How to horizontally center a widget using grid()?

问题

I am using grid() to place widgets in a tkinter window. I am trying to put a label on the horizontal center of a window and have it stay there, even if the window is resized. How could I go about doing this?

I don't want to use pack(), by the way. I would like to keep using grid().

回答1:

There's no trick -- the widget is centered in the area allocated to it by default. Simply place a label in a cell without any sticky attributes and it will be centered.

Now, the other question is, how to get the area it is allocated to be centered. That depends on many other factors, such as what other widgets are there, how they are arranged, etc.

Here's a simple example showing a single centered label. It does this by making sure the row and column it is in takes up all extra space. Notice that the label stays centered no matter how big you make the window.

import Tkinter as tk

class Example(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        label = tk.Label(self, text="This should be centered")
        label.grid(row=1, column=1)
        self.grid_rowconfigure(1, weight=1)
        self.grid_columnconfigure(1, weight=1)

if __name__ == "__main__":
    root = tk.Tk()
    Example(root).grid(sticky="nsew")
    root.grid_rowconfigure(0, weight=1)
    root.grid_columnconfigure(0, weight=1)
    root.mainloop()

You can get a similar effect by giving a weight to all rows and columns except the one with the label.

import Tkinter as tk

class Example(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        label = tk.Label(self, text="This should be centered")
        label.grid(row=1, column=1)

        self.grid_rowconfigure(0, weight=1)
        self.grid_rowconfigure(2, weight=1)
        self.grid_columnconfigure(0, weight=1)
        self.grid_columnconfigure(2, weight=1)

if __name__ == "__main__":
    root = tk.Tk()
    Example(root).grid(sticky="nsew")
    root.grid_rowconfigure(0, weight=1)
    root.grid_columnconfigure(0, weight=1)

    root.mainloop()

回答2:

There is nothing special required. A widget will be in the middle of it's parent automatically. What is required to to tell the parent to fill all available space.

from tkinter import *
root = Tk()
root.geometry("500x500+0+0")
frmMain = Frame(root,bg="blue")

startbutton = Button(frmMain, text="Start",height=1,width=4)
startbutton.grid()

#Configure the row/col of our frame and root window to be resizable and fill all available space
frmMain.grid(row=0, column=0, sticky="NESW")
frmMain.grid_rowconfigure(0, weight=1)
frmMain.grid_columnconfigure(0, weight=1)
root.grid_rowconfigure(0, weight=1)
root.grid_columnconfigure(0, weight=1)

root.mainloop()

This uses grid rather than pack to place the widgets and the grid is configured to fill the entire size of the window. The button will appear in the centre regardless of the size of the window.

来源：https://stackoverflow.com/questions/33046790/how-to-horizontally-center-a-widget-using-grid

标签

python

tkinter

widget

grid-layout