamedScreen` and `EnvironmentScreen`, fixing #546.

- `ViewEnvironment.withComposeInteropSupport()`, which wraps the found `ScreenComposableFactoryFinder` and `ScreenViewFactoryFinder` with implementations that allow Compose contexts to handle renderings bound only to `ScreenViewFactory`, and classic contexts to handle renderings bound only to `ScreenComposableFactory`. Replaces the logic that used to be in the private `ScreenViewFactory.asComposeViewFactory()` extension in `WorkflowRendering()`.

Fixes #546

samples/compose-samples/src/main/java/com/squareup/sample/compose/hellocompose/HelloBinding.kt

@@ -8,10 +8,10 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import com.squareup.sample.compose.hellocompose.HelloWorkflow.Rendering
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.compose.composeScreenViewFactory
+import com.squareup.workflow1.ui.compose.screenComposableFactory
 
 @OptIn(WorkflowUiExperimentalApi::class)
-val HelloBinding = composeScreenViewFactory<Rendering> { rendering, _ ->
+val HelloBinding = screenComposableFactory<Rendering> { rendering, _ ->
   Text(
     rendering.message,
     modifier = Modifier

samples/compose-samples/src/main/java/com/squareup/sample/compose/hellocomposebinding/HelloBinding.kt

@@ -9,11 +9,11 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.tooling.preview.Preview
 import com.squareup.sample.compose.hellocomposebinding.HelloWorkflow.Rendering
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.compose.composeScreenViewFactory
+import com.squareup.workflow1.ui.compose.screenComposableFactory
 import com.squareup.workflow1.ui.compose.tooling.Preview
 
 @OptIn(WorkflowUiExperimentalApi::class)
-val HelloBinding = composeScreenViewFactory<Rendering> { rendering, _ ->
+val HelloBinding = screenComposableFactory<Rendering> { rendering, _ ->
   Text(
     rendering.message,
     modifier = Modifier

samples/compose-samples/src/main/java/com/squareup/sample/compose/hellocomposebinding/HelloBindingActivity.kt

@@ -17,6 +17,7 @@ import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.ViewRegistry
 import com.squareup.workflow1.ui.WorkflowLayout
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.compose.withComposeInteropSupport
 import com.squareup.workflow1.ui.compose.withCompositionRoot
 import com.squareup.workflow1.ui.container.withEnvironment
 import com.squareup.workflow1.ui.plus
@@ -25,13 +26,15 @@ import kotlinx.coroutines.flow.StateFlow
 
 @OptIn(WorkflowUiExperimentalApi::class)
 private val viewEnvironment =
-  (ViewEnvironment.EMPTY + ViewRegistry(HelloBinding)).withCompositionRoot { content ->
-    MaterialTheme(content = content)
-  }
+  (ViewEnvironment.EMPTY + ViewRegistry(HelloBinding))
+    .withCompositionRoot { content ->
+      MaterialTheme(content = content)
+    }
+    .withComposeInteropSupport()
 
 /**
  * Demonstrates how to create and display a view factory with
- * [composeScreenViewFactory][com.squareup.workflow1.ui.compose.composeScreenViewFactory].
+ * [screenComposableFactory][com.squareup.workflow1.ui.compose.screenComposableFactory].
  */
 class HelloBindingActivity : AppCompatActivity() {
   @OptIn(WorkflowUiExperimentalApi::class)

samples/compose-samples/src/main/java/com/squareup/sample/compose/hellocomposeworkflow/HelloComposeWorkflowActivity.kt

@@ -10,9 +10,13 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.squareup.workflow1.WorkflowExperimentalRuntime
 import com.squareup.workflow1.config.AndroidRuntimeConfigTools
+import com.squareup.workflow1.mapRendering
 import com.squareup.workflow1.ui.Screen
+import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowLayout
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.compose.withComposeInteropSupport
+import com.squareup.workflow1.ui.container.withEnvironment
 import com.squareup.workflow1.ui.renderWorkflowIn
 import kotlinx.coroutines.flow.StateFlow
 
