Use enums for Modes and RawModes in C

[eyedav]

Rebase of PR #8510 (Use enums for Modes and RawModes in C) on latest main, done during EuroPython25's Sprint: creating a new PR as agreed with @wiredfool.

[radarhere]

Would you mind writing up an explanation for why this is helpful?

[wiredfool]

One of the things that I'd like to do here is move (almost) all of this stuff from Storage.c into the mode struct:

 } else if (mode == IMAGING_MODE_RGBX) {
        /* 32-bit true colour images with padding */
        im->bands = im->pixelsize = 4;
        im->linesize = xsize * 4;
        strcpy(im->band_names[0], "R");
        strcpy(im->band_names[1], "G");
        strcpy(im->band_names[2], "B");
        strcpy(im->band_names[3], "X");
}

The only thing here that can't be in the mode struct and static per mode is the linesize.

 } else if (mode == IMAGING_MODE_RGBX) {
        /* 32-bit true colour images with padding */
        im->linesize = xsize * 4;
}
... // and then
if (im->mode->bands == 4) {
}

So that gains us a lot less complexity in Storage.c, and 4 fewer allocations for each new image, as the mode bands are static and not generated fresh for each image. It's possible that we can just set im->linesize with a formula, but not clear yet.

(depending on the metadata standard) I'm hoping that we could statically generate the arrow mode metadata and store it there as well. This would work if it's just mode based, but it's less useful if it's going to include image specific metadata, like sizes.

[wiredfool]

@eyedav I've got updates that fix the compilation errors and pass the tests here: https://github.com/wiredfool/Pillow/tree/mode_enums . I can't see how to make a PR or push against your repo -- there should be a setting somewhere to allow admins to push to this branch that you can enable.

[eyedav]

@wiredfool the setting to allow maintainers to push to this branch was actually already enabled, I just tried to uncheck and check it again a moment ago. Could you please try a second time? Otherwise, as a workaround I could temporarily add you as collaborator to my fork.

[wiredfool]

@eyedav I've tried again with no luck. If you can add me I'd appreciate it.

[radarhere]

Suggested change

	types-setuptools>=75.2.0
	types-setuptools

We're currently at 80.9.0. I think this has sufficiently propagated?

[radarhere]

BGR;* modes (but not rawmodes) were removed in #9053