Copy arrowprops argument to FancyAnnotationBbox.

anntzer · anntzer · commit 6345ef6bf324 · 2022-02-12T12:00:53.000+01:00
... so that we don't mutate dicts passed in by the user (we in fact pop
a key from arrowprops a bit later), and so that later mutations to the
dict from the user side don't affect the artist.
diff --git a/lib/matplotlib/offsetbox.py b/lib/matplotlib/offsetbox.py
@@ -1334,7 +1334,7 @@ def __init__(self, offsetbox, xy,
                                        xycoords=xycoords,
                                        annotation_clip=annotation_clip)
         self.offsetbox = offsetbox
-        self.arrowprops = arrowprops
+        self.arrowprops = arrowprops.copy() if arrowprops is not None else None
         self.set_fontsize(fontsize)
         self.xybox = xybox if xybox is not None else xy
         self.boxcoords = boxcoords if boxcoords is not None else xycoords
diff --git a/lib/matplotlib/tests/test_offsetbox.py b/lib/matplotlib/tests/test_offsetbox.py
@@ -325,3 +325,13 @@ def test_annotationbbox_extents():
 
 def test_zorder():
     assert OffsetBox(zorder=42).zorder == 42
+
+
+def test_arrowprops_copied():
+    da = DrawingArea(20, 20, 0, 0, clip=True)
+    arrowprops = {"arrowstyle": "->", "relpos": (.3, .7)}
+    ab = AnnotationBbox(da, [.5, .5], xybox=(-0.2, 0.5), xycoords='data',
+                        boxcoords="axes fraction", box_alignment=(0., .5),
+                        arrowprops=arrowprops)
+    assert ab.arrowprops is not ab
+    assert arrowprops["relpos"] == (.3, .7)
