setContentVIew学习

1.setContentView(int id)
2.Window是一个抽象出来区域的概念，意思是这个区域可以添加很多view
那么抽象类的实现是谁，这里是PhoneWindow
3初始化Activity有一个attach方法
mWindow = new PhoneWindow(this, window, activityConfigCallback);
4原来就是PhoneWindow
public void setContentView(View view, ViewGroup.LayoutParams params) {
if (mContentParent == null) {
installDecor();
} else if (!hasFeature(FEATURE_CONTENT_TRANSITIONS)) {
mContentParent.removeAllViews();
}
mContentParent.addView(view, params);

5学习一下什么叫DecorView本质是一个FrameLayout

mContentParent是一个ViewGroup是content对应的布局

6new DecorView(context, featureId, this, getAttributes());
ViewGroup contentParent = (ViewGroup)findViewById(ID_ANDROID_CONTENT);

        final DecorContentParent decorContentParent = (DecorContentParent) mDecor.findViewById(                R.id.decor_content_parent);        if (decorContentParent != null) {            mDecorContentParent = decorContentParent;

6进入ActivityThead 每个Window最终由WindowManager负责添加，
而addView会new 一个ViewRootImpl负责重绘
final void handleResumeActivity(IBinder token,
boolean clearHide, boolean isForward, boolean reallyResume, int seq, String reason) {
ActivityClientRecord r = mActivities.get(token);
if (!checkAndUpdateLifecycleSeq(seq, r, “resumeActivity”)) {
return;
}

    // If we are getting ready to gc after going to the background, well    // we are back active so skip it.    unscheduleGcIdler();    mSomeActivitiesChanged = true;    // TODO Push resumeArgs into the activity for consideration    r = performResumeActivity(token, clearHide, reason);    if (r != null) {        final Activity a = r.activity;        if (localLOGV) Slog.v(            TAG, "Resume " + r + " started activity: " +            a.mStartedActivity + ", hideForNow: " + r.hideForNow            + ", finished: " + a.mFinished);        final int forwardBit = isForward ?                WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION : 0;        // If the window hasn't yet been added to the window manager,        // and this guy didn't finish itself or start another activity,        // then go ahead and add the window.        boolean willBeVisible = !a.mStartedActivity;        if (!willBeVisible) {            try {                willBeVisible = ActivityManager.getService().willActivityBeVisible(                        a.getActivityToken());            } catch (RemoteException e) {                throw e.rethrowFromSystemServer();            }        }        if (r.window == null && !a.mFinished && willBeVisible) {            r.window = r.activity.getWindow();            View decor = r.window.getDecorView();            decor.setVisibility(View.INVISIBLE);            ViewManager wm = a.getWindowManager();            WindowManager.LayoutParams l = r.window.getAttributes();            a.mDecor = decor;            l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION;            l.softInputMode |= forwardBit;            if (r.mPreserveWindow) {                a.mWindowAdded = true;                r.mPreserveWindow = false;                // Normally the ViewRoot sets up callbacks with the Activity                // in addView->ViewRootImpl#setView. If we are instead reusing                // the decor view we have to notify the view root that the                // callbacks may have changed.                ViewRootImpl impl = decor.getViewRootImpl();                if (impl != null) {                    impl.notifyChildRebuilt();                }            }            if (a.mVisibleFromClient) {                if (!a.mWindowAdded) {                    a.mWindowAdded = true;                    wm.addView(decor, l);