python-如何在pygame中反转“ window.blit”，或删除我已创建的对象（sprite）

Question

i am trying to delete a sprite whenever I click on it, however, i can't get the oringinal item off of the screen. it seems once i render, or 'draw' it there, it stays there permentaelly. How can I change the following code to get rid of the 'blit' i produced in the class once it's clicked on?

import pygame

pygame.init()

window = pygame.display.set_mode((1152,720))

background = pygame.image.load("images/emptyroom.jpg")
image=pygame.image.load("images/smallkey.png")
b = window.blit(pygame.image.load("images/emptyroom.jpg"), (0,0))
spritestay = True

# d = window.blit(pygame.image.load("images/leglamp.png"), (15,500))

class HiddenObject(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)

        self.i1 = pygame.image.load("images/smallkey.png")
        self.i2 = pygame.image.load("images/Clear.png")
        self.rect=self.i1.get_rect()

    def draw(self, x, y):
        while spritestay == True:
            d = window.blit(self.i1, (x,y))
#d.collidepoint(pygame.mouse.get_pos())
        while spritestay == False:
            d = window.blit(self.i1, (x,y))

pygame.display.set_caption("Eye Spy Game Test")

gameLoop = True

while gameLoop:
    for event in pygame.event.get():
        if event.type == pygame.MOUSEBUTTONDOWN:
            spritestay = False

        if event.type == pygame.MOUSEBUTTONUP:
            spritestay = True

        if (event.type==pygame.QUIT):
            gameLoop=False

    yotestvar = HiddenObject()
    d = yotestvar.draw(100,100)


    pygame.display.flip()

pygame.quit()

Answer 1

There are quite a few issues with your code.

Blitting should not be done before the main loop.

It would be better if the Hidden Object new its position. Change it by adding a position in the constructor, and use it in the draw method.

def __init__(self,pos):
    ...
    self.pos = pos

def draw(self):
    window.blit(self.i1, self.pos)

Your draw method never finishes. You need to replace the while statements with if statements. Also you are not drawing the second image when spritestay is False. I guess you wanted to blit Clear.png.

if spritestay:
    window.blit(self.i1, (x,y))
else: 
    window.blit(self.i2, (x,y))

If Clear.png is just an empty image, there is no point of blitting it at all. So this becomes:

if spritestay:
   window.blit(self.i1, (x,y))

You do not return anything from the draw function, so after

d = yotestvar.draw(100,100)

d is None. You don't use d anywhere so you can remove that.

You create the HiddenObject on every frame. I think that it is much better to move it before the loop.

Last issue is the fact that you do not fill the screen with any color. This might be the real issue you have been strugling with. Here is how blitting works.

You are a painter, and in front of you is a canvas. If you take your brush and draw something, how can you get rid of it? Well the only way is to draw something on top of it. In pygame we use the fill method to fill a whole surface with a certain color.

screen.fill((0,0,0)) # fills screen with black color

So in order to have something on the screen, you need to call screen.fill and then draw any other objects you wish to see.

Answer 2

In pygame, once you blit to the screen you cannot simply delete chosen objects. Instead you must clear your screen after every draw and then draw the new updated objects. If for example, you were making something more, you would have to draw it and then erase it, move it very slightly, draw it then erase it again and so on.

Therefore, it is recommended that you clear your screen at the end every time you loop through a while loop. It would look something as follows for your case:

yotestvar = HiddenObject()

while gameLoop:
    window.fill((255, 255, 255)) # (255, 255, 255) RGB value for WHITE
    for event in pygame.event.get():
        if event.type == pygame.MOUSEBUTTONDOWN:
            spritestay = False

        if event.type == pygame.MOUSEBUTTONUP:
            spritestay = True

        if (event.type==pygame.QUIT):
            gameLoop=False

    yotestvar.draw(100,100)
    pygame.display.update()

pygame.quit()