After working on this all day, I cobbled together a solution.
I added an adjustment layer (called “Controller”) with a slider control (called “ColorPicker”) and a Hue/Saturation control. I enabled Colorize on the Hue/Saturation and entered an expression for hue, saturation and brightness. I am only showing hue here for the sake of brevity. Replace xxx, yyy, and zzz with the h/s/l values of your chosen colors.
var cp = Math.round(thisComp.layer("Controller").effect("ColorPicker")(1));
if (cp<2){
hue=xxx;
sat=yyy;
bri=zzz;
}
if (cp>=2 && cp < 3) {
hue=xxx;
sat=yyy;
bri=zzz;
}
if (cp>=3 && cp < 4) {
hue=xxx;
sat=yyy;
bri=zzz;
}
if (cp>=4 && cp <= 5) {
hue=xxx;
sat=yyy;
bri=zzz;
}
hue;
The last line should be changed to sat or bri depending on which item you’re modifying.
Anyway, I added the slider value to my mogrt and now the video editors can drag the slider to select one of the pre-chosen colors.