Use NP_COPY_IF_NEEDED for compatibility with new copy semantics

With NumPy 2.0.0, `copy=False` now raises a ValueError if the copy
cannot be made. The previous behavior to only copy if needed is provided
with `copy=None`. During the transition period, use this symbol instead.
Remove once NumPy 2.0.0 is the minimal required version [1, 2]

This approach was inspired by astropy [3].

[1] https://numpy.org/devdocs/release/2.0.0-notes.html#new-copy-keyword-meaning-for-array-and-asarray-constructors
[2] https://www.github.com/numpy/numpy/pull/25168
[3] https://github.com/astropy/astropy/blob/2390bf8f8f2a1c5b6beffbd87db9af5aa6538df1/astropy/utils/compat/numpycompat.py#L29

TODO.txt

@@ -36,3 +36,5 @@ Post numpy 2
   dependencies. Also remove temporary assert for NumPy 2.0 in
   `nightly_wheel_build.yml`.
 - Remove references to `numpy.bool8` once NumPy 2.0 is minimal required version.
+- Remove `skimage._shared.compat.NP_COPY_IF_NEEDED` and all usages of it
+  once NumPy 2.0.0 is minimal required version.

skimage/_shared/compat.py

@@ -0,0 +1,22 @@
+"""Compatibility helpers for dependencies."""
+
+from packaging.version import parse
+
+import numpy as np
+
+
+__all__ = [
+    "NUMPY_LT_2_0_0",
+    "NP_COPY_IF_NEEDED",
+]
+
+
+NUMPY_LT_2_0_0 = parse(np.__version__) < parse('2.0.0.dev0')
+
+# With NumPy 2.0.0, `copy=False` now raises a ValueError if the copy cannot be
+# made. The previous behavior to only copy if needed is provided with `copy=None`.
+# During the transition period, use this symbol instead.
+# Remove once NumPy 2.0.0 is the minimal required version.
+# https://numpy.org/devdocs/release/2.0.0-notes.html#new-copy-keyword-meaning-for-array-and-asarray-constructors
+# https://github.com/numpy/numpy/pull/25168
+NP_COPY_IF_NEEDED = False if NUMPY_LT_2_0_0 else None

skimage/_shared/meson.build

@@ -36,6 +36,7 @@ python_sources = [
   '_geometry.py',
   '_tempfile.py',
   '_warnings.py',
+  'compat.py',
   'coord.py',
   'dtype.py',
   'filters.py',

skimage/draw/draw.py

@@ -2,6 +2,7 @@
 
 from .._shared._geometry import polygon_clip
 from .._shared.version_requirements import require
+from .._shared.compat import NP_COPY_IF_NEEDED
 from ._draw import (
     _coords_inside_image,
     _line,
@@ -336,7 +337,7 @@ def set_color(image, coords, color, alpha=1):
     if image.ndim == 2:
         image = image[..., np.newaxis]
 
-    color = np.array(color, ndmin=1, copy=False)
+    color = np.array(color, ndmin=1, copy=NP_COPY_IF_NEEDED)
 
     if image.shape[-1] != color.shape[-1]:
         raise ValueError(

skimage/feature/orb.py

@@ -10,6 +10,7 @@
 from .corner import corner_fast, corner_orientations, corner_peaks, corner_harris
 from ..transform import pyramid_gaussian
 from .._shared.utils import check_nD
+from .._shared.compat import NP_COPY_IF_NEEDED
 
 from .orb_cy import _orb_loop
 
@@ -226,7 +227,9 @@ def detect(self, image):
 
     def _extract_octave(self, octave_image, keypoints, orientations):
         mask = _mask_border_keypoints(octave_image.shape, keypoints, distance=20)
-        keypoints = np.array(keypoints[mask], dtype=np.intp, order='C', copy=False)
+        keypoints = np.array(
+            keypoints[mask], dtype=np.intp, order='C', copy=NP_COPY_IF_NEEDED
+        )
         orientations = np.array(orientations[mask], order='C', copy=False)
 
         descriptors = _orb_loop(octave_image, keypoints, orientations)

skimage/transform/_geometric.py

@@ -6,6 +6,7 @@
 from scipy import spatial
 
 from .._shared.utils import safe_as_int
+from .._shared.compat import NP_COPY_IF_NEEDED
 
 
 def _affine_matrix_from_vector(v):
@@ -672,7 +673,7 @@ def _inv_matrix(self):
 
     def _apply_mat(self, coords, matrix):
         ndim = matrix.shape[0] - 1
-        coords = np.array(coords, copy=False, ndmin=2)
+        coords = np.array(coords, copy=NP_COPY_IF_NEEDED, ndmin=2)
 
         src = np.concatenate([coords, np.ones((coords.shape[0], 1))], axis=1)
         dst = src @ matrix.T