BREAKING: Replaces ComposeScreenViewFactory with ScreenComposableFactory

This commit takes advantage of the new `ViewRegistry.Key`, which allows renderings to be bound to multiple UI factories, to fix a long standing problem where wrapper screens -- things like `NamedScreen` and `EnvironmentScreen` -- used in a Compose context would cause needless calls to `@Composeable fun AndroidView()` and `ComposeView()`.

For example, consider this rendering:

```
BodyAndOverlaysScreen(
  body = SomeComposeScreen(
    EnvironmentScreen(
      SomeOtherComposeScreen
    )
  )
)
```

Before this change, that would create a View hierarchy something like this:

```
BodyAndOverlaysContainer : FrameLayout {
  mChildren[0] = ComposeView {
    // compose land
    SomeComposeScreen.Content {
      AndroidView {
        ComposeView {
          // nested compose land
            SomeOtherComposeScreen.Content()
```

Now it will look this way:

```
BodyAndOverlaysContainer : FrameLayout {
  mChildren[0] = ComposeView {
    // compose land
    SomeComposeScreen.Content {
      SomeOtherComposeScreen.Content()
```

`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.

Other introductions, changes:

- `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.

- `ScreenViewFactoryFinder.getViewFactoryForRendering()` can now return `null`. A `requireViewFactoryForRendering()` extension is introduced for use when `null` is not acceptable.

- `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

Author: rjrjr

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.plus
 import com.squareup.workflow1.ui.renderWorkflowIn
@@ -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.plus
 import com.squareup.workflow1.ui.renderWorkflowIn
@@ -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) {