Implement support for callbacks in `colour.continuous.AbstractContinu…

…ousFunction` class.

colour/colorimetry/spectrum.py

@@ -716,6 +716,19 @@ def __init__(
         self._display_name: str = self.name
         self.display_name = kwargs.get("display_name", self._display_name)
 
+        self._shape: SpectralShape | None = None
+
+        def _on_domain_changed(
+            self, name: str, value: NDArrayFloat
+        ) -> NDArrayFloat:
+            """Invalidate *self._shape* when *self._domain* is changed."""
+            if name == "_domain":
+                self._shape = None
+
+            return value
+
+        self.register_callback("on_domain_changed", _on_domain_changed)
+
     @property
     def display_name(self) -> str:
         """
@@ -836,17 +849,20 @@ def shape(self) -> SpectralShape:
         SpectralShape(500.0, 600.0, 10.0)
         """
 
-        wavelengths = self.wavelengths
-        wavelengths_interval = interval(wavelengths)
-        if wavelengths_interval.size != 1:
-            runtime_warning(
-                f'"{self.name}" spectral distribution is not uniform, using '
-                f"minimum interval!"
+        if self._shape is None:
+            wavelengths = self.wavelengths
+            wavelengths_interval = interval(wavelengths)
+            if wavelengths_interval.size != 1:
+                runtime_warning(
+                    f'"{self.name}" spectral distribution is not uniform, '
+                    "using minimum interval!"
+                )
+
+            self._shape = SpectralShape(
+                wavelengths[0], wavelengths[-1], min(wavelengths_interval)
             )
 
-        return SpectralShape(
-            wavelengths[0], wavelengths[-1], min(wavelengths_interval)
-        )
+        return self._shape
 
     def interpolate(
         self,

colour/colorimetry/tests/test_spectrum.py

@@ -1515,30 +1515,35 @@ def test_interpolate(self):
 SpectralDistribution.interpolate` method.
         """
 
+        shape = SpectralShape(self._sd.shape.start, self._sd.shape.end, 1)
+        sd = reshape_sd(self._sd, shape, "Interpolate")
         np.testing.assert_array_almost_equal(
-            reshape_sd(
-                self._sd,
-                SpectralShape(self._sd.shape.start, self._sd.shape.end, 1),
-                "Interpolate",
-            ).values,
+            sd.values,
             DATA_SAMPLE_INTERPOLATED,
             decimal=7,
         )
+        self.assertEqual(sd.shape, shape)
 
+        shape = SpectralShape(
+            self._non_uniform_sd.shape.start,
+            self._non_uniform_sd.shape.end,
+            1,
+        )
+        sd = reshape_sd(self._non_uniform_sd, shape, "Interpolate")
         np.testing.assert_allclose(
-            reshape_sd(
-                self._non_uniform_sd,
-                SpectralShape(
-                    self._non_uniform_sd.shape.start,
-                    self._non_uniform_sd.shape.end,
-                    1,
-                ),
-                "Interpolate",
-            ).values,
+            sd.values,
             DATA_SAMPLE_INTERPOLATED_NON_UNIFORM,
             rtol=0.0000001,
             atol=0.0000001,
         )
+        self.assertEqual(
+            sd.shape,
+            SpectralShape(
+                np.ceil(self._non_uniform_sd.shape.start),
+                np.floor(self._non_uniform_sd.shape.end),
+                1,
+            ),
+        )
 
     def test_extrapolate(self):
         """
@@ -1556,8 +1561,9 @@ def test_extrapolate(self):
         sd = SpectralDistribution(
             np.linspace(0, 1, 10), np.linspace(25, 35, 10)
         )
+        shape = SpectralShape(10, 50, 10)
         sd.extrapolate(
-            SpectralShape(10, 50, 10),
+            shape,
             extrapolator_kwargs={
                 "method": "Linear",
                 "left": None,
@@ -1602,6 +1608,17 @@ def test_normalise(self):
             self._sd.copy().normalise(100).values, DATA_SAMPLE_NORMALISED
         )
 
+    def test_callback_on_domain_changed(self):
+        """
+        Test :class:`colour.colorimetry.spectrum.\
+SpectralDistribution` *on_domain_changed* callback.
+        """
+
+        sd = self._sd.copy()
+        self.assertEqual(sd.shape, SpectralShape(340, 820, 20))
+        sd[840] = 0
+        self.assertEqual(sd.shape, SpectralShape(340, 840, 20))
+
 
 class TestMultiSpectralDistributions(unittest.TestCase):
     """
@@ -1760,26 +1777,25 @@ def test_interpolate(self):
         """
 
