Diego VelÃ zquez ( June 1599 - 6 August 1660 ) was a Spanish painter , the leading artist in the court of King Philip IV . Diego RodrÃ guez de Silva y VelÃ zquez ( ; June 6 , 1599 â `` August 6 , 1660 ) was a Spanish painter who was the leading artist in the court of King Philip IV .