Added support for Leap Motion device events

platypush/backend/__init__.py

@@ -190,8 +190,7 @@ class Backend(Thread):
         Param:
             msg -- The message
         """
-
-        raise NotImplementedError("send_message should be implemented in a derived class")
+        pass
 
 
     def run(self):

platypush/backend/sensor/leap.py

@@ -0,0 +1,167 @@
+import logging
+import time
+
+import Leap
+
+from platypush.backend import Backend
+from platypush.context import get_backend
+from platypush.message.event.sensor.leap import LeapFrameEvent, \
+    LeapFrameStartEvent, LeapFrameStopEvent, LeapConnectEvent, LeapDisconnectEvent
+
+
+class SensorLeapBackend(Backend):
+    """
+    Backend for events generated using a Leap Motion device to track hands and
+    gestures, https://www.leapmotion.com/
+
+    Note that the default SDK is not compatible with Python 3. Follow the
+    instructions on https://github.com/BlackLight/leap-sdk-python3 to build the
+    Python 3 module.
+
+    Also, you'll need the Leap driver and utils installed on your OS (follow
+    instructions at https://www.leapmotion.com/setup/) and the `leapd` daemon
+    running to recognize your controller.
+    """
+
+    def __init__(self,
+                 position_ranges=[
+                     [-300.0, 300.0],  # x axis
+                     [25.0, 600.0],    # y axis
+                     [-300.0, 300.0],  # z axis
+                 ],
+                 position_tolerance=0.2,  # Position variation tolerance in %
+                 *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.position_ranges = position_ranges
+        self.position_tolerance = position_tolerance
+
+
+    def run(self):
+        super().run()
+
+        listener = LeapListener(position_ranges=self.position_ranges,
+                                position_tolerance=self.position_tolerance)
+
+        controller = Leap.Controller()
+
+        if not controller:
+            raise RuntimeError('No Leap Motion controller found - is your ' +
+                               'device connected and is leapd running?')
+
+        controller.add_listener(listener)
+        logging.info('Leap Motion backend initialized')
+
+        try:
+            while not self.should_stop():
+                time.sleep(0.1)
+        finally:
+            controller.remove_listener(listener)
+
+
+
+class LeapListener(Leap.Listener):
+    def __init__(self, position_ranges, position_tolerance, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.prev_frame = None
+        self.position_ranges = position_ranges
+        self.position_tolerance = position_tolerance
+
+
+    def send_event(self, event):
+        backend = get_backend('redis')
+        if not backend:
+            logging.warning('Redis backend not configured, I cannot propagate the following event: {}'.format(event))
+            return
+
+        backend.send_message(event)
+
+
+    def on_init(self, controller):
+        self.prev_frame = None
+        logging.info('Leap controller listener initialized')
+
+    def on_connect(self, controller):
+        logging.info('Leap controller connected')
+        self.prev_frame = None
+        self.send_event(LeapConnectEvent())
+
+    def on_disconnect(self, controller):
+        logging.info('Leap controller disconnected')
+        self.prev_frame = None
+        self.send_event(LeapDisconnectEvent())
+
+    def on_exit(self, controller):
+        logging.info('Leap listener terminated')
+
+    def on_frame(self, controller):
+        frame = controller.frame()
+
+        if len(frame.hands) > 0:
+            hands = self._flatten_hands(frame)
+            if hands:
+                if not self.prev_frame:
+                    self.send_event(LeapFrameStartEvent())
+                self.send_event(LeapFrameEvent(hands=hands))
+            self.prev_frame = frame
+        else:
+            if self.prev_frame:
+                self.send_event(LeapFrameStopEvent())
+            self.prev_frame = None
+
+    def _flatten_hands(self, frame):
+        return [
+            {
+                'confidence': hand.confidence,
+                'direction': [hand.direction[0], hand.direction[1], hand.direction[2]],
+                'id': hand.id,
+                'is_left': hand.is_left,
+                'is_right': hand.is_right,
+                'palm_normal': [hand.palm_normal[0], hand.palm_normal[1], hand.palm_normal[2]],
+                'palm_position': self._normalize_position(hand.palm_position),
+                'palm_velocity': [hand.palm_velocity[0], hand.palm_velocity[1], hand.palm_velocity[2]],
+                'palm_width': hand.palm_width,
+                'sphere_center': [hand.sphere_center[0], hand.sphere_center[1], hand.sphere_center[2]],
+                'sphere_radius': hand.sphere_radius,
+                'stabilized_palm_position': self._normalize_position(hand.stabilized_palm_position),
+                'time_visible': hand.time_visible,
+                'wrist_position': self._normalize_position(hand.wrist_position),
+            }
+            for i, hand in enumerate(frame.hands)
+            if hand.is_valid and (
+                len(frame.hands) != len(self.prev_frame.hands) or
+                self._position_changed(
+                    old_position=self.prev_frame.hands[i].stabilized_palm_position,
+                    new_position=hand.stabilized_palm_position)
+
+                if self.prev_frame
+                else True
+            )
+        ]
+
+    def _normalize_position(self, position):
+        # Normalize absolute position onto a semisphere centered in (0,0)
+        # having x_range = z_range = [-100, 100], y_range = [0, 100]
+
+        return [
+            self._scale_scalar(value=position[0], range=self.position_ranges[0], new_range=[-100.0, 100.0]),
+            self._scale_scalar(value=position[1], range=self.position_ranges[1], new_range=[0.0, 100.0]),
+            self._scale_scalar(value=position[2], range=self.position_ranges[2], new_range=[-100.0, 100.0]),
+        ]
+
+
+    def _scale_scalar(self, value, range, new_range):
+        if value < range[0]: value=range[0]
+        if value > range[1]: value=range[1]
+        return ((new_range[1]-new_range[0])/(range[1]-range[0]))*(value-range[0]) + new_range[0]
+
+
+    def _position_changed(self, old_position, new_position):
+        return (
+            abs(old_position[0]-new_position[0]) > self.position_tolerance or
+            abs(old_position[1]-new_position[1]) > self.position_tolerance or
+            abs(old_position[2]-new_position[2]) > self.position_tolerance)
+
+
+# vim:sw=4:ts=4:et:
+

platypush/message/event/sensor/leap.py

@@ -0,0 +1,30 @@
+from platypush.message.event import Event
+
+
+class LeapFrameEvent(Event):
+    def __init__(self, hands, *args, **kwargs):
+        super().__init__(hands=hands, *args, **kwargs)
+
+
+class LeapFrameStartEvent(Event):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+
+class LeapFrameStopEvent(Event):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+
+class LeapConnectEvent(Event):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+
+class LeapDisconnectEvent(Event):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+
+# vim:sw=4:ts=4:et:
+

setup.py

@@ -83,6 +83,7 @@ setup(
         'Support for custom hotword detection': ['snowboy'],
         'Support for GPIO pins access': ['RPi.GPIO'],
         'Support for MCP3008 analog-to-digital converter plugin': ['adafruit-mcp3008'],
+        # 'Support for Leap Motion backend': ['git+ssh://git@github.com:BlackLight/leap-sdk-python3.git', 'redis'],
         # 'Support for Flic buttons': ['git+ssh://git@github.com/50ButtonsEach/fliclib-linux-hci']
     },
 )