Deeper marker copies in Line2D update_from

evanberkowitz · evanberkowitz · commit 9efef4e070e1 · 2020-09-28T21:45:27.000-04:00
Markers already support a copy construction: `MarkerStyle.set_marker` accepts other instances of `MarkerStyle`. However, some Artists, when copying markers, instead construct the copy from the other instance's `get_marker` and `get_fillstyle` methods. This destroys (unsupported) manipulations the user might make to the marker, as discovered in issue #18600. By switching constructors, we can get a more faithful copy without explicitly relying on any of `MarkerStyle`'s private methods in places they do not belong.
diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
@@ -1299,8 +1299,7 @@ def update_from(self, other):
         self._solidjoinstyle = other._solidjoinstyle
 
         self._linestyle = other._linestyle
-        self._marker = MarkerStyle(other._marker.get_marker(),
-                                   other._marker.get_fillstyle())
+        self._marker = MarkerStyle(marker=other._marker)
         self._drawstyle = other._drawstyle
 
     def set_dash_joinstyle(self, s):
