How do you check for keyboard events with kivy?

Question

So, awhile ago, I started teaching myself kivy. I started with the main kivy website and went through its pong making tutorial and upon finishing that I decided to try and give it key input. I just can't seem to find any kind of guide to key input with kivy! Anyone know some kind of tutorial or can provide some easy to understand code? I did look at the Keyboard Listener in the examples folder of kivy, but I'm not quite sure how to use that if I'm supposed to.

Thanks for any assistance.

score 34 · Answer 1 · edited Apr 21 '16 at 19:53

34

I guess you are asking how to control the paddles with the keyboard. I assume you have the final ping pong codes running on your computer (If not, you can find them at the end of this section).

1 - In the main.py import the Window class:

from kivy.core.window import Window

2 - Redefine the beginning of the PongGame class so it looks like the following:

class PongGame(Widget):
    ball = ObjectProperty(None)
    player1 = ObjectProperty(None)
    player2 = ObjectProperty(None)

    def __init__(self, **kwargs):
        super(PongGame, self).__init__(**kwargs)
        self._keyboard = Window.request_keyboard(self._keyboard_closed, self)
        self._keyboard.bind(on_key_down=self._on_keyboard_down)

    def _keyboard_closed(self):
        self._keyboard.unbind(on_key_down=self._on_keyboard_down)
        self._keyboard = None

    def _on_keyboard_down(self, keyboard, keycode, text, modifiers):
        if keycode[1] == 'w':
            self.player1.center_y += 10
        elif keycode[1] == 's':
            self.player1.center_y -= 10
        elif keycode[1] == 'up':
            self.player2.center_y += 10
        elif keycode[1] == 'down':
            self.player2.center_y -= 10
        return True

Voilà! Press w and s for the left paddle and up and down for the right paddle.

edited Apr 21 '16 at 19:53

illright

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answered Jun 25 '13 at 11:28

toto_tico

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Ah, that seems to work for the time being, but what would I do if I wanted each class to have their own key checking? Would I only have to use the _on_keyboard_down func in each class? Or would I have to initialize the keyboard multiple times? – Alex Jun 25 '13 at 16:42
@Alex, that is a different question. Feel free to ask a new question instead of using the comments. – toto_tico Jun 25 '13 at 16:54
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You would have to use _keyboard.bind() in all the widgets that need it. – Tshirtman Jun 25 '13 at 18:44
It gives an error to me `_on_keyboard_down() takes exactly 5 arguments (6 given) ` – Guglie Dec 12 '17 at 13:49
1

I'm trying this in kivy `v1.10.1.dev0, git-5f62b6b, 20180103` and no joy :( – CpILL Feb 04 '18 at 01:25
pretty sweet additions, thanks! I changed 10 to 50 and it seemed to be a pretty playable game. Though i don't know why, but after making these changes the ball keeps accelerating faster and faster. If left alone, it will eventually go through the left paddle. – FistOfFury Sep 04 '20 at 18:45

How do you check for keyboard events with kivy?

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