Backport PR matplotlib#30186: Fix figure legend when drawing stackplots

Author: timhoffm

lib/matplotlib/legend_handler.py

@@ -800,7 +800,6 @@ def get_first(prop_array):
         legend_handle.set_linewidth(get_first(orig_handle.get_linewidths()))
         legend_handle.set_linestyle(get_first(orig_handle.get_linestyles()))
         legend_handle.set_transform(get_first(orig_handle.get_transforms()))
-        legend_handle.set_figure(orig_handle.get_figure())
         # Alpha is already taken into account by the color attributes.
 
     def create_artists(self, legend, orig_handle,

lib/matplotlib/tests/test_axes.py

@@ -3293,6 +3293,20 @@ def test_stackplot_hatching(fig_ref, fig_test):
     ax_ref.set_ylim((0, 70))
 
 
+def test_stackplot_subfig_legend():
+    # Smoke test for https://github.com/matplotlib/matplotlib/issues/30158
+
+    fig = plt.figure()
+    subfigs = fig.subfigures(nrows=1, ncols=2)
+
+    for _fig in subfigs:
+        ax = _fig.subplots(nrows=1, ncols=1)
+        ax.stackplot([3, 4], [[1, 2]], labels=['a'])
+
+    fig.legend()
+    fig.draw_without_rendering()
+
+
 def _bxp_test_helper(
         stats_kwargs={}, transform_stats=lambda s: s, bxp_kwargs={}):
     np.random.seed(937)