Tkinter 标签未正确更新

Question

今天下午我已经问了一个关于如何在 Tkinter 中更新标签的问题，得到了一个有效的答案。 但是，我发现“解决方案”代码有点长，并试图对其进行改进。 基本上我正在使用updt 函数，它在标签lbl 上执行配置method。该方法将通过调用gravitation 函数来更改标签文本。 每次点击某处时，我都使用整个窗口的bind方法调用updt函数。

现在的问题是程序无法正常运行，因为标签中显示的数字不正确，并且即使行星与以前的距离相同，也不总是显示相同的值。

我仔细阅读了每一行，但由于我对编程很陌生，所以我找不到问题所在。

我正在使用 Python 3。

这是我之前的代码：Update Tkinter Label

这是新的：

from tkinter import *
import math

x, y = 135, 135

def gravitation (obj1,obj2):
    a, b, c, d = can.coords (obj1)
    e, f, g, h = can.coords (obj2)
    dist = math.sqrt ((((a+c)/2)-((e+g)/2))**2+(((b+d)/2)-((f+h)/2))**2)
    if dist != 0:
        grav = 6.67384/dist
    else:
        grav = "Infinite"
    str(grav)
    return grav

def updt (event):
    lbl.configure (text = gravitation(oval1, oval2)) 

def move (ov, lr, tb): # function to move the ball
    coo = can.coords(ov)
    coo[0] = coo[0] + lr
    coo[1] = coo[1] + tb
    coo[2] = coo[0]+30
    coo[3] = coo[1]+30
    can.coords(ov, *coo)


def moveLeft ():
    move(oval1, -10, 0)


def moveRight ():
    move(oval1, 10, 0)


def moveTop ():
    move(oval1, 0, -10)


def moveBottom ():
    move(oval1, 0, 10)


def moveLeft2 ():
    move(oval2, -10, 0)


def moveRight2 ():
    move(oval2, 10, 0)


def moveTop2 ():
    move(oval2, 0, -10)


def moveBottom2 ():
    move(oval2, 0, 10)



##########MAIN############

wind = Tk() # Window and canvas
wind.title ("Move Da Ball")
can = Canvas (wind, width = 300, height = 300, bg = "light blue")
can.grid(row=0, column=1, sticky =W, padx = 5, pady = 5, rowspan =4)
Button(wind, text = 'Quit', command=wind.destroy).grid(row=5, column=1, sticky =W, padx = 5, pady = 5)
wind.bind ("<Button-1>", updt)


oval1 = can.create_oval(x,y,x+30,y+30,width=2,fill='orange') #Planet 1 moving etc
Button(wind, text = 'Left', command=moveLeft).grid(row=0, column=2, sticky =W, padx = 5, pady = 5)
Button(wind, text = 'Right', command=moveRight).grid(row=1, column=2, sticky =W, padx = 5, pady = 5)
Button(wind, text = 'Top', command=moveTop).grid(row=2, column=2, sticky =W, padx = 5, pady = 5)
Button(wind, text = 'Bottom', command=moveBottom).grid(row=3, column=2, sticky =W, padx = 5, pady = 5)



oval2 = can.create_oval(x+50,y+50,x+80,y+80,width=2,fill='blue') #Planet 2 moving etc
Button(wind, text = 'Left', command=moveLeft2).grid(row=0, column=3, sticky =W, padx = 5, pady = 5)
Button(wind, text = 'Right', command=moveRight2).grid(row=1, column=3, sticky =W, padx = 5, pady = 5)
Button(wind, text = 'Top', command=moveTop2).grid(row=2, column=3, sticky =W, padx = 5, pady = 5)
Button(wind, text = 'Bottom', command=moveBottom2).grid(row=3, column=3, sticky =W, padx = 5, pady = 5)




lbl = Label(wind, bg = 'white')#label
lbl.grid(row=4, column=1, sticky =W, padx = 5, pady = 5, columnspan = 3)
gravitation (oval1, oval2)


wind.mainloop()

Answer 1

updt 在用户单击窗口的任何部分时触发，移动功能在用户单击按钮时触发，然后释放它。因此，updt 总是在 move 函数之前被调用。所以标签报告了行星在移动到新位置之前相互之间的引力。

不要将updt绑定到全局点击事件，而是在坐标改变后将其放在move函数中。

def updt():
    lbl.configure (text = gravitation(oval1, oval2)) 

def move (ov, lr, tb): # function to move the ball
    coo = can.coords(ov)
    coo[0] = coo[0] + lr
    coo[1] = coo[1] + tb
    coo[2] = coo[0]+30
    coo[3] = coo[1]+30
    can.coords(ov, *coo)
    updt()