使用Kivy语言添加按钮后将按钮绑定到功能

Question

I'm trying to figure out how to bind a button that's been laid out using Kivy language to a function. I've seen plenty of answers when laying out buttons in Python language. But what about once everything is in place and you're now referencing via a custom class that inherits from Button ?

On press, the code below throws the error TypeError: show() takes 1 positional argument but 2 were given and crashes the program.

class TimerButton(ButtonBehavior, Image):
    timer_container = ObjectProperty(None)
    client_scoreboard = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(TimerButton, self).__init__(**kwargs)
        self.bind(on_press=self.show)
        self.bind(on_release=self.changeImage)

    def show(self):
        print('hi there')
        self.source = 'assets/mainViewTimerButtonPressed.png'
        import kivy.animation as Animate
        anim = Animate.Animation(
            x=self.client_scoreboard.right - self.timer_container.width,
            y=self.timer_container.y,
            duration=0.25)
        anim.start(self.timer_container)
        self.unbind(on_press=self.show)
        self.bind(on_press=self.hide)

    def changeImage(self):
        self.source = 'assets/mainViewTimerButton.png'

    def hide(self):
        import kivy.animation as Animate
        anim = Animate.Animation(
            x=self.client_scoreboard.width,
            y=self.timer_container.y,
            duration=0.25)
        anim.start(self.timer_container)
        self.unbind(on_press=self.hide)
        self.bind(on_press=self.show)

Answer 1

The answer is to include the class name, in this case TimerButton , in the function definitions. This is a concept I don't completely understand since the function is defined within the scope of the TimerButton class. But hey, it works.

class TimerButton(ButtonBehavior, Image):
    timer_container = ObjectProperty(None)
    client_scoreboard = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(TimerButton, self).__init__(**kwargs)
        self.bind(on_press=self.show)
        self.bind(on_release=self.changeImage)

    def show(self):
        print('hi there')
        self.source = 'assets/mainViewTimerButtonPressed.png'
        import kivy.animation as Animate
        anim = Animate.Animation(
            x=self.client_scoreboard.right - self.timer_container.width,
            y=self.timer_container.y,
            duration=0.25)
        anim.start(self.timer_container)
        self.bind(on_press=self.hide)

    def changeImage(self):
        self.source = 'assets/mainViewTimerButton.png'

    def hide(self):
        import kivy.animation as Animate
        anim = Animate.Animation(
            x=self.client_scoreboard.width,
            y=self.timer_container.y,
            duration=0.25)
        anim.start(self.timer_container)
        self.bind(on_press=self.show)

Answer 2

The kivy code that calls the function you set in .bind() is passing an argument which your function isn't prepared for. It's been a while since I last used kivy, so I can't be sure, but I think the event details are passed to the function.

As such, your definitions for event handlers should look like this:

def show(self, event):
    ...

def hide(self, event):
    ...

If you're curious, you could print(event) within those functions, to see what's being sent in.