How to query X11 display resolution?

linux, x11

Solution

Check out display macros and screen macros from the Xlib manual.

Specifically:

- From the first link: `ScreenCount()`, `ScreenOfDisplay()`

- From the second link: `WidthOfScreen()`, `HeightOfScreen()`

Problem

It seems like an simple problem, but I can't find the answer: How do you query (via X11) what monitors exist and their resolutions?

Original source