main.py

from kivy.app import App
from jnius.reflect import autoclass
from jnius.jnius import cast
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.gridlayout import GridLayout
#from kivy.clock import Clock

#from multiprocessing import Process, Pipe
from functools import partial

PythonActivity = autoclass('org.renpy.android.PythonActivity')
BluetoothAdapter = autoclass('android.bluetooth.BluetoothAdapter')
Intent = autoclass('android.content.Intent')
List = autoclass('java.util.ArrayList')


class MyApp(App):
    def build(self):
        root = BoxLayout()

        buttons = BoxLayout(size_hint_x=.2, orientation='vertical')
        root.add_widget(buttons)

        b = Button(text='ask for bluetooth')
        b.bind(on_release=self.ask)
        buttons.add_widget(b)

        b = Button(text='get bonded devices')
        b.bind(on_release=self.get_bonded)
        buttons.add_widget(b)

        b = Button(text='discover')
        b.bind(on_release=self.get_bonded)
        buttons.add_widget(b)

        b = Button(text='cancel discovery')
        b.bind(on_release=self.get_bonded)
        buttons.add_widget(b)

        self.devices = GridLayout(rows=4)
        root.add_widget(self.devices)

        self.adapter = BluetoothAdapter.getDefaultAdapter()

        return root

    def ask(self, *args):
        PythonActivity.mActivity.startActivityForResult(
                Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE), 200)

    def get_bonded(self, args):
        self.populate(self.adapter.getBondedDevices())

    def discover(self, *args):
        if not self.adapter.isEnabled():
            self.ask()

        #TODO

    def connect_async(self, device, *args):
        self.cancel_discovery()
        #parent_conn, child_conn = Pipe()

        #p = Process(target=self.conn_worker, args=(device, child_conn))
        #Clock.schedule_interval(partial(self.check_conn, parent_conn), 1)

        #p.start()

    def conn_worker(self, device, conn):
        socket = device.createRfcommSocketToServiceRecord('OHHY!THX')
        conn.send(socket)

    def connect(self, device):
        self.cancel_discovery()
        socket = device.createRfcommSocketToServiceRecord('OHHY!THX')
        print socket

    def check_conn(self, conn):
        print conn.recv()

    def cancel_discovery(self, *args):
        self.adapter.cancelDiscovery()

    def populate(self, devices):
        self.devices.clear_widgets()
        list_devices = List(devices.size())
        list_devices.addAll(cast('java.util.Collection', devices))

        for d in list_devices:
            b = Button(text=d.getName())
            b.bind(on_release=partial(self.connect, d))
            self.devices.add_widget(b)

    def on_pause(self, *args):
        return True

    def on_resume(self, *args):
        pass


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