3/4 fun View.setBackHandler() replaces val View.backPressedHandler

samples/containers/hello-back-button/src/androidTest/java/com/squareup/sample/hellobackbutton/HelloBackButtonEspressoTest.kt

@@ -27,6 +27,14 @@ class HelloBackButtonEspressoTest {
     .around(IdlingDispatcherRule)
 
   @Test fun wrappedTakesPrecedence() {
+    // The root workflow (AreYouSureWorkflow) wraps its child renderings
+    // (instances of HelloBackButtonScreen) in its own BackButtonScreen,
+    // which shows the "Are you sure" dialog.
+    // That should only be in effect on the Able screen, which sets no backHandler of its
+    // own. The Baker and Charlie screens set their own backHandlers,
+    // which should take precedence over the root one. Thus, we should
+    // be able to push to Charlie and pop all the way back to Able
+    // without seeing the "Are you sure" dialog.
     onView(withId(R.id.hello_message)).apply {
       check(matches(withText("Able")))
       perform(click())

samples/containers/hello-back-button/src/main/java/com/squareup/sample/hellobackbutton/AreYouSureWorkflow.kt

@@ -68,7 +68,7 @@ object AreYouSureWorkflow :
           BackButtonScreen(ableBakerCharlie) {
             // While we always provide a back button handler, by default the view code
             // associated with BackButtonScreen ignores ours if the view created for the
-            // wrapped rendering sets a handler of its own. (Set BackButtonScreen.override
+            // wrapped rendering sets a handler of its own. (Set BackButtonScreen.shadow
             // to change this precedence.)
             context.actionSink.send(maybeQuit)
           }

samples/containers/hello-back-button/src/main/java/com/squareup/sample/hellobackbutton/HelloBackButtonScreen.kt

@@ -6,7 +6,7 @@ import com.squareup.sample.hellobackbutton.databinding.HelloBackButtonLayoutBind
 import com.squareup.workflow1.ui.AndroidScreen
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 data class HelloBackButtonScreen(
@@ -18,6 +18,6 @@ data class HelloBackButtonScreen(
     ScreenViewFactory.fromViewBinding(HelloBackButtonLayoutBinding::inflate) { rendering, _ ->
       helloMessage.text = rendering.message
       helloMessage.setOnClickListener { rendering.onClick() }
-      helloMessage.backPressedHandler = rendering.onBackPressed
+      helloMessage.setBackHandler(rendering.onBackPressed)
     }
 }

samples/containers/poetry/src/main/java/com/squareup/sample/poetry/StanzaListScreen.kt

@@ -1,5 +1,6 @@
 package com.squareup.sample.poetry
 
+import android.annotation.SuppressLint
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
@@ -15,9 +16,9 @@ import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewRunner
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
 import com.squareup.workflow1.ui.container.BackStackConfig
 import com.squareup.workflow1.ui.container.BackStackConfig.Other
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 data class StanzaListScreen(
@@ -40,6 +41,7 @@ private class StanzaListLayoutRunner(view: View) : ScreenViewRunner<StanzaListSc
 
   private val adapter = Adapter()
 
+  @SuppressLint("NotifyDataSetChanged")
   override fun showRendering(
     rendering: StanzaListScreen,
     environment: ViewEnvironment
@@ -53,10 +55,10 @@ private class StanzaListLayoutRunner(view: View) : ScreenViewRunner<StanzaListSc
 
     if (environment[BackStackConfig] == Other) {
       toolbar.setNavigationOnClickListener { rendering.onExit() }
-      toolbar.backPressedHandler = rendering.onExit
+      toolbar.setBackHandler(rendering.onExit)
     } else {
       toolbar.navigationIcon = null
-      toolbar.backPressedHandler = null
+      toolbar.setBackHandler {}
     }
 
     if (rendering.selection >= 0) recyclerView.scrollToPosition(rendering.selection)

samples/containers/poetry/src/main/java/com/squareup/sample/poetry/StanzaScreen.kt

@@ -17,9 +17,9 @@ import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewRunner
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
 import com.squareup.workflow1.ui.container.BackStackConfig
 import com.squareup.workflow1.ui.container.BackStackConfig.None
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 data class StanzaScreen(
@@ -93,8 +93,10 @@ private class StanzaLayoutRunner(private val view: View) : ScreenViewRunner<Stan
       toolbar.navigationIcon = null
     }
 
