| /* |
| * Copyright (C) 2020 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.server.location; |
| |
| import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND_SERVICE; |
| import static android.app.ActivityManager.RunningAppProcessInfo.Importance; |
| |
| import android.annotation.Nullable; |
| import android.app.ActivityManager; |
| import android.content.Context; |
| import android.os.Binder; |
| |
| import com.android.internal.annotations.GuardedBy; |
| import com.android.internal.util.Preconditions; |
| import com.android.server.FgThread; |
| |
| import java.util.Objects; |
| import java.util.concurrent.CopyOnWriteArrayList; |
| |
| /** |
| * Provides accessors and listeners for all application foreground status. An application is |
| * considered foreground if it's uid's importance level is at or more important than |
| * {@link android.app.ActivityManager.RunningAppProcessInfo#IMPORTANCE_FOREGROUND_SERVICE}. |
| */ |
| public class AppForegroundHelper { |
| |
| /** |
| * Listener for application foreground state changes. |
| */ |
| public interface AppForegroundListener { |
| /** |
| * Called when an application's foreground state changes. |
| */ |
| void onAppForegroundChanged(int uid, boolean foreground); |
| } |
| |
| // importance constants decrement with increasing importance - this is our limit for an |
| // importance level we consider foreground. |
| private static final int FOREGROUND_IMPORTANCE_CUTOFF = IMPORTANCE_FOREGROUND_SERVICE; |
| |
| private static boolean isForeground(@Importance int importance) { |
| return importance <= FOREGROUND_IMPORTANCE_CUTOFF; |
| } |
| |
| private final Context mContext; |
| private final CopyOnWriteArrayList<AppForegroundListener> mListeners; |
| |
| @GuardedBy("this") |
| @Nullable private ActivityManager mActivityManager; |
| |
| public AppForegroundHelper(Context context) { |
| mContext = context; |
| mListeners = new CopyOnWriteArrayList<>(); |
| } |
| |
| /** Called when system is ready. */ |
| public synchronized void onSystemReady() { |
| if (mActivityManager != null) { |
| return; |
| } |
| |
| mActivityManager = Objects.requireNonNull(mContext.getSystemService(ActivityManager.class)); |
| mActivityManager.addOnUidImportanceListener(this::onAppForegroundChanged, |
| FOREGROUND_IMPORTANCE_CUTOFF); |
| } |
| |
| /** |
| * Adds a listener for app foreground changed events. Callbacks occur on an unspecified thread. |
| */ |
| public void addListener(AppForegroundListener listener) { |
| mListeners.add(listener); |
| } |
| |
| /** |
| * Removes a listener for app foreground changed events. |
| */ |
| public void removeListener(AppForegroundListener listener) { |
| mListeners.remove(listener); |
| } |
| |
| private void onAppForegroundChanged(int uid, @Importance int importance) { |
| // invoked on ui thread, move to fg thread so we don't block the ui thread |
| boolean foreground = isForeground(importance); |
| FgThread.getHandler().post(() -> { |
| for (AppForegroundListener listener : mListeners) { |
| listener.onAppForegroundChanged(uid, foreground); |
| } |
| }); |
| } |
| |
| /** |
| * Whether the given uid is currently foreground. |
| */ |
| public boolean isAppForeground(int uid) { |
| return isForeground(getImportance(uid)); |
| } |
| |
| /** |
| * Retrieves the current importance of the given uid. |
| * |
| * @deprecated Prefer {@link #isAppForeground(int)}. |
| */ |
| @Deprecated |
| @Importance |
| public int getImportance(int uid) { |
| synchronized (this) { |
| Preconditions.checkState(mActivityManager != null); |
| } |
| |
| long identity = Binder.clearCallingIdentity(); |
| try { |
| return mActivityManager.getUidImportance(uid); |
| } finally { |
| Binder.restoreCallingIdentity(identity); |
| } |
| } |
| } |