  The method devised by Lewis et al. (1993) for calculating the light curve of
a microlensed point source is expanded to two dimensions to enable the
calculation of light curves of extended sources. This method is significantly
faster than the ray shooting method that has been used in the past. The
increased efficiency is used to obtain much higher resolution light curves over
increased timescales. We investigate the signatures arising from different
source geometries in a realistic microlensing model. We show that a large
fraction of high magnification events (HMEs) in image A of Q2237+0305 involve
only one caustic, and could therefore yield information on the structure of the
quasar continuum through the recognition of a characteristic event shape. In
addition, the cataloguing of HMEs into morphological type will, in theory,
enable the direction of the transverse motion, as well as the source size to be
obtained from long term monitoring.
