在pygame中使用set_at时，像素RGB值反转

Question

In a pygame application I'm writing, I directly manipulate pixels using the Surface.set_at() and get_at() methods. It's not time-sensitive, so no problem there. But I'm seeing some weird behavior. After being asked to put together an mcve, I identified the exact set of circumstances where the problem occurs. My code:

import pygame

def is_color(surface,position,color):
    col=surface.get_at(position)
    return (col.r,col.g,col.b)==color
def flood_fill(surface, position, fill_color):
    frontier = [position]
    fill=pygame.Color(fill_color[0],fill_color[1],fill_color[2],255)
    n=0
    while len(frontier) > 0 and n<50000:
        x, y = frontier.pop()
        try:
            col=surface.get_at((x,y))
            if is_color(surface,(x,y),fill_color):
                continue
        except IndexError:
            continue
        surface.set_at((x,y),fill)
        n+=1
        frontier.append((x + 1, y))
        frontier.append((x - 1, y))
        frontier.append((x, y + 1))
        frontier.append((x, y - 1))

ROOD = (150,0,0)
pygame.init()
screen=pygame.display.set_mode((200,200))
colors=pygame.Surface((200,200))
pygame.draw.circle(colors,ROOD,(50,50),20,2)
pygame.draw.circle(colors,ROOD,(150,150),20,2)
flood_fill(colors,(50,50),ROOD)
pygame.image.save(colors,"circles.png")
del colors
colors=pygame.image.load("circles.png")
flood_fill(colors,(150,150),ROOD)
screen.blit(colors,(0,0))
pygame.display.flip()

When I run as is (Windows 10), the first circle is filled, the second fill operation fails. The problem appears to be in the reading from PNG file: when I change the filename to circles.bmp, no problem. So I now have a work-around. Is this a bug in PNG file handling, or am I missing a subtlety of how these things are supposed to work?

Answer 1

我不确定发生了什么，但你可以通过转换加载.png文件后获得的表面来修复问题（通常应该转换（或convert_alpha）新加载的图像）。

colors = pygame.image.load("circles.png").convert()