Factor out for_layout_only backcompat support in get_tightlayout.

This avoids duplicating try... except in a bunch of places, and also
gives a single centralized point if (possibly) we ever want to deprecate
support for subclasses that do *not* support for_layout_only.

Author: anntzer

lib/matplotlib/_constrained_layout.py

@@ -17,7 +17,7 @@
 
 import numpy as np
 
-from matplotlib import _api
+from matplotlib import _api, artist as martist
 import matplotlib.transforms as mtransforms
 import matplotlib._layoutgrid as mlayoutgrid
 
@@ -534,17 +534,12 @@ def get_pos_and_bbox(ax, renderer):
         Position in figure coordinates.
     bbox : Bbox
         Tight bounding box in figure coordinates.
-
     """
     fig = ax.figure
     pos = ax.get_position(original=True)
     # pos is in panel co-ords, but we need in figure for the layout
     pos = pos.transformed(fig.transSubfigure - fig.transFigure)
-    try:
-        tightbbox = ax.get_tightbbox(renderer=renderer, for_layout_only=True)
-    except TypeError:
-        tightbbox = ax.get_tightbbox(renderer=renderer)
-
+    tightbbox = martist._get_tightbbox_for_layout_only(ax, renderer)
     if tightbbox is None:
         bbox = pos
     else:

lib/matplotlib/artist.py

@@ -1301,6 +1301,18 @@ def mouseover(self, val):
                 ax._mouseover_set.discard(self)
 
 
+def _get_tightbbox_for_layout_only(obj, *args, **kwargs):
+    """
+    Matplotlib's `.Axes.get_tightbbox` and `.Axis.get_tightbbox` support a
+    *for_layout_only* kwarg; this helper tries to uses the kwarg but skips it
+    when encountering third-party subclasses that do not support it.
+    """
+    try:
+        return obj.get_tightbbox(*args, **{**kwargs, "for_layout_only": True})
+    except TypeError:
+        return obj.get_tightbbox(*args, **kwargs)
+
+
 class ArtistInspector:
     """
     A helper class to inspect an `~matplotlib.artist.Artist` and return

lib/matplotlib/axes/_base.py

@@ -4582,21 +4582,13 @@ def get_tightbbox(self, renderer, call_axes_locator=True,
 
         if self.axison:
             if self.xaxis.get_visible():
-                try:
-                    bb_xaxis = self.xaxis.get_tightbbox(
-                        renderer, for_layout_only=for_layout_only)
-                except TypeError:
-                    # in case downstream library has redefined axis:
-                    bb_xaxis = self.xaxis.get_tightbbox(renderer)
+                bb_xaxis = martist._get_tightbbox_for_layout_only(
+                    self.xaxis, renderer)
                 if bb_xaxis:
                     bb.append(bb_xaxis)
             if self.yaxis.get_visible():
-                try:
-                    bb_yaxis = self.yaxis.get_tightbbox(
-                        renderer, for_layout_only=for_layout_only)
-                except TypeError:
-                    # in case downstream library has redefined axis:
-                    bb_yaxis = self.yaxis.get_tightbbox(renderer)
+                bb_yaxis = martist._get_tightbbox_for_layout_only(
+                    self.yaxis, renderer)
                 if bb_yaxis:
                     bb.append(bb_yaxis)
         self._update_title_position(renderer)

lib/matplotlib/tight_layout.py

@@ -11,7 +11,7 @@
 
 import numpy as np
 
-from matplotlib import _api, rcParams
+from matplotlib import _api, artist as martist, rcParams
 from matplotlib.font_manager import FontProperties
 from matplotlib.transforms import Bbox
 
@@ -78,10 +78,7 @@ def _auto_adjust_subplotpars(
         bb = []
         for ax in subplots:
             if ax.get_visible():
-                try:
-                    bb += [ax.get_tightbbox(renderer, for_layout_only=True)]
-                except TypeError:
-                    bb += [ax.get_tightbbox(renderer)]
+                bb += [martist._get_tightbbox_for_layout_only(ax, renderer)]
 
         tight_bbox_raw = Bbox.union(bb)
         tight_bbox = fig.transFigure.inverted().transform_bbox(tight_bbox_raw)

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -3287,16 +3287,10 @@ def get_tightbbox(self, renderer, call_axes_locator=True,
         if self._axis3don:
             for axis in self._get_axis_list():
                 if axis.get_visible():
-                    try:
-                        axis_bb = axis.get_tightbbox(
-                            renderer,
-                            for_layout_only=for_layout_only
-                        )
-                    except TypeError:
-                        # in case downstream library has redefined axis:
-                        axis_bb = axis.get_tightbbox(renderer)
-                if axis_bb:
-                    batch.append(axis_bb)
+                    axis_bb = martist._get_tightbbox_for_layout_only(
+                        axis, renderer)
+                    if axis_bb:
+                        batch.append(axis_bb)
         return mtransforms.Bbox.union(batch)
 
     def stem(self, x, y, z, *, linefmt='C0-', markerfmt='C0o', basefmt='C3-',