MNT: be more gentle about resetting the draw method

Author: tacaswell

lib/matplotlib/artist.py

@@ -132,7 +132,9 @@ def __init_subclass__(cls):
 
         # Decorate draw() method so that all artists are able to stop
         # rastrization when necessary.
-        cls.draw = _prevent_rasterization(cls.draw)
+
+        if not hasattr(cls.draw, "_supports_rasterization"):
+            cls.draw = _prevent_rasterization(cls.draw)
 
         # Inject custom set() methods into the subclass with signature and
         # docstring based on the subclasses' properties.

lib/matplotlib/tests/test_artist.py

@@ -535,3 +535,17 @@ def test_format_cursor_data_BoundaryNorm():
         assert img.format_cursor_data(v) == label
 
     plt.close()
+
+
+def test_auto_no_rasterize():
+    class Gen1(martist.Artist):
+        ...
+
+    assert 'draw' in Gen1.__dict__
+    assert Gen1.__dict__['draw'] is Gen1.draw
+
+    class Gen2(Gen1):
+        ...
+
+    assert 'draw' not in Gen2.__dict__
+    assert Gen2.draw is Gen1.draw