Re : making a pdf-file

also always remember that only when endRaw() is called, your drawing will be actually written to pdf. Until you call endRaw() all the drawings are simply kept in memory. 

Thus if you are going to do some sketch which gonna draw something on screen, you need to remember to trigger endRaw() at some moment. Like in the example for http://processing.org/reference/beginRaw_.html where it is writing to file happens inside keyPressed() method.