[racket] Tweaking the graphical coordinate system

While using The Racket Drawing Toolkit, is it possible to flip a dc%
vertically so the bottom left becomes (0, 0)?

I'm also using The Racket Graphical Interface Toolkit to create a
canvas% and grab its dc%, so flipping the canvas% is also a option.

By flipping I mean, the coordinate system is:

 |
-+-------->
 |
 |
 |
 v

And I would like it to be:

 ^
 |
 |
 |
-+------->
 |

--
Diogo F. S. Ramos