Brings back View.environment, adds View.getScreen.

I'd like to bring back the ability to peek at a View and see if/how workflow-ui created it, even though we no longer need that ability at runtime. I don't see how we can preserve our Radiography support without it, and it's also handy for espresso testing (#741).

workflow-ui/core-android/api/core-android.api

@@ -277,6 +277,7 @@ public final class com/squareup/workflow1/ui/ViewShowRenderingKt {
 	public static final fun canShowRendering (Landroid/view/View;Ljava/lang/Object;)Z
 	public static final fun getEnvironment (Landroid/view/View;)Lcom/squareup/workflow1/ui/ViewEnvironment;
 	public static final synthetic fun getRendering (Landroid/view/View;)Ljava/lang/Object;
+	public static final fun getScreen (Landroid/view/View;)Lcom/squareup/workflow1/ui/Screen;
 	public static final fun getShowRendering (Landroid/view/View;)Lkotlin/jvm/functions/Function2;
 	public static final fun getStarter (Landroid/view/View;)Lkotlin/jvm/functions/Function1;
 	public static final fun getStarterOrNull (Landroid/view/View;)Lkotlin/jvm/functions/Function1;

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/RealScreenViewHolder.kt

@@ -15,6 +15,7 @@ internal class RealScreenViewHolder<ScreenT : Screen>(
   override val runner: ScreenViewRunner<ScreenT> =
     ScreenViewRunner { newScreen, newEnvironment ->
       _environment = newEnvironment
+      view.setTag(R.id.workflow_environment, newEnvironment)
       viewRunner.showRendering(newScreen, newEnvironment)
     }
 }

workflow-ui/core-android/src/main/java/com/squareup/workflow1/ui/ViewShowRendering.kt

@@ -1,6 +1,7 @@
 package com.squareup.workflow1.ui
 
 import android.view.View
+import com.squareup.workflow1.ui.ScreenViewHolder.Companion.Showing
 import com.squareup.workflow1.ui.WorkflowViewState.New
 import com.squareup.workflow1.ui.WorkflowViewState.Started
 
@@ -59,7 +60,7 @@ public fun <RenderingT : Any> View.bindShowRendering(
  * - It is an error to call [View.showRendering] without having called this method first.
  */
 @WorkflowUiExperimentalApi
-@Deprecated("Use ScreenViewFactory.start to create a ScreenViewHolder")
+@Deprecated("Use ScreenViewFactory.startShowing to create a ScreenViewHolder")
 public fun View.start() {
   val current = workflowViewStateAsNew
   workflowViewState = Started(current.showing, current.environment, current.showRendering)
@@ -118,7 +119,7 @@ public fun <RenderingT : Any> View.showRendering(
  * @throws ClassCastException if the current rendering is not of type [RenderingT]
  */
 @WorkflowUiExperimentalApi
-@Deprecated("Replaced by ViewEnvironment[Screen]")
+@Deprecated("Replaced by View.getScreen()")
 public inline fun <reified RenderingT : Any> View.getRendering(): RenderingT? {
   // Can't use a val because of the parameter type.
   return when (val showing = workflowViewStateOrNull?.showing) {
@@ -127,14 +128,23 @@ public inline fun <reified RenderingT : Any> View.getRendering(): RenderingT? {
   }
 }
 
+/**
+ * Returns the most recent [Screen] rendering [shown][ScreenViewHolder.show] in this view,
+ * or `null` if the receiver was not created via [ScreenViewFactory.startShowing].
+ */
+@WorkflowUiExperimentalApi
+public fun View.getScreen(): Screen? {
+  return environment?.get(Showing)
+}
+
 /**
  * Returns the most recent [ViewEnvironment] applied to this view, or null if [bindShowRendering]
  * has never been called.
  */
 @WorkflowUiExperimentalApi
-@Deprecated("Replaced by ScreenViewHolder.environment")
 public val View.environment: ViewEnvironment?
   get() = workflowViewStateOrNull?.environment
+    ?: getTag(R.id.workflow_environment) as? ViewEnvironment
 
 /**
  * Returns the function set by the most recent call to [bindShowRendering], or null

workflow-ui/core-android/src/main/res/values/ids.xml

@@ -25,6 +25,6 @@
   <item name="workflow_layout" type="id"/>
   <!-- View Tag used by ModalScreenOverlayDialogFactory to find the content ScreenViewHolder. -->
   <item name="workflow_modal_dialog_content" type="id"/>
-  <!-- View Tag used for ScreenViewRunner. -->
-  <item name="workflow_view_runner" type="id"/>
+  <!-- View Tag for the ViewEnvironment that last updated this view. -->
+  <item name="workflow_environment" type="id"/>
 </resources>

workflow-ui/radiography/src/main/java/com/squareup/workflow1/ui/radiography/WorkflowViewRenderer.kt

@@ -7,15 +7,16 @@ import com.squareup.workflow1.ui.Named
 import com.squareup.workflow1.ui.NamedScreen
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.getRendering
+import com.squareup.workflow1.ui.getScreen
 import radiography.AttributeAppendable
 import radiography.ScannableView
 import radiography.ScannableView.AndroidView
 import radiography.ViewStateRenderer
 import radiography.ViewStateRenderers
 
 /**
- * Renders information about views that were created by view factories, i.e. views with associated
- * rendering tags.
+ * Renders information about views that were created by workflow-ui, i.e. views
+ * that return non-null values from [getRendering] or [getScreen].
  */
 @Suppress("unused")
 public val ViewStateRenderers.WorkflowViewRenderer: ViewStateRenderer
@@ -26,7 +27,7 @@ private object WorkflowViewRendererImpl : ViewStateRenderer {
 
   override fun AttributeAppendable.render(view: ScannableView) {
     val androidView = (view as? AndroidView)?.view ?: return
-    val rendering = androidView.getRendering<Any>() ?: return
+    val rendering = androidView.getRendering<Any>() ?: androidView.getScreen() ?: return
     renderRendering(rendering)
   }