Display names of outputs available to the X server by accessing the xrandr extension via python's ctypes

xlib-xrandr-ctypes-print-output-names.py

#!/usr/bin/env python3

"""
Display names of outputs available to the X server similiar to 'xrandr' command.
Access xlib and xrandr extension via python's ctypes library.

tags: x11, xorg, x.org, xwindow-system, xlib, libx, xrandr, outputs, monitor, display
"""

import ctypes
import sys

Time = ctypes.c_ulong
XID = ctypes.c_ulong
RROutput = XID
RRCrtc = XID
RRMode = XID
Connection = ctypes.c_ushort
SubpixelOrder = ctypes.c_ushort

class XRRScreenResources(ctypes.Structure):
    _fields_ = [
        ('timestamp', Time),
        ('configTimestamp', Time),
        ('ncrtc', ctypes.c_int),
        ('crtcs', ctypes.POINTER(RRCrtc)),
        ('noutput', ctypes.c_int),
        ('outputs', ctypes.POINTER(RROutput)),
        ('nmode', ctypes.c_int),
        ('modes', ctypes.c_void_p), # ctypes.POINTER(XRRModeInfo)
    ]

class XRROutputInfo(ctypes.Structure):
    _fields_ = [
        ('timestamp', Time),
        ('crtc', RRCrtc),
        ('name', ctypes.c_char_p),
        ('nameLen', ctypes.c_int),
        ('mm_width', ctypes.c_ulong),
        ('mm_height', ctypes.c_ulong),
        ('connection', Connection),
        ('subpixel_order', SubpixelOrder),
        ('ncrtc', ctypes.c_int),
        ('crtcs', ctypes.POINTER(RRCrtc)),
        ('nclone', ctypes.c_int),
        ('clones', ctypes.POINTER(RROutput)),
        ('nmode', ctypes.c_int),
        ('npreferred', ctypes.c_int),
        ('modes', ctypes.POINTER(RRMode)),
    ]

X11 = ctypes.cdll.LoadLibrary("libX11.so")
Xrandr = ctypes.cdll.LoadLibrary("libXrandr.so")
Xrandr.XRRGetScreenResourcesCurrent.restype = ctypes.POINTER(XRRScreenResources)
Xrandr.XRRGetOutputInfo.restype = ctypes.POINTER(XRROutputInfo)

xdisplay = X11.XOpenDisplay(None)
root_window = X11.XDefaultRootWindow(xdisplay)
screen_resources = Xrandr.XRRGetScreenResourcesCurrent(xdisplay, root_window)
assert isinstance(screen_resources.contents, XRRScreenResources)
for o in range(screen_resources.contents.noutput):
    output_info = Xrandr.XRRGetOutputInfo(xdisplay, screen_resources, screen_resources.contents.outputs[o])
    print(output_info.contents.name.decode(sys.getfilesystemencoding()))
X11.XCloseDisplay(xdisplay)

example output:

$ python3 xlib-xrandr-ctypes-print-output-names.py
eDP1
DP1
DP2
HDMI1
HDMI2
VGA1