A method of emulating a flat tip brush, said method comprising (a) at a given time, identifying first and second points of contact on a touch sensitive surface; (b) interpolating a line between the first and second points, the line having line data comprising at least a length and an angle relative to the screen; (c) recording the first and second points and the line data; (d) reiterating steps (a)-(c) for at least one subsequent time to determine a plurality of the first points and a plurality of the second points and a plurality of the lines; and (e) displaying on a display screen an image defined by the first points, by the second points and/or by the lines between the first and second points.