ENH: expose font_file in Brain.add_text

doc/changes/dev/13778.newfeature.rst

@@ -0,0 +1 @@
+Added a ``font_file`` parameter to :meth:`mne.viz.Brain.add_text` to support rendering glyphs not available in the default font, by `Pragnya Khandelwal`_.

mne/viz/_brain/_brain.py

@@ -2796,6 +2796,7 @@ def add_text(
         col=0,
         font_size=None,
         justification=None,
+        font_file=None,
     ):
         """Add a text to the visualization.
 
@@ -2824,6 +2825,10 @@ def add_text(
             The font size to use.
         justification : str | None
             The text justification.
+        font_file : str | None
+            Path to an absolute path of a font file to use for rendering
+            the text. See https://freetype.org/freetype2/docs/index.html for a list of
+            supported font file formats.
         """
         _validate_type(name, (str, None), "name")
         name = text if name is None else name
@@ -2840,6 +2845,7 @@ def add_text(
                     color=color,
                     size=font_size,
                     justification=justification,
+                    font_file=font_file,
                 )
                 if "text" not in self._actors:
                     self._actors["text"] = dict()

mne/viz/backends/_abstract.py

@@ -474,7 +474,16 @@ def quiver3d(
         pass
 
     @abstractclassmethod
-    def text2d(self, x_window, y_window, text, size=14, color="white"):
+    def text2d(
+        self,
+        x_window,
+        y_window,
+        text,
+        size=14,
+        color="white",
+        justification=None,
+        font_file=None,
+    ):
         """Add 2d text in the scene.
 
         Parameters
@@ -493,6 +502,13 @@ def text2d(self, x_window, y_window, text, size=14, color="white"):
             The color of the text as a tuple (red, green, blue) of float
             values between 0 and 1 or a valid color name (i.e. 'white'
             or 'w').
+        justification : str | None
+            The text justification. Can be 'left', 'center', or 'right'.
+        font_file : str | None
+            Path to an absolute path of a font file to use for rendering
+            the text. FreeType is used for loading, supporting many font
+            formats beyond ``.ttf`` and ``.ttc``. This can be helpful for
+            non-ASCII glyph coverage.
         """
         pass
 

mne/viz/backends/_pyvista.py

@@ -720,12 +720,24 @@ def quiver3d(
         return actor, mesh
 
     def text2d(
-        self, x_window, y_window, text, size=14, color="white", justification=None
+        self,
+        x_window,
+        y_window,
+        text,
+        size=14,
+        color="white",
+        justification=None,
+        font_file=None,
     ):
         size = 14 if size is None else size
         position = (x_window, y_window)
         actor = self.plotter.add_text(
-            text, position=position, font_size=size, color=color, viewport=True
+            text=text,
+            position=position,
+            font_size=size,
+            color=color,
+            viewport=True,
+            font_file=font_file,
         )
         if isinstance(justification, str):
             if justification == "left":

mne/viz/backends/tests/test_renderer.py

@@ -8,6 +8,7 @@
 
 import numpy as np
 import pytest
+from matplotlib.font_manager import findfont
 
 from mne.utils import run_subprocess
 from mne.viz import Figure3D, get_3d_backend, set_3d_backend
@@ -168,6 +169,14 @@ def test_3d_backend(renderer):
         size=txt_size,
         justification="right",
     )
+    # test font_file passthrough with a real font from matplotlib
+    font_path = findfont("serif")
+    rend.text2d(
+        x_window=txt_x + 0.1,
+        y_window=txt_y + 0.1,
+        text="font test",
+        font_file=font_path,
+    )
     rend.text3d(x=0, y=0, z=0, text=txt_text, scale=1.0)
     rend.set_camera(
         azimuth=180.0, elevation=90.0, distance=cam_distance, focalpoint=center