user interface - Is there a Core Linux API analogous to Windows WINAPI, in particular for creating GUI applications?

Question

I'm moving from windows programming (By windows programming I mean using Windows API) to Linux Programming.

For programming Windows, the option we have is Win32API (MFC is just a C++ wrapper for the same).

I want to know if there is something like Linux API (equivalent to WINAPI) that is exposed directly to the programmer? Where can I find the reference?

With my little knowledge of POSIX library I see that it wraps around part of Linux API. But what about creating GUI applications? POSIX doesn't offer that. I know there are tons of 3rd party Widget toolkits like gtk, Qt etc. But I don't want to use the libraries that encapsulates Linux API. I want to learn using the "Core Linux API".

If there are somethings that I should know, please inform. Any programmer who is familiar with both Windows & Linux programming, please map the terminologies of Linux world so that I can quickly move on.

Any resources (books,tutorials,references) are highly appreciated.

Answer 1

I think you're looking for something that doesn't exactly exist. Unlike the Win32 API, there is no "Linux API" for doing GUI applications. The closest you can get is the X protocol itself, which is a pretty low level way of doing GUI (it's much more detailed and archaic than Win32 GDI, for example). This is why there exist wrappers such as GTK and Qt that hide the details of the X protocol.

The X protocol is available to C programs using XLib.