[Beginner] Toggle Button

[lu...@sliacky.eu]

Hi guys,

sorry for stupid question, but i begin with python and kivy a i have a basic problem:
I try create simple "application" with Checkbox and Toggle Button. Checkbox works fine, but i don't know how to work Toggle Button :/

My python code:
checkbox_forum.py

from kivy.uix.gridlayout import GridLayout
from kivy.app import App
from kivy.properties import StringProperty


class Check(GridLayout):
    Status = StringProperty("Begin State")
    Status1 = StringProperty("Begin ToggleButton")

    def checkActive(self, *args):
        if args[1]:
            self.Status = "Device On"
            print("Turning On")
        else:
            self.Status = "Device Off"
            print("Turning Off")

    def checkActive1(self, *args):
        if args[1]:
            self.Status3 = "Devide On"
            print("Turning On")
        else:
            self.Status3 = "Device Off"
            print("Turning Off")


class Check_forumApp(App):
    def build(self):
        self.title = "Checkboxes and Buttons"
        return Check()

if __name__ == '__main__':
    Check_forumApp().run()

check_forum.kv

<Check>:
    cols: 3
    canvas:
        Color:
            rgb: .2,.2,.2
        Rectangle:
            pos: self.pos
            size: self.size

    Label:
        text: 'A checkbox'
    CheckBox:
        on_active: root.checkActive(*args)
    Label:
        text: root.Status


    Label:
        text: 'Toggle Button'
    ToggleButton:
        text: 'ToggleButton'
        active: True
        on_press: root.checkActive1(*args)
    Label:
        text: root.Status1

In Toggle Button I want same operations like in Checkbox:

Print current Status
Change Status in kivy window.

Can you help to beginner?
Really thanks.

[Bruce Cropley]

When you are first starting out with Kivy, a really useful resource is the examples that come with the distribution. You can often find some code that you can tweak to see how it works.

Good luck :)

[Lukáš Sliacky]

Hi Bruce,

thank for your answer.
Of course, i tried "kivycatalog.py" and "showcase.py", where is a lot of examples, but only "visual cases" and no python functions.
I have problem with actions from kv file to python funcions (i.e. print() ).

[ZenCODE]

In your kv, try changing:

    on_press: root.checkActive1(*args)

to

    on_active: root.checkActive1(*args)

That not what you are looking for?

Cheers




[Lukáš Sliacky]

Hi ZenCODE,

thanks for your answer.

your code:


on_active: root.checkActive1(*args)

i was try before, but answer of terminal is

 ...
      18:        text: 'Toggle Button'
      19:    ToggleButton:
 >>   20:        on_active: root.checkActive1(*args)
      21:        text: 'ToggleButton'
      22:    Label:
 ...
 KeyError: 'active'

and this is my problem :/



[ZenCODE]

Sorry, try:

     on_state: root.checkActive1(*args)





[Lukáš Sliacky]

Hmm,

on_state: root.checkActive1(*args)

is better, works without errors, but not switching states.

kivy:

    Label:
        text: 'Toggle Button'
    ToggleButton:

        on_state: root.checkActive1(*args)
        text: 'ToggleButton'
    Label:
        text: root.Status1

Python:

    def checkActive1(self, *args):
        if args[1]:

            self.Status1 = "Device On"

            print("Turning On")
        else:

            self.Status1 = "Device Off"
            print("Turning Off")

Terminal (clicking on ToggleButton):

Turning On
Turning On
Turning On
Turning On
Turning On

and Status1 is only "Device On".

Checkbox switching states normally, but i don't know, why ToggleButton, not...

[ZenCODE]

Have a look at when parameters are coming through to checkActive1:

    def checkActive1(self, *args):
        print "args=" + str(args)
        if args[1]: ....

You might find that you need to used args[0]?

[Lukáš Sliacky]

Hi ZenCODE, 

python:

    def checkActive1(self, *args):
        print ("args=" + str(args))
        if args[0]:

            self.Status1 = "Device On"
            print("Turning On")
        else:
            self.Status1 = "Device Off"
            print("Turning Off")

terminal:

args=(<kivy.uix.togglebutton.ToggleButton object at 0x7f19828c0ca8>, 'down')
Turning On
args=(<kivy.uix.togglebutton.ToggleButton object at 0x7f19828c0ca8>, 'normal')
Turning On
args=(<kivy.uix.togglebutton.ToggleButton object at 0x7f19828c0ca8>, 'down')
Turning On
args=(<kivy.uix.togglebutton.ToggleButton object at 0x7f19828c0ca8>, 'normal')
Turning On
args=(<kivy.uix.togglebutton.ToggleButton object at 0x7f19828c0ca8>, 'down')

args[0] or args[1] have same output...

[ZenCODE]

Hi

Well, not really the same output. args[0] is the toggle button itself and args[1] the state. Your code is testing:

    if args[0]:

That will always be True because the any object (here a toggle button) evaluates to True, and only None to False in the Python Truthiness universe. When you need to do is test the state of the button, so either:

    if args[0].state == 'down':

or, more optimally:

    if args[1] == 'down':

That should do it? Take note of the technique here of printing stuff to explore what information is coming through. Python introspection makes it easy to do this and it's an invaluable help in figuring out what is going wrong...;-)

Cheers

[Lukáš Sliacky]

Wow,

now works great.
Really thanks for your willingness and patience :)

[ZenCODE]

It's a pleasure :-)