Android11/Android Q split screen function realization

android11/Q split screen implementation.

1. First confirm that split screen is supported.

调用boolean supportsSplitScreenMultiWindow = 

                ActivityTaskManager.supportsSplitScreenMultiWindow(mContext);

Check whether split screen is supported.

If it returns false, modify frameworks\base\core\res\res\values\config.xml

 config_supportsSplitScreenMultiWindow为true

2. Split-screen call

mActivityTaskMgr.getService().setTaskWindowingModeSplitScreenPrimary(mLeftTask.id, false);
mActivityTaskMgr.getService().resizeTask(mLeftTask.id,mSplitScreenRect,0);

可参考frameworks\base\packages\SystemUI\src\com\android\systemui\recents\OverviewProxyRecentsImpl.java

3. Exit split screen

mActivityTaskMgr.getService().setTaskWindowingMode(mLeftTask.id, WINDOWING_MODE_FULLSCREEN, false);

4. The dividing line in the middle

frameworks\base\packages\SystemUI\src\com\android\systemui\stackdivider

Divider.java added.

Encounter problems:

1. After calling the split-screen interface setTaskWindowingModeSplitScreenPrimary, and calling the split-screen interface again to exit the split-screen, the application appears a black screen. I hope that anyone who encounters this problem can explain it.

2. Please also ask, after entering the split screen, you can switch the application in the right window. Is there a way to replace the application in the left window?