Fix positioning of wide mathtext accents.

anntzer · QuLogic · commit c2fa7bacc36f · 2026-02-05T22:34:09.000-05:00
A wide accent over more than one character should just be centered over
the underlying box.  In any case this works better than the current
strategy of shifting by an amount depending on the box's width (which
results in absurdly large shifts for wide boxes).

When positioning over a single character the behavior is different --
TeX uses specific font metrics info for that case, and we can try
rendering as combining characters instead (not done in this PR).
diff --git a/lib/matplotlib/_mathtext.py b/lib/matplotlib/_mathtext.py
@@ -2324,12 +2324,13 @@ def accent(self, toks: ParseResults) -> T.Any:
         if accent in self._wide_accents:
             accent_box = AutoWidthChar(
                 '\\' + accent, sym.width, state, char_class=Accent)
+            centered = HCentered([accent_box])
         else:
             accent_box = Accent(self._accent_map[accent], state)
-        if accent == 'mathring':
-            accent_box.shrink()
-            accent_box.shrink()
-        centered = HCentered([Hbox(sym.width / 4.0), accent_box])
+            if accent == 'mathring':
+                accent_box.shrink()
+                accent_box.shrink()
+            centered = HCentered([Hbox(sym.width / 4.0), accent_box])
         centered.hpack(sym.width, 'exactly')
         return Vlist([
                 centered,
