Colours

Hi not sure what I'm trying to do can actually be done.. but here goes.

I have 2 products. In each product, people can add text to the item. 1 product has a black mug and the other has a white mug. I want the text that the customer adds to only show in white when they are on the black mug, and only show black text on the white mug.

I have disabled the colour picker as they should only be able to use the above.

Can this be done? Or can it be custom-made for a fee?

Many thanks.