Add View.findOnBackInvokedDispatcher

To make it easier for developer to migrate away from KEYCODE_BACK
without having to walk up the view hierachy in order to find an
OnBackDispatcher, introduce findOnBackInvokedDispatcher.

Bug: 227301455
Test: android.view.cts.OnBackInvokedDispatcherTest#testGetDispatcherOnView
Change-Id: I7f3e76df596d306fa26d72df8115d5b15d7ac564

4 files changed, 64 insertions, 0 deletions

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index 7d823b1c100d..0fc365784e49 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -162,6 +162,7 @@ import android.view.translation.ViewTranslationResponse;
 import android.widget.Checkable;
 import android.widget.FrameLayout;
 import android.widget.ScrollBarDrawable;
+import android.window.OnBackInvokedDispatcher;
 
 import com.android.internal.R;
 import com.android.internal.util.ArrayUtils;
@@ -12098,6 +12099,23 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
         return null;
     }
 
+
+    /**
+     * Walk up the View hierarchy to find the nearest {@link OnBackInvokedDispatcher}.
+     *
+     * @return The {@link OnBackInvokedDispatcher} from this or the nearest
+     * ancestor, or null if this view is both not attached and have no ancestor providing an
+     * {@link OnBackInvokedDispatcher}.
+     */
+    @Nullable
+    public final OnBackInvokedDispatcher findOnBackInvokedDispatcher() {
+        ViewParent parent = getParent();
+        if (parent != null) {
+            return parent.findOnBackInvokedDispatcherForChild(this, this);
+        }
+        return null;
+    }
+
     /**
      * @hide Compute the insets that should be consumed by this view and the ones
      * that should propagate to those under it.
diff --git a/core/java/android/view/ViewGroup.java b/core/java/android/view/ViewGroup.java
index fe672327346a..9f0ad1169a8e 100644
--- a/core/java/android/view/ViewGroup.java
+++ b/core/java/android/view/ViewGroup.java
@@ -72,6 +72,7 @@ import android.view.inspector.InspectableProperty.EnumEntry;
 import android.view.translation.TranslationCapability;
 import android.view.translation.TranslationSpec.DataFormat;
 import android.view.translation.ViewTranslationRequest;
+import android.window.OnBackInvokedDispatcher;
 
 import com.android.internal.R;
 
@@ -9296,4 +9297,25 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
                     requests);
         }
     }
+
+    /**
+     * Walk up the View hierarchy to find the nearest {@link OnBackInvokedDispatcher}.
+     *
+     * @return The {@link OnBackInvokedDispatcher} from this or the nearest
+     * ancestor, or null if the view is both not attached and have no ancestor providing an
+     * {@link OnBackInvokedDispatcher}.
+     *
+     * @param child The direct child of this view for which to find a dispatcher.
+     * @param requester The requester that will use the dispatcher. Can be the same as child.
+     */
+    @Nullable
+    @Override
+    public OnBackInvokedDispatcher findOnBackInvokedDispatcherForChild(@NonNull View child,
+            @NonNull View requester) {
+        ViewParent parent = getParent();
+        if (parent != null) {
+            return parent.findOnBackInvokedDispatcherForChild(this, requester);
+        }
+        return null;
+    }
 }
diff --git a/core/java/android/view/ViewParent.java b/core/java/android/view/ViewParent.java
index 128da314e907..1020d2ef02be 100644
--- a/core/java/android/view/ViewParent.java
+++ b/core/java/android/view/ViewParent.java
@@ -22,6 +22,7 @@ import android.graphics.Rect;
 import android.graphics.Region;
 import android.os.Bundle;
 import android.view.accessibility.AccessibilityEvent;
+import android.window.OnBackInvokedDispatcher;
 
 /**
  * Defines the responsibilities for a class that will be a parent of a View.
@@ -697,4 +698,20 @@ public interface ViewParent {
             getParent().onDescendantUnbufferedRequested();
         }
     }
+
+    /**
+     * Walk up the View hierarchy to find the nearest {@link OnBackInvokedDispatcher}.
+     *
+     * @return The {@link OnBackInvokedDispatcher} from this or the nearest
+     * ancestor, or null if the view is both not attached and have no ancestor providing an
+     * {@link OnBackInvokedDispatcher}.
+     *
+     * @param child The direct child of this view for which to find a dispatcher.
+     * @param requester The requester that will use the dispatcher. Can be the same as child.
+     */
+    @Nullable
+    default OnBackInvokedDispatcher findOnBackInvokedDispatcherForChild(@NonNull View child,
+            @NonNull View requester) {
+        return null;
+    }
 }
diff --git a/core/java/android/view/ViewRootImpl.java b/core/java/android/view/ViewRootImpl.java
index 931ae2748785..9edf29d6b8c7 100644
--- a/core/java/android/view/ViewRootImpl.java
+++ b/core/java/android/view/ViewRootImpl.java
@@ -10736,6 +10736,13 @@ public final class ViewRootImpl implements ViewParent,
         return mOnBackInvokedDispatcher;
     }
 
+    @NonNull
+    @Override
+    public OnBackInvokedDispatcher findOnBackInvokedDispatcherForChild(
+            @NonNull View child, @NonNull View requester) {
+        return getOnBackInvokedDispatcher();
+    }
+
     /**
      * When this ViewRootImpl is added to the window manager, transfers the first
      * {@link OnBackInvokedCallback} to be called to the server.