@@ -30,7 +34,9 @@ class HelloComposeWorkflowActivity : AppCompatActivity() {
     @OptIn(WorkflowUiExperimentalApi::class)
     val renderings: StateFlow<Screen> by lazy {
       renderWorkflowIn(
-        workflow = HelloWorkflow,
+        workflow = HelloWorkflow.mapRendering {
+          it.withEnvironment(ViewEnvironment.EMPTY.withComposeInteropSupport())
+        },
         scope = viewModelScope,
         savedStateHandle = savedState,
         runtimeConfig = AndroidRuntimeConfigTools.getAppWorkflowRuntimeConfig()

samples/compose-samples/src/main/java/com/squareup/sample/compose/inlinerendering/InlineRenderingActivity.kt

@@ -10,9 +10,13 @@ import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import com.squareup.workflow1.WorkflowExperimentalRuntime
 import com.squareup.workflow1.config.AndroidRuntimeConfigTools
+import com.squareup.workflow1.mapRendering
 import com.squareup.workflow1.ui.Screen
+import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowLayout
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.compose.withComposeInteropSupport
+import com.squareup.workflow1.ui.container.withEnvironment
 import com.squareup.workflow1.ui.renderWorkflowIn
 import kotlinx.coroutines.flow.StateFlow
 
@@ -34,7 +38,9 @@ class InlineRenderingActivity : AppCompatActivity() {
     @OptIn(WorkflowUiExperimentalApi::class)
     val renderings: StateFlow<Screen> by lazy {
       renderWorkflowIn(
-        workflow = InlineRenderingWorkflow,
+        workflow = InlineRenderingWorkflow.mapRendering {
+          it.withEnvironment(ViewEnvironment.EMPTY.withComposeInteropSupport())
+        },
         scope = viewModelScope,
         savedStateHandle = savedState,
         runtimeConfig = AndroidRuntimeConfigTools.getAppWorkflowRuntimeConfig()

samples/compose-samples/src/main/java/com/squareup/sample/compose/inlinerendering/InlineRenderingWorkflow.kt

@@ -21,14 +21,14 @@ import com.squareup.workflow1.StatefulWorkflow
 import com.squareup.workflow1.WorkflowExperimentalRuntime
 import com.squareup.workflow1.config.AndroidRuntimeConfigTools
 import com.squareup.workflow1.parse
-import com.squareup.workflow1.ui.AndroidScreen
+import com.squareup.workflow1.ui.Screen
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.compose.ComposeScreen
 import com.squareup.workflow1.ui.compose.WorkflowRendering
 import com.squareup.workflow1.ui.compose.renderAsState
 
-object InlineRenderingWorkflow : StatefulWorkflow<Unit, Int, Nothing, AndroidScreen<*>>() {
+object InlineRenderingWorkflow : StatefulWorkflow<Unit, Int, Nothing, Screen>() {
 
   override fun initialState(
     props: Unit,
@@ -39,7 +39,7 @@ object InlineRenderingWorkflow : StatefulWorkflow<Unit, Int, Nothing, AndroidScr
     renderProps: Unit,
     renderState: Int,
     context: RenderContext
-  ): AndroidScreen<*> = ComposeScreen {
+  ) = ComposeScreen {
     Box {
       Button(onClick = context.eventHandler { state += 1 }) {
         Text("Counter: ")

samples/compose-samples/src/main/java/com/squareup/sample/compose/launcher/Samples.kt

@@ -37,7 +37,7 @@ val samples = listOf(
   Sample(
     "Hello Compose Binding",
     HelloBindingActivity::class,
-    "Creates a ViewFactory using composeViewFactory."
+    "Creates a ScreenComposableFactory using screenComposableFactory()."
   ) { DrawHelloRenderingPreview() },
   Sample(
     "Nested Renderings",

samples/compose-samples/src/main/java/com/squareup/sample/compose/nestedrenderings/LegacyRunner.kt

@@ -11,6 +11,7 @@ import com.squareup.workflow1.ui.ScreenViewFactory.Companion.fromViewBinding
 import com.squareup.workflow1.ui.ScreenViewRunner
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.compose.asComposableFactory
 import com.squareup.workflow1.ui.compose.tooling.Preview
 
