Retrieve color scheme colors to use for other plugin setting

Question

I am trying to use a colorized parenthesis plugin. However, the colors don't match my current color scheme. The help page mentions ways to change the colors, but I don't know which magical words I have to use for the colors of my current color scheme. Is there some way I can call a getter in my vimrc for the colors of the color scheme applied?

let g:rainbow_conf = {
\   'guifgs': ['royalblue3', 'darkorange3', 'seagreen3', 'firebrick'],
\}

Something like?

let g:rainbow_conf = {
\   'guifgs': [colorscheme.getcolor(1), colorscheme.getcolor(2), colorscheme.getcolor(3), colorscheme.getcolor(4)],
\}

Answer 1

You may get the colors in effect for a particular highlight group using synIDattr:

:echo synIDattr(hlID('Normal'), 'fg')
#ffff00

Other values are bg for background, fg#, bg#, for hex color in gui, and sp (underline/undercurl). See :help synIDattr(.