More flexible modality.

Introduces the `ModalOverlay` interface. Moves as much code as possible from `BodyAndModalsContainer` to `LayeredDialogs`, and allows them to turn on modal event blocking behavior per managed `Overlay` instance, rather than always enforcing it.

Very sad that I wasn't able to get rid of `BodyAndOverlaysContainer.onAttachedToWindow`, but the SavedStateRegistry timing is just too fussy to allow it.

Git was dumb about diff'ing across renames, so they aren't all done in this commit for ease of review. The rest of the renames follow.

Author: rjrjr

benchmarks/performance-poetry/complex-poetry/src/main/java/com/squareup/benchmarks/performance/complex/poetry/views/MayBeLoadingScreen.kt

@@ -27,4 +27,4 @@ val MayBeLoadingScreen.baseScreen: OverviewDetailScreen
 
 @OptIn(WorkflowUiExperimentalApi::class)
 val MayBeLoadingScreen.loaders: List<LoaderSpinner>
-  get() = modals.map { it.content }
+  get() = overlays.map { it.content }

samples/containers/common/src/main/java/com/squareup/sample/container/panel/PanelOverlay.kt

@@ -2,9 +2,10 @@ package com.squareup.sample.container.panel
 
 import com.squareup.workflow1.ui.Screen
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.container.ModalOverlay
 import com.squareup.workflow1.ui.container.ScreenOverlay
 
 @OptIn(WorkflowUiExperimentalApi::class)
 class PanelOverlay<T : Screen>(
   override val content: T
-) : ScreenOverlay<T>
+) : ScreenOverlay<T>, ModalOverlay

samples/tictactoe/common/src/main/java/com/squareup/sample/mainworkflow/TicTacToeWorkflow.kt

@@ -58,7 +58,7 @@ class TicTacToeWorkflow(
     renderState: MainState,
     context: RenderContext
   ): BodyAndModalsScreen<ScrimScreen<*>, *> {
-    val bodyAndModals: BodyAndModalsScreen<*, *> = when (renderState) {
+    val bodyAndOverlays: BodyAndModalsScreen<*, *> = when (renderState) {
       is Authenticating -> {
         val authBackStack = context.renderChild(authWorkflow) { handleAuthResult(it) }
         // We always show an empty GameScreen behind the PanelOverlay that
@@ -101,8 +101,8 @@ class TicTacToeWorkflow(
     }
 
     // Add the scrim. Dim it only if there is a panel showing.
-    val dim = bodyAndModals.modals.any { modal -> modal is PanelOverlay<*> }
-    return bodyAndModals.mapBody { body -> ScrimScreen(body, dimmed = dim) }
+    val dim = bodyAndOverlays.overlays.any { modal -> modal is PanelOverlay<*> }
+    return bodyAndOverlays.mapBody { body -> ScrimScreen(body, dimmed = dim) }
   }
 
   override fun snapshotState(state: MainState): Snapshot = state.toSnapshot()

samples/tictactoe/common/src/test/java/com/squareup/sample/mainworkflow/TicTacToeWorkflowTest.kt

@@ -64,7 +64,7 @@ class TicTacToeWorkflowTest {
     BackStackScreen<Screen>(S(wrapped))
 
   private val BodyAndModalsScreen<ScrimScreen<*>, *>.panels: List<PanelOverlay<*>>
-    get() = modals.mapNotNull { it as? PanelOverlay<*> }
+    get() = overlays.mapNotNull { it as? PanelOverlay<*> }
 
   private fun authWorkflow(
     screen: String = DEFAULT_AUTH

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

@@ -7,7 +7,6 @@ import android.view.View
 import android.view.Window
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
-import com.squareup.workflow1.ui.environment
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.cancel
@@ -40,7 +39,7 @@ internal fun <D : Dialog> D.maintainBounds(
   environment: ViewEnvironment,
   onBoundsChange: (D, Rect) -> Unit
 ) {
-  maintainBounds(environment[ModalArea].bounds, onBoundsChange)
+  maintainBounds(environment[OverlayArea].bounds, onBoundsChange)
 }
 
