FIX: do not warn when calling tight_layout multiple times

tacaswell · tacaswell · commit 18e19b3f2ff0 · 2023-07-12T17:55:42.000-04:00
Closes #26290
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -53,7 +53,7 @@
 from matplotlib.gridspec import GridSpec
 from matplotlib.layout_engine import (
     ConstrainedLayoutEngine, TightLayoutEngine, LayoutEngine,
-    PlaceHolderLayoutEngine
+    PlaceHolderLayoutEngine, TLPlaceHolderLayoutEngine
 )
 import matplotlib.legend as mlegend
 from matplotlib.patches import Rectangle
@@ -3522,17 +3522,25 @@ def tight_layout(self, *, pad=1.08, h_pad=None, w_pad=None, rect=None):
         # note that here we do not permanently set the figures engine to
         # tight_layout but rather just perform the layout in place and remove
         # any previous engines.
-        engine = TightLayoutEngine(pad=pad, h_pad=h_pad, w_pad=w_pad,
-                                   rect=rect)
+        engine = TightLayoutEngine(pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
         try:
             previous_engine = self.get_layout_engine()
             self.set_layout_engine(engine)
             engine.execute(self)
-            if not isinstance(previous_engine, TightLayoutEngine) \
-                    and previous_engine is not None:
-                _api.warn_external('The figure layout has changed to tight')
+            if previous_engine is not None and not isinstance(
+                previous_engine, (TightLayoutEngine, TLPlaceHolderLayoutEngine)
+            ):
+                _api.warn_external("The figure layout has changed to tight")
         finally:
-            self.set_layout_engine('none')
+            if previous_engine is not None:
+                self.set_layout_engine(
+                    TLPlaceHolderLayoutEngine(
+                        previous_engine.adjust_compatible,
+                        previous_engine.colorbar_gridspec
+                    )
+                )
+            else:
+                self.set_layout_engine(TLPlaceHolderLayoutEngine(True, True))
 
 
 def figaspect(arg):
diff --git a/lib/matplotlib/layout_engine.py b/lib/matplotlib/layout_engine.py
@@ -129,6 +129,11 @@ def execute(self, fig):
         return
 
 
+class TLPlaceHolderLayoutEngine(PlaceHolderLayoutEngine):
+    """Special place holder class used by Figure.tight_layout"""
+    ...
+
+
 class TightLayoutEngine(LayoutEngine):
     """
     Implements the ``tight_layout`` geometry management.  See
diff --git a/lib/matplotlib/layout_engine.pyi b/lib/matplotlib/layout_engine.pyi
@@ -18,6 +18,9 @@ class PlaceHolderLayoutEngine(LayoutEngine):
     ) -> None: ...
     def execute(self, fig: Figure) -> None: ...
 
+class TLPlaceHolderLayoutEngine(PlaceHolderLayoutEngine):
+    ...
+
 class TightLayoutEngine(LayoutEngine):
     def __init__(
         self,
diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
@@ -701,6 +701,14 @@ def test_layout_change_warning(layout):
         plt.tight_layout()
 
 
+def test_repeated_tightlayout():
+    fig = Figure()
+    fig.tight_layout()
+    # subsequent calls should not warn
+    fig.tight_layout()
+    fig.tight_layout()
+
+
 @check_figures_equal(extensions=["png", "pdf"])
 def test_add_artist(fig_test, fig_ref):
     fig_test.dpi = 100
