如何使用线性插值和链接列表创建颜色渐变？

I am currently trying to make a rainbow trail that follows your mouse. i used Linkedlist to plot the points of my mouse so the trail follows along. The trail itself looks perfect its only the colors in the trail that don't look right. I'm wanting them to fade into each other. Someone told me to use linear interpolation and after looking into it for awhile it seems like it would work i just don't know how to implement it.I am currently trying to make a rainbow trail t