Single-shot ultrahigh-speed mapping photography is essential for analyzing fast dynamic processes across various scientific disciplines. Among available techniques, optical diffraction has recently been implemented as a nanosecond time gate for mapping photography. Despite attractive features in light throughput and cost efficiency, existing systems in this approach can sense only light intensity with limited sequence depth and imaging speed. To overcome these limitations, we develop diffraction-gated real-time ultrahigh-speed mapping schlieren (DRUMS) photography. Using a digital micromirror device as a coded dynamic two-dimensional blazed grating, DRUMS photography can record schlieren images of transient events in real time at an imaging speed of 9.8 million frames per second and a sequence depth of 13 frames. We present the working principle of DRUMS photography in both theoretical derivation and numerical simulation, and we apply DRUMS photography to the single-shot real-time video recording of laser-induced breakdown in water.