Add more a11y support to BottomSheetBehavior.

PiperOrigin-RevId: 266403799

Author: Material Design Team

catalog/java/io/material/catalog/bottomsheet/BottomSheetMainDemoFragment.java

@@ -58,6 +58,7 @@ public View onCreateDemoView(
     button.setOnClickListener(
         v -> {
           bottomSheetDialog.show();
+          bottomSheetDialog.setTitle(getText(R.string.cat_bottomsheet_title));
           Button button0 = bottomSheetInternal.findViewById(R.id.cat_bottomsheet_modal_button);
           button0.setOnClickListener(
               v0 ->

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

@@ -41,6 +41,9 @@
 import androidx.core.math.MathUtils;
 import androidx.customview.view.AbsSavedState;
 import androidx.core.view.ViewCompat;
+import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
+import androidx.core.view.accessibility.AccessibilityNodeInfoCompat.AccessibilityActionCompat;
+import androidx.core.view.accessibility.AccessibilityViewCommand;
 import androidx.customview.widget.ViewDragHelper;
 import android.util.AttributeSet;
 import android.util.TypedValue;
@@ -50,7 +53,6 @@
 import android.view.ViewConfiguration;
 import android.view.ViewGroup;
 import android.view.ViewParent;
-import android.view.accessibility.AccessibilityEvent;
 import androidx.coordinatorlayout.widget.CoordinatorLayout;
 import androidx.coordinatorlayout.widget.CoordinatorLayout.LayoutParams;
 import com.google.android.material.resources.MaterialResources;
@@ -63,6 +65,15 @@
 /**
  * An interaction behavior plugin for a child view of {@link CoordinatorLayout} to make it work as a
  * bottom sheet.
+ *
+ * <p>For a persistent bottom sheet, to send useful accessibility events, use {@link
+ * ViewCompat#setAccessibilityPaneTitle(View, CharSequence)} to set a title when in an expanded
+ * state, and to remove the title when in a collapsed state. This can be tracked in {@link
+ * BottomSheetCallback}.
+ *
+ * <p>For BottomSheetDialog use {@link BottomSheetDialog#setTitle(int)}, and for
+ * BottomSheetDialogFragment use {@link ViewCompat#setAccessibilityPaneTitle(View, CharSequence)}.
+ * The titles need to only be set once here as the views behave like windows in all states.
  */
 public class BottomSheetBehavior<V extends View> extends CoordinatorLayout.Behavior<V> {
 
@@ -362,6 +373,11 @@ public boolean onLayoutChild(
         isShapeExpanded = state == STATE_EXPANDED;
         materialShapeDrawable.setInterpolation(isShapeExpanded ? 0f : 1f);
       }
+      updateAccessibilityActions();
+      if (ViewCompat.getImportantForAccessibility(child)
+          == ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_AUTO) {
+        ViewCompat.setImportantForAccessibility(child, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES);
+      }
     }
     if (viewDragHelper == null) {
       viewDragHelper = ViewDragHelper.create(parent, dragCallback);
@@ -678,6 +694,8 @@ public void setFitToContents(boolean fitToContents) {
     }
     // Fix incorrect expanded settings depending on whether or not we are fitting sheet to contents.
     setStateInternal((this.fitToContents && state == STATE_HALF_EXPANDED) ? STATE_EXPANDED : state);
+
+    updateAccessibilityActions();
   }
 
   /**
@@ -796,6 +814,7 @@ public void setHideable(boolean hideable) {
         // Lift up to collapsed state
         setState(STATE_COLLAPSED);
       }
+      updateAccessibilityActions();
     }
   }
 
@@ -950,14 +969,11 @@ void setStateInternal(@State int state) {
       updateImportantForAccessibility(false);
     }
 
