Use enums for Modes and RawModes in C #9100

eyedav · 2025-07-19T15:46:21Z

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 · 2025-07-20T01:05:07Z

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

wiredfool · 2025-07-20T07:39:41Z

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 · 2025-07-20T09:35:23Z

@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 · 2025-07-20T17:31:32Z

@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 · 2025-07-21T07:46:29Z

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

.ci/requirements-mypy.txt

radarhere · 2025-07-20T23:26:16Z

src/libImaging/Mode.c

+    [IMAGING_MODE_RGBa] = {"RGBa"},     [IMAGING_MODE_YCbCr] = {"YCbCr"},
+
+    [IMAGING_MODE_BGR_15] = {"BGR;15"}, [IMAGING_MODE_BGR_16] = {"BGR;16"},
+    [IMAGING_MODE_BGR_24] = {"BGR;24"},


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

setup.py

src/_imaging.c

src/libImaging/Filter.c

src/libImaging/Pack.c

src/libImaging/Resample.c

src/libImaging/Unpack.c

wiredfool · 2025-08-26T15:56:01Z

src/libImaging/Pack.c

    {IMAGING_MODE_I_16N, IMAGING_RAWMODE_I_16N, 16, copy2},
-    {IMAGING_MODE_I_16, IMAGING_RAWMODE_I_16N, 16, packI16N_I16
-    },  // LibTiff native->image endian.
+    {IMAGING_MODE_I_16,


This is actively bad formatting, destroying all of the symmetry of the lines above and below.

I've added more changes to rearrange the code.

src/libImaging/Pack.c

src/libImaging/Unpack.c

hugovk · 2025-08-27T15:46:43Z

setup.py

 from setuptools import Extension, setup
 from setuptools.command.build_ext import build_ext

+if TYPE_CHECKING:


Skip the import:

Suggested change

if TYPE_CHECKING:

TYPE_CHECKING = False

if TYPE_CHECKING:

hugovk · 2025-08-27T15:46:50Z

setup.py

 import sys
 import warnings
 from collections.abc import Iterator
+from typing import TYPE_CHECKING


Suggested change

from typing import TYPE_CHECKING

Yay295 and others added 30 commits July 19, 2025 14:29

use a struct for mode names instead of just a string

cd93629

add special modes

63a45ad

use mode structs in _imaging.c

12409e4

use mode structs in tkImaging.c

a37f53c

use mode structs in encode.c and decode.c

a12dc30

use mode structs in Access.c

0df2ed0

use mode structs in AlphaComposite.c

82182ba

use mode structs in Bands.c

d0541a7

use mode structs in Blend.c

38c75b9

use mode structs in BoxBlur.c

6f6e1f9

use mode structs in Chops.c

ecf1fce

use mode structs in Convert.c

9bf3495

use mode structs in Draw.c

bcfe5f2

use mode structs in Effects.c

b5c4b82

use mode structs in File.c

19c0d1d

use mode structs in Fill.c

6202eef

use mode structs in Filter.c

af22363

use mode structs in Geometry.c

cfe9155

use mode structs in GetBBox.c

2668338

use mode structs in Histo.c

2749770

use mode structs in Jpeg2KDecode.c

3327258

use mode structs in Jpeg2KEncode.c

98a2c63

use mode structs in JpegDecode.c

30d4cd0

use mode structs in JpegEncode.c

0abfdd2

use mode structs in Matrix.c

378c3bd

add function isModeI16() to check if a mode is an I;16 mode

4906285

use mode structs in Pack.c

e5bc5b4

use mode structs in Palette.c

af3c24e

use mode structs in Paste.c

2a9d712

use mode structs in Point.c

7e48697

radarhere mentioned this pull request Jul 19, 2025

Use enums for Modes and RawModes in C #8510

Closed

radarhere changed the title ~~Rebase of Use enums for Modes and RawModes in C~~ Use enums for Modes and RawModes in C Jul 19, 2025

Fix Compliation errors from rebase

adfb66f

radarhere reviewed Jul 22, 2025

View reviewed changes

Merge branch 'main' into mode_enums

726de49

radarhere mentioned this pull request Aug 1, 2025

pre-commit fixes eyedav/Pillow#2

Closed

Removed setuptools version requirement

59d6f31