TKInter - Confused about frames and scrolling - python-3.x

Question

I am trying to code a tkinter application that has three frames - a top frame, where the user inputs some text, a dynamically constructed middle section where some pre-analysis is conducted on the text, and a bottom frame where, once the user has selected which option they want in the middle section, the output will be produced.
The problem is that, depending upon the input, there could be around 10-20 (and in the worst case 30) lines displayed and on a small monitor the output will disappear off the screen.
What I would like is for the top (input) and bottom (output) frames to be visible no matter how the screen is re-sized, and for the middle section to scroll (if required) and still allow the user to select their choice.
I am confused as to how to get the middle section to resize when the screen is resized, show a scrollbar if required, and still allow all of the content to be accessed.
I have created a cut-down version here (for simplicity, I have removed the processing methods and have instead created some fake output in a loop that resembles what the actual middle section would look like).
Please ignore the hideous colour-scheme - I was just trying to understand which frame went where (I will remove the colours as soon as I can!)
Thank you for any suggestions...
import tkinter as tk
from tkinter import scrolledtext
class MyApp(tk.Tk):
def __init__(self, title="Sample App", *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
self.title(title)
self.configure(background="Gray")
self.columnconfigure(0, weight=1)
self.rowconfigure(0, weight=1)
# Create the overall frame:
master_frame = tk.Frame(self, bg="Light Blue", bd=3, relief=tk.RIDGE)
master_frame.grid(sticky=tk.NSEW)
master_frame.rowconfigure([0, 2], minsize=90) # Set min size for top and bottom
master_frame.rowconfigure(1, weight=1) # Row 1 should adjust to window size
master_frame.columnconfigure(0, weight=1) # Column 0 should adjust to window size
# Create the frame to hold the input field and action button:
input_frame = tk.LabelFrame(master_frame, text="Input Section", bg="Green", bd=2, relief=tk.GROOVE)
input_frame.grid(row=0, column=0, padx = 5, pady = 5, sticky=tk.NSEW)
input_frame.columnconfigure(0, weight=1)
input_frame.rowconfigure(0, weight=1)
# Create a frame for the middle (processing) section.
middle_frame = tk.LabelFrame(master_frame, text = "Processing Section")
middle_frame.grid(row=1, column=0, padx=5, pady=5, sticky=tk.NSEW)
# Create the frame to hold the output:
output_frame = tk.LabelFrame(master_frame, text="Output Section", bg="Blue", bd=2, relief=tk.GROOVE)
output_frame.grid(row=2, column=0, columnspan=3, padx=5, pady=5, sticky=tk.NSEW)
output_frame.columnconfigure(0, weight=1)
output_frame.rowconfigure(0, weight=1)
# Add a canvas in the middle frame.
self.canvas = tk.Canvas(middle_frame, bg="Yellow")
self.canvas.grid(row=0, column=0)
# Create a vertical scrollbar linked to the canvas.
vsbar = tk.Scrollbar(middle_frame, orient=tk.VERTICAL, command=self.canvas.yview)
vsbar.grid(row=0, column=1, sticky=tk.NS)
self.canvas.configure(yscrollcommand=vsbar.set)
# Content for the input frame, (one label, one input box and one button).
tk.Label(input_frame,
text="Please type, or paste, the text to be analysed into this box:").grid(row=0, columnspan = 3, sticky=tk.NSEW)
self.input_box = scrolledtext.ScrolledText(input_frame, height=5, wrap=tk.WORD)
self.input_box.columnconfigure(0, weight=1)
self.input_box.grid(row=1, column=0, columnspan = 3, sticky=tk.NSEW)
tk.Button(input_frame,
text="Do it!",
command=self.draw_choices).grid(row=2, column=2, sticky=tk.E)
# Content for the output frame, (one text box only).
self.output_box = scrolledtext.ScrolledText(output_frame, width=40, height=5, wrap=tk.WORD)
self.output_box.grid(row=0, column=0, columnspan=3, sticky=tk.NSEW)
def draw_choices(self):
""" This method will dynamically create the content for the middle frame"""
self.option = tk.IntVar() # Variable used to hold user's choice
self.get_input_text()
for i in range(30):
tk.Radiobutton(self.canvas,
text=f"Option {i + 1}: ", variable=self.option,
value=i,
command=self.do_analysis
).grid(row=i, column=0, sticky=tk.W)
tk.Label(self.canvas,
text=f"If you pick Option {i + 1}, the output will look like this: {self.shortText}.",
anchor=tk.W
).grid(row=i, column=1, sticky=tk.W)
self.canvas.configure(scrollregion=self.canvas.bbox("all"))
def get_input_text(self):
""" Will get the text from the input box and also create a shortened version to display on one line"""
screenWidth = 78
self.input_text = self.input_box.get(0.0, tk.END)
if len(self.input_text) > screenWidth:
self.shortText = self.input_text[:screenWidth]
else:
self.shortText = self.input_text[:]
self.shortText = self.shortText.replace('\n', ' ') # strip out carriage returns just in case
def do_analysis(self):
"""This will ultimately process and display the results"""
option = self.option.get() # Get option from radio button press
output_txt = f"You picked option {option + 1} and here is the output: \n{self.input_text}"
self.output_box.delete(0.0, tk.END)
self.output_box.insert(0.0, output_txt)
if __name__ == "__main__":
app = MyApp("My Simple Text Analysis Program")
app.mainloop()

Answer 1

I understand that you can't mix grid and pack geometries in the same container, and that a scrollbar must be attached to a canvas, and objects to be placed on that canvas must therefore be in yet another container so, attempting to follow Bryan's example, I created a minimal version of what I want - window with three sections - top, middle and bottom. The Top and bottom sections will contain a simple text field, the middle section will contain dynamic content and must be able to scroll as required.
Imports:
ScrollbarFrame
Extends class tk.Frame to support a scrollable Frame]
import tkinter as tk
class App(tk.Tk):
def __init__(self):
super().__init__()
self.title("A simple GUI")
# Top frame
self.top_frame = tk.Frame(self, bg="LIGHT GREEN")
self.top_frame.pack(fill=tk.X)
tk.Label(self.top_frame, bg=self.top_frame.cget('bg'),
text="This is a label on the top frame")\
.grid(row=0, columnspan=3, sticky=tk.NSEW)
# Middle Frame
# Import from https://stackoverflow.com/a/62446457/7414759
# and don't change anything
sbf = ScrollbarFrame(self, bg="LIGHT BLUE")
sbf.pack(fill=tk.X, expand=True)
# self.middle_frame = tk.Frame(self, bg="LIGHT BLUE")
self.middle_frame = sbf.scrolled_frame
# Force scrolling by adding multiple Label
for _ in range(25):
tk.Label(self.middle_frame, bg=self.middle_frame.cget('bg'),
text="This is a label on the dynamic (middle) section")\
.grid()
# Bottom Frame
self.bottom_frame = tk.Frame(self, bg="WHITE")
self.bottom_frame.pack(fill=tk.X)
tk.Label(self.bottom_frame, bg=self.bottom_frame.cget('bg'),
text="This is a label on the bottom section")\
.grid(row=0, columnspan=3, sticky=tk.NSEW)
if __name__ == '__main__':
App().mainloop()