Add support for keyboard shortcuts panel on TV

The keyboard shortcuts panel lists available shortcuts for the currently
focused app + system shortcuts.
Apps can request the panel to be shown by calling
Activity#requestShowKeyboardShortcuts.

Calling this method on TV caused SystemUI to crash, as
KeyboardShortcutsReceiver couldn't be instantiated.
Adding the KeyboardShortcutsModule on TV fixes this crash.

Adding the override for toggleKeyboardShortcutsMenu in TvStatusBar
enables the global toggle shortcuts panel shortcut to work.

The other changes are to improve usability of the dialog on TV:
- Make the list rows focusable
- Give the whole row a suitable contentDescription for a11y
- Give the items a background that highlights the focused row
- Hide the "Recents" row on devices that do not support it (like TV)

Bug: 278514212
Test: manual on TV device
Change-Id: Ia8285d5b05ad909cecb16eb087cbbc56ed86475a

packages/SystemUI/res/drawable/list_item_background.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+    Copyright (C) 2023 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.
+-->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_focused="true" android:drawable="@*android:drawable/list_choice_background_material" />
+    <item android:drawable="@android:color/transparent" />
+</selector>

packages/SystemUI/res/layout/keyboard_shortcut_app_item.xml

@@ -17,6 +17,8 @@
 <com.android.systemui.statusbar.KeyboardShortcutAppItemLayout
         xmlns:android="http://schemas.android.com/apk/res/android"
         android:orientation="horizontal"
+        android:background="@drawable/list_item_background"
+        android:focusable="true"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:minHeight="48dp"
@@ -55,6 +57,5 @@
             android:layout_alignParentEnd="true"
             android:textSize="14sp"
             android:scrollHorizontally="false"
-            android:layout_centerVertical="true"
-            android:focusable="true"/>
+            android:layout_centerVertical="true"/>
 </com.android.systemui.statusbar.KeyboardShortcutAppItemLayout>

packages/SystemUI/res/layout/keyboard_shortcuts_category_title.xml

@@ -16,10 +16,11 @@
   ~ limitations under the License
   -->
 <TextView xmlns:android="http://schemas.android.com/apk/res/android"
-          android:layout_width="wrap_content"
+          android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:textSize="14sp"
           android:fontFamily="sans-serif-medium"
+          android:importantForAccessibility="yes"
           android:paddingStart="24dp"
           android:paddingTop="20dp"
           android:paddingEnd="24dp"

packages/SystemUI/src/com/android/systemui/statusbar/KeyboardShortcuts.java

@@ -440,10 +440,15 @@ public final class KeyboardShortcuts {
                 mContext.getString(R.string.keyboard_shortcut_group_system_back),
                 KeyEvent.KEYCODE_DEL,
                 KeyEvent.META_META_ON));
-        systemGroup.addItem(new KeyboardShortcutInfo(
-                mContext.getString(R.string.keyboard_shortcut_group_system_recents),
-                KeyEvent.KEYCODE_TAB,
-                KeyEvent.META_ALT_ON));
+
+        // Some devices (like TV) don't have recents
+        if (mContext.getResources().getBoolean(com.android.internal.R.bool.config_hasRecents)) {
+            systemGroup.addItem(new KeyboardShortcutInfo(
+                    mContext.getString(R.string.keyboard_shortcut_group_system_recents),
+                    KeyEvent.KEYCODE_TAB,
+                    KeyEvent.META_ALT_ON));
+        }
+
         systemGroup.addItem(new KeyboardShortcutInfo(
                 mContext.getString(
                         R.string.keyboard_shortcut_group_system_notifications),
@@ -683,8 +688,10 @@ public final class KeyboardShortcuts {
                 ViewGroup shortcutItemsContainer = (ViewGroup) shortcutView
                         .findViewById(R.id.keyboard_shortcuts_item_container);
                 final int shortcutKeysSize = shortcutKeys.size();
+                final List<String> humanReadableShortcuts = new ArrayList<>();
                 for (int k = 0; k < shortcutKeysSize; k++) {
                     StringDrawableContainer shortcutRepresentation = shortcutKeys.get(k);
+                    humanReadableShortcuts.add(shortcutRepresentation.mString);
                     if (shortcutRepresentation.mDrawable != null) {
                         ImageView shortcutKeyIconView = (ImageView) inflater.inflate(
                                 R.layout.keyboard_shortcuts_key_icon_view, shortcutItemsContainer,
@@ -714,6 +721,11 @@ public final class KeyboardShortcuts {
                         shortcutItemsContainer.addView(shortcutKeyTextView);
                     }
                 }
+                CharSequence contentDescription = info.getLabel();
+                if (!humanReadableShortcuts.isEmpty()) {
+                    contentDescription += ": " + String.join(", ", humanReadableShortcuts);
+                }
+                shortcutView.setContentDescription(contentDescription);
                 shortcutContainer.addView(shortcutView);
             }
             keyboardShortcutsLayout.addView(shortcutContainer);

packages/SystemUI/src/com/android/systemui/statusbar/tv/TvStatusBar.java

@@ -27,11 +27,12 @@ import com.android.systemui.CoreStartable;
 import com.android.systemui.assist.AssistManager;
 import com.android.systemui.dagger.SysUISingleton;
 import com.android.systemui.statusbar.CommandQueue;
-
-import javax.inject.Inject;
+import com.android.systemui.statusbar.KeyboardShortcuts;
 
 import dagger.Lazy;
 
+import javax.inject.Inject;
+
 /**
  * Status bar implementation for "large screen" products that mostly present no on-screen nav.
  * Serves as a collection of UI components, rather than showing its own UI.
@@ -78,4 +79,9 @@ public class TvStatusBar implements CoreStartable, CommandQueue.Callbacks {
                 new Intent(ACTION_SHOW_PIP_MENU).setPackage(mContext.getPackageName()),
                 SYSTEMUI_PERMISSION);
     }
+
+    @Override
+    public void toggleKeyboardShortcutsMenu(int deviceId) {
+        KeyboardShortcuts.show(mContext, deviceId);
+    }
 }

packages/SystemUI/src/com/android/systemui/tv/TvSystemUIModule.java

@@ -48,6 +48,7 @@ import com.android.systemui.shade.ShadeController;
 import com.android.systemui.shade.ShadeControllerImpl;
 import com.android.systemui.shade.ShadeExpansionStateManager;
 import com.android.systemui.statusbar.CommandQueue;
+import com.android.systemui.statusbar.KeyboardShortcutsModule;
 import com.android.systemui.statusbar.NotificationListener;
 import com.android.systemui.statusbar.NotificationLockscreenUserManager;
 import com.android.systemui.statusbar.NotificationLockscreenUserManagerImpl;
@@ -96,6 +97,7 @@ import javax.inject.Named;
                 ReferenceScreenshotModule.class,
                 StatusBarEventsModule.class,
                 VolumeModule.class,
+                KeyboardShortcutsModule.class
         }
 )
 public abstract class TvSystemUIModule {