How do frameworks like Qt create a graphical interface if there is no functionality for C ++?

Question

From the answers received for the question here: Graphics using only standard C ++?

It seems that C ++ itself does not have GUI functions. So, how do other frameworks like Qt do it that support the C ++ GUI? Do they use any other language domestically or is there some other standard protocol / protocol for the graphical interface?

And I am only concerned about the scope of the C ++ language.

Thanks.

Answer 1

They invoke operating system APIs or APIs in other frameworks to create GUI components.

Eg. on Windows, they call the Windows CreateWindow API to create the window.

If the environment runs on multiple platforms, it contains different GUI codes for each of these platforms, calling CreateWindow on Windows or, for example, the Mac equivalent on Mac.