Backcompat for get_layout_engine

Author: mwaskom

seaborn/_compat.py

@@ -1,5 +1,9 @@
+from __future__ import annotations
+from typing import Literal
+
 import numpy as np
 import matplotlib as mpl
+from matplotlib.figure import Figure
 from seaborn.utils import _version_predates
 
 
@@ -84,19 +88,31 @@ def register_colormap(name, cmap):
         mpl.cm.register_cmap(name, cmap)
 
 
-def set_layout_engine(fig, engine):
+def set_layout_engine(
+    fig: Figure,
+    engine: Literal["constrained", "compressed", "tight", "none"],
+) -> None:
     """Handle changes to auto layout engine interface in 3.6"""
     if hasattr(fig, "set_layout_engine"):
         fig.set_layout_engine(engine)
     else:
         # _version_predates(mpl, 3.6)
         if engine == "tight":
-            fig.set_tight_layout(True)
+            fig.set_tight_layout(True)  # type: ignore  # predates typing
         elif engine == "constrained":
-            fig.set_constrained_layout(True)
+            fig.set_constrained_layout(True)  # type: ignore
         elif engine == "none":
-            fig.set_tight_layout(False)
-            fig.set_constrained_layout(False)
+            fig.set_tight_layout(False)  # type: ignore
+            fig.set_constrained_layout(False)  # type: ignore
+
+
+def get_layout_engine(fig: Figure) -> mpl.layout_engine.LayoutEngine | None:
+    """Handle changes to auto layout engine interface in 3.6"""
+    if hasattr(fig, "get_layout_engine"):
+        return fig.get_layout_engine()
+    else:
+        # _version_predates(mpl, 3.6)
+        return None
 
 
 def share_axis(ax0, ax1, which):

seaborn/_core/plot.py

@@ -40,7 +40,7 @@
 )
 from seaborn._core.exceptions import PlotSpecError
 from seaborn._core.rules import categorical_order
-from seaborn._compat import set_layout_engine
+from seaborn._compat import get_layout_engine, set_layout_engine
 from seaborn.rcmod import axes_style, plotting_context
 from seaborn.palettes import color_palette
 
@@ -1811,7 +1811,7 @@ def _finalize_figure(self, p: Plot) -> None:
             set_layout_engine(self._figure, "tight")
 
         if (extent := p._layout_spec.get("extent")) is not None:
-            engine = self._figure.get_layout_engine()
+            engine = get_layout_engine(self._figure)
             if engine is None:
                 self._figure.subplots_adjust(*extent)
             else:

tests/_core/test_plot.py

@@ -1091,11 +1091,19 @@ def test_layout_size(self):
         p = Plot().layout(size=size).plot()
         assert tuple(p._figure.get_size_inches()) == size
 
+    @pytest.mark.skipif(
+        _version_predates(mpl, "3.6"),
+        reason="mpl<3.6 does not have get_layout_engine",
+    )
     def test_layout_extent(self):
 
         p = Plot().layout(extent=(.1, .2, .6, 1)).plot()
         assert p._figure.get_layout_engine().get()["rect"] == [.1, .2, .5, .8]
 
+    @pytest.mark.skipif(
+        _version_predates(mpl, "3.6"),
+        reason="mpl<3.6 does not have get_layout_engine",
+    )
     def test_constrained_layout_extent(self):
 
         p = Plot().layout(engine="constrained", extent=(.1, .2, .6, 1)).plot()