Checkbutton Introduction#

alt theme checkbutton states

Showing Checkbutton States run in the alt Theme#

None of the checkbuttons have been activated, they are all in the alternate mode (tri-state or indeterminate)

The checkbutton (checkbox) is a widget that allows the user to have a two-way choice, if several checkboxes are present in a group all choices are inclusive, so normally no selection will prevent the other checkboxes being selected. The widget is split into an indicator and label that has the text part.

Although a simple widget, the various states that could occur are quite numerous, and will need to be closely examined. Using a themed widget, when none of the checkbuttons in the group are selected they will show as alternate, which is the tri-state or indeterminate mode. When the widget is clicked several different states are activated in turn. As the mouse hovers over the widget the state changes to active the mouse button is depressed and the state changes to pressed then shows selected, if the button had already been selected then it swiches state to !selected (unselected). When the mouse leaves the widget it has a chained line around it showing it is in the focus state, this changes from one button to the next depending which was altered last. So just pressing a button changes the state five times, none of this is programmed in the script, it is part of how the widget works.

As seen above there is a state (active) which occurs as the mouse hovers over the widget, this is a positive feedback to the user showing that they are on a particular widget or not. This feedback is shown by lightening the widget colour, for the checkbutton the surrounding rectangle of the widget changes from a dark to a light colour. In no way is the checkbutton changed from alternate, unselected or selected to one of the other states just by hovering.

There is another state that has sofar been left untouched, which is disabled. This is programmed into the script. Whenever disabled is activated the widget is greyed out and cannot be selected/unselected by direct action on the widget. When disabled the widget should show its previous greyed out state, then when disabled is removed (!disabled) the previous state is restored.

Run the script test_check.py, this will show four checkbuttons, the top one changes the state of the second widget. When initially opened all four widgets are in the alternate state, semi greyed out. Move the cursor over one of the checkbuttons the widget lightens but the indicator does not change. Click the topmost checkbutton, it will disable/!disable the second button and print the state of the second button. Only disable is being controlled, using only disable or !disable, but this results in ('disabled',), ('disabled', 'alternate') or ('disabled', 'selected') depending on the widget's original state, disabled by itself occurs when the second widget was unselected. Change the controlled state from disabled to active using active and !active it then cycles through ('active',), ('active', 'alternate') and ('active', 'selected'), active cannot affect a disabled widget.

Note

Apart from the opportunity to print the widget states and keeping the widget in the active state, controlling active should be no different to hovering over the widget with a mouse.

In all this activity the check buttons reacted independantly.

The following states can be called up or changed directly by a mouse click:

  • alternate

  • unselected (for want of a better name)

  • selected

  • active

  • active, selected

  • active, alternate

  • pressed

  • pressed selected

  • focus

The following states are changed through the script:

  • disabled

  • disabled, alternate

  • disabled, selected

Show/Hide Code test_check.py

'''
test checkbuttons - use the properties of the theme to check for
active, selected
disabled, alternate
disabled, selected
'''
from tkinter import Tk
from tkinter.ttk import Style, Checkbutton, Button, Label

switch = 0

def change():
    global switch
    if switch == 0:
        c1.state(['disabled']) # active
        #print(c1.state())
    else:
        c1.state(['!disabled']) # !active
    switch = 1 if switch == 0 else 0

def look():
    print(c1.state())
    lb1['text'] = c1.state()

root = Tk()

s = Style()
s.theme_use('alt')

c = Checkbutton(root, text='disabled', command=change)
c.grid(column=0, row=0, pady=5, sticky='w')
l = Label(root, text= 'Checkbutton to disable/enable\n the button below')
l.grid(column=1, row=0, pady=5, padx=5, sticky='w')
c1 = Checkbutton(root, text='good')
c1.grid(column=0, row=1, pady=5, sticky='w')
l1 = Label(root, text= 'Checkbutton being tested')
l1.grid(column=1, row=1, pady=5, padx=5, sticky='w')
c2 = Checkbutton(root, text='OK')
c2.grid(column=0, row=2, pady=5, sticky='w')
c3 = Checkbutton(root, text='poor')
c3.grid(column=0, row=3, pady=5, sticky='w')

b = Button(root, text='lookup', command=look)
b.grid(column=0, row=3, pady=5, sticky='w')
lb = Label(root, text= 'Show current state')
lb.grid(column=1, row=3, pady=5, padx=5, sticky='w')
lb1 = Label(root, text= 'Current state')
lb1.grid(column=1, row=4, pady=5, padx=5, sticky='w')

root.mainloop()

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