How to turn scaling off? Screen grab always has scaling with factor 2 applied

[orange-puff]

General information:

• OS name: macOS Big Sur

• OS version: 11.1

• OS architecture: 64 bits

• Resolutions:

  • Monitor 1: 2560x1600

• Python version: 3.10.7

• MSS version: 9.0.1

Description

When I run the following code:

import pyautogui
import mss

w, h = pyautogui.size()
with mss.mss() as sct:
    monitor = {"top": 0, "left": 0, "width": w, "height": h}
    mss_image = sct.grab(monitor)
    print(f'({w}, {h}) ({mss_image.width}, {mss_image.height})')

it results in
(1440, 900) (2880, 1800)

This interferes with my ability to then use pyautogui to find certain pixels with a given color and click them. Is there a way to turn scaling off in mss, or is this perhaps a macOS issue?

[BoboTiG]

It's funny, I was thinking about that exact behavior.
I think I will make the auto-scaling an optional feature rather than the default behavior. It will also fix several issues I saw here, and there, like:

• https://stackoverflow.com/q/72851164/1117028
• https://stackoverflow.com/q/74107626/1117028

I will try something and rely on the CI (and maybe you) for the testing, since I don't own a Mac machine yet.

[orange-puff]

I would be happy to test this.
Also, sorry for the off topic question. Is there a link to any documentation of why mss is so fast compared to pillow or pyautogui? It's performing much better on my computer than either of them.

[orange-puff]

I was hoping to test this locally, but the docs look outdated, https://python-mss.readthedocs.io/developers.html python -m pip install -r tests-requirements.txt but this file doesn't seem to exist.

Is there an updated guide for getting things running locally? I am also getting

    from . import __version__
ImportError: attempted relative import with no known parent package

when attempting to run main.py. I've researched this error extensively in other contexts and I cannot find a working solution for it

[BoboTiG]

Thanks for pointing the documentation issue, it's broken since my last commit, and I'll fix it.

To run main:

cd src
python -m mss

You should remove any older MSS installation first:

python -m pip uninstall -y mss

And here is the correct installation command:

python -m pip install -e '.[test]'

[orange-puff]

So I did this, then added

import pyautogui
if __name__ == "__main__":  # pragma: nocover
    w, h = pyautogui.size()
    print(w,h)
    with mss() as sct:
        monitor = {"top": 0, "left": 0, "width": w, "height": h}
        mss_image = sct.grab(monitor)
        print(f'({w}, {h}) ({mss_image.width}, {mss_image.height})')

to src/mss/__main__.py
and I get

1440 900
zsh: segmentation fault  python3 -m mss

[orange-puff]

The line that is throwing the exception is; https://github.com/BoboTiG/python-mss/blob/main/src/mss/darwin.py#L181
If I rerun I also get
zsh: bus error python3 -m mss
zsh: illegal hardware instruction python3 -m mss

Without knowing what the underlying dll looks like, it's not easy to go deeper. But I will try to look at the arg and how the PR might have contributed

[BoboTiG]

Actually the PR isn't working. I quickly tried something, but without a Mac machine it's complex.
I will receive a Mac machine by the next week, and will be able to work on it then.

[brycedrennan]

Somewhat related, I was looking at maximizing the performance of my screenshotting tool so I wanted to deal with images at the Nominal resolution. I found that CGWindowListCreateImage can be configured to return images in the nominal resolution

This improved the grab time from 115.8 ms to 46.0 ms (nominal 6880x2520, scaled 13760x5040)

If you want to make a similar change this is the relevant code in darwin.py:

import Quartz.CoreGraphics as CG

    def _grab_impl(self, monitor, /) -> ScreenShot:
        """Retrieve all pixels from a monitor. Pixels have to be RGB."""
        core = self.core
        rect = CGRect((monitor["left"], monitor["top"]), (monitor["width"], monitor["height"]))
        imageOption = (
            CG.kCGWindowImageBoundsIgnoreFraming | CG.kCGWindowImageShouldBeOpaque | CG.kCGWindowImageNominalResolution
        )
        image_ref = core.CGWindowListCreateImage(rect, 1, 0, imageOption)

[BoboTiG]

Given the optimization, I am now questioning if scaling is a feature users want at all?
I do not recall why I bothered with it, but maybe can we introduce a flag to enable/disable scaling.