[Predictive Back][Bottom Sheet] Fix bug where standard hideable bottom sheets don't stay hidden after predictive back

It wasn't an issue for modal bottom sheets because they dismiss the whole window when the bottom sheet behavior is hidden

Also updated Bottom App Bar demo drawer to opt into predictive back, which is a standard hideable bottom sheet

PiperOrigin-RevId: 520312905

Author: dsn5ft

catalog/java/io/material/catalog/bottomappbar/BottomAppBarMainDemoFragment.java

@@ -18,6 +18,7 @@
 
 import io.material.catalog.R;
 
+import android.os.Build.VERSION_CODES;
 import android.os.Bundle;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
@@ -28,10 +29,12 @@
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityEvent;
+import android.window.BackEvent;
 import androidx.activity.OnBackPressedCallback;
 import androidx.annotation.LayoutRes;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
 import androidx.coordinatorlayout.widget.CoordinatorLayout;
 import com.google.android.material.bottomappbar.BottomAppBar;
 import com.google.android.material.bottomappbar.BottomAppBarTopEdgeTreatment;
@@ -56,9 +59,27 @@ public class BottomAppBarMainDemoFragment extends DemoFragment {
 
   private final OnBackPressedCallback bottomDrawerOnBackPressedCallback =
       new OnBackPressedCallback(/* enabled= */ false) {
+        @RequiresApi(VERSION_CODES.UPSIDE_DOWN_CAKE)
+        @Override
+        public void handleOnBackStarted(@NonNull BackEvent backEvent) {
+          bottomDrawerBehavior.startBackProgress(backEvent);
+        }
+
+        @RequiresApi(VERSION_CODES.UPSIDE_DOWN_CAKE)
+        @Override
+        public void handleOnBackProgressed(@NonNull BackEvent backEvent) {
+          bottomDrawerBehavior.updateBackProgress(backEvent);
+        }
+
         @Override
         public void handleOnBackPressed() {
-          bottomDrawerBehavior.setState(BottomSheetBehavior.STATE_HIDDEN);
+          bottomDrawerBehavior.handleBackInvoked();
+        }
+
+        @RequiresApi(VERSION_CODES.UPSIDE_DOWN_CAKE)
+        @Override
+        public void handleOnBackCancelled() {
+          bottomDrawerBehavior.cancelBackProgress();
         }
       };
 
@@ -196,9 +217,22 @@ protected void setUpBottomDrawer(View view) {
         new BottomSheetCallback() {
           @Override
           public void onStateChanged(@NonNull View bottomSheet, int newState) {
-            bottomDrawerOnBackPressedCallback.setEnabled(
-                newState == BottomSheetBehavior.STATE_EXPANDED
-                    || newState == BottomSheetBehavior.STATE_HALF_EXPANDED);
+            switch (newState) {
+              case BottomSheetBehavior.STATE_EXPANDED:
+              case BottomSheetBehavior.STATE_HALF_EXPANDED:
+                bottomDrawerOnBackPressedCallback.setEnabled(true);
+                break;
+              case BottomSheetBehavior.STATE_COLLAPSED:
+              case BottomSheetBehavior.STATE_HIDDEN:
+                bottomDrawerOnBackPressedCallback.setEnabled(false);
+                break;
+              case BottomSheetBehavior.STATE_DRAGGING:
+              case BottomSheetBehavior.STATE_SETTLING:
+              default:
+                // Do nothing, only change callback enabled for "stable" states.
+                break;
+            }
+
             if (newState == BottomSheetBehavior.STATE_HIDDEN) {
               barNavView.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_FOCUSED);
             }

lib/java/com/google/android/material/bottomsheet/BottomSheetBehavior.java

@@ -1597,6 +1597,9 @@ public void handleBackInvoked() {
             public void onAnimationEnd(Animator animation) {
               // Hide immediately following the built-in predictive back slide down animation.
               setStateInternal(STATE_HIDDEN);
+              if (viewRef != null && viewRef.get() != null) {
+                viewRef.get().requestLayout();
+              }
             }
           });
     } else {