From 90991428fa4ca39076efa6329792f30b962d7d49 Mon Sep 17 00:00:00 2001
From: Nulano <nulano@nulano.eu>
Date: Mon, 1 Jan 2024 20:05:16 +0100
Subject: [PATCH] add LCMS2 flags to ImageCms

---
 Tests/test_imagecms.py | 10 +++++++
 src/PIL/ImageCms.py    | 63 ++++++++++++++++++++++++++++++++++--------
 2 files changed, 61 insertions(+), 12 deletions(-)

diff --git a/Tests/test_imagecms.py b/Tests/test_imagecms.py
index 0dde82bd7..fec482f43 100644
--- a/Tests/test_imagecms.py
+++ b/Tests/test_imagecms.py
@@ -90,6 +90,16 @@ def test_sanity():
     hopper().point(t)
 
 
+def test_flags():
+    assert ImageCms.Flags.NONE == 0
+    assert ImageCms.Flags.GRIDPOINTS(0) == ImageCms.Flags.NONE
+    assert ImageCms.Flags.GRIDPOINTS(256) == ImageCms.Flags.NONE
+
+    assert ImageCms.Flags.GRIDPOINTS(255) == (255 << 16)
+    assert ImageCms.Flags.GRIDPOINTS(-1) == ImageCms.Flags.GRIDPOINTS(255)
+    assert ImageCms.Flags.GRIDPOINTS(511) == ImageCms.Flags.GRIDPOINTS(255)
+
+
 def test_name():
     skip_missing()
     # get profile information for file
diff --git a/src/PIL/ImageCms.py b/src/PIL/ImageCms.py
index 643fce830..eafafd583 100644
--- a/src/PIL/ImageCms.py
+++ b/src/PIL/ImageCms.py
@@ -16,8 +16,10 @@
 # below for the original description.
 from __future__ import annotations
 
+import operator
 import sys
-from enum import IntEnum
+from enum import IntEnum, IntFlag
+from functools import reduce
 
 from . import Image
 
@@ -119,6 +121,48 @@ class Direction(IntEnum):
 #
 # flags
 
+
+class Flags(IntFlag):
+    # These are taken from lcms2.h (including comments)
+    NONE = 0
+    NOCACHE = 0x0040  # Inhibit 1-pixel cache
+    NOOPTIMIZE = 0x0100  # Inhibit optimizations
+    NULLTRANSFORM = 0x0200  # Don't transform anyway
+    GAMUTCHECK = 0x1000  # Out of Gamut alarm
+    SOFTPROOFING = 0x4000  # Do softproofing
+    BLACKPOINTCOMPENSATION = 0x2000
+    NOWHITEONWHITEFIXUP = 0x0004  # Don't fix scum dot
+    HIGHRESPRECALC = 0x0400  # Use more memory to give better accuracy
+    LOWRESPRECALC = 0x0800  # Use less memory to minimize resources
+    # this should be 8BITS_DEVICELINK, but that is not a valid name in Python:
+    USE_8BITS_DEVICELINK = 0x0008  # Create 8 bits devicelinks
+    GUESSDEVICECLASS = 0x0020  # Guess device class (for transform2devicelink)
+    KEEP_SEQUENCE = 0x0080  # Keep profile sequence for devicelink creation
+    FORCE_CLUT = 0x0002  # Force CLUT optimization
+    CLUT_POST_LINEARIZATION = 0x0001  # create postlinearization tables if possible
+    CLUT_PRE_LINEARIZATION = 0x0010  # create prelinearization tables if possible
+    NONEGATIVES = 0x8000  # Prevent negative numbers in floating point transforms
+    COPY_ALPHA = 0x04000000  # Alpha channels are copied on cmsDoTransform()
+    NODEFAULTRESOURCEDEF = 0x01000000
+
+    _GRIDPOINTS_1 = 1 << 16
+    _GRIDPOINTS_2 = 2 << 16
+    _GRIDPOINTS_4 = 4 << 16
+    _GRIDPOINTS_8 = 8 << 16
+    _GRIDPOINTS_16 = 16 << 16
+    _GRIDPOINTS_32 = 32 << 16
+    _GRIDPOINTS_64 = 64 << 16
+    _GRIDPOINTS_128 = 128 << 16
+
+    @staticmethod
+    def GRIDPOINTS(n: int) -> Flags:
+        # Fine-tune control over number of gridpoints
+        return Flags.NONE | ((n & 0xFF) << 16)
+
+
+_MAX_FLAG = reduce(operator.or_, Flags)
+
+
 FLAGS = {
     "MATRIXINPUT": 1,
     "MATRIXOUTPUT": 2,
@@ -142,11 +186,6 @@ FLAGS = {
     "GRIDPOINTS": lambda n: (n & 0xFF) << 16,  # Gridpoints
 }
 
-_MAX_FLAG = 0
-for flag in FLAGS.values():
-    if isinstance(flag, int):
-        _MAX_FLAG = _MAX_FLAG | flag
-
 
 # --------------------------------------------------------------------.
 # Experimental PIL-level API
@@ -218,7 +257,7 @@ class ImageCmsTransform(Image.ImagePointHandler):
         intent=Intent.PERCEPTUAL,
         proof=None,
         proof_intent=Intent.ABSOLUTE_COLORIMETRIC,
-        flags=0,
+        flags=Flags.NONE,
     ):
         if proof is None:
             self.transform = core.buildTransform(
@@ -303,7 +342,7 @@ def profileToProfile(
     renderingIntent=Intent.PERCEPTUAL,
     outputMode=None,
     inPlace=False,
-    flags=0,
+    flags=Flags.NONE,
 ):
     """
     (pyCMS) Applies an ICC transformation to a given image, mapping from
@@ -420,7 +459,7 @@ def buildTransform(
     inMode,
     outMode,
     renderingIntent=Intent.PERCEPTUAL,
-    flags=0,
+    flags=Flags.NONE,
 ):
     """
     (pyCMS) Builds an ICC transform mapping from the ``inputProfile`` to the
@@ -482,7 +521,7 @@ def buildTransform(
         raise PyCMSError(msg)
 
     if not isinstance(flags, int) or not (0 <= flags <= _MAX_FLAG):
-        msg = "flags must be an integer between 0 and %s" + _MAX_FLAG
+        msg = f"flags must be an integer between 0 and {_MAX_FLAG}"
         raise PyCMSError(msg)
 
     try:
@@ -505,7 +544,7 @@ def buildProofTransform(
     outMode,
     renderingIntent=Intent.PERCEPTUAL,
     proofRenderingIntent=Intent.ABSOLUTE_COLORIMETRIC,
-    flags=FLAGS["SOFTPROOFING"],
+    flags=Flags.SOFTPROOFING,
 ):
     """
     (pyCMS) Builds an ICC transform mapping from the ``inputProfile`` to the
@@ -586,7 +625,7 @@ def buildProofTransform(
         raise PyCMSError(msg)
 
     if not isinstance(flags, int) or not (0 <= flags <= _MAX_FLAG):
-        msg = "flags must be an integer between 0 and %s" + _MAX_FLAG
+        msg = f"flags must be an integer between 0 and {_MAX_FLAG}"
         raise PyCMSError(msg)
 
     try: