matplotlib · trygvrad · Jan 18, 2026 · Jan 24, 2026
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -1043,6 +1043,8 @@ def remove(self):
 
         try:
             ax = self.mappable.axes
+            if ax is None:
+                return
         except AttributeError:
             return
         try:

diff --git a/lib/matplotlib/colorizer.py b/lib/matplotlib/colorizer.py
@@ -1,3 +1,3 @@
 """
 The Colorizer class which handles the data to color pipeline via a
 normalization and a colormap.
@@ -514,7 +514,51 @@
         return g_sig_digits
 
 
-class _ScalarMappable(_ColorizerInterface):
+class _ColorbarMappable(_ColorizerInterface):
+
+    def __init__(self, colorizer, **kwargs):
+        """
+        Base class for objects that can connect to a colorbar.
+
+        All classes that can act as a mappable for `fig.colorbar(mappable)`
+        will subclass this class.
+        """
+        super().__init__(**kwargs)
+        self._colorizer = colorizer
+        self.colorbar = None
+        self._id_colorizer = self._colorizer.callbacks.connect('changed', self.changed)
+        self.callbacks = cbook.CallbackRegistry(signals=["changed"])
+        self._axes = None
+
+    @property
+    def axes(self):
+        return self._axes
+
+    @axes.setter
+    def axes(self, axes):
+        self._axes = axes
+
+    @property
+    def colorizer(self):
+        return self._colorizer
+
+    @colorizer.setter
+    def colorizer(self, cl):
+        _api.check_isinstance(Colorizer, colorizer=cl)
+        self._colorizer.callbacks.disconnect(self._id_colorizer)
+        self._colorizer = cl
+        self._id_colorizer = cl.callbacks.connect('changed', self.changed)
+
+    def changed(self):
+        """
+        Call this whenever the mappable is changed to notify all the
+        callbackSM listeners to the 'changed' signal.
+        """
+        self.callbacks.process('changed')
+        self.stale = True
+
+
+class _ScalarMappable(_ColorbarMappable):
     """
     A mixin class to map one or multiple sets of scalar data to RGBA.
 
@@ -550,13 +594,9 @@
         cmap : str or `~matplotlib.colors.Colormap`
             The colormap used to map normalized data values to RGBA colors.
         """
-        super().__init__(**kwargs)
         self._A = None
-        self._colorizer = self._get_colorizer(colorizer=colorizer, norm=norm, cmap=cmap)
-
-        self.colorbar = None
-        self._id_colorizer = self._colorizer.callbacks.connect('changed', self.changed)
-        self.callbacks = cbook.CallbackRegistry(signals=["changed"])
+        colorizer = self._get_colorizer(colorizer=colorizer, norm=norm, cmap=cmap)
+        super().__init__(colorizer, **kwargs)
 
     def set_array(self, A):
         """
@@ -600,14 +640,6 @@
         """
         return self._A
 
-    def changed(self):
-        """
-        Call this whenever the mappable is changed to notify all the
-        callbackSM listeners to the 'changed' signal.
-        """
-        self.callbacks.process('changed', self)
-        self.stale = True
-
     @staticmethod
     def _check_exclusionary_keywords(colorizer, **kwargs):
         """
@@ -710,17 +742,6 @@
         _api.check_isinstance(Colorizer, colorizer=colorizer)
         super().__init__(colorizer=colorizer, **kwargs)
 
-    @property
-    def colorizer(self):
-        return self._colorizer
-
-    @colorizer.setter
-    def colorizer(self, cl):
-        _api.check_isinstance(Colorizer, colorizer=cl)
-        self._colorizer.callbacks.disconnect(self._id_colorizer)
-        self._colorizer = cl
-        self._id_colorizer = cl.callbacks.connect('changed', self.changed)
-
     def _set_colorizer_check_keywords(self, colorizer, **kwargs):
         """
         Raises a ValueError if any kwarg is not None while colorizer is not None.

diff --git a/lib/matplotlib/colorizer.pyi b/lib/matplotlib/colorizer.pyi
@@ -1,4 +1,4 @@
-from matplotlib import cbook, colorbar, colors, artist
+from matplotlib import cbook, colorbar, colors, artist, axes as maxes
 
 import numpy as np
 from numpy.typing import ArrayLike
@@ -71,7 +71,24 @@ class _ColorizerInterface:
     def autoscale_None(self) -> None: ...
 
 
-class _ScalarMappable(_ColorizerInterface):
+class _ColorbarMappable(_ColorizerInterface):
+    def __init__(
+        self,
+        colorizer: Colorizer | None,
+        **kwargs
+    ) -> None: ...
+    @property
+    def colorizer(self) -> Colorizer: ...
+    @colorizer.setter
+    def colorizer(self, cl: Colorizer) -> None: ...
+    def changed(self) -> None: ...
+    @property
+    def axes(self) -> maxes._base._AxesBase | None: ...
+    @axes.setter
+    def axes(self, new_axes: maxes._base._AxesBase | None) -> None: ...
+
+
+class _ScalarMappable(_ColorbarMappable):
     def __init__(
         self,
         norm: colors.Norm | None = ...,
@@ -82,7 +99,6 @@ class _ScalarMappable(_ColorizerInterface):
     ) -> None: ...
     def set_array(self, A: ArrayLike | None) -> None: ...
     def get_array(self) -> np.ndarray | None: ...
-    def changed(self) -> None: ...
 
