i turned to the left i saw another 172 fly towards me and over head at fairly close quarters; i wonder if they ever saw me? i got the controller’s attention and was cleared for the usual straight-in runway 28l. at about 2 miles out i was told that a plane would be taking the runway and holding in position (presumably until after i landed) but as soon as i acknowledged the information i saw the plane take off! not sure what happened there, i did not hear any instruction to take off or, as i expected, a verbal smacking for leaving without permission. i was a little high when 