-    view.backPressedHandler = rendering.onGoBack
+    val goBackOrUp = rendering.onGoBack
       ?: rendering.onGoUp.takeIf { environment[OverviewDetailConfig] != Detail }
+
+    view.setBackHandler(goBackOrUp)
   }
 
   private fun TextView.setTabulatedText(lines: List<String>) {

samples/dungeon/timemachine-shakeable/src/main/java/com/squareup/sample/timemachine/shakeable/ShakeableTimeMachineLayoutRunner.kt

@@ -13,7 +13,7 @@ import com.squareup.workflow1.ui.ScreenViewRunner
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.WorkflowViewStub
-import com.squareup.workflow1.ui.backPressedHandler
+import com.squareup.workflow1.ui.setBackHandler
 import kotlin.time.Duration
 import kotlin.time.Duration.Companion.milliseconds
 import kotlin.time.ExperimentalTime
@@ -44,7 +44,7 @@ class ShakeableTimeMachineLayoutRunner(
     environment: ViewEnvironment
   ) {
     // Only handle back presses explicitly if in playback mode.
-    view.backPressedHandler = rendering.onResumeRecording.takeUnless { rendering.recording }
+    view.setBackHandler(rendering.onResumeRecording.takeUnless { rendering.recording })
 
     seek.max = rendering.totalDuration.toProgressInt()
     seek.progress = rendering.playbackPosition.toProgressInt()

samples/tictactoe/app/src/main/java/com/squareup/sample/authworkflow/LoginViewFactory.kt

@@ -4,7 +4,7 @@ import com.squareup.sample.tictactoe.databinding.LoginLayoutBinding
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewFactory.Companion.fromViewBinding
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 internal val LoginViewFactory: ScreenViewFactory<LoginScreen> =
@@ -15,5 +15,5 @@ internal val LoginViewFactory: ScreenViewFactory<LoginScreen> =
       rendering.onLogin(loginEmail.text.toString(), loginPassword.text.toString())
     }
 
-    root.backPressedHandler = { rendering.onCancel() }
+    root.setBackHandler(rendering.onCancel)
   }

samples/tictactoe/app/src/main/java/com/squareup/sample/authworkflow/SecondFactorViewFactory.kt

@@ -4,12 +4,12 @@ import com.squareup.sample.tictactoe.databinding.SecondFactorLayoutBinding
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewFactory.Companion.fromViewBinding
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 internal val SecondFactorViewFactory: ScreenViewFactory<SecondFactorScreen> =
   fromViewBinding(SecondFactorLayoutBinding::inflate) { rendering, _ ->
-    root.backPressedHandler = { rendering.onCancel() }
+    root.setBackHandler(rendering.onCancel)
     secondFactorToolbar.setNavigationOnClickListener { rendering.onCancel() }
 
     secondFactorErrorMessage.text = rendering.errorMessage

samples/tictactoe/app/src/main/java/com/squareup/sample/gameworkflow/GameOverLayoutRunner.kt

@@ -15,7 +15,7 @@ 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.backPressedHandler
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 internal class GameOverLayoutRunner(
@@ -40,14 +40,15 @@ internal class GameOverLayoutRunner(
       rendering.onPlayAgain()
       true
     }
-    binding.root.backPressedHandler = { rendering.onExit() }
+    binding.root.setBackHandler(rendering.onExit)
 
     when (rendering.endGameState.syncState) {
       SAVING -> {
         saveItem.isEnabled = false
         saveItem.title = "saving…"
         saveItem.setOnMenuItemClickListener(null)
       }
+
       SAVE_FAILED -> {
         saveItem.isEnabled = true
         saveItem.title = "Unsaved"
@@ -56,6 +57,7 @@ internal class GameOverLayoutRunner(
           true
         }
       }
+
       SAVED -> {
         saveItem.isVisible = false
         saveItem.setOnMenuItemClickListener(null)

samples/tictactoe/app/src/main/java/com/squareup/sample/gameworkflow/GamePlayViewFactory.kt

@@ -6,7 +6,7 @@ import com.squareup.sample.tictactoe.databinding.GamePlayLayoutBinding
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewFactory.Companion.fromViewBinding
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 internal val GamePlayViewFactory: ScreenViewFactory<GamePlayScreen> =
@@ -15,7 +15,7 @@ internal val GamePlayViewFactory: ScreenViewFactory<GamePlayScreen> =
     rendering.gameState.board.render(gamePlayBoard.root)
 
     setCellClickListeners(gamePlayBoard.root, rendering.gameState, rendering.onClick)
-    root.backPressedHandler = rendering.onQuit
+    root.setBackHandler(rendering.onQuit)
   }
 
 private fun setCellClickListeners(

samples/tictactoe/app/src/main/java/com/squareup/sample/gameworkflow/NewGameViewFactory.kt