 
 class ColorizingArtist(_ScalarMappable, artist.Artist):

diff --git a/lib/mpl_toolkits/mplot3d/art3d.py b/lib/mpl_toolkits/mplot3d/art3d.py
@@ -1,3 +1,3 @@
 # art3d.py, original mplot3d version by John Porter
 # Parts rewritten by Reinier Heeres <reinier@heeres.eu>
 # Minor additions by Ben Axelrod <baxelrod@coroware.com>
@@ -15,11 +15,12 @@
 
 from matplotlib import (
     _api, artist, cbook, colors as mcolors, lines, text as mtext,
-    path as mpath, rcParams)
+    path as mpath, rcParams, colorizer as mcolorizer)
 from matplotlib.collections import (
     Collection, LineCollection, PolyCollection, PatchCollection, PathCollection)
 from matplotlib.patches import Patch
 from . import proj3d
+import collections
 
 
 def _norm_angle(a):
@@ -1206,22 +1207,26 @@
         and _edgecolors properties.
         """
         if shade:
-            normals = _generate_normals(verts)
+            self.shaded = True
+            self.normals = _generate_normals(verts)
+            self.lightsource = lightsource
             facecolors = kwargs.get('facecolors', None)
             if facecolors is not None:
                 kwargs['facecolors'] = _shade_colors(
-                    facecolors, normals, lightsource
+                    facecolors, self.normals, self.lightsource
                 )
 
             edgecolors = kwargs.get('edgecolors', None)
             if edgecolors is not None:
                 kwargs['edgecolors'] = _shade_colors(
-                    edgecolors, normals, lightsource
+                    edgecolors, self.normals, self.lightsource
                 )
             if facecolors is None and edgecolors is None:
                 raise ValueError(
                     "You must provide facecolors, edgecolors, or both for "
                     "shade to work.")
+        else:
+            self.shaded = False
         super().__init__(verts, *args, **kwargs)
         if isinstance(verts, np.ndarray):
             if verts.ndim != 3:
@@ -1233,6 +1238,37 @@
         self._codes3d = None
         self._axlim_clip = axlim_clip
 
+    def update_scalarmappable(self):
+        """
+        Update colors from the scalar mappable array, if any.
+
+        This overrides `Collection.update_scalarmappable()`.
+        This function differs in the following way:
+        1. This function only sets facecolors, never edgecolors
+        2. This function applies shading.
+        3. self._A is assumed to have the correct shape
+        """
+        if not self._set_mappable_flags():
+            return
+        # Allow possibility to call 'self.set_array(None)'.
+        if self._A is not None:
+            if np.iterable(self._alpha):
+                if self._alpha.size != self._A.size:
+                    raise ValueError(
+                        f'Data array shape, {self._A.shape} '
+                        'is incompatible with alpha array shape, '
+                        f'{self._alpha.shape}. '
+                        )
+                self._alpha = self._alpha.reshape(self._A.shape)
+            self._mapped_colors = self.to_rgba(self._A, self._alpha)
+            if self.shaded:
+                self._mapped_colors = _shade_colors(
+                        self._mapped_colors, self.normals, self.lightsource
+                    )
+
+            self._facecolors = self._mapped_colors
+        self.stale = True
+
     _zsort_functions = {
         'average': np.average,
         'min': np.min,
@@ -1675,3 +1711,70 @@
         colors = np.asanyarray(color).copy()
 
     return colors
+
+
+class VoxelDict(mcolorizer._ColorbarMappable,
+                collections.abc.MutableMapping):
+    """
+    A mapping indexed by coordinate, where ``faces[i, j, k]``
+    is a `.Poly3DCollection` of the faces drawn for the voxel
+    ``filled[i, j, k]``. If no faces were drawn for a given voxel,
+    either because it was not asked to be drawn, or it is fully
+    occluded, then ``(i, j, k) not in faces``.
+
+    This class also supports the functionality required to act as a mappable
+    for a colorbar.
+    """
+
+    def __init__(self, colorizer, axes):
+        """
+        Parameters
+        ----------
+        colorizer : `mpl.colorizer.Colorizer`
+            The colorizer uset to convert data to color.
+
+        axes : `mplot3d.axes3d.Axes3D`
+            The axes the voxels are contained in.
+
+        """
+
+        super().__init__(colorizer)
+        self.axes = axes
+        self._A = None
+        self._mapping = dict()
+
+    def __getitem__(self, key):
+        return self._mapping[key]
+
+    def __setitem__(self, key, val):
+        self._mapping[key] = val
+
+    def __delitem__(self, key):
+        del self._mapping[key]
+
+    def __len__(self):
+        return len(self._mapping)
+
+    def __iter__(self):
+        return reversed(self._mapping)
+
+    def get_array(self):
+        """
+        Return the array of values, that are mapped to colors.
+        """
+        return self._A
+
+    def set_array(self, A):
+        """
+        Set the value array from array-like *A*.
+
+        Parameters
+        ----------
+        A : array-like of length equal to the number of voxels.
+            The values that are mapped to colors.
+
+        """
+
+        self._A = A
+        for a, k in zip(A, self.keys()):
+            self[k].set_array(a)
-Original file line number
+Diff line change
@@ Expand Up / @@ -1043,6 +1043,8 @@ def remove(self): @@
             try:
                 ax = self.mappable.axes
+                if ax is None:
+                    return
             except AttributeError:
                 return
             try:
@@ Expand Down @@