/**
* Contructor.
* @param[in] center The center of the gradient circle onto which the 0% gradient stop is mapped.
* @param[in] radius The radius of the outmost circle onto which the 100% gradient stop is mapped.
*/
/**
* Contructor.
* @param[in] center The center of the gradient circle onto which the 0% gradient stop is mapped.
* @param[in] radius The radius of the outmost circle onto which the 100% gradient stop is mapped.
*/