- glyph-provided font glyphprocedure
If the glyph is provided by the font, this procedure returns a positive integer, indicating the glyph's index position in the font. If the glyph is not provided by the font, this procedure returns #f. See TTF_GlyphIsProvided.
glyph may be an integer (representing a 16-bit Unicode character) or a Scheme character in the ASCII range. Results may be incorrect if given a Scheme character outside the ASCII range.