How to open Tkinter GUI on second monitor/display? (Windows)

Question

I'd like to incorporate a way to have my GUI open on a second monitor, if available. I want to add in some type of error handling so if there is a second monitor, use it, else open on the center of the detected display. Can this be done?

Answer 1

I've been using this snippet using the win32 API to enumerate monitors on windows:

import ctypes
user = ctypes.windll.user32

class RECT(ctypes.Structure):
  _fields_ = [
    ('left', ctypes.c_long),
    ('top', ctypes.c_long),
    ('right', ctypes.c_long),
    ('bottom', ctypes.c_long)
    ]
  def dump(self):
    return [int(val) for val in (self.left, self.top, self.right, self.bottom)]

class MONITORINFO(ctypes.Structure):
  _fields_ = [
    ('cbSize', ctypes.c_ulong),
    ('rcMonitor', RECT),
    ('rcWork', RECT),
    ('dwFlags', ctypes.c_ulong)
    ]

def get_monitors():
  retval = []
  CBFUNC = ctypes.WINFUNCTYPE(ctypes.c_int, ctypes.c_ulong, ctypes.c_ulong, ctypes.POINTER(RECT), ctypes.c_double)
  def cb(hMonitor, hdcMonitor, lprcMonitor, dwData):
    r = lprcMonitor.contents
    #print("cb: %s %s %s %s %s %s %s %s" % (hMonitor, type(hMonitor), hdcMonitor, type(hdcMonitor), lprcMonitor, type(lprcMonitor), dwData, type(dwData)))
    data = [hMonitor]
    data.append(r.dump())
    retval.append(data)
    return 1
  cbfunc = CBFUNC(cb)
  temp = user.EnumDisplayMonitors(0, 0, cbfunc, 0)
  #print(temp)
  return retval

def monitor_areas():
  retval = []
  monitors = get_monitors()
  for hMonitor, extents in monitors:
    data = [hMonitor]
    mi = MONITORINFO()
    mi.cbSize = ctypes.sizeof(MONITORINFO)
    mi.rcMonitor = RECT()
    mi.rcWork = RECT()
    res = user.GetMonitorInfoA(hMonitor, ctypes.byref(mi))
    data = mi.rcMonitor.dump()
#    data.append(mi.rcWork.dump())
    retval.append(data)
  return retval


if __name__ == "__main__":
  print(monitor_areas())

On my system that prints [[0, 0, 3440, 1440], [3440, 0, 5120, 1050]]

In tkinter you can then move your app window to a given location with

appwindow.geometry('+1720+720')

Which puts it 1720px in from the left and 720 down from the top.

Any monitors that are to the left of or above your primary monitor may get negative coordinates, but they should work just fine.