-    ViewCompat.setImportantForAccessibility(
-        bottomSheet, ViewCompat.IMPORTANT_FOR_ACCESSIBILITY_YES);
-    bottomSheet.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED);
-
     updateDrawableForTargetState(state);
     if (callback != null) {
       callback.onStateChanged(bottomSheet, state);
     }
+    updateAccessibilityActions();
   }
 
   private void updateDrawableForTargetState(@State int state) {
@@ -1469,4 +1485,61 @@ private void updateImportantForAccessibility(boolean expanded) {
       importantForAccessibilityMap = null;
     }
   }
+
+  private void updateAccessibilityActions() {
+    if (viewRef == null) {
+      return;
+    }
+    V child = viewRef.get();
+    if (child == null) {
+      return;
+    }
+    ViewCompat.removeAccessibilityAction(child, AccessibilityNodeInfoCompat.ACTION_COLLAPSE);
+    ViewCompat.removeAccessibilityAction(child, AccessibilityNodeInfoCompat.ACTION_EXPAND);
+    ViewCompat.removeAccessibilityAction(child, AccessibilityNodeInfoCompat.ACTION_DISMISS);
+
+    if (hideable && state != STATE_HIDDEN) {
+      addAccessibilityActionForState(child, AccessibilityActionCompat.ACTION_DISMISS, STATE_HIDDEN);
+    }
+
+    switch (state) {
+      case STATE_EXPANDED:
+        {
+          int nextState = fitToContents ? STATE_COLLAPSED : STATE_HALF_EXPANDED;
+          addAccessibilityActionForState(
+              child, AccessibilityActionCompat.ACTION_COLLAPSE, nextState);
+          break;
+        }
+      case STATE_HALF_EXPANDED:
+        {
+          addAccessibilityActionForState(
+              child, AccessibilityActionCompat.ACTION_COLLAPSE, STATE_COLLAPSED);
+          addAccessibilityActionForState(
+              child, AccessibilityActionCompat.ACTION_EXPAND, STATE_EXPANDED);
+          break;
+        }
+      case STATE_COLLAPSED:
+        {
+          int nextState = fitToContents ? STATE_EXPANDED : STATE_HALF_EXPANDED;
+          addAccessibilityActionForState(child, AccessibilityActionCompat.ACTION_EXPAND, nextState);
+          break;
+        }
+      default: // fall out
+    }
+  }
+
+  private void addAccessibilityActionForState(
+      V child, AccessibilityActionCompat action, final int state) {
+    ViewCompat.replaceAccessibilityAction(
+        child,
+        action,
+        null,
+        new AccessibilityViewCommand() {
+          @Override
+          public boolean perform(@NonNull View view, @Nullable CommandArguments arguments) {
+            setState(state);
+            return true;
+          }
+        });
+  }
 }

tests/javatests/com/google/android/material/bottomsheet/BottomSheetBehaviorTest.java

@@ -16,6 +16,7 @@
 
 package com.google.android.material.bottomsheet;
 
+import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.not;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -24,10 +25,12 @@
 import static org.junit.Assert.fail;
 
 import android.content.Context;
+import android.os.Build.VERSION;
 import android.os.SystemClock;
 import androidx.annotation.LayoutRes;
 import androidx.annotation.NonNull;
 import androidx.core.view.ViewCompat;
+import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
 import androidx.core.widget.NestedScrollView;
 import android.view.LayoutInflater;
 import android.view.MotionEvent;
@@ -56,6 +59,7 @@
 import com.google.android.material.floatingactionbutton.FloatingActionButton;
 import com.google.android.material.testapp.BottomSheetBehaviorActivity;
 import com.google.android.material.testapp.R;
+import com.google.android.material.testutils.CoordinatorLayoutUtils;
 import com.google.android.material.testutils.DesignViewActions;
 import org.hamcrest.Matcher;
 import org.hamcrest.Matchers;
@@ -283,6 +287,7 @@ public void testInitialSetup() {
     CoordinatorLayout coordinatorLayout = getCoordinatorLayout();
     ViewGroup bottomSheet = getBottomSheet();
     assertThat(bottomSheet.getTop(), is(coordinatorLayout.getHeight() - behavior.getPeekHeight()));
+    assertAccessibilityActions(behavior, getBottomSheet());
   }
 