 @WorkflowUiExperimentalApi

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

@@ -1,7 +1,6 @@
 package com.squareup.workflow1.ui.container
 
 import android.content.Context
-import android.graphics.Rect
 import android.os.Parcel
 import android.os.Parcelable
 import android.os.Parcelable.Creator
@@ -10,124 +9,72 @@ import android.view.KeyEvent
 import android.view.MotionEvent
 import android.view.ViewGroup
 import android.view.ViewGroup.LayoutParams.MATCH_PARENT
-import android.view.ViewTreeObserver.OnGlobalLayoutListener
 import android.widget.FrameLayout
 import com.squareup.workflow1.ui.Compatible
-import com.squareup.workflow1.ui.Compatible.Companion.keyFor
 import com.squareup.workflow1.ui.R
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewHolder
 import com.squareup.workflow1.ui.ScreenViewHolder.Companion.Showing
 import com.squareup.workflow1.ui.ViewEnvironment
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 import com.squareup.workflow1.ui.WorkflowViewStub
-import com.squareup.workflow1.ui.androidx.WorkflowAndroidXSupport
-import kotlinx.coroutines.flow.MutableStateFlow
 
 @WorkflowUiExperimentalApi
+// TODO Rename this BodyAndOverlaysContainer
 internal class BodyAndModalsContainer @JvmOverloads constructor(
   context: Context,
   attributeSet: AttributeSet? = null,
   defStyle: Int = 0,
   defStyleRes: Int = 0
 ) : FrameLayout(context, attributeSet, defStyle, defStyleRes) {
   /**
-   * Unique identifier for this view for SavedStateRegistry purposes. Based on the
-   * [Compatible.keyFor] the current rendering. Taking this approach allows
-   * feature developers to take control over naming, e.g. by wrapping renderings
-   * with [NamedScreen][com.squareup.workflow1.ui.NamedScreen].
    */
   private lateinit var savedStateParentKey: String
 
   private val baseViewStub: WorkflowViewStub = WorkflowViewStub(context).also {
     addView(it, ViewGroup.LayoutParams(MATCH_PARENT, MATCH_PARENT))
   }
 
-  private val dialogs = LayeredDialogs(view = this, modal = true)
-
-  // The bounds of this view in global (display) coordinates, as reported
-  // by getGlobalVisibleRect.
-  //
-  // Made available to managed ModalScreenOverlayDialogFactory instances
-  // via the ModalArea key in ViewEnvironment. When this updates their
-  // updateBounds methods will fire. They should resize themselves to
-  // avoid covering peers of this view.
-  private val bounds = MutableStateFlow(Rect())
-  private val boundsRect = Rect()
-
-  private val boundsListener = OnGlobalLayoutListener {
-    if (getGlobalVisibleRect(boundsRect) && boundsRect != bounds.value) {
-      bounds.value = Rect(boundsRect)
-    }
-    // Should we close the dialogs if getGlobalVisibleRect returns false?
-    // https://github.com/square/workflow-kotlin/issues/599
-  }
-
-  // Note similar code in DialogHolder.
-  private var allowEvents = true
-    set(value) {
-      val was = field
-      field = value
-      if (value != was) {
-        // https://stackoverflow.com/questions/2886407/dealing-with-rapid-tapping-on-buttons
-        // If any motion events were enqueued on the main thread, cancel them.
-        dispatchCancelEvent { super.dispatchTouchEvent(it) }
-        // When we cancel, have to warn things like RecyclerView that handle streams
-        // of motion events and eventually dispatch input events (click, key pressed, etc.)
-        // based on them.
-        cancelPendingInputEvents()
-      }
-    }
+  private val dialogs = LayeredDialogs.forView(
+    view = this,
+    superDispatchTouchEvent = { super.dispatchTouchEvent(it) }
+  )
 
   fun update(
     newScreen: BodyAndModalsScreen<*, *>,
     viewEnvironment: ViewEnvironment
   ) {
-    savedStateParentKey = keyFor(viewEnvironment[Showing])
-
-    val showingModals = newScreen.modals.isNotEmpty()
+    savedStateParentKey = Compatible.keyFor(viewEnvironment[Showing])
 
