Android FrameWork深入分析DreamManagerService實現自己的系統屏保
Framework分析DreamService，實現自己的系統屏保
現在有一個需求是在手機一段時間不用的情況下，顯示自己的系統屏保功能
下面是涉及到的程式碼
- /frameworks/base/services/core/java/com/android/server/power/PowerManagerService.java 顯示屏保功能的入口
- /frameworks/base/services/core/java/com/android/server/dreams/DreamManagerService.java 管理屏保APP
- /frameworks/base/services/core/java/com/android/server/dreams/DreamController.java 屏保具體的呼起
- /packages/apps/DeskClock/src/com/android/deskclock/Screensaver.java 鬧鐘模組預設的屏保
首先需要熟悉PowerManagerService的主要邏輯
這邊個人推薦blog:http://blog.chinaunix.net/xmlrpc.php?r=blog/article&uid=30510400&id=5569393 接著上面的部落格介紹，大概畫了一個流程，其實我們只要在系統啟動屏保的時候繫結到自己的APP就行了 
現在我們主要分析DreamManagerService的邏輯
DreamManagerService怎麼找到屏保APP？
找到入口了，那麼DreamManagerService怎麼啟動屏保app呢?
private final class LocalService extends DreamManagerInternal {
@Override
public void startDream(boolean doze) {
startDreamInternal(doze);
}
}
private void startDreamInternal(boolean doze) {
final int userId = ActivityManager.getCurrentUser();
//獲得屏保指定的app
final ComponentName dream = chooseDreamForUser(doze, userId);
if (dream != null) {
synchronized (mLock) {
startDreamLocked(dream, false /isTest
}
}
}
我們分析一下chooseDreamForUser（）做了什麼處理
//doze是系統另外一種狀態了，系統處於節電狀態，網路什麼都會禁止掉
//我們讓PowerMangerService呼叫startDream()的時候傳入doze = false;
//可以看出這邊是找到所有的屏保app預設使用第一個
private ComponentName chooseDreamForUser(boolean doze, int userId) {
Slog.w(TAG, “Dream 0 ” + doze + userId);
if (doze) {
ComponentName dozeComponent = getDozeComponent(userId);
return validateDream(dozeComponent) ? dozeComponent : null;
}
ComponentName[] dreams = getDreamComponentsForUser(userId);
return dreams != null && dreams.length != 0 ? dreams[0] : null;
}
看一下getDreamComponentsForUser（）做了什麼處理
private ComponentName[] getDreamComponentsForUser(int userId) {
//這裡是從settings.db獲得預設的屏保app中dreameService的包名
String names = Settings.Secure.getStringForUser(mContext.getContentResolver(),
Settings.Secure.SCREENSAVER_COMPONENTS,
userId);
//我們這邊寫死定義為自己的app這
names = “com.ucon.displaydream/com.ucon.displaydream.”;
Slog.w(TAG, “names 1 : ” + names);
ComponentName[] components = componentsFromString(names);
Slog.w(TAG, “names 2 : ” + components);
// first, ensure components point to valid services
List<ComponentName> validComponents = new ArrayList<ComponentName>();
if (components != null) {
for (ComponentName component : components) {
if (validateDream(component)) {
validComponents.add(component);
}
}
}
}
**Settings.Secure.getStringForUser(mContext.getContentResolver(),Settings.Secure.SCREENSAVER_COMPONENTS, userId);獲得預設的componentName
是 com.android.deskclock/com.android.deskclock.Screensaver**
然後開啟screensaver的程式碼
package com.android.deskclock;
import android.app.AlarmManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.res.Configuration;
import android.os.Handler;
import android.preference.PreferenceManager;
import android.service.dreams.DreamService;
import android.util.Log;
import android.view.View;
import android.widget.TextClock;
import com.android.deskclock.Utils.ScreensaverMoveSaverRunnable;
public class Screensaver extends DreamService {
public static final int ORIENTATION_CHANGE_DELAY_MS = 250;
private static final boolean DEBUG = false;
private static final String TAG = "DeskClock/Screensaver";
private View mContentView, mSaverView;
private View mAnalogClock, mDigitalClock;
private String mDateFormat;
private String mDateFormatForAccessibility;
private final Handler mHandler = new Handler();
private final ScreensaverMoveSaverRunnable mMoveSaverRunnable;
// Thread that runs every midnight and refreshes the date.
private final Runnable mMidnightUpdater = new Runnable() {
@Override
public void run() {
Utils.updateDate(mDateFormat, mDateFormatForAccessibility, mContentView);
Utils.setMidnightUpdater(mHandler, mMidnightUpdater);
}
};
/**
* Receiver to handle time reference changes.
