Tkinter绘制迷宫仅全部生成后显示，加sleep阻塞无法动态渲染如何解决

Tkinter采用单线程事件驱动模型，所有UI渲染、交互响应逻辑都运行在主线程的主事件循环中。time.sleep()会直接暂停主线程的全部执行，包括UI刷新逻辑，因此即便你调用了root.update()，sleep期间界面也会完全卡住，无法看到逐步更新的效果，最终只能看到所有颜色一次性渲染完成。

使用Tkinter内置的after()方法替代sleep实现延迟。after()方法可以指定毫秒级延迟后异步执行目标函数，不会阻塞主事件循环的正常运行。我们需要将原有的嵌套循环上色逻辑改造为迭代执行的形式，每次处理一个网格单元后，延迟一段时间再处理下一个单元。

from tkinter import Tk, Canvas, Frame, BOTH
import random

class Labyrinth(Frame):

    def __init__(self):
        super().__init__()
        self.master.title("Laby")
        self.pack(fill=BOTH, expand=1)

    def creat_grid(self, square_side, laby_side):
        grid = []
        canvas = Canvas(self, width = laby_side * square_side, height = laby_side * square_side)
        for y in range(laby_side):
            subgrid = []
            for x in range(laby_side):
                if ((y % 2 == 0 or y == laby_side - 1 or x % 2 == 0) and not (x == 0 and y == 1) and not (x == laby_side - 1 and y == laby_side - 2)):
                    subgrid.append(1)
                    canvas.create_rectangle(square_side * x, square_side * y, square_side * x + square_side, square_side * y + square_side, fill="black")
                else:
                    subgrid.append(0)
            grid.append(subgrid)

        canvas.pack(fill=BOTH, expand=1)
        return canvas, grid

def color_grid(root, canvas, grid, square_side, delay=50):
    # 生成所有待处理坐标的迭代器
    coords = ((y, x) for y in range(len(grid)) for x in range(len(grid)))
    def process_next():
        try:
            y, x = next(coords)
            if (grid[y][x] == 0 and not (x == 0 and y == 1) and not (x == len(grid) - 1 and y == len(grid) - 2)):
                color = '#%03x' % random.randrange(16**3)
                while (color in grid):
                    color = '#%03x' % random.randrange(16**3)
                grid[y][x] = color
                canvas.create_rectangle(square_side * x, square_side * y, square_side * x + square_side, square_side * y + square_side, fill=color)
            # 延迟后处理下一个网格单元
            root.after(delay, process_next)
        except StopIteration:
            # 所有单元处理完成
            canvas.pack(fill=BOTH, expand=1)
    process_next()

def main():
    root = Tk()
    laby = Labyrinth()

    square_side = 10
    laby_side = 51

    canvas, grid = laby.creat_grid(square_side, laby_side)
    color_grid(root, canvas, grid, square_side)
    root.mainloop()


if __name__ == '__main__':
    main()

你可以调整color_grid函数的delay参数（单位为毫秒）来修改上色速度，数值越大上色节奏越慢。

内容的提问来源于stack exchange，提问作者Louis FELDMAR