Python 更新Tkinter标签

我使用Python3，我对编程非常陌生。我写了一个代码，它应该显示一个窗口，在这个窗口中你可以绕着两颗行星移动，并看到它们之间的引力。 除了用来显示原力的标签外，一切都正常。经过多次尝试和搜索，我就是不知道如何在每次行星移动时更新它

我想我的问题应该在最后一行：

lbl = Label(wind, bg = 'white', text = gravitation(oval1, oval2)).pack(padx=5, pady=5)

我曾尝试使用StringVar和textvariable参数，但我没有真正了解它的概念

这是我的密码。我想答案很简单，但我没有经验

from tkinter import *
import math

x, y = 135, 135
gravitation = 0

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)
    grav = 6.67384/dist
    return grav

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.pack (side = LEFT,padx = 5, pady = 5)
Button(wind, text = 'Quit', command=wind.destroy).pack(padx = 5, pady = 5)

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

oval2 = can.create_oval(x+50,y+50,x+80,y+80,width=2,fill='orange') #Planet 2 moving etc
Button(wind, text = 'Left', command=moveLeft2).pack(padx = 5, pady = 5)
Button(wind, text = 'Right', command=moveRight2).pack(padx = 5, pady = 5)
Button(wind, text = 'Top', command=moveTop2).pack(padx = 5, pady = 5)
Button(wind, text = 'Bottom', command=moveBottom2).pack(padx = 5, pady = 5)


lbl = Label(wind, bg = 'white', text = gravitation(oval1, oval2)).pack(padx=5, pady=5)

wind.mainloop()

---

好的，有几件事需要做。首先，让您的标签如下所示：

lbl = Label(wind, bg = 'white', text = gravitation(oval1, oval2))
lbl.pack(padx=5, pady=5)
# Put this on its own line so that there are no errors since 'lbl' isn't defined yet
gravitation(oval1, oval2)

这将使

lbl

像应该的那样引用标签，而不是

pack

，后者返回

None

其次，您需要将以下内容：

gravitation(oval1, oval2)

在

移动

功能的末尾，这样每次在任何方向上移动时，它都会更新标签

第三，不要在

引力

中返回

重力

，而是将其放在末尾：

lbl["text"] = grav

现在，每次调用

引力

，标签都会更新

总之，这应该满足您的要求：

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)
    grav = 6.67384/dist
    ##################
    lbl["text"] = grav
    ##################

def move (ov, lr, tb):
    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)
    ########################
    gravitation(oval1, oval2)
    ########################


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)



wind = Tk()
wind.title ("Move Da Ball")
can = Canvas (wind, width = 300, height = 300, bg = "light blue")
can.pack (side = LEFT,padx = 5, pady = 5)
Button(wind, text = 'Quit', command=wind.destroy).pack(padx = 5, pady = 5)

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

oval2 = can.create_oval(x+50,y+50,x+80,y+80,width=2,fill='orange') #Planet 2 moving etc
Button(wind, text = 'Left', command=moveLeft2).pack(padx = 5, pady = 5)
Button(wind, text = 'Right', command=moveRight2).pack(padx = 5, pady = 5)
Button(wind, text = 'Top', command=moveTop2).pack(padx = 5, pady = 5)
Button(wind, text = 'Bottom', command=moveBottom2).pack(padx = 5, pady = 5)

###############################
lbl = Label(wind, bg = 'white')
lbl.pack(padx=5, pady=5)
gravitation(oval1, oval2)
##############################

wind.mainloop()

---

我把我改变的东西都放在评论框里。另外，我在一开始就删除了

gravitation=0

，因为定义

gravitation

函数将覆盖它。希望这有帮助

嘿。谢谢你的帮助。事实上，我希望有其他的方法来做这件事，但这一个有效。我会再等一会儿，看看有没有人有什么想法，否则我会把它作为答案。@Pierreconom:你不喜欢这个解决方案的什么地方？我在编程方面不是很有经验，所以我可能不知道说什么我不喜欢这个解决方案，因为我自己也没有任何线索。但如果我要提到的话，我需要在每一个移动函数中调用引力函数。如果可以的话，我更愿意让我的代码更通用。我正在做其他的事情，一个几乎可以用的东西，除了一个小问题。我正在写一个新问题，你可以看一看。@PierreOcinom-我只是想到了一些事情（不知道为什么我之前没有想到）。在阅读了您的上述评论之后，我开始思考一种方法，在每次移动函数中不调用

重力

就可以完成任务。我的解决方案是在

move

函数中调用

gravitation

。请参阅我的编辑。这样就不需要一直调用

引力
。哈哈哈。事实上，这是如此容易，甚至我应该看到它。谢谢。