I moved from California to another state. I had capital gains/losses, almost all in the stock market. How do I interpret the Allocating Capital Gain or Loss screen?

This question is confusing, how do I calculate the amount? "Earned/Rec'd From CA Source as if CA Nonresident for Full Year" What's considered a CA Source and am I really supposed to imagine myself as if I'm a nonresident of CA? Help me understand, hehehe.