Finally implement the IrisWipeBase (thanks Thorsten, although I still don't understand why what I did wasn't working), now all other IrisWipe can be implemented just by reimplementing setShape() and drawing the shape around the point (0,0).

Just one issue remains:
how make sure thet the shape is big enough to cover the whole screen without scaling over and over and asking if the whole screen is overlapped, for an example of this problem see the Diamond effect.