How can I perform a dynamic drag behavior

[qq651083680]

How can I perform a dynamic drag behavior
I want to simulate operating some mobile game joysticks to control character movements.How to create an dynamic action that I can cancel it or change its endpoint while it running.And it should be running in background i think.

[qq651083680]

How can I perform a dynamic drag behavior.
it should running in backthread.And I calculate its next endpoint in main thread then add the point to let it move to the point.Please help me .