Simplify wx _print_image.

anntzer · anntzer · commit cda955b7ac7f · 2021-12-21T00:12:07.000+01:00
Instead of swapping the bitmap attribute, it is enough to create a new
renderer with a different target and save that target to a file.

The isinstance(..., wx.Image) check is always false (we have a wx.Bitmap
instead), so skip it.
diff --git a/lib/matplotlib/backends/backend_wx.py b/lib/matplotlib/backends/backend_wx.py
@@ -842,34 +842,18 @@ def draw(self, drawDC=None):
         self.gui_repaint(drawDC=drawDC)
 
     def _print_image(self, filetype, filename):
-        origBitmap = self.bitmap
-
-        self.bitmap = wx.Bitmap(math.ceil(self.figure.bbox.width),
-                                math.ceil(self.figure.bbox.height))
-        renderer = RendererWx(self.bitmap, self.figure.dpi)
-
-        gc = renderer.new_gc()
-        self.figure.draw(renderer)
-
-        # image is the object that we call SaveFile on.
-        image = self.bitmap
-
-        # Now that we have rendered into the bitmap, save it to the appropriate
-        # file type and clean up.
-        if (cbook.is_writable_file_like(filename) and
-                not isinstance(image, wx.Image)):
-            image = image.ConvertToImage()
-        if not image.SaveFile(filename, filetype):
+        bitmap = wx.Bitmap(math.ceil(self.figure.bbox.width),
+                           math.ceil(self.figure.bbox.height))
+        self.figure.draw(RendererWx(bitmap, self.figure.dpi))
+        saved_obj = (bitmap.ConvertToImage()
+                     if cbook.is_writable_file_like(filename)
+                     else bitmap)
+        if not saved_obj.SaveFile(filename, filetype):
             raise RuntimeError(f'Could not save figure to {filename}')
-
-        # Restore everything to normal
-        self.bitmap = origBitmap
-
-        # Note: draw is required here since bits of state about the
-        # last renderer are strewn about the artist draw methods.  Do
-        # not remove the draw without first verifying that these have
-        # been cleaned up.  The artist contains() methods will fail
-        # otherwise.
+        # draw() is required here since bits of state about the last renderer
+        # are strewn about the artist draw methods.  Do not remove the draw
+        # without first verifying that these have been cleaned up.  The artist
+        # contains() methods will fail otherwise.
         if self._isDrawn:
             self.draw()
         # The "if self" check avoids a "wrapped C/C++ object has been deleted"
