I want to expand the scope of the scrollbar in tkinter.

Prerequisites

Tkinter uses Canvas and Scrollbar to create a list box with Checkbutton.

What do you want to do

I'd like to expand the scrollbar range.
Currently, scrolling works only if there is a cursor on the scroll bar.
I want to make it work even if there is a cursor on Canvas or Checkbutton.

Source Codes Affected

import tkinter ask
from tkinter import ttk

classItemListFrame(tk.Frame):
    
    def__init__(self, master):
        tk.Frame.__init__(self, master, width=100, height=100,
                          borderwidth=1,relief=tk.GROOVE)
        
        # Widget Deployment
        self.place_widget()
        
    place_widget(self):
        
        #Create Canvas
        canvas=tk.Canvas (master=self, width=300, height=200, bg='white')
        canvas.grid (row=0, column=0)
        
        # scrollbar
        vbar=ttk.Scrollbar(master=self, orient=tk.VERTICAL)#vertical
        vbar.grid (row=0, column=1, sticky=tk.NS)
        
        # Process to notify Canvas of scrollbar control
        vbar.config (command=canvas.yview)
        
        # The process of notifying the scrollbar of the Canvas range of motion.
        canvas.config (yscrollcommand=vbar.set)
        
        # scroll range
        canvas.config(scrollregion=(0,0,300,5000))
        
        # Create Frame and place it in canvas
        frame=tk.Frame(master=canvas,bg='white')
        canvas.create_window(0,0), window=frame, anchor=tk.NW, width=canvas.cget('width')))
        
        self.vars = [ ]
        for i in range (50):
            var=tk.BooleanVar()
            self.vars.append(var)
            check_button=tk.Checkbutton(master=frame, text=i, variable=var)
            check_button.grid(row=i, column=0)
            
root=tk.Tk()
frame = ItemListFrame(root)
frame.pack()
root.mainloop()

Supplementary information (for example, FW/Tool Version)

Python 3.10
Windows 10 VScode

python tkinter

2022-09-29 21:45

1 Answers

Assuming the source code is as intended, mouse wheel scrolling will look like this:

In this case, bind the "event" to the canvas, frame, and check buttons to reflect the amount of scroll movement.

import tkinter ask
from tkinter import ttk


classItemListFrame(tk.Frame):

    def__init__(self, master):
        tk.Frame.__init__(self, master, width=100, height=100,
                          borderwidth=1,relief=tk.GROOVE)

        # widget placement
        self.place_widget()

    place_widget(self):
        inframe=tk.Frame(master=self,bg='white')
        inframe.grid (row=0, column=0)

        # Canvas Creation
        canvas=tk.Canvas(master=inframe, width=300, height=200, bg='white')
        canvas.grid (row=0, column=0)

        # scroll bar
        vbar=ttk.Scrollbar(master=inframe, orient=tk.VERTICAL)#vertical
        vbar.grid (row=0, column=1, sticky=tk.NS)

        # The process of notifying Canvas of scrollbar control
        vbar.config (command=canvas.yview)

        # The process of notifying the scrollbar of the Canvas range of motion.
        canvas.config (yscrollcommand=vbar.set)

        # scroll range
        canvas.config(scrollregion=(0,0,300,5000))

        # Create a Frame and Place it in Canvas
        frame=tk.Frame(master=canvas,bg='white')
        canvas.create_window(0,0), window=frame,
                             anchor=tk.NW, width=canvas.cget('width'))
        frame.bind("<MouseWheel>",
                   lambda event:self._mousewheel_(event,canvas))
        canvas.bind("<MouseWheel>",
                    lambda event:self._mousewheel_(event,canvas))

        self.vars = [ ]
        for i in range (50):
            var=tk.BooleanVar()
            self.vars.append(var)
            check_button=tk.Checkbutton(master=frame, text=i, variable=var)
            check_button.grid(row=i, column=0)
            check_button.bind("<MouseWheel>",
                              lambda event:self._mousewheel_(event,canvas))

    def_mousewheel_(self, event, canvas):
        canvas.yview_scroll (int(-1*(event.delta/120)), "units")
        print(event)


root=tk.Tk()
frame = ItemListFrame(root)
frame.pack()
root.mainloop()

2022-09-29 21:45

If you have any answers or tips

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