[NavigationRail][a11y] Add a11y announcements for when nav rail is expanded or collapsed

PiperOrigin-RevId: 689858577

Author: imhappi

catalog/java/io/material/catalog/navigationrail/NavigationRailSubMenuDemoFragment.java

@@ -71,14 +71,17 @@ public View onCreateDemoView(
 
     ImageView button =
         navigationRailView.getHeaderView().findViewById(R.id.cat_navigation_rail_expand_button);
+    button.setContentDescription(getResources().getString(R.string.cat_navigation_rail_expand_button_description));
     button.setOnClickListener(
         v -> {
           if (efab.isExtended()) {
             efab.shrink();
             navigationRailView.collapse();
+            button.setContentDescription(getResources().getString(R.string.cat_navigation_rail_expand_button_description));
           } else {
             efab.extend();
             navigationRailView.expand();
+            button.setContentDescription(getResources().getString(R.string.cat_navigation_rail_collapse_button_description));
           }
         });
     return view;

catalog/java/io/material/catalog/navigationrail/res/layout/cat_navigation_rail_efab_header_view.xml

@@ -28,7 +28,8 @@
     android:layout_width="56dp"
     android:layout_height="56dp"
     android:src="@drawable/ic_drawer_menu_24px"
-    android:contentDescription="@null"
+    android:contentDescription=
+      "@string/cat_navigation_rail_expand_button_description"
     android:scaleType="center" />
   <com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
     android:id="@+id/cat_navigation_rail_efab"

catalog/java/io/material/catalog/navigationrail/res/values/strings.xml

@@ -129,6 +129,7 @@
   <string name="cat_navigation_rail_efab_text" description="The text on the button to expand the navigation rail [CHAR_LIMIT=NONE]">Label</string>
   <string name="cat_navigation_rail_center_text" description="The text in the content centered in the remaining space beside the navigation rail [CHAR_LIMIT=NONE]">center</string>
   <string name="cat_navigation_rail_efab_message" description="The message to display when the extended floating action button is clicked [CHAR_LIMIT=NONE]">Button clicked</string>
-  <string name="cat_navigation_rail_expand_collapse_button_description" description="The content description for the button that expands and collapses the navigation rail [CHAR_LIMIT=NONE]">Button to expand or collapse the navigation rail</string>
+  <string name="cat_navigation_rail_expand_button_description" description="The content description for the button that expands the navigation rail [CHAR_LIMIT=NONE]">Expand navigation rail</string>
+  <string name="cat_navigation_rail_collapse_button_description" description="The content description for the button that collapses the navigation rail [CHAR_LIMIT=NONE]">Collapse navigation rail</string>
 
 </resources>

lib/java/com/google/android/material/navigationrail/NavigationRailView.java

@@ -374,7 +374,11 @@ private void setExpanded(boolean expanded) {
 
   /** Expand the navigation rail. */
   public void expand() {
+    if (expanded) {
+      return;
+    }
     setExpanded(true);
+    announceForAccessibility(getResources().getString(R.string.nav_rail_expanded_a11y_label));
   }
 
   /** Returns whether or not the navigation rail is currently expanded. **/
@@ -384,7 +388,11 @@ public boolean isExpanded() {
 
   /** Collapse the navigation rail. */
   public void collapse() {
+    if (!expanded) {
+      return;
+    }
     setExpanded(false);
+    announceForAccessibility(getResources().getString(R.string.nav_rail_collapsed_a11y_label));
   }
 
   private void applyWindowInsets() {

lib/java/com/google/android/material/navigationrail/res/values/strings.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+-->
+<resources>
+  <string name="nav_rail_expanded_a11y_label" description="Screen reader announcement for when navigation rail is expanded [CHAR LIMIT=NONE]">
+    Expanded
+  </string>
+  <string name="nav_rail_collapsed_a11y_label" description="Screen reader announcement for when navigation rail is collapsed [CHAR LIMIT=NONE]">
+    Collapsed
+  </string>
+</resources>