如何在python中每次将项目附加到列表中

Question

Lets say I have a list called my_list and a function called my_function and my_function appends items to my_list based on which portion of the surface gameDisplay was clicked on. However whenever you hold down the mouse for more than one frame, it appends more than one of that item to my_list. This is not the result I am going for. I was wondering if there was a way you could do this without appending more than one of each item to my_list

Thanks for your help

Answer 1

You didn't show code but I guess you use pygame.mouse.get_pressed() which gives True all the time when you keep button pressed. And this can be your problem.

You can do one of two things:

use event.MOUSEBUTTONDOWN which is created only once - when button change state from not-pressed into pressed .

Or:

use extra variable which will remeber pygame.mouse.get_pressed() from previous frame. And then compare if now button is pressed but in previous frame was not-pressed then add element to list.

---

EDIT: old code from different question which use event.MOUSEBUTTONDOWN to change color.

#!/usr/bin/env python

# http://stackoverflow.com/questions/33856739/how-to-cycle-3-images-on-a-rect-button

import pygame

# - init -

pygame.init()
screen = pygame.display.set_mode((300,200))

# - objects -

# create three images with different colors
images = [
    pygame.Surface((100,100)),    
    pygame.Surface((100,100)),    
    pygame.Surface((100,100)),    
]    

images[0].fill((255,0,0))
images[1].fill((0,255,0))
images[2].fill((0,0,255))

images_rect = images[0].get_rect()

# choose first image
index = 0

# - mainloop -

running = True

while running:

    # - events -

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

        elif event.type == pygame.MOUSEBUTTONDOWN:

            if event.button == 1 and images_rect.collidepoint(event.pos):
                # cycle index
                index = (index+1) % 3

    # - draws -

    screen.blit(images[index], images_rect)
    pygame.display.flip()

# - end -

pygame.quit()

GitHub: furas/python-examples/pygame/button-click-cycle-color