Discover which fallback font was used in gvim

Question

My &guifont is set using let &guifont="SauceCodePro NF 11,Source code pro 11".

Calling set guifont? returns the full option, guifont=SauceCodePro NF 11,Source code pro 11.

Is there a way to check which of the two fonts gvim eventually used, if any?

Reading :h guifont didn't give me any ideas.

Answer 1

If there really isn't a simple query to find the information then we'll have to brute-force it...

Two key behaviors are described in :h 'guifonts':

[If a list of fonts is given] the first valid font is used.

and

[If a single font is given and] the font cannot be found you will get an error message.

That suggests something like this function:

func! ReportFirstValidGuiFont()
    " preserve existing value
    let l:fonts = &guifont

    for font in split(l:fonts, ",") 
        try
            exe "set guifont=" . font
            echo "Applied GUI font: " . font
            return
        catch /E596/
            " ie: Vim(set):E596: Invalid font(s): guifont=<font-name>
            echo v:exception
        finally
            " always restore original value
            let &guifont = l:fonts
        endtry
    endfor
endfunc

Call with :call ReportFirstValidGuiFont() and it will iterate over the comma separated font list, setting each font as the sole guifonts value. It will print a message naming the first one that doesn't cause an error and exit. The printed name should be the font that is currently applied.