WindowManagerService

private WindowManagerService(Context context, InputManagerService inputManager,
  boolean haveInputMethods, boolean showBootMsgs, boolean onlyCore) {
   // 成员变量的赋值
   mContext = context;
   // ....
   // 获取显示服务
   mDisplayManager = (DisplayManager)context.getSystemService(Context.DISPLAY_SERVICE);

   // 构造APP事务对象
   mAppTransition = new AppTransition(context, mH);
   
   // 获取IActivityManager对象
   mActivityManager = ActivityManagerNative.getDefault();
   
   // 构造Window对象
   mAnimator = new WindowAnimator(this);
   
   // 初始化窗口管理策略
   initPolicy();
   
   // 开启Surface事务
   SurfaceControl.openTransaction();    
}

public class WindowManagerService extends IWindowManager.Stub
        implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs {
    // 已经完成启动的应用
    final ArrayList<AppWindowToken> mFinishedStarting = new ArrayList<AppWindowToken>();

    // 渐变窗口
    final ArrayList<FakeWindowImpl> mFakeWindows = new ArrayList<FakeWindowImpl>();

    // 尺寸正在改变的窗口
    final ArrayList<WindowState> mResizingWindows = new ArrayList<WindowState>();

    // 动画结束的窗口
    final ArrayList<WindowState> mPendingRemove = new ArrayList<WindowState>();
      
    // 即将释放Surface的窗口
    final ArrayList<WindowState> mDestroySurface = new ArrayList<WindowState>();

    // 失去焦点的窗口
    ArrayList<WindowState> mLosingFocus = new ArrayList<WindowState>();

    // 为了释放内存需要关闭的窗口
    ArrayList<WindowState> mForceRemoves;
    
    // 正在打开的应用
    final ArraySet<AppWindowToken> mOpeningApps = new ArraySet<AppWindowToken>();
    
    // 正在关闭的应用
    final ArraySet<AppWindowToken> mClosingApps = new ArraySet<AppWindowToken>();
    
    // 当前获得焦点的窗口
    WindowState mCurrentFocus = null;
    
    // 上一个获得焦点的窗口
    WindowState mLastFocus = null;
    
    // 输入法窗口下方的窗口
    WindowState mInputMethodTarget = null;
    
    // 输入法窗口
    WindowState mInputMethodWindow = null;
    
    // 墙纸窗口
    WindowState mWallpaperTarget = null;
    
    // 在切换过程中位于墙纸z-order下方的窗口
    WindowState mLowerWallpaperTarget = null;
    
    // 在切换过程中位于墙纸z-order上方的窗口
    WindowState mUpperWallpaperTarget = null;
    
    // 得到焦点的窗口
    AppWindowToken mFocusedApp = null; 
}

@Override
public int addToDisplay(IWindow window, int seq, WindowManager.LayoutParams attrs,
       int viewVisibility, int displayId, Rect outContentInsets,
       InputChannel outInputChannel) {
   return mService.addWindow(this, window, seq, attrs, viewVisibility, displayId,
           outContentInsets, outInputChannel);
}