python - 如何在Pygame中画一条连续的线？

Question

我想在 Pygame 框架中鼠标点击和移动时画一条线，如果我移动鼠标很慢，它会是一条线。但是，如果我快速移动鼠标，它只是不连续的点。问题是如何在鼠标移动时绘制一条连续的线？提前致谢。

import pygame, sys
from pygame.locals import *

def main():
    pygame.init()

    WHITE = (255, 255, 255)
    BLACK = (0, 0, 0)

    mouse_position = (0, 0)
    drawing = False
    screen = pygame.display.set_mode((600, 800), 0, 32)
    screen.fill(WHITE)
    pygame.display.set_caption("ScratchBoard")

    while True:
        for event in pygame.event.get():
            if event.type == QUIT:
                pygame.quit()
                sys.exit()
            elif event.type == MOUSEMOTION:
                if (drawing):
                    mouse_position = pygame.mouse.get_pos()
                    pygame.draw.line(screen, BLACK, mouse_position, mouse_position, 1)
            elif event.type == MOUSEBUTTONUP:
                mouse_position = (0, 0)
                drawing = False
            elif event.type == MOUSEBUTTONDOWN:
                drawing = True

        pygame.display.update()

if __name__ == "__main__":
    main()

Answer 1

通过使用相同的参数 (mouse_position) 调用 pygame.draw.line 两次，您绘制的不是一条线，而是一个像素，因为 start_pos 和 end_pos 是相同的。

要获得连续的线，您需要保存最后一个位置并在它和下一个位置之间画一条线，如下所示(更改为带有 last_pos 的线):

import pygame, sys
from pygame.locals import *

def main():
    pygame.init()

    WHITE = (255, 255, 255)
    BLACK = (0, 0, 0)

    mouse_position = (0, 0)
    drawing = False
    screen = pygame.display.set_mode((600, 800), 0, 32)
    screen.fill(WHITE)
    pygame.display.set_caption("ScratchBoard")

    last_pos = None

    while True:
        for event in pygame.event.get():
            if event.type == QUIT:
                pygame.quit()
                sys.exit()
            elif event.type == MOUSEMOTION:
                if (drawing):
                    mouse_position = pygame.mouse.get_pos()
                    if last_pos is not None:
                        pygame.draw.line(screen, BLACK, last_pos, mouse_position, 1)
                    last_pos = mouse_position
            elif event.type == MOUSEBUTTONUP:
                mouse_position = (0, 0)
                drawing = False
            elif event.type == MOUSEBUTTONDOWN:
                drawing = True

        pygame.display.update()

if __name__ == "__main__":
    main()