Using the kivy Clock to change the screen

[Xavier Biancardi]

I'm fairly new with Kivy and am trying to create what is essentially a screensaver for my app. I am currently trying to set up a kivy clock to set the screen manager's current page to the screensaver one.

Below are my screen and screenmanager classes, the MyScreenManager class has the change_screen function which is the one that changes the current screen to the screensaver. I have tested the functionality of the change_screen function by calling it with a button and it worked fine.

However, when I call the function with the Clock.schedule_one(..., ...) it fails and gives me this error:

self.add_widget(ss)
AttributeError: 'float' object has no attribute 'add_widget'

Looked online and couldn't find any definitive solution, any help would be awesome!

Thanks,

Xavier

[Alexander Taylor]

 You schedule the change_screen function at class level, not instance level, so it receives no implicit self argument (effectively you're calling it as a normal function). It automatically receives an argument from Clock.schedule_once, the argument is the time since the scheduling or something like that. That argument is a float, so self is a float, so you get the error you see.

The code doesn't really make sense as it stands, please provide a minimal runnable example demonstrating where you want to add functionality but can't work out how.

[Xavier Biancardi]

Thanks for your reply Alexander,

Below is a link to the code, the Clock.schedule_once has been commented out so that it can load. Essentially my current goal is to create a screensaver that after say 20 seconds without user input the app changes the screen to a screen with a company logo or something (currently just the screen titled ScreenSaver).

https://github.com/zahoov/FuelGauge/blob/master/reconstruction.py

Thanks

[Xavier Biancardi]

Just following up on your previous reply. I am currently trying to do two things: create a screensaver so that if there is no user input for 20s it changes screen to a desired screensaver, and secondly to have the needle automatically rotate a bit every couple seconds.

I am fairly new to Kivy so it is entirely possible that I am missing something obvious but I just can't seem to call the Clock.schedule_once automatically on startup and not through a button.

Additionally I have been trying to have a value (dash_val) increase by 10 every 2 seconds so that the needle rotates automatically as a test, however, in a similar vein to the screensaver I can't figure out how the clock is/isn't working.

My code is at: https://github.com/zahoov/FuelGauge/blob/master/reconstruction.py

Sorry if my questions seem a bit vague, I can try to clarify if needed.

Thanks.

On Friday, August 2, 2019 at 1:40:32 PM UTC-7, Alexander Taylor wrote:

[Elliot Garbus]

Here is a simple example I helped another user with that shows how to use Clock.schedule_interval.  You can use Clock.schedule_once the same way.  Code attached.

 

 

class SimClock(Label):
    current_time = StringProperty(strftime('%H:%M:%S'))

    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.timer = Clock.schedule_interval(self.update_time, 1)

    def update_time(self, dt):
        self.current_time = strftime('%H:%M:%S')

    def cancel_time(self):
        self.timer.cancel()

 

There is a class SimClock derived from a label.  When the class is constructed, the schedule is started.

Once a second update_time() is called.  It reads the current time and updates the value on the label, using the string property current time.

 

Looking at part of the KV code…

 

ImageButton:
    size_hint_x: 1
    size_hint_y: 0.8
    source: './clock.jpeg'
    on_release:
        mylabel.cancel_time()
        self.source = './play.png'
        mylabel.text = 'wakey wakey eggs and beaky'

 

When the mouse button is released on the clock image, the cancel_time() method is called, stopping the schedule.

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