Trying to display a png file in pygame using pygam

问题:

The image is a playing card. We are using pygame 4.5 community edition and pycharm 2.6.9 because 2.7 does not support pygame (this is a school). Here is the code:

import pygame
pygame.init()
picture=pygame.image.load("cards/S01.png")
pygame.display.set_mode(picture.get_size())
main_surface = pygame.display.get_surface()
main_surface.blit(picture, (0,0))
pygame.display.update()

Why does the window disappear?

回答1:

Try this:

import pygame
pygame.init()
picture=pygame.image.load("cards/S01.png")
pygame.display.set_mode(picture.get_size())
main_surface = pygame.display.get_surface()
main_surface.blit(picture, (0,0))
while True:
   main_surface.blit(picture, (0,0))
   pygame.display.update()

pygame.display.update() updates a frame. There are multiple frames per second depending on what what you draw onto the surface.

回答2:

The problem is, after you update the screen with pygame.display.update(), you do nothing, and your program simply ends. pygame.display.update() does not block.

You need what is usually called a main loop. Here's a simple example with event handling:

import pygame
pygame.init()
picture = pygame.image.load("cards/S01.png")

# display.set_mode already returns the screen surface
screen = pygame.display.set_mode(picture.get_size())

# a simple flag to show if the application is running
# there are other ways to do this, of course
running = True
while running:

    # it's important to get all events from the 
    # event queue; otherwise it may get stuck
    for e in pygame.event.get():
        # if there's a QUIT event (someone wants to close the window)
        # then set the running flag to False so the while loop ends
        if e.type == pygame.QUIT:
            running = False

    # draw stuff
    screen.blit(picture, (0,0))
    pygame.display.update()

This way, your application does not, only when someone closes the window.