无法删除画布上的 tkinter 对象 [英] Cannot delete tkinter object on canvas

问题描述

我创建了一个类对象 Dot()，一个函数 update() 更新其位置，然后在 canvas，将它们添加到列表中.我运行了一个不断更新点位置的循环，这工作正常，但我还想在每次循环运行时删除 Dot() 的一个实例.

我尝试了很多方法，但都没有成功.通过使用 canvas.delete() 函数，我只冻结"了实例化，但它保留在屏幕上.我该如何解决这个问题?

将 numpy 导入为 np随机导入导入时间从 tkinter 导入 *#创建画布#屏幕 = Tk()嘿 = 600宽度 = 600画布 = 画布(屏幕，宽度=宽度，高度=黑)画布.pack()颜色 = [红色"，绿色"，蓝色"]类点:def __init__(self):self.l = random.randrange(100,200)self.t = random.randrange(100,200)self.l2= self.l-10self.t2 = self.t-10颜色 = random.choice(colors)self.shape = canvas.create_oval(self.l, self.t, self.l2, self.t2, fill=color)self.speedx = random.randrange(1,3)self.speedy = random.randrange(1,3)定义更新(自我):canvas.move(self.shape, self.speedx, self.speedy)pos = canvas.coords(self.shape)抖动 = random.randrange(0,200)如果 pos[2] >= wid+jitter 或 pos[0] <= -jitter:self.speedx *= -1如果 pos[3] >= hei+jitter 或 pos[1] <= -jitter:self.speedy *= -1点 = []对于我在范围内(100):dots.append(Dot())为真:删除点[-1]canvas.delete(点[-1])对于点中点:点.更新()屏幕更新()时间.睡眠(0.005)screen.mainloop()

解决方案

delete 方法采用画布项的标识符，而不是画布项本身.

此外，您可能应该在超时函数中进行删除，否则 GUI 将无法正常运行.

试试这个代码:

随机导入从 tkinter 导入 *屏幕 = Tk()嘿 = 600宽度 = 600画布 = 画布(屏幕，宽度=宽度，高度=黑)画布.pack()颜色 = [红色"，绿色"，蓝色"]类点:def __init__(self):self.l = random.randrange(100, 200)self.t = random.randrange(100, 200)self.l2 = self.l-10self.t2 = self.t-10颜色 = random.choice(colors)self.shape = canvas.create_oval(self.l, self.t, self.l2, self.t2, fill=color)self.speedx = random.randrange(1, 3)self.speedy = random.randrange(1, 3)定义更新(自我):canvas.move(self.shape, self.speedx, self.speedy)pos = canvas.coords(self.shape)抖动 = random.randrange(0, 200)如果 pos[2] >= wid+jitter 或 pos[0] <= -jitter:self.speedx *= -1如果 pos[3] >= hei+jitter 或 pos[1] <= -jitter:self.speedy *= -1点 = []对于我在范围内(100):dots.append(Dot())定义超时():如果点:canvas.delete(dots[-1].shape)删除点[-1]对于点中点:点.更新()screen.after(5, 超时)screen.after(5, 超时)screen.mainloop()

(使用 Python 3 测试)

I have created a class object Dot(), a function update() that updates its position and then generated many instances of it on canvas, adding them to a list. I run a loop that keeps updating the position of the dots, and this works fine, but I also want to delete one instantiation of Dot() at each run of the loop.

I've tried many ways but with no success. By using canvas.delete() function I only "freeze" the instantiation, but it remains on screen. How can I fix this?

import numpy as np
import random
import time
from tkinter import *

#create Canvas#
screen = Tk()
hei = 600
wid = 600
canvas = Canvas(screen,width=wid,height=hei)
canvas.pack()

colors = ["red", "green", "blue"]


class Dot:
    def __init__(self):
        self.l = random.randrange(100,200)
        self.t = random.randrange(100,200)
        self.l2= self.l-10
        self.t2 = self.t-10
        color = random.choice(colors)
        self.shape = canvas.create_oval(self.l, self.t, self.l2, self.t2, fill=color)
        self.speedx = random.randrange(1,3)
        self.speedy = random.randrange(1,3)

    def update(self):
        canvas.move(self.shape, self.speedx, self.speedy)
        pos = canvas.coords(self.shape)
        jitter = random.randrange(0,200)
        if pos[2] >= wid+jitter or pos[0] <= -jitter:
            self.speedx *= -1
        if pos[3] >= hei+jitter or pos[1] <= -jitter:
            self.speedy *= -1


dots = []
for i in range(100):
    dots.append(Dot())

while True:
    del dots[-1]
    canvas.delete(dots[-1])
    for dot in dots:
        dot.update()
    screen.update()
    time.sleep(0.005)



screen.mainloop()

解决方案

The delete method takes the identifier of a canvas item, not the canvas item itself.

Additionally, you should probably do the deletion in a timeout function, otherwise, the GUI won't function properly.

Try this code:

import random
from tkinter import *

screen = Tk()
hei = 600
wid = 600
canvas = Canvas(screen, width=wid, height=hei)
canvas.pack()

colors = ["red", "green", "blue"]


class Dot:
    def __init__(self):
        self.l = random.randrange(100, 200)
        self.t = random.randrange(100, 200)
        self.l2 = self.l-10
        self.t2 = self.t-10
        color = random.choice(colors)
        self.shape = canvas.create_oval(self.l, self.t, self.l2, self.t2, fill=color)
        self.speedx = random.randrange(1, 3)
        self.speedy = random.randrange(1, 3)

    def update(self):
        canvas.move(self.shape, self.speedx, self.speedy)
        pos = canvas.coords(self.shape)
        jitter = random.randrange(0, 200)
        if pos[2] >= wid+jitter or pos[0] <= -jitter:
            self.speedx *= -1
        if pos[3] >= hei+jitter or pos[1] <= -jitter:
            self.speedy *= -1


dots = []
for i in range(100):
    dots.append(Dot())


def timeout():
    if dots:
        canvas.delete(dots[-1].shape)
        del dots[-1]
        for dot in dots:
            dot.update()
        screen.after(5, timeout)


screen.after(5, timeout)
screen.mainloop()

(Tested with Python 3)

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