How does PyPen Really Work?

PyPen currently utilizes Pyglet in the background for event and window-management. For drawing, Cairo (through PyCairo) is used, making for a stable and quick svg drawing backend.

When you call pypen <> PyPen ‘imports’ your sketch, launces a Pyglet window, executes your start() function, and schedules the update() function according to the specified framerate. It then interprets and translates all your drawing functions and properly routes Pyglet events to easy functions exposed to you and plants useful variables such as DELTA_TIME, WIDTH and more inside your sketch.

This means that all the PyPen user ever has to worry about is the fun parts of creating a sketch, rather than all the boilerplate code usually involved (though some might disagree with the assessment of what is the fun part here xP).