Scrollbar

There are 4 widgets who can have a scrollbar:

  • Text()
  • Treeview()
  • Canvas()
  • Listbox()
  • Entry()

In order to add scrollbars to these widgets we define a class which adds them and use multiple inheritance.

In order for scrollbar and widget to interact, callback functions are assigned on both sides.

  • The scrollbar calls the widget’s xview and yview methods.
  • The widget has [x/y]scrollcommmand options to update the scrollbar
../_images/scrollbar1.png 
"""Display scrollbars."""
from tklib import *

class Demo(App):
    def __init__(self): 
        super().__init__()
        Label("Scrollbars", font="Arial 18")

        ttk.Scrollbar(App.stack[-1], orient=tk.HORIZONTAL).grid()
        ttk.Scrollbar(App.stack[-1], orient=tk.VERTICAL).grid()
       
Demo().run()

scrollbar1.py

Listbox with scrollbars

../_images/scrollbar2.png 
"""Listbox with a scrollbar."""
from tklib import *

class Demo(App):
    def __init__(self): 
        super().__init__()
        Label("Listbox with scrollbars", font="Arial 18")

        lb = Listbox(list(range(100)))
        sb = ttk.Scrollbar(App.stack[-1])
        sb.grid(row=1, column=1, sticky='ns')

        lb.config(yscrollcommand=sb.set)
        sb.config(command=lb.yview)

Demo().run()

scrollbar2.py

Text with scrollbars

../_images/scrollbar3.png 
"""Text with a scrollbar."""
from tklib import *

class Demo(App):
    def __init__(self): 
        super().__init__()
        Label('Scrollable text', font='Arial 24')

        text = 'long ' * 20
        text += 'line\n' * 20

        Label("No scrollbars")
        Text(text, height=5, wrap='none')

        Label("X scrollbars")
        Text(text, height=5, scroll='x', wrap='none')

        Label("Y scrollbars")
        Text(text, height=5, scroll='y', wrap='none')

        Label("XY scrollbars")
        Text(text, height=5, scroll='xy', wrap='none')

Demo().run()

scrollbar3.py

Canvas with scrollbars

../_images/scrollbar5.png 
"""Canvas with a scrollbar."""
from tklib import *

class Canvas(tk.Canvas):
    def __init__(self, scroll='', scrollregion=(0, 0, 1000, 1000), **kwargs):
        self = Scrollable(tk.Canvas, scroll=scroll, scrollregion=scrollregion, **kwargs)

class Demo(App):
    def __init__(self): 
        super().__init__()
        text = 'hello ' * 100
        Label("Canvas with scrollbars", font="Arial 18")
        h = 80

        Label('scroll=')
        Canvas(height=h)
        
        Label('scroll=x')
        Canvas(height=h, scroll='x')

        Label('scroll=y')
        Canvas(height=h, scroll='y')

        Label('scroll=xy')
        Canvas(height=h, scroll='xy')

Demo().run()

scrollbar5.py