tkinter 中的动画仅在循环开始时起作用

Question

我一直在尝试使用 tkinter 在 python 中进行冒泡排序可视化，但它不起作用。当我只放几个小节时，什么也没有发生，但如果尝试放很多小节，它们会移动，看起来应该是这样（至少一开始是这样）。我的问题是，我的逻辑中是否有我看不到的错误，或者只是 tkinter？我开始认为是后者。提前致谢。这是我的代码：

import tkinter
import time
import random

width = 800
height = 800
canvas = tkinter.Canvas(height=height, width=width, background='black')
canvas.pack()

thickness = 20

values = [random.randrange(height) for i in range(width//thickness)]

cc = {}

for value in values:
    cc[value] = 0

print(values)

x1 = 0
for value in values:
    canvas.create_rectangle(x1,800, x1+thickness,value, fill='white', tag=value)
    cc[value] = x1
    x1 += thickness

for i in range(len(values)):
    for j in range(len(values)-i-1):
        if values[j] > values[j+1]:
            values[j], values[j+1] = values[j+1], values[j]
            canvas.move(values[j], cc[values[j+1]] - cc[values[j]], 0)
            canvas.move(values[j+1], cc[values[j]]- cc[values[j+1]], 0)
            cc[values[j]] += (cc[values[j+1]]- cc[values[j]])
            cc[values[j+1]] += (cc[values[j]]- cc[values[j+1]])
            canvas.update()
            canvas.after(50)
            canvas.update()
        else:
            canvas.after(5)

canvas.mainloop()

print(values)

Answer 1

如果values 中的多个项目具有相同的值，则使用create_rectangle() 中的tag=value 来识别矩形项目可能会出现问题。

我会使用 list 来保存矩形项目，并在排序期间根据values 中相同位置的值更新它们的高度：

import tkinter as tk
import random

width = 800
height = 800
thickness = 20

# generate values
values = [random.randrange(10, height) for i in range(width//thickness)]
print(values) # initial sequence

root = tk.Tk()

canvas = tk.Canvas(root, height=height, width=width, background='black')
canvas.pack()

# create the bars
cc = []  # hold the bar items (canvas rectangle item)
for i, value in enumerate(values):
    x = i * thickness
    item = canvas.create_rectangle(x, height, x+thickness, height-value, fill='white')
    cc.append(item)

def swap_items(a, b):
    values[a], values[b] = values[b], values[a]
    # update the bar height at positons a and b
    canvas.coords(cc[a], (a*thickness, height, (a+1)*thickness, height-values[a]))
    canvas.coords(cc[b], (b*thickness, height, (b+1)*thickness, height-values[b]))

for i in range(len(values)):
    for j in range(len(values)-i-1):
        if values[j] > values[j+1]:
            swap_items(j, j+1)
            canvas.update()
            canvas.after(50)
        else:
            canvas.after(5)
print(values) # sorted sequence

root.mainloop()