如何正确制作在 canvas (tkinter 3.x) 中画线的函数

Question

我正在制作一个画线的程序（你用 sliders/scales 决定它的开始和结束位置），问题是当我按下时出现这些错误（我希望我能理解） psy 按钮（错误下方的代码）：

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\python351\lib\tkinter\__init__.py", line 1549, in __call__
    return self.func(*args)
  File "C:/Users/Koteu/PycharmProjects/guji/fsd.py", line 23, in creat
    cans.create_line(ar1,ar2,br1,br2)
  File "C:\python351\lib\tkinter\__init__.py", line 2331, in create_line
    return self._create('line', args, kw)
  File "C:\python351\lib\tkinter\__init__.py", line 2319, in _create
    *(args + self._options(cnf, kw))))
_tkinter.TclError: bad screen distance ".14855536.14855504"

Process finished with exit code 0

无论如何，代码：

import os
import sys
from tkinter import *
root = Tk()
app=Frame(root)

root.geometry("1200x1200")
ar1 = Scale(root,from_=0,to=600)
ar2= Scale(app,from_=0,to=600,deafultvar=0)#app instead of root because the button for unknown to me reason 
#wouldn't appear in GUI otherwise
br1= Scale(root,from_=0,to=600)
br2= Scale(root,from_=0,to=600)





cans = Canvas(root,width = 500,height = 500)

cans.create_line(600,50,0,50) #This has nothing to do with the actual program by my understanding


def creat():
    cans.create_line(ar1,ar2,br1,br2)#< this is what causes the problem i don't understand 


psy=Button(root,command=creat,text="karole")
psy.pack()
cans.pack()
ar1.pack()
ar2.pack()
br1.pack()
br2.pack()

mainloop()

此外，如果有帮助，我正在使用 py345

Answer 1

cans.create_line(x0, y0, ...) 将偶数个整数坐标作为位置参数。您传递了小部件，这些小部件被转换为它们的字符串标识符。在".14855536.14855504"中，'.'代表根，'14855536'是canvas，'14855504'是尺度ar1。相反，您需要在秤上使用 .get() 方法来获取它们的整数值。以下作品。

from tkinter import *
root = Tk()

root.geometry("1200x1200")
ar1 = Scale(root,from_=0,to=600)
ar2= Scale(root,from_=0, to=600)
br1= Scale(root,from_=0, to=600)
br2= Scale(root,from_=0, to=600)

cans = Canvas(root, width=500, height=500)

def creat():
    cans.create_line(ar1.get(), ar2.get(), br1.get(), br2.get())
psy=Button(root, command=creat, text="karole")
ar1.pack()
ar2.pack()
br1.pack()
br2.pack()
psy.pack()
cans.pack()

root.mainloop()

其他几个修复：defaultvar 选项无效并导致错误； mainloop() 而不是 root.mainloop() 导致 tk 创建第二个 Tk 对象，这是个坏主意。

编辑：添加了有效的代码。

如何正确制作在 canvas (tkinter 3.x) 中画线的函数

How to make functions that draw lines in canvas (tkinter 3.x) properly

tkinter

python-3.x

tkinter-canvas