Improve handling of specified font name

manim/mobject/text/text_mobject.py

@@ -444,8 +444,21 @@ def __init__(
         **kwargs,
     ) -> None:
         self.line_spacing = line_spacing
-        if font and warn_missing_font and font not in Text.font_list():
-            logger.warning(f"Font {font} not in {Text.font_list()}.")
+        if font and warn_missing_font:
+            fonts_list = Text.font_list()
+            # handle special case of sans/sans-serif
+            if font.lower() == "sans-serif":
+                font = "sans"
+            if font not in fonts_list:
+                # check if the capitalized version is in the supported fonts
+                if font.capitalize() in fonts_list:
+                    font = font.capitalize()
+                elif font.lower() in fonts_list:
+                    font = font.lower()
+                elif font.title() in fonts_list:
+                    font = font.title()
+                else:
+                    logger.warning(f"Font {font} not in {fonts_list}.")
         self.font = font
         self._font_size = float(font_size)
         # needs to be a float or else size is inflated when font_size = 24
@@ -1169,8 +1182,21 @@ def __init__(
     ) -> None:
         self.text = text
         self.line_spacing = line_spacing
-        if font and warn_missing_font and font not in Text.font_list():
-            logger.warning(f"Font {font} not in {Text.font_list()}.")
+        if font and warn_missing_font:
+            fonts_list = Text.font_list()
+            # handle special case of sans/sans-serif
+            if font.lower() == "sans-serif":
+                font = "sans"
+            if font not in fonts_list:
+                # check if the capitalized version is in the supported fonts
+                if font.capitalize() in fonts_list:
+                    font = font.capitalize()
+                elif font.lower() in fonts_list:
+                    font = font.lower()
+                elif font.title() in fonts_list:
+                    font = font.title()
+                else:
+                    logger.warning(f"Font {font} not in {fonts_list}.")
         self.font = font
         self._font_size = float(font_size)
         self.slant = slant

tests/module/mobject/text/test_text_mobject.py

@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+from contextlib import redirect_stdout
+from io import StringIO
+
 from manim.mobject.text.text_mobject import MarkupText, Text
 
 
@@ -11,3 +14,20 @@ def test_font_size():
 
     assert round(text_string.font_size, 5) == 14.4
     assert round(markuptext_string.font_size, 5) == 14.4
+
+
+def test_font_warnings():
+    def warning_printed(font: str, **kwargs) -> bool:
+        io = StringIO()
+        with redirect_stdout(io):
+            Text("hi!", font=font, **kwargs)
+        txt = io.getvalue()
+        return "Font" in txt and "not in" in txt
+
+    # check for normal fonts (no warning)
+    assert not warning_printed("System-ui", warn_missing_font=True)
+    # should be converted to sans before checking
+    assert not warning_printed("Sans-serif", warn_missing_font=True)
+
+    # check random string (should be warning)
+    assert warning_printed("Manim!" * 3, warn_missing_font=True)