@@ -4,7 +4,7 @@ import com.squareup.sample.tictactoe.databinding.NewGameLayoutBinding
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewFactory.Companion.fromViewBinding
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 internal val NewGameViewFactory: ScreenViewFactory<NewGameScreen> =
@@ -16,5 +16,5 @@ internal val NewGameViewFactory: ScreenViewFactory<NewGameScreen> =
       rendering.onStartGame(playerX.text.toString(), playerO.text.toString())
     }
 
-    root.backPressedHandler = { rendering.onCancel() }
+    root.setBackHandler(rendering.onCancel)
   }

samples/todo-android/app/src/main/java/com/squareup/sample/todo/TodoEditorScreen.kt

@@ -12,10 +12,10 @@ import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewRunner
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.backPressedHandler
 import com.squareup.workflow1.ui.container.BackStackConfig
 import com.squareup.workflow1.ui.container.BackStackConfig.Other
 import com.squareup.workflow1.ui.control
+import com.squareup.workflow1.ui.setBackHandler
 
 @OptIn(WorkflowUiExperimentalApi::class)
 data class TodoEditorScreen(
@@ -62,7 +62,7 @@ private class Runner(
 
       if (environment[BackStackConfig] == Other) {
         todoEditorToolbar.setNavigationOnClickListener { rendering.onGoBackClicked() }
-        root.backPressedHandler = { rendering.onGoBackClicked() }
+        root.setBackHandler(rendering.onGoBackClicked)
       } else {
         todoEditorToolbar.navigationIcon = null
       }

workflow-ui/container-android/src/main/java/com/squareup/workflow1/ui/modal/ModalViewContainer.kt

@@ -18,7 +18,9 @@ import com.squareup.workflow1.ui.ScreenViewHolder
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.ViewRegistry
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.androidx.WorkflowAndroidXSupport.onBackPressedDispatcherOwner
 import com.squareup.workflow1.ui.androidx.WorkflowAndroidXSupport.onBackPressedDispatcherOwnerOrNull
+import com.squareup.workflow1.ui.androidx.WorkflowLifecycleOwner
 import com.squareup.workflow1.ui.asScreen
 import com.squareup.workflow1.ui.bindShowRendering
 import com.squareup.workflow1.ui.container.BackButtonScreen
@@ -79,7 +81,17 @@ public open class ModalViewContainer @JvmOverloads constructor(
         initialEnvironment = initialViewEnvironment,
         contextForNewView = this.context,
         container = this
-      )
+      ) { view, doStart ->
+        // Note that we never call destroyOnDetach for this owner. That's okay because
+        // ModalContainer.update puts one in place above us on the decor view,
+        // and cleans it up. It's in place by the time we attach to the window, and
+        // so becomes our parent.
+        WorkflowLifecycleOwner.installOn(
+          view,
+          initialViewEnvironment.onBackPressedDispatcherOwner(view)
+        )
+        doStart()
+      }
 
     return buildDialogForView(viewHolder.view)
       .apply {

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

@@ -162,6 +162,12 @@ public final class com/squareup/workflow1/ui/TextControllerControlEditTextKt {
 	public static final fun control (Lcom/squareup/workflow1/ui/TextController;Landroid/widget/EditText;)V
 }
 
+public final class com/squareup/workflow1/ui/ViewBackHandlerKt {
+	public static final fun setBackHandler (Landroid/view/View;Lkotlin/jvm/functions/Function0;)V
+	public static final fun setBackHandler (Landroid/view/View;ZLkotlin/jvm/functions/Function0;)V
+	public static synthetic fun setBackHandler$default (Landroid/view/View;ZLkotlin/jvm/functions/Function0;ILjava/lang/Object;)V
+}
+
 public final class com/squareup/workflow1/ui/ViewBindingScreenViewFactory : com/squareup/workflow1/ui/ScreenViewFactory {
 	public fun <init> (Lkotlin/reflect/KClass;Lkotlin/jvm/functions/Function3;Lkotlin/jvm/functions/Function1;)V
 	public fun buildView (Lcom/squareup/workflow1/ui/Screen;Lcom/squareup/workflow1/ui/ViewEnvironment;Landroid/content/Context;Landroid/view/ViewGroup;)Lcom/squareup/workflow1/ui/ScreenViewHolder;

workflow-ui/core-android/src/androidTest/java/com/squareup/workflow1/ui/BackPressedHandlerTest.kt

@@ -1,3 +1,5 @@
+@file:Suppress("DEPRECATION")
+
 package com.squareup.workflow1.ui
 
 import android.view.View

workflow-ui/core-android/src/androidTest/java/com/squareup/workflow1/ui/ViewBackHandlerTest.kt

