WindowManagerService启动流程

WindowManagerService启动流程

版本：android 10

启动流程

SystemServer.java

private void startOtherServices() {
	WindowManagerService wm = null;
	 //创建PhoneWindowManager对象，传递给WindowManagerService，同时创建WindowManagerService对象。
      wm = WindowManagerService.main(context, inputManager, !mFirstBoot, mOnlyCore,
                    new PhoneWindowManager(), 		mActivityManagerService.mActivityTaskManager);
      //将WindowManagerService添加到bindler 服务管理中
      ServiceManager.addService(Context.WINDOW_SERVICE, wm, /* allowIsolated= */ false,
                    DUMP_FLAG_PRIORITY_CRITICAL | DUMP_FLAG_PROTO);
      //...
      //初始化PhoneWindowManager
      wm.onInitReady();
      //display相关
      wm.displayReady();
      //..
      wm.systemReady();
}

解析WindowManagerService.java

 public static WindowManagerService main(final Context context, final InputManagerService 		im,final boolean showBootMsgs, final boolean onlyCore, WindowManagerPolicy policy,
            ActivityTaskManagerService atm, TransactionFactory transactionFactory) {
        DisplayThread.getHandler().runWithScissors(() ->
               //创建WindowManagerService对象
               sInstance = new WindowManagerService(context, im, showBootMsgs, onlyCore, policy,
                        atm, transactionFactory), 0);
        return sInstance;
    }

查看WindowManagerService构造方法

    private WindowManagerService(Context context, InputManagerService inputManager,
            boolean showBootMsgs, boolean onlyCore, WindowManagerPolicy policy,
            ActivityTaskManagerService atm, TransactionFactory transactionFactory) {
        //...
        //保存PhoneWindowManager对象
        mPolicy = policy;
        mAnimator = new WindowAnimator(this);
        //RootWindowContainer窗口容器的根容器,DisplayContent 用于管理屏幕，一块屏幕对应一个 DisplayContent 对象，
        //虽然手机只有一个显示屏，但是可以创建多个 DisplayContent 对象，如投屏时，可以创建一个虚拟的 DisplayContent
        mRoot = new RootWindowContainer(this);
        //...
        //将PhoneWindowManager放入LocalServices
        LocalServices.addService(WindowManagerPolicy.class, mPolicy);
        //获取Display的代理对象
        mDisplayManager =(DisplayManager)context.getSystemService(Context.DISPLAY_SERVICE);
        //创建WindowManagerService内部类LocalService，并且添加到LocalServices
        LocalServices.addService(WindowManagerInternal.class, new LocalService());
	}

SystemServer中有调用wm.onInitReady()，我们跟踪下这个方法

  public void onInitReady() {
        //初始化PhoneWindowManagerService
        initPolicy();
        //...
 }
 
  private void initPolicy() {
        UiThread.getHandler().runWithScissors(new Runnable() {
            @Override
            public void run() {
                //调用PhoneWindowManagerService的init初始化方法
                mPolicy.init(mContext, WindowManagerService.this, WindowManagerService.this);
            }
        }, 0);
    }

跟踪PhoneWindowManagerService的init方法

@Override
    public void init(Context context, IWindowManager windowManager,
            WindowManagerFuncs windowManagerFuncs) {
        mContext = context;
        //WindowManagerService
        mWindowManager = windowManager;
        mWindowManagerFuncs = windowManagerFuncs;
        //获取WindowManagerService的内部类LocalService
        mWindowManagerInternal = LocalServices.getService(WindowManagerInternal.class);
        //创建Handler
        mHandler = new PolicyHandler();
        //用于广播监听SettingProvider中的数据变化，进行相关逻辑操作
        mSettingsObserver = new SettingsObserver(mHandler);
        //观察所有的用户改变
        mSettingsObserver.observe();
        //...
        //注册截屏广播
        // register for screenshot broadcasts
        filter=new IntentFilter();
        filter.addAction("android.intent.action.SCREENSHOT");
        context.registerReceiver(mScreenshotReceiver, filter);
        //一些对象的初始化
        //...
    }

SystemServer中调用wm.systemReady()，我们跟踪下该方法

 public void systemReady() {
        mSystemReady = true;
        //调用PhoneWindowManager的systemReady方法
        mPolicy.systemReady();
        //调用RootWindowContainer的forAllDisplayPolicies
        mRoot.forAllDisplayPolicies(DisplayPolicy::systemReady);
  }