font-at

font-at is a built-in function in `C source code'.

(font-at POSITION &optional WINDOW STRING)

Return a font-object for displaying a character at POSITION.
Optional second arg WINDOW, if non-nil, is a window displaying
the current buffer. It defaults to the currently selected window.
Optional third arg STRING, if non-nil, is a string containing the target
character at index specified by POSITION.