DOC : added warning to doc of get_window_extent

tacaswell · tacaswell · commit 244dd1877c72 · 2014-07-04T13:17:27.000-04:00
This is in response to issues raised in #2831. Closes #3055
diff --git a/lib/matplotlib/artist.py b/lib/matplotlib/artist.py
@@ -193,6 +193,13 @@ def get_window_extent(self, renderer):
         Subclasses should override for inclusion in the bounding box
         "tight" calculation. Default is to return an empty bounding
         box at 0, 0.
+
+        Be careful when using this function, the results will not update
+        if the artist window extent of the artist changes.  The extent can
+        change due to any changes in the transform stack, such as changing
+        the axes limits, the figure size, or the canvas used (as is done when
+        saving a figure).  This can lead to expected behavior where interactive
+        figures will look fine on the screen, but will save incorrectly.
         """
         return Bbox([[0, 0], [0, 0]])
 
@@ -644,7 +651,7 @@ def set_clip_on(self, b):
         """
         Set whether artist uses clipping.
 
-        When False artists will be visible out side of the axes which 
+        When False artists will be visible out side of the axes which
         can lead to unexpected results.
 
         ACCEPTS: [True | False]