 /**
@@ -36,7 +37,7 @@ class LegacyRunner(private val binding: LegacyViewBinding) : ScreenViewRunner<Le
 @Preview(widthDp = 200, heightDp = 150, showBackground = true)
 @Composable
 private fun LegacyRunnerPreview() {
-  LegacyRunner.Preview(
+  LegacyRunner.asComposableFactory().Preview(
     rendering = LegacyRendering(StringRendering("child")),
     placeholderModifier = Modifier.fillMaxSize()
   )

samples/compose-samples/src/main/java/com/squareup/sample/compose/nestedrenderings/NestedRenderingsActivity.kt

@@ -18,6 +18,7 @@ import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.ViewRegistry
 import com.squareup.workflow1.ui.WorkflowLayout
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.compose.withComposeInteropSupport
 import com.squareup.workflow1.ui.compose.withCompositionRoot
 import com.squareup.workflow1.ui.container.withEnvironment
 import com.squareup.workflow1.ui.plus
@@ -32,11 +33,13 @@ private val viewRegistry = ViewRegistry(
 
 @OptIn(WorkflowUiExperimentalApi::class)
 private val viewEnvironment =
-  (ViewEnvironment.EMPTY + viewRegistry).withCompositionRoot { content ->
-    CompositionLocalProvider(LocalBackgroundColor provides Color.Green) {
-      content()
+  (ViewEnvironment.EMPTY + viewRegistry)
+    .withCompositionRoot { content ->
+      CompositionLocalProvider(LocalBackgroundColor provides Color.Green) {
+        content()
+      }
     }
-  }
+    .withComposeInteropSupport()
 
 @WorkflowUiExperimentalApi
 class NestedRenderingsActivity : AppCompatActivity() {

samples/compose-samples/src/main/java/com/squareup/sample/compose/nestedrenderings/RecursiveViewFactory.kt

@@ -27,7 +27,7 @@ import com.squareup.workflow1.ui.Screen
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.compose.WorkflowRendering
-import com.squareup.workflow1.ui.compose.composeScreenViewFactory
+import com.squareup.workflow1.ui.compose.screenComposableFactory
 import com.squareup.workflow1.ui.compose.tooling.Preview
 
 /**
@@ -39,7 +39,7 @@ val LocalBackgroundColor = compositionLocalOf<Color> { error("No background colo
  * A `ViewFactory` that renders [RecursiveWorkflow.Rendering]s.
  */
 @OptIn(WorkflowUiExperimentalApi::class)
-val RecursiveViewFactory = composeScreenViewFactory<Rendering> { rendering, viewEnvironment ->
+val RecursiveViewFactory = screenComposableFactory<Rendering> { rendering, viewEnvironment ->
   // Every child should be drawn with a slightly-darker background color.
   val color = LocalBackgroundColor.current
   val childColor = remember(color) {

samples/compose-samples/src/main/java/com/squareup/sample/compose/preview/PreviewActivity.kt

@@ -23,7 +23,7 @@ import androidx.compose.ui.unit.dp
 import com.squareup.workflow1.ui.Screen
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.compose.WorkflowRendering
-import com.squareup.workflow1.ui.compose.composeScreenViewFactory
+import com.squareup.workflow1.ui.compose.screenComposableFactory
 import com.squareup.workflow1.ui.compose.tooling.Preview
 
 class PreviewActivity : AppCompatActivity() {
@@ -65,7 +65,7 @@ data class ContactDetailsRendering(
 ) : Screen
 
 private val contactViewFactory =
-  composeScreenViewFactory<ContactRendering> { rendering, environment ->
+  screenComposableFactory<ContactRendering> { rendering, environment ->
     Card(
       modifier = Modifier
         .padding(8.dp)

samples/compose-samples/src/main/java/com/squareup/sample/compose/textinput/TextInputViewFactory.kt

@@ -20,11 +20,11 @@ import com.squareup.sample.compose.textinput.TextInputWorkflow.Rendering
 import com.squareup.workflow1.ui.TextController
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.compose.asMutableState
-import com.squareup.workflow1.ui.compose.composeScreenViewFactory
+import com.squareup.workflow1.ui.compose.screenComposableFactory
 import com.squareup.workflow1.ui.compose.tooling.Preview
 
