pygame_demo.py

"""
Using Pygame, provided requirements with Nix, make a smiley take
a random walk around the display

Put a smiley.png in the same folder, and execute with:

python -m pygame_demo
"""

import pygame
from pygame import locals as ls
from random import normalvariate, randint
from time import sleep

class App:
    def __init__(self):
        self.image = pygame.image.load("smiley.png")
        self._running = True
        self._display_surf = None
        self.size = self.width, self.height = 640, 400
        self.walker_position = (
                randint(0, self.width), randint(0, self.height))
    def on_init(self):
        pygame.init()
        self._display_surf = pygame.display.set_mode(
          self.size, pygame.HWSURFACE | pygame.DOUBLEBUF)
        self._running = True # redundant to __init__
    def on_event(self, event):
        if event.type == pygame.QUIT:
            self._running = False
    def on_loop(self):
        lateral = round(normalvariate(0, 50))
        vertical = round(normalvariate(0, 50))
        lateral_pos, vertical_pos = self.walker_position
        self.walker_position = (
                max(0, min(self.width-250, lateral_pos + lateral)),
                max(0, min(self.height-250, vertical_pos + vertical)))
        sleep(.1)
    def on_render(self):
        self._display_surf.blit(self.image, self.walker_position)
        pygame.display.flip()
    def on_cleanup(self):
        pygame.quit()
    def on_execute(self):
        if self.on_init() == False:
            self._running = False
        while(self._running):
            for event in pygame.event.get():
                self.on_event(event)
            self.on_loop()
            self.on_render()
        self.on_cleanup()

def main():
    theApp = App()
    theApp.on_execute()

if __name__ == "__main__":
    main()