wx.Bitmap() will complain (at least on MacOS) if width or height is zero

Author: newville

lib/matplotlib/backends/backend_wx.py

@@ -694,14 +694,14 @@ def _onSize(self, event):
                 # no change in size
                 return
         self._width, self._height = size
-        # Create a new, correctly sized bitmap
-        self.bitmap = wx.Bitmap(self._width, self._height)
-
         self._isDrawn = False
 
         if self._width <= 1 or self._height <= 1:
             return  # Empty figure
 
+        # Create a new, correctly sized bitmap
+        self.bitmap = wx.Bitmap(self._width, self._height)
+
         dpival = self.figure.dpi
         winch = self._width / dpival
         hinch = self._height / dpival