How to detect menubar color?

Hi guys, I'm getting crazy trying to manage the menubar color change with Xbar. I'm using several colors and they don't show correctly if bar is white or black.

As you know the last versions of MacOS change the menubar dinamically according to the background image: if the top is light the bar is white(ish), if it's dark the bar is black(ish). It's also black with apps in full screen. All this indipendently from the light/dark system scheme.

Is there a way to detect it? I see several menubar apps manage correctly the change of colors so I guess there's a system value somewhere.

Thanks.