Add configuration of Shadow and pie shadow

oscargus · oscargus · commit a39e43cbfbd2 · 2023-03-26T17:15:36.000+02:00
diff --git a/doc/users/next_whats_new/pie_shadow_control.rst b/doc/users/next_whats_new/pie_shadow_control.rst
@@ -0,0 +1,5 @@
+The pie chart shadow can be controlled
+--------------------------------------
+
+The *shadow* argument to `~.Axes.pie` can now be a dict, allowing more control
+of the `.Shadow`-patch used.
diff --git a/doc/users/next_whats_new/shadow_shade.rst b/doc/users/next_whats_new/shadow_shade.rst
@@ -0,0 +1,6 @@
+Shadow shade can be controlled
+------------------------------
+
+The `.Shadow` patch now has a *shade* argument to control the shadow darkness.
+If 0, the shadow is black, if 1, the shadow has the same color as the patch that
+is shadowed. The default value, which earlier was fixed, is 0.3.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -3102,8 +3102,12 @@ def pie(self, x, explode=None, labels=None, colors=None,
             If set to ``None``, labels are not drawn but are still stored for
             use in `.legend`.
 
-        shadow : bool, default: False
-            Draw a shadow beneath the pie.
+        shadow : bool or dict, default: False
+            If bool, whether to draw a shadow beneath the pie. If dict, draw a shadow
+            passing the properties in the dict to `.Shadow`.
+
+            .. versionadded:: 3.8
+                *shadow* can be a dict.
 
         startangle : float, default: 0 degrees
             The angle by which the start of the pie is rotated,
@@ -3231,8 +3235,10 @@ 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_')
-                self.add_patch(shad)
+                shadow_dict = {'ox': -0.02, 'oy': -0.02, 'label': '_nolegend_'}
+                if isinstance(shadow, dict):
+                    shadow_dict.update(shadow)
+                self.add_patch(mpatches.Shadow(w, **shadow_dict))
 
             if labeldistance is not None:
                 xt = x + labeldistance * radius * math.cos(thetam)
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -614,12 +614,12 @@ def __str__(self):
         return f"Shadow({self.patch})"
 
     @_docstring.dedent_interpd
-    def __init__(self, patch, ox, oy, **kwargs):
+    def __init__(self, patch, ox, oy, *, shade=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 *shade*.
 
         Parameters
         ----------
@@ -628,6 +628,12 @@ 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.
+        shade : 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*.
+
+            .. versionadded:: 3.8
+
         **kwargs
             Properties of the shadow patch. Supported keys are:
 
@@ -639,7 +645,9 @@ 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 <= shade <= 1:
+            raise ValueError("shade must be between 0 and 1.")
+        color = shade * 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),
