PIL.features: Add a compile-time zlib-ng feature flag and version number

Author: nulano

docs/reference/features.rst

@@ -54,6 +54,7 @@ Feature version numbers are available only where stated.
 Support for the following features can be checked:
 
 * ``libjpeg_turbo``: (compile time) Whether Pillow was compiled against the libjpeg-turbo version of libjpeg. Compile-time version number is available.
+* ``zlib_ng``: (compile time) Whether Pillow was compiled against the zlib-ng version of zlib. Compile-time version number is available.
 * ``raqm``: Raqm library, required for ``ImageFont.Layout.RAQM`` in :py:func:`PIL.ImageFont.truetype`. Run-time version number is available for Raqm 0.7.0 or newer.
 * ``libimagequant``: (compile time) ImageQuant quantization support in :py:func:`PIL.Image.Image.quantize`. Run-time version number is available.
 * ``xcb``: (compile time) Support for X11 in :py:func:`PIL.ImageGrab.grab` via the XCB library.

src/PIL/features.py

@@ -127,6 +127,7 @@ def get_supported_codecs() -> list[str]:
     "fribidi": ("PIL._imagingft", "HAVE_FRIBIDI", "fribidi_version"),
     "harfbuzz": ("PIL._imagingft", "HAVE_HARFBUZZ", "harfbuzz_version"),
     "libjpeg_turbo": ("PIL._imaging", "HAVE_LIBJPEGTURBO", "libjpeg_turbo_version"),
+    "zlib_ng": ("PIL._imaging", "HAVE_ZLIBNG", "zlib_ng_version"),
     "libimagequant": ("PIL._imaging", "HAVE_LIBIMAGEQUANT", "imagequant_version"),
     "xcb": ("PIL._imaging", "HAVE_XCB", None),
 }
@@ -308,7 +309,11 @@ def pilinfo(out: IO[str] | None = None, supported_formats: bool = True) -> None:
                     # this check is also in src/_imagingcms.c:setup_module()
                     version_static = tuple(int(x) for x in v.split(".")) < (2, 7)
                 t = "compiled for" if version_static else "loaded"
-                if name == "raqm":
+                if name == "zlib":
+                    zlib_ng_version = version_feature("zlib_ng")
+                    if zlib_ng_version is not None:
+                        v += ", compiled for zlib-ng " + zlib_ng_version
+                elif name == "raqm":
                     for f in ("fribidi", "harfbuzz"):
                         v2 = version_feature(f)
                         if v2 is not None:

src/_imaging.c

@@ -4397,6 +4397,20 @@ setup_module(PyObject *m) {
     }
 #endif
 
+    PyObject *have_zlibng;
+#ifdef ZLIBNG_VERSION
+    have_zlibng = Py_True;
+    {
+        PyObject *v = PyUnicode_FromString(ZLIBNG_VERSION);
+        PyDict_SetItemString(d, "zlib_ng_version", v ? v : Py_None);
+        Py_XDECREF(v);
+    }
+#else
+    have_zlibng = Py_False;
+#endif
+    Py_INCREF(have_zlibng);
+    PyModule_AddObject(m, "HAVE_ZLIBNG", have_zlibng);
+
 #ifdef HAVE_LIBTIFF
     {
         extern const char *ImagingTiffVersion(void);