Add configuration of Shadow and pie shadow

oscargus · oscargus · commit 160ed3caf804 · 2023-03-05T13:59:01.000+01:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -3075,7 +3075,8 @@ def pie(self, x, explode=None, labels=None, colors=None,
             autopct=None, pctdistance=0.6, shadow=False, labeldistance=1.1,
             startangle=0, radius=1, counterclock=True,
             wedgeprops=None, textprops=None, center=(0, 0),
-            frame=False, rotatelabels=False, *, normalize=True, hatch=None):
+            frame=False, rotatelabels=False, *, normalize=True, hatch=None,
+            shadow_factor=0.3, shadow_offset=(-0.02, -0.02), shadow_alpha=1):
         """
         Plot a pie chart.
 
@@ -3163,6 +3164,16 @@ def pie(self, x, explode=None, labels=None, colors=None,
             ``sum(x) == 1``. *False* makes a partial pie if ``sum(x) <= 1``
             and raises a `ValueError` for ``sum(x) > 1``.
 
+        shadow_factor : float, default: 0.3
+            How the darkness of the shadow relates to the original color. If 0, the
+            shadow is black, if 1, the shadow has the same color as the *patch*.
+
+        shadow_offset : (float, float), default: (-0.02, -0.02)
+            The (x, y)-offset of the shadow.
+
+        shadow_alpha : float, default: 0.5
+            The alpha value of the shadow.
+
         data : indexable object, optional
             DATA_PARAMETER_PLACEHOLDER
 
@@ -3255,7 +3266,8 @@ def get_next_color():
             if shadow:
                 # Make sure to add a shadow after the call to add_patch so the
                 # figure and transform props will be set.
-                shad = mpatches.Shadow(w, -0.02, -0.02, label='_nolegend_')
+                shad = mpatches.Shadow(w, *shadow_offset, shadow_factor=shadow_factor,
+                                       alpha=shadow_alpha, label='_nolegend_')
                 self.add_patch(shad)
 
             if labeldistance is not None:
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -615,12 +615,12 @@ def __str__(self):
         return f"Shadow({self.patch})"
 
     @_docstring.dedent_interpd
-    def __init__(self, patch, ox, oy, **kwargs):
+    def __init__(self, patch, ox, oy, *, shadow_factor=0.3, **kwargs):
         """
         Create a shadow of the given *patch*.
 
         By default, the shadow will have the same face color as the *patch*,
-        but darkened.
+        but darkened. The darkness can be controlled by *shadow_factor*.
 
         Parameters
         ----------
@@ -629,6 +629,9 @@ def __init__(self, patch, ox, oy, **kwargs):
         ox, oy : float
             The shift of the shadow in data coordinates, scaled by a factor
             of dpi/72.
+        shadow_factor : float, default: 0.3
+            How the darkness of the shadow relates to the original color. If 0, the
+            shadow is black, if 1, the shadow has the same color as the *patch*.
         **kwargs
             Properties of the shadow patch. Supported keys are:
 
@@ -640,7 +643,9 @@ def __init__(self, patch, ox, oy, **kwargs):
         self._shadow_transform = transforms.Affine2D()
 
         self.update_from(self.patch)
-        color = .3 * np.asarray(colors.to_rgb(self.patch.get_facecolor()))
+        if not 0 <= shadow_factor <= 1:
+            raise ValueError("shadow_factor must be between 0 and 1.")
+        color = shadow_factor * np.asarray(colors.to_rgb(self.patch.get_facecolor()))
         self.update({'facecolor': color, 'edgecolor': color, 'alpha': 0.5,
                      # Place shadow patch directly behind the inherited patch.
                      'zorder': np.nextafter(self.patch.zorder, -np.inf),