   @Test
@@ -377,7 +382,9 @@ public void testSwipeDownToHideFullyExpanded() throws Throwable {
   @Test
   @MediumTest
   public void testSkipCollapsed() throws Throwable {
+    assertAccessibilityActions(getBehavior(), getBottomSheet());
     getBehavior().setSkipCollapsed(true);
+    assertAccessibilityActions(getBehavior(), getBottomSheet());
     checkSetState(BottomSheetBehavior.STATE_EXPANDED, ViewMatchers.isDisplayed());
     Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
         .perform(
@@ -779,6 +786,7 @@ private void checkSetState(final int state, Matcher<View> matcher) throws Throwa
       Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
           .check(ViewAssertions.matches(matcher));
       assertThat(getBehavior().getState(), is(state));
+      assertAccessibilityActions(getBehavior(), getBottomSheet());
     } finally {
       unregisterIdlingResourceCallback();
     }
@@ -811,6 +819,30 @@ private void withFabVisibilityChange(boolean shown, Runnable action) {
     }
   }
 
+  private static void assertAccessibilityActions(
+      BottomSheetBehavior<?> behavior, ViewGroup bottomSheet) {
+    if (VERSION.SDK_INT >= 21) {
+      int state = behavior.getState();
+      boolean hasExpandAction =
+          state == BottomSheetBehavior.STATE_COLLAPSED
+              || state == BottomSheetBehavior.STATE_HALF_EXPANDED;
+      boolean hasCollapseAction =
+          state == BottomSheetBehavior.STATE_EXPANDED
+              || state == BottomSheetBehavior.STATE_HALF_EXPANDED;
+      boolean hasDismissAction = state != BottomSheetBehavior.STATE_HIDDEN && behavior.isHideable();
+      assertThat(
+          CoordinatorLayoutUtils.hasAction(
+              bottomSheet, AccessibilityNodeInfoCompat.ACTION_COLLAPSE),
+          equalTo(hasCollapseAction));
+      assertThat(
+          CoordinatorLayoutUtils.hasAction(bottomSheet, AccessibilityNodeInfoCompat.ACTION_EXPAND),
+          equalTo(hasExpandAction));
+      assertThat(
+          CoordinatorLayoutUtils.hasAction(bottomSheet, AccessibilityNodeInfoCompat.ACTION_DISMISS),
+          equalTo(hasDismissAction));
+    }
+  }
+
   private ViewGroup getBottomSheet() {
     return activityTestRule.getActivity().mBottomSheet;
   }

tests/javatests/com/google/android/material/testutils/CoordinatorLayoutUtils.java

@@ -16,8 +16,11 @@
 
 package com.google.android.material.testutils;
 
+import androidx.core.view.accessibility.AccessibilityNodeInfoCompat.AccessibilityActionCompat;
 import android.view.View;
 import androidx.coordinatorlayout.widget.CoordinatorLayout;
+import com.google.android.material.testapp.R;
+import java.util.ArrayList;
 
 public class CoordinatorLayoutUtils {
 
@@ -33,4 +36,24 @@ public boolean layoutDependsOn(CoordinatorLayout parent, View child, View depend
       return this.dependency != null && dependency == this.dependency;
     }
   }
+
+  public static boolean hasAction(View view, int actionId) {
+    ArrayList<AccessibilityActionCompat> actions = getActionList(view);
+    for (int i = 0; i < actions.size(); i++) {
+      if (actions.get(i).getId() == actionId) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  private static ArrayList<AccessibilityActionCompat> getActionList(View view) {
+    @SuppressWarnings("unchecked")
+    ArrayList<AccessibilityActionCompat> actions =
+        (ArrayList<AccessibilityActionCompat>) view.getTag(R.id.tag_accessibility_actions);
+    if (actions == null) {
+      actions = new ArrayList<>();
+    }
+    return actions;
+  }
 }