Add wai-aria property to the artist accessibility annotations.

tonyfast · tonyfast · commit 2d2856486576 · 2021-10-09T18:17:59.000-07:00
diff --git a/lib/matplotlib/artist.py b/lib/matplotlib/artist.py
@@ -161,6 +161,7 @@ def __init__(self):
         self._clippath = None
         self._clipon = True
         self._label = ''
+        self._aria = None
         self._picker = None
         self._rasterized = False
         self._agg_filter = None
@@ -1069,6 +1070,33 @@ def update(self, props):
             self.stale = True
         return ret
 
+    def get_aria(self):
+        """Return any ARIA properties assigned to the artist"""
+        return dict(self._aria)
+
+    def set_aria(self, aria):
+        """
+        Set ARIA properties to the artist.
+
+        A primary use of this method is to attach aria-label to the artist to provide alt text to figures.
+        
+        Parameters
+        ----------
+        aria : dict
+        """
+        # TODO validation
+        if not isinstance(aria, dict):
+            if aria is not None:
+                raise TypeError(
+                    f'aria must be dict or None, not {type(aria)}')
+        self._aria = aria
+
+    def update_aria(self, **aria): 
+        """Update WAI-ARIA properties on the artist"""
+        # TODO validation
+        for k, v in aria.items():
+            self._aria[k] = v
+
     def get_label(self):
         """Return the label used for this artist in the legend."""
         return self._label
diff --git a/lib/matplotlib/tests/test_artist.py b/lib/matplotlib/tests/test_artist.py
@@ -374,3 +374,9 @@ class MyArtist4(MyArtist3):
         pass
 
     assert MyArtist4.set is MyArtist3.set
+
+def test_set_aria():
+    art = martist.Artist()
+    with pytest.raises(TypeError, match='^aria must be dict'):
+        art.set_aria([])
+    art.set_aria(dict(label="artist alt text"))
