| /* |
| * Copyright (C) 2021 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. |
| */ |
| |
| package com.android.systemui.accessibility; |
| |
| import android.content.ContentResolver; |
| import android.content.Context; |
| import android.database.ContentObserver; |
| import android.os.Handler; |
| import android.os.Looper; |
| import android.os.UserHandle; |
| import android.provider.Settings; |
| |
| import androidx.annotation.NonNull; |
| |
| import com.android.internal.annotations.VisibleForTesting; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Objects; |
| |
| /** |
| * Provides basic methods for adding, removing arbitrary listeners and inquiry given {@code |
| * secureSettingsKey} value; it must comes from {@link Settings.Secure}. |
| * |
| * This abstract class is intended to be subclassed and specialized to maintain |
| * a registry of listeners of specific types and dispatch changes to them. |
| * |
| * @param <T> The listener type |
| */ |
| public abstract class SecureSettingsContentObserver<T> { |
| |
| private final ContentResolver mContentResolver; |
| @VisibleForTesting |
| final ContentObserver mContentObserver; |
| |
| private final String mKey; |
| |
| @VisibleForTesting |
| final List<T> mListeners = new ArrayList<>(); |
| |
| protected SecureSettingsContentObserver(Context context, String secureSettingsKey) { |
| mKey = secureSettingsKey; |
| mContentResolver = context.getContentResolver(); |
| mContentObserver = new ContentObserver(new Handler(Looper.getMainLooper())) { |
| @Override |
| public void onChange(boolean selfChange) { |
| updateValueChanged(); |
| } |
| }; |
| } |
| |
| /** |
| * Registers a listener to receive updates from given settings key {@code secureSettingsKey}. |
| * |
| * @param listener A listener to be added to receive the changes |
| */ |
| public void addListener(@NonNull T listener) { |
| Objects.requireNonNull(listener, "listener must be non-null"); |
| |
| mListeners.add(listener); |
| |
| if (mListeners.size() == 1) { |
| mContentResolver.registerContentObserver( |
| Settings.Secure.getUriFor(mKey), /* notifyForDescendants= */ |
| false, mContentObserver, UserHandle.USER_ALL); |
| } |
| } |
| |
| /** |
| * Unregisters a listener previously registered with {@link #addListener(T listener)}. |
| * |
| * @param listener A listener to be removed from receiving the changes |
| */ |
| public void removeListener(@NonNull T listener) { |
| Objects.requireNonNull(listener, "listener must be non-null"); |
| |
| mListeners.remove(listener); |
| |
| if (mListeners.isEmpty()) { |
| mContentResolver.unregisterContentObserver(mContentObserver); |
| } |
| } |
| |
| /** |
| * Gets the value from the current user's secure settings. |
| * |
| * See {@link Settings.Secure}. |
| */ |
| public final String getSettingsValue() { |
| return Settings.Secure.getStringForUser(mContentResolver, mKey, UserHandle.USER_CURRENT); |
| } |
| |
| private void updateValueChanged() { |
| final String value = getSettingsValue(); |
| final int listenerSize = mListeners.size(); |
| for (int i = 0; i < listenerSize; i++) { |
| onValueChanged(mListeners.get(i), value); |
| } |
| } |
| |
| /** |
| * Called when the registered value from {@code secureSettingsKey} changes. |
| * |
| * @param listener A listener could be used to receive the updates |
| * @param value Content changed value from {@code secureSettingsKey} |
| */ |
| abstract void onValueChanged(T listener, String value); |
| } |