Get rid of RealDisplaySizeMM C-Extension

[eoyilmaz]

The RealDisplaySizeMM C-Extension seems to be doing something that can be done using pure Python. Though, this needs further investigation.

Also, this ticket is related to #6, if this ticket is solved, there is no need to solve #6 .

[eoyilmaz]

Under Linux systems, xrandr --verbose gives all the info we need, including EDID which needs to be decoded:

import codecs
edid = codecs.decode(xrandr_edid_data, "hex")

I have no experience with Wayland though, so I don't know if xrandr behaves the same.

[p5k369]

I think the main reason for using the C-Extension at the time was getting the proper display dimensions under macos, maybe that is obsolete now.
Heres the story how RealDisplaySizeMM found its way into DisplayCAL:
https://www.python-forum.de/viewtopic.php?f=19&t=15859

[eoyilmaz]

Thanks for the link. It was delighting to read. Though, it is really not enough motivation to use a C-Extension as far as I'm concerned. We should definitely remove it.

[eoyilmaz]

Let's do this... 😎

[eoyilmaz]

Good news, currently on my Macbook Pro running MacOS I can run DisplayCAL and do a full calibration and profiling without needing to build and use the extension. All the information is extracted from the dispwin command, which currently is the display name, width, height and the position. There are other data that needs to be gathered, but I think DisplayCAL will fallback to default values if the required data doesn't exist.

But, under Linux, the DisplayCAL.edid.get_edid() was using DisplayCAL.RealDisplaySizeMM._enumerate() to extract the EDID information. We need to update the code to extract the EDID from xrandr --verbose command. So I need some sample outputs of the xrandr --verbose command to build my tests around.

Any help is appreciated.

@p5k369 I think you were using a Linux machine, can you help me with this, please?

[p5k369]

Hey @eoyilmaz,
great work. I think mac OS was the main reason why the c-extension was used in the first place.
Find attached the output for one display connected.
xrandr_output.txt

edit:
Find also attached example for multiple displays connected.
xrandr_output_multi.txt

[eoyilmaz]

Great, many thanks @p5k369

[eoyilmaz]

@p5k369 can you also send me the output of dispwin -v -d0 for those two conditions too please, many thanks.

[eoyilmaz]

Ah, I was able to mock the output of dispwin through the information available through the xrandr output 👍

[eoyilmaz]

This should now work properly under Linux