In Android , Is it possible to display one application(rendering Video) as a floating screen in one half of the screen. and at the same time interacting with another application(e.g chat application or any other application. ).The floating screen appliction will be my application so that it will allow the user to do multitasking.
The idea is to keep the surfaceview of the application, which is rendering the video, on top, and at the same time interact with other applications.e.g gallery or any other application..
If by "two active applications" then you mean real applications (i.e. with activities, back stack, &c) active at the same time, then no (except in some specialized devices, with custom APIs).
However, there is a trick you can use to achieve a similar effect. Applications with the android.permission.SYSTEM_ALERT_WINDOW (displayed as "draw over other apps" in Play Store) can create windows from a service and show them. So you could probably get the effect you want with this method.
There is an open source library called StandOut which provides this behavior in an easy to use manner. You might want to take a look at it.