Introduces ScreenOverlay and ModalScreenOverlayDialogFactory

`ScreenOverlay` marks an `Overlay` with a `Screen` defining its content.

`ModalScreenOverlayDialogFactory` can show a `ScreenOverlay` as an
`android.app.Dialog`, taking care of updating the content view and managing
the Back button. It's the much simpler replacement for `ModalViewContainer`.

Also introduces two new `ViewEnvironment` values:

 - `ModalArea`, which allows dialogs to restrict themselves to a subset
   of the screen. `ModalScreenOverlayDialogFactory` applies this automatically
 - `CoveredByModal`, used by `BodyAndModalsContainer` and `LayeredDialogs` to
   disable touch and keyboard events reliably

In sample code, `PanelOverlay` replaces `PanelContainerScreen`, and the Tic
Tac Toe sample is updated to use the new hotness. I think the diff of the
sample code really highlights how much the new marker interfaces improve our
composition story.

That said, the `ScrimScreen` bit in the sample is a little rough. In the old
code we magically swizzled the scrim into place automatically. This PR
seems big enough already, so I'll follow up with a clean up that does
something similar and deletes all the deprecated sample code.

Fixes #259, #138, #99, #204, #314, #589

Author: rjrjr

samples/containers/android/src/main/java/com/squareup/sample/container/SampleContainers.kt

@@ -1,12 +1,11 @@
 package com.squareup.sample.container
 
 import com.squareup.sample.container.overviewdetail.OverviewDetailContainer
-import com.squareup.sample.container.panel.PanelContainer
-import com.squareup.sample.container.panel.ScrimContainer
-import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.sample.container.panel.PanelOverlayDialogFactory
 import com.squareup.workflow1.ui.ViewRegistry
+import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
 
 @OptIn(WorkflowUiExperimentalApi::class)
 val SampleContainers = ViewRegistry(
-    BackButtonViewFactory, OverviewDetailContainer, PanelContainer, ScrimContainer
+  BackButtonViewFactory, OverviewDetailContainer, PanelOverlayDialogFactory, ScrimContainer
 )

samples/containers/android/src/main/java/com/squareup/sample/container/panel/ScrimContainer.kt renamed to samples/containers/android/src/main/java/com/squareup/sample/container/ScrimContainer.kt

@@ -1,12 +1,12 @@
-package com.squareup.sample.container.panel
+package com.squareup.sample.container
 
 import android.animation.ValueAnimator
 import android.content.Context
 import android.util.AttributeSet
 import android.view.View
 import android.view.ViewGroup
 import androidx.core.content.ContextCompat
-import com.squareup.sample.container.R
+import com.squareup.sample.container.panel.ScrimScreen
 import com.squareup.workflow1.ui.ManualScreenViewFactory
 import com.squareup.workflow1.ui.ScreenViewFactory
 import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
@@ -17,9 +17,9 @@ import com.squareup.workflow1.ui.bindShowRendering
  * A view that renders only its first child, behind a smoke scrim if
  * [isDimmed] is true (tablets only). Other children are ignored.
  *
- * Able to [render][com.squareup.workflow1.ui.showRendering] [ScrimContainerScreen].
+ * Able to [render][com.squareup.workflow1.ui.showRendering] [ScrimScreen].
  */
-class ScrimContainer @JvmOverloads constructor(
+internal class ScrimContainer @JvmOverloads constructor(
   context: Context,
   attributeSet: AttributeSet? = null,
   defStyle: Int = 0,
@@ -91,21 +91,21 @@ class ScrimContainer @JvmOverloads constructor(
   }
 
   @OptIn(WorkflowUiExperimentalApi::class)
-  companion object : ScreenViewFactory<ScrimContainerScreen<*>> by ManualScreenViewFactory(
-      type = ScrimContainerScreen::class,
+  companion object : ScreenViewFactory<ScrimScreen<*>> by ManualScreenViewFactory(
+      type = ScrimScreen::class,
       viewConstructor = { initialRendering, initialViewEnvironment, contextForNewView, _ ->
         val stub = WorkflowViewStub(contextForNewView)
 
         ScrimContainer(contextForNewView)
-            .apply {
-              layoutParams = LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)
-              addView(stub)
+            .also { view ->
+              view.layoutParams = LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)
+              view.addView(stub)
 
