Pygame Key Press

问题

I'm writing a basic drawing program to practice Pygame, but I have a problem I'm using key press events to change the drawing color but when you let go of the key it goes back to the default color black. I'm sure there is a easy way to fix this I just don't know how!

Here is my code:

import pygame
from pygame.locals import *
import sys

RED = (255,0,0)
GREEN = (0,255,0)
BLUE = (0,0,255)
WHITE = (255,255,255)

class Draw(object):


    def update(self, screen):
        color = (0,0,0)
        key = pygame.key.get_pressed()
        if key[pygame.K_r]:
            color = RED
        if key[pygame.K_g]:
            color = GREEN
        if key[pygame.K_b]:
            color = BLUE
        if key[pygame.K_w]:
            color = WHITE

        mouse_pos = pygame.mouse.get_pos()
        pygame.draw.circle(screen, (color), (mouse_pos),30)


    def main(self):

        pygame.init()
        screen = pygame.display.set_mode((640, 480))
        pygame.display.set_caption('Basic Pygame program')
        background = pygame.Surface(screen.get_size())
        background = background.convert()
        background.fill((0, 0, 0))
        screen.blit(background, (0, 0))
        while 1:
            for event in pygame.event.get():
                if event.type == QUIT:
                     sys.exit()
            self.update(screen)
            pygame.display.flip()


if __name__ == '__main__':
    draw = Draw()
    draw.main()

Also any pointers or easier ways to write my code are much appreciated

Thank You!

回答1:

At each update, you set color to (0,0,0). If a key is not pressed this is not changed. You need to maintain a color variable that is initially black, changes if the key is pressed, and is not reset at each update.

来源：https://stackoverflow.com/questions/16869940/pygame-key-press