*/
private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (DEBUG) Log.v(TAG, "Screensaver onReceive, action: " + action);
if (action == null) {
return;
}
if (action.equals(Intent.ACTION_TIME_CHANGED)
|| action.equals(Intent.ACTION_TIMEZONE_CHANGED)) {
Utils.updateDate(mDateFormat, mDateFormatForAccessibility, mContentView);
Utils.refreshAlarm(Screensaver.this, mContentView);
Utils.setMidnightUpdater(mHandler, mMidnightUpdater);
} else if (action.equals(AlarmManager.ACTION_NEXT_ALARM_CLOCK_CHANGED)) {
Utils.refreshAlarm(Screensaver.this, mContentView);
}
}
};
public Screensaver() {
if (DEBUG) Log.d(TAG, "Screensaver allocated");
mMoveSaverRunnable = new ScreensaverMoveSaverRunnable(mHandler);
}
@Override
public void onCreate() {
if (DEBUG) Log.d(TAG, "Screensaver created");
super.onCreate();
setTheme(R.style.DeskClockParentTheme);
mDateFormat = getString(R.string.abbrev_wday_month_day_no_year);
mDateFormatForAccessibility = getString(R.string.full_wday_month_day_no_year);
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
if (DEBUG) Log.d(TAG, "Screensaver configuration changed");
super.onConfigurationChanged(newConfig);
mHandler.removeCallbacks(mMoveSaverRunnable);
layoutClockSaver();
mHandler.postDelayed(mMoveSaverRunnable, ORIENTATION_CHANGE_DELAY_MS);
}
@Override
public void onAttachedToWindow() {
if (DEBUG) Log.d(TAG, "Screensaver attached to window");
super.onAttachedToWindow();
// We want the screen saver to exit upon user interaction.
setInteractive(false);
setFullscreen(true);
layoutClockSaver();
// Setup handlers for time reference changes and date updates.
IntentFilter filter = new IntentFilter();
filter.addAction(Intent.ACTION_TIME_CHANGED);
filter.addAction(Intent.ACTION_TIMEZONE_CHANGED);
registerReceiver(mIntentReceiver, filter);
Utils.setMidnightUpdater(mHandler, mMidnightUpdater);
mHandler.post(mMoveSaverRunnable);
}
@Override
public void onDetachedFromWindow() {
if (DEBUG) Log.d(TAG, "Screensaver detached from window");
super.onDetachedFromWindow();
mHandler.removeCallbacks(mMoveSaverRunnable);
// Tear down handlers for time reference changes and date updates.
Utils.cancelMidnightUpdater(mHandler, mMidnightUpdater);
unregisterReceiver(mIntentReceiver);
}
private void setClockStyle() {
Utils.setClockStyle(this, mDigitalClock, mAnalogClock,
ScreensaverSettingsActivity.KEY_CLOCK_STYLE);
mSaverView = findViewById(R.id.main_clock);
boolean dimNightMode = PreferenceManager.getDefaultSharedPreferences(this)
.getBoolean(ScreensaverSettingsActivity.KEY_NIGHT_MODE, false);
Utils.dimClockView(dimNightMode, mSaverView);
setScreenBright(!dimNightMode);
}
private void layoutClockSaver() {
setContentView(R.layout.desk_clock_saver);
mDigitalClock = findViewById(R.id.digital_clock);
mAnalogClock = findViewById(R.id.analog_clock);
setClockStyle();
Utils.setTimeFormat((TextClock)mDigitalClock,
(int)getResources().getDimension(R.dimen.main_ampm_font_size));
mContentView = (View) mSaverView.getParent();
mSaverView.setAlpha(0);
mMoveSaverRunnable.registerViews(mContentView, mSaverView);
Utils.updateDate(mDateFormat, mDateFormatForAccessibility, mContentView);
Utils.refreshAlarm(Screensaver.this, mContentView);
}
}
我們就知道DreamService與系統屏保的關係了，但是怎麼bind啟動屏保的dreameService的呢？
DreamManagerService的實現程式碼在DreamController中實現的
public void startDream(Binder token, ComponentName name,
boolean isTest, boolean canDoze, int userId) {
stopDream(true /immediate/);
Trace.traceBegin(Trace.TRACE_TAG_POWER, "startDream");
try {
// Close the notification shade. Don't need to send to all, but better to be explicit.
mContext.sendBroadcastAsUser(mCloseNotificationShadeIntent, UserHandle.ALL);
Slog.i(TAG, "Starting dream: name=" + name
+ ", isTest=" + isTest + ", canDoze=" + canDoze
+ ", userId=" + userId);
mCurrentDream = new DreamRecord(token, name, isTest, canDoze, userId);
try {
mIWindowManager.addWindowToken(token, WindowManager.LayoutParams.TYPE_DREAM);
} catch (RemoteException ex) {
Slog.e(TAG, "Unable to add window token for dream.", ex);
stopDream(true /*immediate*/);
return;
}
Intent intent = new Intent(DreamService.SERVICE_INTERFACE);
intent.setComponent(name);
intent.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
try {
//這邊就是怎麼啟動屏保的service了
if (!mContext.bindServiceAsUser(intent, mCurrentDream,
Context.BIND_AUTO_CREATE, new UserHandle(userId))) {
Slog.e(TAG, "Unable to bind dream service: " + intent);
stopDream(true /*immediate*/);
return;
}
}
我們看一下DreamService顯示屏保的時候怎麼退出和喚醒螢幕
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
// TODO: create more flexible version of mInteractive that allows use of KEYCODE_BACK
if (!mInteractive) {
if (mDebug) Slog.v(TAG, “Waking up on keyEvent”);
wakeUp();
return true;
} else if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
if (mDebug) Slog.v(TAG, “Waking up on back key”);
//喚醒螢幕
wakeUp();
return true;
}
return mWindow.superDispatchKeyEvent(event);
}
/** {@inheritDoc} */
@Override
public boolean dispatchKeyShortcutEvent(KeyEvent event) {
if (!mInteractive) {
if (mDebug) Slog.v(TAG, "Waking up on keyShortcutEvent");
wakeUp();
return true;
}
return mWindow.superDispatchKeyShortcutEvent(event);
}
public void onWakeUp() {
//螢幕喚醒後消滅自己
finish();
}