-              bindShowRendering(
-                  initialRendering, initialViewEnvironment
+              view.bindShowRendering(
+                initialRendering, initialViewEnvironment
               ) { rendering, environment ->
-                stub.show(rendering.wrapped, environment)
-                isDimmed = rendering.dimmed
+                stub.show(rendering.content, environment)
+                view.isDimmed = rendering.dimmed
               }
             }
       }

samples/containers/android/src/main/java/com/squareup/sample/container/panel/Contexts.kt

@@ -2,15 +2,9 @@ package com.squareup.sample.container.panel
 
 import android.content.Context
 import android.content.Context.WINDOW_SERVICE
-import android.view.Display
 import android.view.WindowManager
 import com.squareup.sample.container.R
 
-val Context.isPortrait: Boolean get() = resources.getBoolean(R.bool.is_portrait)
-
 val Context.isTablet: Boolean get() = resources.getBoolean(R.bool.is_tablet)
 
 val Context.windowManager: WindowManager get() = getSystemService(WINDOW_SERVICE) as WindowManager
-
-@Suppress("DEPRECATION")
-val Context.defaultDisplay: Display get() = windowManager.defaultDisplay

samples/containers/android/src/main/java/com/squareup/sample/container/panel/PanelContainer.kt

@@ -0,0 +1,55 @@
+package com.squareup.sample.container.panel
+
+import android.app.Dialog
+import android.graphics.drawable.ColorDrawable
+import android.util.TypedValue
+import android.view.View
+import com.squareup.sample.container.R
+import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.container.Bounds
+import com.squareup.workflow1.ui.container.ModalScreenOverlayDialogFactory
+import com.squareup.workflow1.ui.container.setBounds
+
+/**
+ * Android support for [PanelOverlay].
+ */
+@OptIn(WorkflowUiExperimentalApi::class)
+internal object PanelOverlayDialogFactory : ModalScreenOverlayDialogFactory<PanelOverlay<*>>(
+  type = PanelOverlay::class
+) {
+  override fun buildDialogWithContentView(contentView: View): Dialog {
+    val context = contentView.context
+    return Dialog(context, R.style.PanelDialog).also { dialog ->
+      dialog.setContentView(contentView)
+
+      val typedValue = TypedValue()
+      context.theme.resolveAttribute(android.R.attr.windowBackground, typedValue, true)
+      if (typedValue.type in TypedValue.TYPE_FIRST_COLOR_INT..TypedValue.TYPE_LAST_COLOR_INT) {
+        dialog.window!!.setBackgroundDrawable(ColorDrawable(typedValue.data))
+      }
+    }
+  }
+
+  override fun updateBounds(
+    dialog: Dialog,
+    bounds: Bounds
+  ) {
+    val refinedBounds: Bounds = if (!dialog.context.isTablet) {
+      // On a phone, fill the bounds entirely.
+      bounds
+    } else {
+      if (bounds.height > bounds.width) {
+        val margin = bounds.height - bounds.width
+        val topDelta = margin / 2
+        val bottomDelta = margin - topDelta
+        bounds.copy(top = bounds.top + topDelta, bottom = bounds.bottom - bottomDelta)
+      } else {
+        val margin = bounds.width - bounds.height
+        val leftDelta = margin / 2
+        val rightDelta = margin - leftDelta
+        bounds.copy(left = bounds.left + leftDelta, right = bounds.right - rightDelta)
+      }
+    }
+    dialog.setBounds(refinedBounds)
+  }
+}

samples/containers/android/src/main/java/com/squareup/sample/container/panel/PanelOverlayDialogFactory.kt

@@ -1,5 +1,4 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
-  <bool name="is_portrait">true</bool>
   <bool name="is_tablet">false</bool>
 </resources>

samples/containers/android/src/main/res/values-land/bools.xml

@@ -5,6 +5,7 @@ plugins {
 
 dependencies {
   implementation(project(":workflow-ui:container-common"))
+  implementation(project(":workflow-ui:core-android"))
   implementation(project(":workflow-core"))
 
   implementation(Dependencies.Kotlin.Stdlib.jdk6)

samples/containers/android/src/main/res/values/bools.xml

@@ -0,0 +1,10 @@
+package com.squareup.sample.container.panel
+
+import com.squareup.workflow1.ui.Screen
+import com.squareup.workflow1.ui.WorkflowUiExperimentalApi
+import com.squareup.workflow1.ui.container.ScreenOverlay
+
+@OptIn(WorkflowUiExperimentalApi::class)
+class PanelOverlay<T : Screen>(
+  override val content: T
+) : ScreenOverlay<T>