-    // There is a long wait from when we show a dialog until it starts blocking
-    // events for us. To compensate we ignore all touches while any dialogs exist.
-    allowEvents = !showingModals
-
-    val baseEnv = if (showingModals) viewEnvironment + (CoveredByModal to true) else viewEnvironment
-    baseViewStub.show(newScreen.body, baseEnv)
-
-    // Allow modal dialogs to restrict themselves to cover only this view.
-    val dialogsEnv = if (showingModals) viewEnvironment + ModalArea(bounds) else viewEnvironment
-
-    dialogs.update(newScreen.modals, dialogsEnv)
+    dialogs.update(newScreen.overlays, viewEnvironment) { env ->
+      baseViewStub.show(newScreen.body, env)
+    }
   }
 
   override fun onAttachedToWindow() {
-    super.onAttachedToWindow()
-    boundsListener.onGlobalLayout()
-    viewTreeObserver.addOnGlobalLayoutListener(boundsListener)
+    // I tried to move this to the attachStateChangeListener in LayeredDialogs.Companion.forView,
+    // but that fires too late and we crash with the dreaded
+    // "You can consumeRestoredStateForKey only after super.onCreate of corresponding component".
 
+    super.onAttachedToWindow()
     // Wire up dialogs to our parent SavedStateRegistry.
-    val parentRegistryOwner = WorkflowAndroidXSupport.stateRegistryOwnerFromViewTreeOrContext(this)
-    dialogs.attachToParentRegistryOwner(savedStateParentKey, parentRegistryOwner)
+    dialogs.onAttachedToWindow(savedStateParentKey, this)
   }
 
   override fun onDetachedFromWindow() {
     // Disconnect dialogs from our parent SavedStateRegistry so that it doesn't get asked
     // to save state anymore.
-    dialogs.detachFromParentRegistry()
-    // Don't leak the dialogs if we're suddenly yanked out of view.
-    // https://github.com/square/workflow-kotlin/issues/314
-    dialogs.update(emptyList(), ViewEnvironment.EMPTY)
-    viewTreeObserver.removeOnGlobalLayoutListener(boundsListener)
-    bounds.value = Rect()
+    dialogs.onDetachedFromWindow()
+
     super.onDetachedFromWindow()
   }
 
   override fun dispatchTouchEvent(event: MotionEvent): Boolean {
-    return !allowEvents || super.dispatchTouchEvent(event)
+    return !dialogs.allowEvents || super.dispatchTouchEvent(event)
   }
 
   override fun dispatchKeyEvent(event: KeyEvent): Boolean {
-    return !allowEvents || super.dispatchKeyEvent(event)
+    return !dialogs.allowEvents || super.dispatchKeyEvent(event)
   }
 
   override fun onSaveInstanceState(): Parcelable {

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

@@ -5,7 +5,7 @@ import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 
 /**
  * True in views managed by [BodyAndModalsScreen] when their events are being blocked
- * by a modal [Overlay].
+ * by a [ModalOverlay].
  */
 @WorkflowUiExperimentalApi
 internal object CoveredByModal : ViewEnvironmentKey<Boolean>(type = Boolean::class) {

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

@@ -22,15 +22,12 @@ import com.squareup.workflow1.ui.compatible
 
 /**
  * Used by [LayeredDialogs] to keep a [Dialog] tied to its [rendering] and [environment].
- *
- * @param modal if true, ignore keyboard and touch events when [CoveredByModal] is also true
  */
 @WorkflowUiExperimentalApi
 internal class DialogHolder<T : Overlay>(
   initialRendering: T,
   initialViewEnvironment: ViewEnvironment,
   index: Int,
-  private val modal: Boolean,
   private val context: Context,
   private val factory: OverlayDialogFactory<T>
 ) {
@@ -42,9 +39,11 @@ internal class DialogHolder<T : Overlay>(
   var environment: ViewEnvironment = initialViewEnvironment
     private set
 
+  private val modal = initialRendering is ModalOverlay
+
   private var dialogOrNull: Dialog? = null
 
-  // Note similar code in BodyAndModalsContainer
+  // Note similar code in LayeredDialogs
   private var allowEvents = true
     set(value) {
       val was = field