pygame example

game.py

import pygame
from pygame.locals import *
import random



class App:
    def __init__(self):
        self._running = True
        self._display_surf = None
        self._image_surf = None

        self.WIDTH = 640
        self.HEIGHT = 480
        self.BLACK = [0, 0, 0]
        self.WHITE = [255, 255, 255]
        self.GREEN = [0, 255, 0]
        self.NUMSNOW = 500

        self.one_x = int(self.WIDTH / 2)
        self.one_y = int(self.HEIGHT * 3 / 4)
 
    def on_init(self):
        pygame.init()
        pygame.display.set_caption("Snow Animation")
 
        self._display_surf = pygame.display.set_mode((self.WIDTH, self.HEIGHT), pygame.HWSURFACE)
        self._running = True
        #self._image_surf = pygame.image.load("myimage.jpg").convert()
 
    def on_event(self, event):
        if event.type == QUIT:
            self._running = False
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_q:
                self.on_cleanup()
            if event.key == pygame.K_LEFT:
                self.one_x -= 10
            if event.key == pygame.K_RIGHT:
                self.one_x += 10

    def on_loop(self):
        # Set the screen background
        self._display_surf.fill(self.BLACK)
     
        # Process each snow flake in the list
        for i in range(len(self.snow_list)):
     
            # Draw the snow flake
            pygame.draw.circle(self._display_surf, self.WHITE, self.snow_list[i], 2)
     
            # Move the snow flake down one pixel
            self.snow_list[i][1] += 1
     
            # If the snow flake has moved off the bottom of the screen
            if self.snow_list[i][1] > self.HEIGHT:
                # Reset it just above the top
                y = random.randrange(-50, -10)
                self.snow_list[i][1] = y
                # Give it a new x position
                x = random.randrange(0, self.WIDTH)
                self.snow_list[i][0] = x

        pygame.draw.circle(self._display_surf, self.GREEN, [self.one_x, self.one_y], 10)
     
        # Go ahead and update the screen with what we've drawn.
        self.on_render()
        self.clock.tick(20)

    def on_render(self):
        #self._display_surf.blit(self._image_surf,(0,0))
        pygame.display.flip()
 
    def on_cleanup(self):
        pygame.quit()
 
    def on_execute(self):
        if self.on_init() == False:
            self._running = False
         
        # Set the height and width of the screen
        self.SIZE = [self.WIDTH, self.HEIGHT]
         
        # Create an empty array
        self.snow_list = []

        # Loop 50 times and add a snow flake in a random x,y position
        for i in range(self.NUMSNOW):
            x = random.randrange(0, self.WIDTH)
            y = random.randrange(0, self.HEIGHT)
            self.snow_list.append([x, y])
         
        self.clock = pygame.time.Clock()
         
        while self._running:
            for event in pygame.event.get():
                self.on_event(event)
            self.on_loop()
            self.on_render()

         
        self.on_cleanup()
 

if __name__ == "__main__" :
    theApp = App()
    theApp.on_execute()