Using tkinter to produce n labels where n is variable

问题

I'm looking to implement a top level window which has a controllable number of label widgets on it. In my first window, there is a scale widget which you can use to select the number of labels on the top level. These labels then need to be updated in real time. I have code for generating the top level window, as well as for dynamically updating one label on it using the After utility.

I can't figure out how to produce a variable set of labels which I can then update later in the code. My first thought is to do something like so:

for i in range(n):
  label = Label(top_level, text = "Text")
  label.pack()

The issue with this is how it generates the same label n times and that means you can't update them independently (or at all). This means I can't implement my after argument to update them with real-time data. What is the correct way to approach this problem?

回答1:

The issue with this is how it generates the same label n times

This is incorrect. You do create n different labels, but in every iteration of the loop you overwrite the reference to the previous label. Therefore, when the loop ends, you have a reference to only the last label.

What you can do is save the different labels in a list. That way, you can access them individually using their index:

from tkinter import *

top_level = Tk()

n = 5
label_list = []

for i in range(n):
    label_list.append(Label(top_level, text = "Text"))
    label_list[i].pack()

for i in range(n):
    label_list[i].config(text="Text {}".format(i))

top_level.mainloop()

回答2:

Question: how to produce a variable set of labels which I can then update later in the code

The following example allows to update all Labels in a Toplevel widget.

Note: If you have also other widgets in your Toplevel, use a Frame for the Label's and loop the self.frame.children.

The data to update, has to be a dict with predefined keys.

import tkinter as tk
from collections import OrderedDict

class Toplevel(tk.Toplevel):
    def __init__(self, parent, label_dict):
        super().__init__(parent)

        for key, text in label_dict.items():
            label = tk.Label(self, text=text)
            label.key = key
            label.pack()

    def update_labels(self, data):
        children = self.children
        for c in children:
            label = children[c]
            label.configure(text=data[label.key])

class App(tk.Tk):
    def __init__(self):
        super().__init__()
        self.menubar = tk.Menu()
        self.menubar.add_command(label='Update', command=self.update)

        self.labels = OrderedDict({'label_1':'Label 1', 'label_2':'Label 2', 'label_3':'Label 3'})
        self.top = Toplevel(self, self.labels)


    def update(self):
        for key, text in self.labels.items():
            self.labels[key] = 'Updated {}'.format(text)

        self.top.update_labels(self.labels)

if __name__ == "__main__":
    App().mainloop()

Tested with Python: 3.5

来源：https://stackoverflow.com/questions/55104813/using-tkinter-to-produce-n-labels-where-n-is-variable

标签

python

tkinter

label