Importing pyautogui breaks monitor DPI detection with ctypes

[GeorgeWashingtonABCDEFG]

import ctypes
# import pyautogui
dpix = ctypes.c_uint()
dpiy = ctypes.c_uint()
ctypes.windll.shcore.SetProcessDpiAwareness(2)
ctypes.windll.shcore.GetDpiForMonitor(1186359,0,ctypes.byref(dpix),ctypes.byref(dpiy))
print(dpix.value)

# output
144 # this is correct

import ctypes
import pyautogui
dpix = ctypes.c_uint()
dpiy = ctypes.c_uint()
ctypes.windll.shcore.SetProcessDpiAwareness(2)
ctypes.windll.shcore.GetDpiForMonitor(1186359,0,ctypes.byref(dpix),ctypes.byref(dpiy))
print(dpix.value)

# output
96 # this is wrong. The monitor's dpi is 144. Note the monitor is scaled in windows.
# Everything I do about detecting window size, location, etc is all broken by simply importing your module.

[bersbersbers]

Here's something related:

"""
QtWarningMsg:
setProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2) failed:
COM error 0x5  (Access is denied.)
"""
import pyautogui  # noqa # pylint:disable=unused-import
from PySide6.QtWidgets import QApplication

QApplication()

It outputs the warning

qt.qpa.windows: setProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2) failed: COM error 0x5 (Access is denied.)

According to MS docs,

Possible errors are [..] ERROR_ACCESS_DENIED if the default API awareness mode for the process has already been set (via a previous API call or within the application manifest).

https://learn.microsoft.com/th-th/windows/win32/api/winuser/nf-winuser-setprocessdpiawarenesscontext

So it seems pyautogui sets DPI awareness somewhere before. I find it in https://github.com/asweigart/pyautogui/blob/ad7609c6c277831e5fb5809272139f7db8ccdbeb/pyautogui/_pyautogui_win.py#L14-L18

I am considering monkey-patching ctypes before importing pyautogui to remove that call.

[bersbersbers]

Here's a workaround:

"""Workaround."""
import ctypes

import pytest
from PySide6.QtWidgets import QApplication

with pytest.MonkeyPatch.context() as mp:
    mp.setattr(ctypes.windll.user32, "SetProcessDPIAware", lambda: None)
    import pyautogui  # noqa # pylint:disable=unused-import

QApplication()

[bersbersbers]

Much nicer workaround with the standard library:

"""Workaround."""
from unittest.mock import patch
from PySide6.QtWidgets import QApplication
with patch("ctypes.windll.user32.SetProcessDPIAware", autospec=True):
    import pyautogui  # noqa # pylint:disable=unused-import

QApplication()

[bersbersbers]

Importantly, that Qt warning message will go away: https://bugreports.qt.io/browse/PYSIDE-2105

This will solve my issue (and make my patch pointless), but it will not solve @GeorgeWashingtonABCDEFG's issue (for which my patch may still be useful).

In the end, pyautogui should probably stop calling SetProcessDPIAware unless necessary (and if so, call it as late as possible).

[bersbersbers]

Related: https://github.com/asweigart/pyautogui/commit/9cd04d3405d3bbb2c477f9b35ae5fbaabc3acce2

[Avasam]

Much nicer workaround with the standard library:

"""Workaround."""
from unittest.mock import patch
from PySide6.QtWidgets import QApplication
with patch("ctypes.windll.user32.SetProcessDPIAware", autospec=True):
    import pyautogui  # noqa # pylint:disable=unused-import

QApplication()

The unittest workaround significantly increases build time, boot time and build size with PyInstaller. So I went with some sort of postinstall powershell script that patches all offending libraries, and uninstalls those I don't actually need.

# Prevent pyautogui and pywinctl from setting Process DPI Awareness, which Qt tries to do then throws warnings about it.
# The unittest workaround significantly increases build time, boot time and build size with PyInstaller.
# https://github.com/asweigart/pyautogui/issues/663#issuecomment-1296719464
$libPath = python -c 'import pyautogui as _; print(_.__path__[0])'
(Get-Content "$libPath/_pyautogui_win.py").replace('ctypes.windll.user32.SetProcessDPIAware()', 'pass') |
  Set-Content "$libPath/_pyautogui_win.py"
$libPath = python -c 'import pymonctl as _; print(_.__path__[0])'
(Get-Content "$libPath/_pymonctl_win.py").replace('ctypes.windll.shcore.SetProcessDpiAwareness', 'pass # ') |
  Set-Content "$libPath/_pymonctl_win.py"
$libPath = python -c 'import pywinbox as _; print(_.__path__[0])'
(Get-Content "$libPath/_pywinbox_win.py").replace('ctypes.windll.shcore.SetProcessDpiAwareness', 'pass # ') |
  Set-Content "$libPath/_pywinbox_win.py"
# Uninstall optional dependencies that PyInstaller picks up
python -m pip uninstall pyscreeze mouseinfo pyperclip -y

To find where it's called in the first place, I simply added the following at the top of my main/entrypoint module:

# flake8: noqa
def find_culprit(*_):
    raise Exception
import ctypes
ctypes.windll.shcore.SetProcessDpiAwareness = find_culprit
ctypes.windll.user32.SetProcessDPIAware = find_culprit

[Avasam]

I think I found an even better workaround. This is what I'm using now. If you did need SetProcessDPIAware or SetProcessDpiAwareness yourself, just assign it to a variable first.

import sys

# Prevent PyAutoGUI and pywinctl from setting Process DPI Awareness, which Qt tries to do then throws warnings about it.
# The unittest workaround significantly increases build time, boot time and build size with PyInstaller.
# https://github.com/asweigart/pyautogui/issues/663#issuecomment-1296719464
# QT doesn't call those from Python/ctypes, meaning we can stop other programs from setting it.
if sys.platform == "win32":
    import ctypes
    # pyautogui._pyautogui_win.py
    ctypes.windll.user32.SetProcessDPIAware = lambda: None  # pyright: ignore[reportAttributeAccessIssue]
    # pymonctl._pymonctl_win.py
    # pywinbox._pywinbox_win.py
    ctypes.windll.shcore.SetProcessDpiAwareness = (  # pyright: ignore[reportAttributeAccessIssue]
        lambda _: None  # pyright: ignore[reportUnknownLambdaType]
    )