Merge pull request #17747 from meeseeksmachine/auto-backport-of-pr-17731-on-v3.3.x

tacaswell · web-flow · commit 887f9a91fe01 · 2020-06-24T18:54:51.000-04:00
Backport PR #17731 on branch v3.3.x ("Fix" tight_layout for template backend.)
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -1534,7 +1534,6 @@ def _get_renderer(figure, print_method=None):
 
     If you need a renderer without any active draw methods use
     renderer._draw_disabled to temporary patch them out at your call site.
-
     """
     # This is implemented by triggering a draw, then immediately jumping out of
     # Figure.draw() by raising an exception.
@@ -1545,15 +1544,23 @@ class Done(Exception):
     def _draw(renderer): raise Done(renderer)
 
     with cbook._setattr_cm(figure, draw=_draw):
+        orig_canvas = figure.canvas
         if print_method is None:
             fmt = figure.canvas.get_default_filetype()
-            print_method = getattr(figure.canvas, f"print_{fmt}")
+            # Even for a canvas' default output type, a canvas switch may be
+            # needed, e.g. for FigureCanvasBase.
+            print_method = getattr(
+                figure.canvas._get_output_canvas(None, fmt), f"print_{fmt}")
         try:
             print_method(io.BytesIO(), dpi=figure.dpi)
         except Done as exc:
             renderer, = figure._cachedRenderer, = exc.args
-
-    return renderer
+            return renderer
+        else:
+            raise RuntimeError(f"{print_method} did not call Figure.draw, so "
+                               f"no renderer is available")
+        finally:
+            figure.canvas = orig_canvas
 
 
 def _is_non_interactive_terminal_ipython(ip):
diff --git a/lib/matplotlib/backends/backend_template.py b/lib/matplotlib/backends/backend_template.py
@@ -208,6 +208,7 @@ def print_foo(self, filename, *args, **kwargs):
         to their original values after this call, so you don't need to
         save and restore them.
         """
+        self.draw()
 
     def get_default_filetype(self):
         return 'foo'