 @OptIn(WorkflowUiExperimentalApi::class)
-val TextInputViewFactory = composeScreenViewFactory<Rendering> { rendering, _ ->
+val TextInputViewFactory = screenComposableFactory<Rendering> { rendering, _ ->
   Column(
     modifier = Modifier
       .fillMaxSize()

workflow-ui/compose-tooling/api/compose-tooling.api

@@ -6,6 +6,6 @@ public final class com/squareup/workflow1/ui/compose/tooling/ComposableSingleton
 }
 
 public final class com/squareup/workflow1/ui/compose/tooling/ViewFactoriesKt {
-	public static final fun Preview (Lcom/squareup/workflow1/ui/ScreenViewFactory;Lcom/squareup/workflow1/ui/Screen;Landroidx/compose/ui/Modifier;Landroidx/compose/ui/Modifier;Lkotlin/jvm/functions/Function1;Landroidx/compose/runtime/Composer;II)V
+	public static final fun Preview (Lcom/squareup/workflow1/ui/compose/ScreenComposableFactory;Lcom/squareup/workflow1/ui/Screen;Landroidx/compose/ui/Modifier;Landroidx/compose/ui/Modifier;Lkotlin/jvm/functions/Function1;Landroidx/compose/runtime/Composer;II)V
 }
 

workflow-ui/compose-tooling/src/androidTest/java/com/squareup/workflow1/ui/compose/tooling/PreviewViewFactoryTest.kt

@@ -18,7 +18,7 @@ import com.squareup.workflow1.ui.Screen
 import com.squareup.workflow1.ui.ViewEnvironmentKey
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.compose.WorkflowRendering
-import com.squareup.workflow1.ui.compose.composeScreenViewFactory
+import com.squareup.workflow1.ui.compose.screenComposableFactory
 import com.squareup.workflow1.ui.internal.test.IdleAfterTestRule
 import com.squareup.workflow1.ui.internal.test.IdlingDispatcherRule
 import leakcanary.DetectLeaksAfterTestSuccess
@@ -96,7 +96,7 @@ internal class PreviewViewFactoryTest {
   }
 
   private val ParentWithOneChild =
-    composeScreenViewFactory<TwoStrings> { rendering, environment ->
+    screenComposableFactory<TwoStrings> { rendering, environment ->
       Column {
         BasicText(rendering.first.text)
         WorkflowRendering(rendering.second, environment)
@@ -109,7 +109,7 @@ internal class PreviewViewFactoryTest {
   }
 
   private val ParentWithTwoChildren =
-    composeScreenViewFactory<ThreeStrings> { rendering, environment ->
+    screenComposableFactory<ThreeStrings> { rendering, environment ->
       Column {
         WorkflowRendering(rendering.first, environment)
         BasicText(rendering.second.text)
@@ -156,7 +156,7 @@ internal class PreviewViewFactoryTest {
   ) : Screen
 
   private val ParentRecursive =
-    composeScreenViewFactory<RecursiveRendering> { rendering, environment ->
+    screenComposableFactory<RecursiveRendering> { rendering, environment ->
       Column {
         BasicText(rendering.text)
         rendering.child?.let { child ->
@@ -198,7 +198,7 @@ internal class PreviewViewFactoryTest {
     override val default: String get() = error("Not specified")
   }
 
-  private val ParentConsumesCustomKey = composeScreenViewFactory<TwoStrings> { _, environment ->
+  private val ParentConsumesCustomKey = screenComposableFactory<TwoStrings> { _, environment ->
     BasicText(environment[TestEnvironmentKey])
   }
 

workflow-ui/compose-tooling/src/main/java/com/squareup/workflow1/ui/compose/tooling/PlaceholderViewFactory.kt

@@ -25,15 +25,18 @@ import androidx.compose.ui.unit.dp
 import com.squareup.workflow1.ui.Screen
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.compose.composeScreenViewFactory
+import com.squareup.workflow1.ui.compose.ScreenComposableFactory
+import com.squareup.workflow1.ui.compose.screenComposableFactory
 
