本次源码基于Android11分析
相干源码：
/frameworks/base/services/java/com/android/server/SystemServer.java/frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java/frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java1. WMS的启动过程
WindowManagerService服务在system_server历程中被启动，在其startOtherServices()方法中调用WMS.main()方法开始实例化WMS,如下是WMS的团体启动流程：
public final class SystemServer { private void run() { try { // 启动服务 startBootstrapServices(t); startCoreServices(t); startOtherServices(t); } catch (Throwable ex) { throw ex; } } private void startOtherServices(@NonNull TimingsTraceAndSlog t) { try { //... // 1. WindowManagerService启动 wm = WindowManagerService.main(context, inputManager, !mFirstBoot, mOnlyCore, new PhoneWindowManager(), mActivityManagerService.mActivityTaskManager); // 2. 调用WindowManagerService的onInitReady()方法 wm.onInitReady(); //... // 3.调用WindowManagerService的displayReady()方法 wm.displayReady(); // 4.调用WindowManagerService的systemReady()方法 wm.systemReady( } }}首先调用WMS.main()实例化WindowManagerService对象，之后分别调用WMS.onInitReady()、WMS.displayReady()、WMS.systemReady()方法做后续的初始化使用。
1.2 WMS.main()
public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs { @VisibleForTesting public static WindowManagerService main(final Context context, final InputManagerService im, final boolean showBootMsgs, final boolean onlyCore, WindowManagerPolicy policy, ActivityTaskManagerService atm, Supplier<SurfaceControl.Transaction> transactionFactory, Supplier<Surface> surfaceFactory, Function<SurfaceSession, SurfaceControl.Builder> surfaceControlFactory) { // DisplayThread线程的创建WindowManagerService DisplayThread.getHandler().runWithScissors(() -> // 创建WindowManagerService()实例， sInstance = new WindowManagerService(context, im, showBootMsgs, onlyCore, policy, atm, transactionFactory, surfaceFactory, surfaceControlFactory), 0); return sInstance; }private WindowManagerService(Context context, InputManagerService inputManager, boolean showBootMsgs, boolean onlyCore, WindowManagerPolicy policy, ActivityTaskManagerService atm, Supplier<SurfaceControl.Transaction> transactionFactory, Supplier<Surface> surfaceFactory, Function<SurfaceSession, SurfaceControl.Builder> surfaceControlFactory) { installLock(this, INDEX_WINDOW); mGlobalLock = atm.getGlobalLock(); mAtmService = atm; mContext = context; mIsPc = mContext.getPackageManager().hasSystemFeature(FEATURE_PC); mAllowBootMessages = showBootMsgs; mOnlyCore = onlyCore; mLimitedAlphaCompositing = context.getResources().getBoolean( com.android.internal.R.bool.config_sf_limitedAlpha); mHasPermanentDpad = context.getResources().getBoolean( com.android.internal.R.bool.config_hasPermanentDpad); mInTouchMode = context.getResources().getBoolean( com.android.internal.R.bool.config_defaultInTouchMode); inputManager.setInTouchMode(mInTouchMode); mDrawLockTimeoutMillis = context.getResources().getInteger( com.android.internal.R.integer.config_drawLockTimeoutMillis); mAllowAnimationsInLowPowerMode = context.getResources().getBoolean( com.android.internal.R.bool.config_allowAnimationsInLowPowerMode); mMaxUiWidth = context.getResources().getInteger( com.android.internal.R.integer.config_maxUiWidth); mDisableTransitionAnimation = context.getResources().getBoolean( com.android.internal.R.bool.config_disableTransitionAnimation); mPerDisplayFocusEnabled = context.getResources().getBoolean( com.android.internal.R.bool.config_perDisplayFocusEnabled); mAssistantOnTopOfDream = context.getResources().getBoolean( com.android.internal.R.bool.config_assistantOnTopOfDream); mInputManager = inputManager; // Must be before createDisplayContentLocked. mDisplayManagerInternal = LocalServices.getService(DisplayManagerInternal.class); mSurfaceControlFactory = surfaceControlFactory; mTransactionFactory = transactionFactory; mSurfaceFactory = surfaceFactory; mTransaction = mTransactionFactory.get(); mDisplayWindowSettings = new DisplayWindowSettings(this); mPolicy = policy; mAnimator = new WindowAnimator(this); mRoot = new RootWindowContainer(this); mUseBLAST = DeviceConfig.getBoolean( DeviceConfig.NAMESPACE_WINDOW_MANAGER_NATIVE_BOOT, WM_USE_BLAST_ADAPTER_FLAG, false); mWindowPlacerLocked = new WindowSurfacePlacer(this); mTaskSnapshotController = new TaskSnapshotController(this); mWindowTracing = WindowTracing.createDefaultAndStartLooper(this, Choreographer.getInstance()); LocalServices.addService(WindowManagerPolicy.class, mPolicy); mDisplayManager = (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE); mKeyguardDisableHandler = KeyguardDisableHandler.create(mContext, mPolicy, mH); mPowerManager = (PowerManager) context.getSystemService(Context.POWER_SERVICE); mPowerManagerInternal = LocalServices.getService(PowerManagerInternal.class); if (mPowerManagerInternal != null) { mPowerManagerInternal.registerLowPowerModeObserver( new PowerManagerInternal.LowPowerModeListener() { @Override public int getServiceType() { return ServiceType.ANIMATION; } @Override public void onLowPowerModeChanged(PowerSaveState result) { synchronized (mGlobalLock) { final boolean enabled = result.batterySaverEnabled; if (mAnimationsDisabled != enabled && !mAllowAnimationsInLowPowerMode) { mAnimationsDisabled = enabled; dispatchNewAnimatorScaleLocked(null); } } } }); mAnimationsDisabled = mPowerManagerInternal .getLowPowerState(ServiceType.ANIMATION).batterySaverEnabled; } mScreenFrozenLock = mPowerManager.newWakeLock( PowerManager.PARTIAL_WAKE_LOCK, "SCREEN_FROZEN"); mScreenFrozenLock.setReferenceCounted(false); mDisplayNotificationController = new DisplayWindowListenerController(this); mActivityManager = ActivityManager.getService(); mActivityTaskManager = ActivityTaskManager.getService(); mAmInternal = LocalServices.getService(ActivityManagerInternal.class); mAtmInternal = LocalServices.getService(ActivityTaskManagerInternal.class); mAppOps = (AppOpsManager) context.getSystemService(Context.APP_OPS_SERVICE); AppOpsManager.OnOpChangedInternalListener opListener = new AppOpsManager.OnOpChangedInternalListener() { @Override public void onOpChanged(int op, String packageName) { updateAppOpsState(); } }; mAppOps.startWatchingMode(OP_SYSTEM_ALERT_WINDOW, null, opListener); mAppOps.startWatchingMode(AppOpsManager.OP_TOAST_WINDOW, null, opListener); mPmInternal = LocalServices.getService(PackageManagerInternal.class); final IntentFilter suspendPackagesFilter = new IntentFilter(); suspendPackagesFilter.addAction(Intent.ACTION_PACKAGES_SUSPENDED); suspendPackagesFilter.addAction(Intent.ACTION_PACKAGES_UNSUSPENDED); context.registerReceiverAsUser(new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { final String[] affectedPackages = intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST); final boolean suspended = Intent.ACTION_PACKAGES_SUSPENDED.equals(intent.getAction()); updateHiddenWhileSuspendedState(new ArraySet<>(Arrays.asList(affectedPackages)), suspended); } }, UserHandle.ALL, suspendPackagesFilter, null, null); final ContentResolver resolver = context.getContentResolver(); // Get persisted window scale setting mWindowAnimationScaleSetting = Settings.Global.getFloat(resolver, Settings.Global.WINDOW_ANIMATION_SCALE, mWindowAnimationScaleSetting); mTransitionAnimationScaleSetting = Settings.Global.getFloat(resolver, Settings.Global.TRANSITION_ANIMATION_SCALE, context.getResources().getFloat( R.dimen.config_appTransitionAnimationDurationScaleDefault)); setAnimatorDurationScale(Settings.Global.getFloat(resolver, Settings.Global.ANIMATOR_DURATION_SCALE, mAnimatorDurationScaleSetting)); mForceDesktopModeOnExternalDisplays = Settings.Global.getInt(resolver, DEVELOPMENT_FORCE_DESKTOP_MODE_ON_EXTERNAL_DISPLAYS, 0) != 0; IntentFilter filter = new IntentFilter(); // Track changes to DevicePolicyManager state so we can enable/disable keyguard. filter.addAction(ACTION_DEVICE_POLICY_MANAGER_STATE_CHANGED); mContext.registerReceiverAsUser(mBroadcastReceiver, UserHandle.ALL, filter, null, null); mLatencyTracker = LatencyTracker.getInstance(context); mSettingsObserver = new SettingsObserver(); mHoldingScreenWakeLock = mPowerManager.newWakeLock( PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ON_AFTER_RELEASE, TAG_WM); mHoldingScreenWakeLock.setReferenceCounted(false); mSurfaceAnimationRunner = new SurfaceAnimationRunner(mTransactionFactory, mPowerManagerInternal); mAllowTheaterModeWakeFromLayout = context.getResources().getBoolean( com.android.internal.R.bool.config_allowTheaterModeWakeFromWindowLayout); mTaskPositioningController = new TaskPositioningController( this, mInputManager, mActivityTaskManager, mH.getLooper()); mDragDropController = new DragDropController(this, mH.getLooper()); mHighRefreshRateBlacklist = HighRefreshRateBlacklist.create(context.getResources()); mConstants = new WindowManagerConstants(this, DeviceConfigInterface.REAL); mConstants.start(new HandlerExecutor(mH)); LocalServices.addService(WindowManagerInternal.class, new LocalService()); mEmbeddedWindowController = new EmbeddedWindowController(mAtmService); mDisplayAreaPolicyProvider = DisplayAreaPolicy.Provider.fromResources( mContext.getResources()); setGlobalShadowSettings(); }}通过DisplayThread线程的Handler,并调用其runWithScissors()方法，该方法会将当前的实行线程壅闭，并直到要实行的使命完成后，在重新叫醒被壅闭的线程：
public class Handler { public final boolean runWithScissors(@NonNull Runnable r, long timeout) { // 对runnable和time举行查抄 if (r == null) { throw new IllegalArgumentException("runnable must not be null"); } if (timeout < 0) { throw new IllegalArgumentException("timeout must be non-negative"); } // 查抄当火线程的Looper是否便是此mLooper if (Looper.myLooper() == mLooper) { r.run(); // 直接运行Runnable.run return true; } BlockingRunnable br = new BlockingRunnable(r); return br.postAndWait(this, timeout); } private static final class BlockingRunnable implements Runnable { private final Runnable mTask; private boolean mDone; public BlockingRunnable(Runnable task) { mTask = task; } @Override public void run() { try { // 实行Runnable创建WMS mTask.run(); } finally { synchronized (this) { mDone = true; notifyAll(); } } } public boolean postAndWait(Handler handler, long timeout) { // 将BlockingRunnable加入到handler中 if (!handler.post(this)) { return false; } // 没实行完run()方法则调用wait()让调用的线程等待 synchronized (this) { if (timeout > 0) { final long expirationTime = SystemClock.uptimeMillis() + timeout; while (!mDone) { long delay = expirationTime - SystemClock.uptimeMillis(); if (delay <= 0) { return false; // timeout } try { wait(delay); } catch (InterruptedException ex) { } } } else { // 没实行完run()方法则调用 while (!mDone) { try { wait(); } catch (InterruptedException ex) { } } } } return true; } }}会判断当前实行的线程跟调用的Handler线程是否相称，相称则实行Runnable。如果不想等，则在封装一个Runnable，并在这个Runnable类中判断是否实行了run()方法，如果没有则壅闭当前的实行线程，直到实行完Run方法后才重新叫醒。
以是在DisplayThread线程中创建了WindowManagerService实例对象。
1.3 WMS.onInitReady()
public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs { public void onInitReady() { // 调用initPolicy()方法 initPolicy(); //... } private void initPolicy() { UiThread.getHandler().runWithScissors(new Runnable() { @Override public void run() { WindowManagerPolicyThread.set(Thread.currentThread(), Looper.myLooper()); // 此mPolicy在构造函数中赋值，由SystemServer类中传入，为PhoneWindowManager() mPolicy.init(mContext, WindowManagerService.this, WindowManagerService.this); } }, 0); }}public class PhoneWindowManager implements WindowManagerPolicy { // 在UiThread线程中实行 public void init(Context context, IWindowManager windowManager, WindowManagerFuncs windowManagerFuncs) { mContext = context; mWindowManager = windowManager; mWindowManagerFuncs = windowManagerFuncs; mWindowManagerInternal = LocalServices.getService(WindowManagerInternal.class); mActivityManagerInternal = LocalServices.getService(ActivityManagerInternal.class); mActivityTaskManagerInternal = LocalServices.getService(ActivityTaskManagerInternal.class); mInputManagerInternal = LocalServices.getService(InputManagerInternal.class); mDreamManagerInternal = LocalServices.getService(DreamManagerInternal.class); mPowerManagerInternal = LocalServices.getService(PowerManagerInternal.class); mAppOpsManager = mContext.getSystemService(AppOpsManager.class); ... mHandler = new PolicyHandler(); mWakeGestureListener = new MyWakeGestureListener(mContext, mHandler); ... mPowerManager = (PowerManager) context.getSystemService(Context.POWER_SERVICE); mBroadcastWakeLock = mPowerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, " honeWindowManager.mBroadcastWakeLock"); mPowerKeyWakeLock = mPowerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "honeWindowManager.mPowerKeyWakeLock"); ... mGlobalKeyManager = new GlobalKeyManager(mContext); if (!mPowerManager.isInteractive()) { startedGoingToSleep(WindowManagerPolicy.OFF_BECAUSE_OF_USER); finishedGoingToSleep(WindowManagerPolicy.OFF_BECAUSE_OF_USER); } mWindowManagerInternal.registerAppTransitionListener(new AppTransitionListener() { @Override public int onAppTransitionStartingLocked(int transit, long duration, long statusBarAnimationStartTime, long statusBarAnimationDuration) { return handleStartTransitionForKeyguardLw(transit, duration); } @Override public void onAppTransitionCancelledLocked(int transit) { handleStartTransitionForKeyguardLw(transit, 0 /* duration */); } }); }}在UiThread线程的Handler中实行PhoneWindowManager.init()方法，举行一些变量的的初始化使用。
1.4 WMS.displayReady()、systemReady()
public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs { // 继续在system_server历程中实行WMS.displayReady()方法 public void displayReady() { synchronized (mGlobalLock) { if (mMaxUiWidth > 0) { mRoot.forAllDisplays(displayContent -> displayContent.setMaxUiWidth(mMaxUiWidth)); } applyForcedPropertiesForDefaultDisplay(); mAnimator.ready(); mDisplayReady = true; // Reconfigure all displays to make sure that forced properties and // DisplayWindowSettings are applied. mRoot.forAllDisplays(DisplayContent::reconfigureDisplayLocked); mIsTouchDevice = mContext.getPackageManager().hasSystemFeature( PackageManager.FEATURE_TOUCHSCREEN); } try { mActivityTaskManager.updateConfiguration(null); } catch (RemoteException e) { } } // 继续在system_server历程中实行WMS.systemReady()方法 public void systemReady() { mSystemReady = true; // 实行PhoneWindowManager.systemReady()方法 mPolicy.systemReady(); mRoot.forAllDisplayPolicies(DisplayPolicy::systemReady); mTaskSnapshotController.systemReady(); mHasWideColorGamutSupport = queryWideColorGamutSupport(); mHasHdrSupport = queryHdrSupport(); UiThread.getHandler().post(mSettingsObserver::loadSettings); IVrManager vrManager = IVrManager.Stub.asInterface( ServiceManager.getService(Context.VR_SERVICE)); if (vrManager != null) { try { final boolean vrModeEnabled = vrManager.getVrModeState(); synchronized (mGlobalLock) { vrManager.registerListener(mVrStateCallbacks); if (vrModeEnabled) { mVrModeEnabled = vrModeEnabled; mVrStateCallbacks.onVrStateChanged(vrModeEnabled); } } } catch (RemoteException e) { // Ignore, we cannot do anything if we failed to register VR mode listener } } }}WMS.systemReady()方法会调用PhoneWindowManager.systemReady()方法：
public class PhoneWindowManager implements WindowManagerPolicy { public void systemReady() { // In normal flow, systemReady is called before other system services are ready. // So it is better not to bind keyguard here. mKeyguardDelegate.onSystemReady(); mVrManagerInternal = LocalServices.getService(VrManagerInternal.class); if (mVrManagerInternal != null) { mVrManagerInternal.addPersistentVrModeStateListener(mPersistentVrModeListener); } readCameraLensCoverState(); updateUiMode(); mDefaultDisplayRotation.updateOrientationListener(); synchronized (mLock) { mSystemReady = true; mHandler.post(new Runnable() { @Override public void run() { updateSettings(); } }); // If this happens, for whatever reason, systemReady came later than systemBooted. // And keyguard should be already bound from systemBooted if (mSystemBooted) { mKeyguardDelegate.onBootCompleted(); } } mAutofillManagerInternal = LocalServices.getService(AutofillManagerInternal.class); }}至此WindowManagerService在system_server历程的启动就完成了，WMS重要有四大功能：
- Window窗口的管理
- Surface的管理
- Input系统的管理
- 窗口动画
如下是WindowManagerService的关联图：
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