MNT: consolidate the no-op logic into a RenderBase method

tacaswell · tacaswell · commit 7a412cdc65be · 2020-06-08T22:43:43.000-04:00
Be forgiving about renderer instances that do not inherit from
RendereBase.
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -25,7 +25,7 @@
     The base class for the Toolbar class of each interactive backend.
 """
 
-from contextlib import contextmanager
+from contextlib import contextmanager, suppress
 from enum import Enum, IntEnum
 import functools
 import importlib
@@ -709,6 +709,23 @@ def stop_filter(self, filter_func):
         Currently only supported by the agg renderer.
         """
 
+    def _draw_disabled(self):
+        """
+        Context manager to temporary disable drawing.
+
+        This is used for getting the drawn size of Artists.  This lets us
+        run the draw process to update any Python state but does not pay the
+        cost of the draw_XYZ calls on the canvas.
+        """
+        no_ops = {
+            meth_name: lambda *args, **kwargs: None
+            for meth_name in dir(RendererBase)
+            if (meth_name.startswith("draw_")
+                or meth_name in ["open_group", "close_group"])
+        }
+
+        return _setattr_cm(self, **no_ops)
+
 
 class GraphicsContextBase:
     """An abstract base class that provides color, line styles, etc."""
@@ -2089,14 +2106,10 @@ def print_figure(
                         functools.partial(
                             print_method, orientation=orientation)
                     )
-                    no_ops = {
-                        meth_name: lambda *args, **kwargs: None
-                        for meth_name in dir(RendererBase)
-                        if (meth_name.startswith("draw_")
-                            or meth_name in ["open_group", "close_group"])
-                    }
-
-                    with _setattr_cm(renderer, **no_ops):
+                    ctx = (renderer._draw_disabled()
+                           if hasattr(renderer, '_draw_disabled')
+                           else suppress())
+                    with ctx:
                         self.figure.draw(renderer)
 
                     bbox_inches = self.figure.get_tightbbox(
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -2392,9 +2392,7 @@ def tight_layout(self, renderer=None, pad=1.08, h_pad=None, w_pad=None,
 
         from .tight_layout import (
             get_renderer, get_subplotspec_list, get_tight_layout_figure)
-        from .cbook import _setattr_cm
-        from .backend_bases import RendererBase
-
+        from contextlib import suppress
         subplotspec_list = get_subplotspec_list(self.axes)
         if None in subplotspec_list:
             cbook._warn_external("This figure includes Axes that are not "
@@ -2403,15 +2401,10 @@ def tight_layout(self, renderer=None, pad=1.08, h_pad=None, w_pad=None,
 
         if renderer is None:
             renderer = get_renderer(self)
-
-        no_ops = {
-            meth_name: lambda *args, **kwargs: None
-            for meth_name in dir(RendererBase)
-            if (meth_name.startswith("draw_")
-                or meth_name in ["open_group", "close_group"])
-        }
-
-        with _setattr_cm(renderer, **no_ops):
+        ctx = (renderer._draw_disabled()
+               if hasattr(renderer, '_draw_disabled')
+               else suppress())
+        with ctx:
             kwargs = get_tight_layout_figure(
                 self, self.axes, subplotspec_list, renderer,
                 pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
