Make draggable callbacks check that artist has not been removed.

anntzer · anntzer · commit 53f4fb598ee2 · 2018-03-28T00:36:24.000-07:00
diff --git a/lib/matplotlib/offsetbox.py b/lib/matplotlib/offsetbox.py
@@ -1631,14 +1631,14 @@ def __init__(self, ref_artist, use_blit=False):
         self.cids = [c2, c3]
 
     def on_motion(self, evt):
-        if self.got_artist:
+        if self._check_still_parented() and self.got_artist:
             dx = evt.x - self.mouse_x
             dy = evt.y - self.mouse_y
             self.update_offset(dx, dy)
             self.canvas.draw()
 
     def on_motion_blit(self, evt):
-        if self.got_artist:
+        if self._check_still_parented() and self.got_artist:
             dx = evt.x - self.mouse_x
             dy = evt.y - self.mouse_y
             self.update_offset(dx, dy)
@@ -1647,7 +1647,7 @@ def on_motion_blit(self, evt):
             self.canvas.blit(self.ref_artist.figure.bbox)
 
     def on_pick(self, evt):
-        if evt.artist == self.ref_artist:
+        if self._check_still_parented() and evt.artist == self.ref_artist:
 
             self.mouse_x = evt.mouseevent.x
             self.mouse_y = evt.mouseevent.y
@@ -1668,14 +1668,21 @@ def on_pick(self, evt):
             self.save_offset()
 
     def on_release(self, event):
-        if self.got_artist:
+        if self._check_still_parented() and self.got_artist:
             self.finalize_offset()
             self.got_artist = False
             self.canvas.mpl_disconnect(self._c1)
 
             if self._use_blit:
                 self.ref_artist.set_animated(False)
 
+    def _check_still_parented(self):
+        if self.ref_artist.axes is None:
+            self.disconnect()
+            return False
+        else:
+            return True
+
     def disconnect(self):
         """disconnect the callbacks"""
         for cid in self.cids:
