在 Tkinter Canvas 中移动球 [英] Moving balls in Tkinter Canvas

问题描述

这是一个非常基本的程序，我想用它制作两个移动的球，但实际上只有一个球在移动.

This is a very basic program with which I want to make two moving balls, but only one of them actually moves.

我也尝试了一些变化，但无法让第二个球移动；另一个相关问题 - 有些人使用 move(object) 方法来实现这一点，而其他人则使用 delete(object) 然后重新绘制它.我应该使用哪一个?为什么?

I have tried some variations as well but can't get the second ball moving; another related question - some people use the move(object) method to achieve this, while others do a delete(object) and then redraw it. Which one should I use and why?

这是我的代码，它只对一个球进行动画/移动:

This is my code that is only animating/moving one ball:

from Tkinter import *

class Ball:
    def __init__(self, canvas, x1, y1, x2, y2):
    self.x1 = x1
    self.y1 = y1
    self.x2 = x2
    self.y2 = y2
    self.canvas = canvas
    self.ball = canvas.create_oval(self.x1, self.y1, self.x2, self.y2, fill="red")

    def move_ball(self):
        while True:
            self.canvas.move(self.ball, 2, 1)
            self.canvas.after(20)
            self.canvas.update()

# initialize root Window and canvas
root = Tk()
root.title("Balls")
root.resizable(False,False)
canvas = Canvas(root, width = 300, height = 300)
canvas.pack()

# create two ball objects and animate them
ball1 = Ball(canvas, 10, 10, 30, 30)
ball2 = Ball(canvas, 60, 60, 80, 80)

ball1.move_ball()
ball2.move_ball()

root.mainloop()

推荐答案

你不应该在 GUI 程序中放置无限循环——已经有一个无限循环在运行.如果您希望您的球独立移动，只需取出循环并让 move_ball 方法在事件循环中对其自身进行新调用.这样，您的球将永远继续移动(这意味着您应该在那里进行某种检查以防止这种情况发生)

You should never put an infinite loop inside a GUI program -- there's already an infinite loop running. If you want your balls to move independently, simply take out the loop and have the move_ball method put a new call to itself on the event loop. With that, your balls will continue to move forever (which means you should put some sort of check in there to prevent that from happening)

我通过删除无限循环、稍微减慢动画速度以及对它们移动的方向使用随机值对您的程序进行了轻微修改.所有这些更改都在 move_ball 方法中.

I've modified your program slightly by removing the infinite loop, slowing down the animation a bit, and also using random values for the direction they move. All of that changes are inside the move_ball method.

from Tkinter import *
from random import randint

class Ball:
    def __init__(self, canvas, x1, y1, x2, y2):
        self.x1 = x1
        self.y1 = y1
        self.x2 = x2
        self.y2 = y2
        self.canvas = canvas
        self.ball = canvas.create_oval(self.x1, self.y1, self.x2, self.y2, fill="red")

    def move_ball(self):
        deltax = randint(0,5)
        deltay = randint(0,5)
        self.canvas.move(self.ball, deltax, deltay)
        self.canvas.after(50, self.move_ball)

# initialize root Window and canvas
root = Tk()
root.title("Balls")
root.resizable(False,False)
canvas = Canvas(root, width = 300, height = 300)
canvas.pack()

# create two ball objects and animate them
ball1 = Ball(canvas, 10, 10, 30, 30)
ball2 = Ball(canvas, 60, 60, 80, 80)

ball1.move_ball()
ball2.move_ball()

root.mainloop()

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