Python/Tkinter: expanding fontsize dynamically to fill frame

Question

I know you can get frame widgets to expand and fill all of the area available to them in their container via these commands: frameName.pack(fill = 'both', expand = True)

What would do the same for a text's font size? Currently my text is an attribute of a label widget. The label widget's parent is frameName.

I guess I could define my own function to call labelName.config(fontsize = N) to update the font size as the frame get's bigger, but I'm not sure how to correlate them.

This is what my program looks like right now:

Each of those blocks is a frame widget. I'd like the text to expand to fill up in some capacity the frame, and respond to resizing of the window as well.

Answer 1

You can use tkFont.font

When you initialize the label set the font to a variable such as:

self.font = SOME_BASE_FONT
self.labelName.config(font = self.font)

Then you can use:

self.font = tkFont.Font(size = PIXEL_HEIGHT)

This you can scale to the height of the label. You can bind a '<Configure>' Event to the widget, and make your callback function adjust the label size.

frameName.bind('<Configure>', self.resize)

def resize(self, event):
    self.font = tkFont(size = widget_height)

For more info see the documentation here.

Answer 2

I've been trying to figure out how to get the text to automatically resize in tkinter.

The key to getting it working for me was to assign the calculated height to the size in the custom font object. Like so: self.label_font['size'] = height

Full example:

from tkinter import font
import tkinter as tk


class SimpleGUIExample:
    def __init__(self, master):
        self.master = master
        self.master.title("A simple Label")
        self.master.bind('<Configure>', self.resize)

        self.label_font = font.Font(self.master, family='Arial', size=12, weight='bold')

        self.label = tk.Label(self.master, text="Simple Label Resizing!")
        self.label.config(font=self.label_font)
        self.label.pack(fill=tk.BOTH, expand=tk.YES)

        self.close_button = tk.Button(self.master, text="Close", command=master.quit)
        self.close_button.pack()

    def resize(self, event):
        height = self.label.winfo_height()
        width = self.label.winfo_width()
        height = height // 2
        print('height %s' % height)
        print('width %s' % width)
        if height < 10 or width < 200:
            height = 10
        elif width < 400 and height > 20:
            height = 20
        elif width < 600 and height > 30:
            height = 30
        else:
            height = 40
        print('height %s' % height)

        self.label_font['size'] = height
        print(self.label_font.actual())


root = tk.Tk()
simple_gui = SimpleGUIExample(root)
root.mainloop()