Pilot reported a taxiing aircraft collided with their parked aircraft on the ramp.

Narrative

Flight from ZZZ1 to ZZZ airport under day VFR. Flight was uneventful and weather was beautiful. Landed on runway XX and taxied to the transient ramp. I stopped my airplane perpendicular to the ramp directly in front of my desired tiedown spot so that I was positioned correctly to push back into the spot. As I was accomplishing the engine shutdown checklist; my right seat passenger alerted me to an aircraft which was rapidly approaching from the right. By the time I looked up; the wingtip of the taxing aircraft was about two seconds away from striking my propeller. Before I could shut my engine down (which was at idle; with the rotating beacon still on); Aircraft Y's left wingtip struck my propeller sending bits and pieces into my cowling; windshield and elevator as well as the ramp area in front of my plane. Aircraft Y stopped about 100 feet later and shut down. The pilot came over to my aircraft to apologize and admitted the incident was entirely his fault. He said his airplane had just completed its annual inspection and he was just taxiing it back to his hangar. He was watching his wingtip clearance to his right and said he never looked to his left where I was located. He also stated he hadn't felt well that day and seemed a bit dazed by what had just happened. Contributing factors were his physical/mental health being less than ideal; his failure to adequately clear his taxi route and taxiing too fast. My propeller substantially damaged approximately 12 inches of his left wingtip. My prop and windshield were also damaged. My engine will require an inspection to determine if it was damaged.