matplotlib · thesanatt · Apr 23, 2026 · Apr 23, 2026 · timhoffm · Apr 23, 2026
diff --git a/lib/matplotlib/backends/qt_editor/figureoptions.py b/lib/matplotlib/backends/qt_editor/figureoptions.py
@@ -248,11 +248,13 @@ def apply_callback(data):
         if generate_legend:
             draggable = None
             ncols = 1
+            legend_kwargs = {}
             if axes.legend_ is not None:
                 old_legend = axes.get_legend()
                 draggable = old_legend._draggable is not None
                 ncols = old_legend._ncols
-            new_legend = axes.legend(ncols=ncols)
+                legend_kwargs = old_legend._get_properties()
+            new_legend = axes.legend(ncols=ncols, **legend_kwargs)
             if new_legend:
                 new_legend.set_draggable(draggable)
 

diff --git a/lib/matplotlib/legend.py b/lib/matplotlib/legend.py
@@ -1098,6 +1098,34 @@ def set_frame_on(self, b):
 
     draw_frame = set_frame_on  # Backcompat alias.
 
+    def _get_properties(self):
+        """
+        Return a dictionary of legend properties for recreation.
+
+        This is used by the Qt figure options dialog to preserve legend
+        settings when regenerating the legend.
+        """
+        props = {
+            'loc': self._loc,
+            'fontsize': self._fontsize,
+            'frameon': self.get_frame_on(),
+            'shadow': self.shadow,
+            'framealpha': self.get_frame().get_alpha(),
+            'title': self.get_title().get_text(),
+            'columnspacing': self.columnspacing,
+            'labelspacing': self.labelspacing,
+            'handlelength': self.handlelength,
+            'handletextpad': self.handletextpad,
+            'borderpad': self.borderpad,
+            'borderaxespad': self.borderaxespad,
+            'markerscale': self.markerscale,
+        }
+        if self._bbox_to_anchor is not None:
+            props['bbox_to_anchor'] = self._bbox_to_anchor.bounds
+        if self._mode is not None:
+            props['mode'] = self._mode
+        return props
+
     def get_bbox_to_anchor(self):
         """Return the bbox that the legend will be anchored to."""
         if self._bbox_to_anchor is None:

diff --git a/lib/matplotlib/tests/test_figureoptions_legend.py b/lib/matplotlib/tests/test_figureoptions_legend.py
@@ -0,0 +1,126 @@
+"""Tests for legend property preservation."""
+import matplotlib
+matplotlib.use('Agg')
+import matplotlib.pyplot as plt
+
+
+def test_get_properties_basic():
+    """
+    Test that Legend._get_properties() returns the correct properties.
+    """
+    fig, ax = plt.subplots()
+    ax.plot(range(5), label='a')
+    ax.plot(range(3)[::-1], label='b')
+
+    ax.legend(
+        loc='upper right',
+        fontsize=14,
+        frameon=False,
+        shadow=True,
+        title='My Legend',
+        ncols=2,
+        columnspacing=3.0,
+        labelspacing=1.5,
+        handlelength=4.0,
+        handletextpad=1.2,
+    )
-    ax.legend(
-        loc='upper right',
-        fontsize=14,
-        frameon=False,
-        shadow=True,
-        title='My Legend',
-        ncols=2,
-        columnspacing=3.0,
-        labelspacing=1.5,
-        handlelength=4.0,
-        handletextpad=1.2,
-    )
+    initial_props = dict(
+        loc='upper right',
+        fontsize=14,
+        frameon=False,
+        shadow=True,
+        title='My Legend',
+        columnspacing=3.0,
+        labelspacing=1.5,
+        handlelength=4.0,
+        handletextpad=1.2,
+    )
+    legend = ax.legend(ncols=2, **props)
-    ax.legend(
-        loc='upper right',
-        fontsize=14,
-        frameon=False,
-        shadow=True,
-        title='My Legend',
-        ncols=2,
-        columnspacing=3.0,
-        labelspacing=1.5,
-        handlelength=4.0,
-        handletextpad=1.2,
-    )
+    initial_props = dict(
+        loc='upper right',
+        fontsize=14,
+        frameon=False,
+        shadow=True,
+        title='My Legend',
+        columnspacing=3.0,
+        labelspacing=1.5,
+        handlelength=4.0,
+        handletextpad=1.2,
+    )
+    legend = ax.legend(ncols=2, **props)
+
+    legend = ax.get_legend()
-    legend = ax.get_legend()
-    legend = ax.get_legend()
+    props = legend._get_properties()
+
+    assert props['loc'] == legend._loc
+    assert props['fontsize'] == 14
+    assert props['frameon'] is False
+    assert props['shadow'] is True
+    assert props['title'] == 'My Legend'
+    assert props['columnspacing'] == 3.0
+    assert props['labelspacing'] == 1.5
+    assert props['handlelength'] == 4.0
+    assert props['handletextpad'] == 1.2
+    assert 'bbox_to_anchor' not in props
+    assert 'mode' not in props
-    assert props['loc'] == legend._loc
-    assert props['fontsize'] == 14
-    assert props['frameon'] is False
-    assert props['shadow'] is True
-    assert props['title'] == 'My Legend'
-    assert props['columnspacing'] == 3.0
-    assert props['labelspacing'] == 1.5
-    assert props['handlelength'] == 4.0
-    assert props['handletextpad'] == 1.2
-    assert 'bbox_to_anchor' not in props
-    assert 'mode' not in props
+    assert props == initial_props
-    assert props['loc'] == legend._loc
-    assert props['fontsize'] == 14
-    assert props['frameon'] is False
-    assert props['shadow'] is True
-    assert props['title'] == 'My Legend'
-    assert props['columnspacing'] == 3.0
-    assert props['labelspacing'] == 1.5
-    assert props['handlelength'] == 4.0
-    assert props['handletextpad'] == 1.2
-    assert 'bbox_to_anchor' not in props
-    assert 'mode' not in props
+    assert props == initial_props
+
+    plt.close(fig)
-    plt.close(fig)
-    plt.close(fig)
+
+
+def test_get_properties_with_mode_and_bbox():
+    """
+    Test that _get_properties() includes mode and bbox_to_anchor
+    when they are set.
+    """
+    fig, ax = plt.subplots()
+    ax.plot(range(5), label='a')
+
+    ax.legend(
+        bbox_to_anchor=(0, 1.02, 1, 0.2),
+        loc='lower left',
+        mode='expand',
+        ncols=2,
+    )
+
+    legend = ax.get_legend()
+    props = legend._get_properties()
+
+    assert props['mode'] == 'expand'
+    assert 'bbox_to_anchor' in props
+
+    plt.close(fig)
+
+
+def test_get_properties_roundtrip():
+    """
+    Test that properties from _get_properties() can be used to
+    recreate a legend with the same settings.
+    """
+    fig, ax = plt.subplots()
+    ax.plot(range(5), label='a')
+    ax.plot(range(3)[::-1], label='b')
+
+    ax.legend(
+        loc='upper right',
+        fontsize=14,
+        frameon=False,
+        shadow=True,
+        title='My Legend',
+        ncols=2,
+        columnspacing=3.0,
+        labelspacing=1.5,
+        handlelength=4.0,
+        handletextpad=1.2,
+    )
+
+    old_legend = ax.get_legend()
+    props = old_legend._get_properties()
+    ncols = old_legend._ncols
+
+    # Recreate legend using extracted properties
+    new_legend = ax.legend(ncols=ncols, **props)
+
+    assert new_legend._fontsize == 14
+    assert new_legend.get_frame_on() is False
+    assert new_legend.shadow is True
+    assert new_legend.get_title().get_text() == 'My Legend'
+    assert new_legend._ncols == 2
+    assert new_legend.columnspacing == 3.0
+    assert new_legend.labelspacing == 1.5
+    assert new_legend.handlelength == 4.0
+    assert new_legend.handletextpad == 1.2
+
+    plt.close(fig)
+
+
+def test_legend_regeneration_no_existing_legend():
+    """
+    Test that regenerating a legend when none exists still works.
+    """
+    fig, ax = plt.subplots()
+    ax.plot(range(5), label='a')
+
+    assert ax.get_legend() is None
+
+    new_legend = ax.legend(ncols=1)
+    assert new_legend is not None
+    assert len(new_legend.get_texts()) == 1
+    assert new_legend.get_texts()[0].get_text() == 'a'
+
+    plt.close(fig)