#### 8.2.3 Window的更新过程 到这里，Window的删除过程已经分析完毕了，下面分析Window的更新过程，还是要看WindowManagerGlobal的updateViewLayout方法，如下所示。 public void updateViewLayout(View view, ViewGroup.LayoutParams params) { if (view == null) { throw new IllegalArgumentException("view must not be null"); } if (! (params instanceof WindowManager.LayoutParams)) { throw new IllegalArgumentException("Params must be WindowManager. LayoutParams"); } final WindowManager.LayoutParams wparams = (WindowManager.Layout- Params)params; view.setLayoutParams(wparams); synchronized (mLock) { int index = findViewLocked(view, true); ViewRootImpl root = mRoots.get(index); mParams.remove(index); mParams.add(index, wparams); root.setLayoutParams(wparams, false); } } updateViewLayout方法做的事情就比较简单了，首先它需要更新View的LayoutParams并替换掉老的LayoutParams，接着再更新ViewRootImpl中的LayoutParams，这一步是通过ViewRootImpl的setLayoutParams方法来实现的。在ViewRootImpl中会通过scheduleTraversals方法来对View重新布局，包括测量、布局、重绘这三个过程。除了View本身的重绘以外，ViewRootImpl还会通过WindowSession来更新Window的视图，这个过程最终是由WindowManagerService的relayoutWindow()来具体实现的，它同样是一个IPC过程