 /**
  * A [ScreenViewFactory] that will be used any time a [PreviewScreenViewFactoryFinder]
  * is asked to show a rendering. It displays a placeholder graphic and the rendering's
  * `toString()` result.
  */
-internal fun placeholderScreenViewFactory(modifier: Modifier): ScreenViewFactory<Screen> =
-  composeScreenViewFactory { rendering, _ ->
+internal fun placeholderScreenComposableFactory(
+  modifier: Modifier
+): ScreenComposableFactory<Screen> =
+  screenComposableFactory { rendering, _ ->
     BoxWithConstraints {
       BasicText(
         modifier = modifier

workflow-ui/compose-tooling/src/main/java/com/squareup/workflow1/ui/compose/tooling/PreviewViewEnvironment.kt

@@ -7,52 +7,56 @@ import androidx.compose.runtime.Immutable
 import androidx.compose.runtime.remember
 import androidx.compose.ui.Modifier
 import com.squareup.workflow1.ui.Screen
-import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewFactoryFinder
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.compose.ScreenComposableFactory
+import com.squareup.workflow1.ui.compose.ScreenComposableFactoryFinder
 
 /**
  * Creates and [remember]s a [ViewEnvironment] that has a special [ScreenViewFactoryFinder]
  * and any additional elements as configured by [viewEnvironmentUpdater].
  *
  * The [ScreenViewFactoryFinder] will contain [mainFactory] if specified, as well as a
- * [placeholderScreenViewFactory] that will be used to show any renderings that don't match
+ * [placeholderScreenComposableFactory] that will be used to show any renderings that don't match
  * [mainFactory]'s type. All placeholders will have [placeholderModifier] applied.
  */
 @Composable internal fun rememberPreviewViewEnvironment(
   placeholderModifier: Modifier,
   viewEnvironmentUpdater: ((ViewEnvironment) -> ViewEnvironment)? = null,
-  mainFactory: ScreenViewFactory<*>? = null
+  mainFactory: ScreenComposableFactory<*>? = null
 ): ViewEnvironment {
   val finder = remember(mainFactory, placeholderModifier) {
-    PreviewScreenViewFactoryFinder(mainFactory, placeholderScreenViewFactory(placeholderModifier))
+    PreviewScreenComposableFactoryFinder(
+      mainFactory,
+      placeholderScreenComposableFactory(placeholderModifier)
+    )
   }
   return remember(finder, viewEnvironmentUpdater) {
-    (ViewEnvironment.EMPTY + (ScreenViewFactoryFinder to finder)).let { environment ->
+    (ViewEnvironment.EMPTY + (ScreenComposableFactoryFinder to finder)).let { environment ->
       // Give the preview a chance to add its own elements to the ViewEnvironment.
       viewEnvironmentUpdater?.let { it(environment) } ?: environment
     }
   }
 }
 
 /**
- * A [ScreenViewFactoryFinder] that uses [mainFactory] for rendering [RenderingT]s,
+ * A [ScreenComposableFactoryFinder] that uses [mainFactory] for rendering [RenderingT]s,
  * and [placeholderFactory] for all other
  * [WorkflowRendering][com.squareup.workflow1.ui.compose.WorkflowRendering] calls.
  */
 @Immutable
-private class PreviewScreenViewFactoryFinder<RenderingT : Screen>(
-  private val mainFactory: ScreenViewFactory<RenderingT>? = null,
-  private val placeholderFactory: ScreenViewFactory<Screen>
-) : ScreenViewFactoryFinder {
-  override fun <ScreenT : Screen> getViewFactoryForRendering(
+private class PreviewScreenComposableFactoryFinder<RenderingT : Screen>(
+  private val mainFactory: ScreenComposableFactory<RenderingT>? = null,
+  private val placeholderFactory: ScreenComposableFactory<Screen>
+) : ScreenComposableFactoryFinder {
+  override fun <ScreenT : Screen> getComposableFactoryForRendering(
     environment: ViewEnvironment,
     rendering: ScreenT
-  ): ScreenViewFactory<ScreenT> =
+  ): ScreenComposableFactory<ScreenT> =
     @Suppress("UNCHECKED_CAST")
     if (rendering::class == mainFactory?.type) {
-      mainFactory as ScreenViewFactory<ScreenT>
+      mainFactory as ScreenComposableFactory<ScreenT>
     } else {
       placeholderFactory
     }