I would like to have my monitors controlled from Windows (simple stuff such as changing the input source), but cannot find a way of sending DDC/CI commands from Python...
Any clue about a library or method that could help here?
ddcutil is a Linux program for managing monitor settings, such as brightness, color levels, and input source.
This package contains the software application that allows users to configure their Dell monitor settings such as Brightness, Contrast and Preset Modes. This application requires Display Data Channel Command Interface (DDC/CI) to work. Dell monitors support DDC/CI on VGA, DVI, DP and HDMI inputs.
This is easily possible using the windows monitor API. I don't think there are any Python bindings out there and pywin32 doesn't contain those functions. However, using ctypes
to call them is not that hard.
Here's an example that switches the monitor to soft-off and then back on; it should be pretty easy to adapt it to changing the input source etc. The only complicated part is getting the handles for the physical monitors after all:
from ctypes import windll, byref, Structure, WinError, POINTER, WINFUNCTYPE
from ctypes.wintypes import BOOL, HMONITOR, HDC, RECT, LPARAM, DWORD, BYTE, WCHAR, HANDLE
_MONITORENUMPROC = WINFUNCTYPE(BOOL, HMONITOR, HDC, POINTER(RECT), LPARAM)
class _PHYSICAL_MONITOR(Structure):
_fields_ = [('handle', HANDLE),
('description', WCHAR * 128)]
def _iter_physical_monitors(close_handles=True):
"""Iterates physical monitors.
The handles are closed automatically whenever the iterator is advanced.
This means that the iterator should always be fully exhausted!
If you want to keep handles e.g. because you need to store all of them and
use them later, set `close_handles` to False and close them manually."""
def callback(hmonitor, hdc, lprect, lparam):
monitors.append(HMONITOR(hmonitor))
return True
monitors = []
if not windll.user32.EnumDisplayMonitors(None, None, _MONITORENUMPROC(callback), None):
raise WinError('EnumDisplayMonitors failed')
for monitor in monitors:
# Get physical monitor count
count = DWORD()
if not windll.dxva2.GetNumberOfPhysicalMonitorsFromHMONITOR(monitor, byref(count)):
raise WinError()
# Get physical monitor handles
physical_array = (_PHYSICAL_MONITOR * count.value)()
if not windll.dxva2.GetPhysicalMonitorsFromHMONITOR(monitor, count.value, physical_array):
raise WinError()
for physical in physical_array:
yield physical.handle
if close_handles:
if not windll.dxva2.DestroyPhysicalMonitor(physical.handle):
raise WinError()
def set_vcp_feature(monitor, code, value):
"""Sends a DDC command to the specified monitor.
See this link for a list of commands:
ftp://ftp.cis.nctu.edu.tw/pub/csie/Software/X11/private/VeSaSpEcS/VESA_Document_Center_Monitor_Interface/mccsV3.pdf
"""
if not windll.dxva2.SetVCPFeature(HANDLE(monitor), BYTE(code), DWORD(value)):
raise WinError()
# Switch to SOFT-OFF, wait for the user to press return and then back to ON
for handle in _iter_physical_monitors():
set_vcp_feature(handle, 0xd6, 0x04)
raw_input()
set_vcp_feature(handle, 0xd6, 0x01)
It's your lucky day, you don't have to deal with those ctypes anymore. Somebody actually made a python package that does this for you and exposes a simple api. It's called monitorcontrol.
Here's a quick example of setting luminance on all monitors:
from monitorcontrol import get_monitors
for monitor in get_monitors():
with monitor:
monitor.set_luminance(50)
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