@@ -0,0 +1,54 @@
+package com.squareup.workflow1.ui
+
+import android.view.View
+import androidx.activity.ComponentActivity
+import androidx.test.ext.junit.rules.ActivityScenarioRule
+import com.google.common.truth.Truth.assertThat
+import com.squareup.workflow1.ui.androidx.WorkflowLifecycleOwner
+import com.squareup.workflow1.ui.internal.test.IdlingDispatcherRule
+import leakcanary.DetectLeaksAfterTestSuccess
+import org.junit.Rule
+import org.junit.Test
+import org.junit.rules.RuleChain
+
+@OptIn(WorkflowUiExperimentalApi::class)
+internal class ViewBackHandlerTest {
+  private val scenarioRule = ActivityScenarioRule(ComponentActivity::class.java)
+  private val scenario get() = scenarioRule.scenario
+
+  @get:Rule val rules: RuleChain = RuleChain.outerRule(DetectLeaksAfterTestSuccess())
+    .around(scenarioRule)
+    .around(IdlingDispatcherRule)
+
+  private var viewHandlerCount = 0
+  private fun viewBackHandler() {
+    viewHandlerCount++
+  }
+
+  @Test fun itWorksWhenHandlerIsAddedBeforeAttach() {
+    scenario.onActivity { activity ->
+      val view = View(activity)
+      WorkflowLifecycleOwner.installOn(view, activity)
+      view.setBackHandler { viewBackHandler() }
+
+      activity.setContentView(view)
+      assertThat(viewHandlerCount).isEqualTo(0)
+
+      activity.onBackPressedDispatcher.onBackPressed()
+      assertThat(viewHandlerCount).isEqualTo(1)
+    }
+  }
+
+  @Test fun itWorksWhenHandlerIsAddedAfterAttach() {
+    scenario.onActivity { activity ->
+      val view = View(activity)
+      activity.setContentView(view)
+
+      view.setBackHandler { viewBackHandler() }
+      assertThat(viewHandlerCount).isEqualTo(0)
+
+      activity.onBackPressedDispatcher.onBackPressed()
+      assertThat(viewHandlerCount).isEqualTo(1)
+    }
+  }
+}

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

@@ -13,6 +13,7 @@ import com.squareup.workflow1.ui.androidx.WorkflowAndroidXSupport.onBackPressedD
  * A function passed to [View.backPressedHandler], to be called if the back
  * button is pressed while that view is attached to a window.
  */
+@Deprecated("Use View.backHandler()")
 @WorkflowUiExperimentalApi
 public typealias BackPressHandler = () -> Unit
 
@@ -24,7 +25,9 @@ public typealias BackPressHandler = () -> Unit
  * That means that this is a last-registered-first-served mechanism, and that it is
  * compatible with Compose back button handling.
  */
+@Suppress("DEPRECATION")
 @WorkflowUiExperimentalApi
+@Deprecated("Use setOrClearBackHandler")
 public var View.backPressedHandler: BackPressHandler?
   get() = observerOrNull?.handler
   set(value) {
@@ -37,9 +40,9 @@ public var View.backPressedHandler: BackPressHandler?
 
 @WorkflowUiExperimentalApi
 private var View.observerOrNull: AttachStateAndLifecycleObserver?
-  get() = getTag(R.id.view_back_handler) as AttachStateAndLifecycleObserver?
+  get() = getTag(R.id.view_deprecated_back_handler) as AttachStateAndLifecycleObserver?
   set(value) {
-    setTag(R.id.view_back_handler, value)
+    setTag(R.id.view_deprecated_back_handler, value)
   }
 
 /**
@@ -79,7 +82,7 @@ private var View.observerOrNull: AttachStateAndLifecycleObserver?
 @WorkflowUiExperimentalApi
 private class AttachStateAndLifecycleObserver(
   private val view: View,
-  val handler: BackPressHandler
+  @Suppress("DEPRECATION") val handler: BackPressHandler
 ) : OnAttachStateChangeListener, DefaultLifecycleObserver {
   private val onBackPressedCallback = NullableOnBackPressedCallback()
   private var lifecycleOrNull: Lifecycle? = null
@@ -130,6 +133,7 @@ private class AttachStateAndLifecycleObserver(
 
 @WorkflowUiExperimentalApi
 internal class NullableOnBackPressedCallback : OnBackPressedCallback(false) {
+  @Suppress("DEPRECATION")
   var handlerOrNull: BackPressHandler? = null
 
   override fun handleOnBackPressed() {