set_image_coord_tracker.h

 
const char* set_image_coord_tracker = R"JS(
function set_image_coord_tracker(img, func){
    img.addEventListener("mousemove", (ev) => {
    const bbox  = img.getBoundingClientRect();
    func((ev.clientX - bbox.left)/bbox.width, (ev.clientY - bbox.top)/bbox.height)
    })
};
)JS";