Add joystick example (#4862)

* Add joystick example

* pep8 fix

examples/miscellaneous/joystick.py

@@ -0,0 +1,83 @@
+# Joystick / Gamepad example
+# STOP_FIRE from https://wiki.libsdl.org/SDL_JoyAxisEvent
+
+from kivy.app import App
+from kivy.clock import Clock
+from kivy.uix.widget import Widget
+from kivy.core.window import Window
+from kivy.properties import ObjectProperty, ListProperty
+
+
+class Listener(Widget):
+    # fire / trigger axis
+    FIRE = (2, 5)
+    STOP_FIRE = -32767
+
+    # min value for user to actually trigger axis
+    OFFSET = 15000
+
+    # current values + event instance
+    VALUES = ListProperty([])
+    HOLD = ObjectProperty(None)
+
+    def __init__(self, **kwargs):
+        super(Listener, self).__init__(**kwargs)
+
+        # get joystick events first
+        Window.bind(on_joy_hat=self.on_joy_hat)
+        Window.bind(on_joy_ball=self.on_joy_ball)
+        Window.bind(on_joy_axis=self.on_joy_axis)
+        Window.bind(on_joy_button_up=self.on_joy_button_up)
+        Window.bind(on_joy_button_down=self.on_joy_button_down)
+
+    # show values in console
+    def print_values(self, *args):
+        print(self.VALUES)
+
+    def joy_motion(self, event, id, axis, value):
+        # HAT first, returns max values
+        if isinstance(value, tuple):
+            if not value[0] and not value[1]:
+                Clock.unschedule(self.HOLD)
+            else:
+                self.VALUES = [event, id, axis, value]
+                self.HOLD = Clock.schedule_interval(self.print_values, 0)
+            return
+
+        # unschedule if at zero or at minimum (FIRE)
+        if axis in self.FIRE and value < self.STOP_FIRE:
+            Clock.unschedule(self.HOLD)
+            return
+        elif abs(value) < self.OFFSET or self.HOLD:
+            Clock.unschedule(self.HOLD)
+
+        # schedule if over OFFSET (to prevent accidental event with low value)
+        if (axis in self.FIRE and value > self.STOP_FIRE or
+                axis not in self.FIRE and abs(value) >= self.OFFSET):
+            self.VALUES = [event, id, axis, value]
+            self.HOLD = Clock.schedule_interval(self.print_values, 0)
+
+    # replace window instance with identifier
+    def on_joy_axis(self, win, stickid, axisid, value):
+        self.joy_motion('axis', stickid, axisid, value)
+
+    def on_joy_ball(self, win, stickid, ballid, value):
+        self.joy_motion('ball', ballid, axisid, value)
+
+    def on_joy_hat(self, win, stickid, hatid, value):
+        self.joy_motion('hat', stickid, hatid, value)
+
+    def on_joy_button_down(self, win, stickid, buttonid):
+        print('button_down', stickid, buttonid)
+
+    def on_joy_button_up(self, win, stickid, buttonid):
+        print('button_up', stickid, buttonid)
+
+
+class JoystickApp(App):
+    def build(self):
+        return Listener()
+
+
+if __name__ == '__main__':
+    JoystickApp().run()