1. A system comprising: a touch path module to receive a plurality of touch events and to generate an output based on the touch events; and a rendering module to: receive a video image; receive the output of the touch path module; determine a plurality of points defining a boundary of a shape, the shape being determined based on the output of the touch path module; combine the video image with overlay data in accordance with the plurality of points to generate a combined display image; and output the combined display image.