Write directly to screen with c++

Hello I am new to c++ and am wonderi开发者_如何学JAVAng where to go about looking to print directly to the screen? For example the HUD interface that appears on laptops when you change the volume. I'm not really looking for any fancy graphics, just, say, a variable or info from a file.

I've tried googling but havn't come up with anything yet. So...where should I begin looking?

Thanks!

Under windows there are a few ways to do it. You could use DirectDraw Overlays (If the system supports them). Or you could create a layered window (WS_EX_LAYERED) and make everything but the bit you want to display transparent.

Pure C++ has only one screen interface, in the library. That's text-oriented. To do graphics, you need another OS-specific interface. So, you'd be looking at the API documentation for your OS.

BTW, the overlay graphics when you change the volume on your laptop are really special, IIRC. They're generated by your laptop itself, using System Management Mode - not the OS itself, and certainly not a program.