         # pylint: disable=E1102
-        msds = reshape_msds(
-            self._sample_msds,
-            SpectralShape(
-                self._sample_msds.shape.start, self._sample_msds.shape.end, 1
-            ),
-            "Interpolate",
+        shape = SpectralShape(
+            self._sample_msds.shape.start, self._sample_msds.shape.end, 1
         )
+        msds = reshape_msds(self._sample_msds, shape, "Interpolate")
         for signal in msds.signals.values():
             np.testing.assert_array_almost_equal(
                 signal.values, DATA_SAMPLE_INTERPOLATED, decimal=7
             )
+        self.assertEqual(msds.shape, shape)
 
         # pylint: disable=E1102
+        shape = SpectralShape(
+            self._non_uniform_sample_msds.shape.start,
+            self._non_uniform_sample_msds.shape.end,
+            1,
+        )
         msds = reshape_msds(
             self._non_uniform_sample_msds,
-            SpectralShape(
-                self._non_uniform_sample_msds.shape.start,
-                self._non_uniform_sample_msds.shape.end,
-                1,
-            ),
+            shape,
             "Interpolate",
         )
         for signal in msds.signals.values():
@@ -1789,6 +1805,14 @@ def test_interpolate(self):
                 rtol=0.0000001,
                 atol=0.0000001,
             )
+        self.assertEqual(
+            msds.shape,
+            SpectralShape(
+                np.ceil(self._non_uniform_sample_msds.shape.start),
+                np.floor(self._non_uniform_sample_msds.shape.end),
+                1,
+            ),
+        )
 
     def test_extrapolate(self):
         """
@@ -1853,7 +1877,7 @@ def test_trim(self):
 
     def test_normalise(self):
         """
-                Test :func:`colour.colorimetry.spectrum.
+        Test :func:`colour.colorimetry.spectrum.
         MultiSpectralDistributions.normalise` method.
         """
 
@@ -1875,6 +1899,18 @@ def test_to_sds(self):
             self.assertEqual(sd.name, self._labels[i])
             self.assertEqual(sd.display_name, self._display_labels[i])
 
+    def test_callback_on_domain_changed(self):
+        """
+        Test underlying :class:`colour.colorimetry.spectrum.\
+SpectralDistribution` *on_domain_changed* callback when used with
+        :class:`colour.colorimetry.spectrum.MultiSpectralDistributions` class.
+        """
+
+        msds = self._msds.copy()
+        self.assertEqual(msds.shape, SpectralShape(380, 780, 5))
+        msds[785] = 0
+        self.assertEqual(msds.shape, SpectralShape(380, 785, 5))
+
 
 class TestReshapeSd(unittest.TestCase):
     """

colour/continuous/abstract.py

@@ -29,6 +29,7 @@
     Type,
 )
 from colour.utilities import (
+    MixinCallback,
     as_float,
     attest,
     closest,
@@ -49,7 +50,7 @@
 ]
 
 
-class AbstractContinuousFunction(ABC):
+class AbstractContinuousFunction(ABC, MixinCallback):
     """
     Define the base class for abstract continuous function.
 

colour/continuous/signal.py

@@ -948,8 +948,7 @@ def _fill_domain_nan(
             variable.
         """
 
-        self._domain = fill_nan(self._domain, method, default)
-        self._function = None  # Invalidate the underlying continuous function.
+        self.domain = fill_nan(self.domain, method, default)
 
     def _fill_range_nan(
         self,
@@ -974,8 +973,7 @@ def _fill_range_nan(
             variable.
         """
 
-        self._range = fill_nan(self._range, method, default)
-        self._function = None  # Invalidate the underlying continuous function.
+        self.range = fill_nan(self.range, method, default)
 
     def arithmetical_operation(
         self,

colour/utilities/__init__.py

@@ -11,6 +11,10 @@
     LazyCanonicalMapping,
     Node,
 )
+from .callback import (
+    Callback,
+    MixinCallback,
+)
 from .common import (
     CacheRegistry,
     CACHE_REGISTRY,
@@ -124,6 +128,10 @@
     "LazyCanonicalMapping",
     "Node",
 ]
+__all__ += [
+    "Callback",
+    "MixinCallback",
+]
 __all__ += [
     "CacheRegistry",
     "CACHE_REGISTRY",