multitouch/tests/hand.py

from src.tracker import GestureTracker, Gesture
from src.geometry import Positionable


class HandGesture(Gesture):
    def __init__(self, hand, finger=None):
        self.hand = hand
        self.finger = finger

    def get_hand(self):
        return self.hand

    def get_finger(self):
        return self.finger


class HandDownGesture(HandGesture):
    _type = 'hand_down'


class HandUpGesture(HandGesture):
    _type = 'hand_up'


class FingerDownGesture(HandGesture):
    _type = 'finger_down'


class FingerMoveGesture(HandGesture):
    _type = 'finger_move'


class FingerUpGesture(HandGesture):
    _type = 'finger_up'


class Hand(Positionable):
    def __init__(self):
        self.fingers = []
        self.centroid = None

    def __len__(self):
        return len(self.fingers)

    def __iter__(self):
        return iter(self.fingers)

    def __str__(self):
        return '<Hand fingers=%s centroid=%s>' \
               % (self.fingers, self.get_centroid())

    def __repr__(self):
        return str(self)

    def add_finger(self, finger):
        self.fingers.append(finger)
        self.update_centroid()

    def remove_finger(self, finger):
        self.fingers.remove(finger)
        self.update_centroid()

    def update_centroid(self):
        l = len(self.fingers)

        if not l:
            self.centroid = None
            return

        coords = [f.get_position() for f in self.fingers]
        all_x, all_y = zip(*coords)
        self.centroid = sum(all_x) / l, sum(all_y) / l

    def get_centroid(self):
        return self.centroid


class HandTracker(GestureTracker):
    supported_gestures = [HandDownGesture, HandUpGesture, FingerDownGesture,
                          FingerMoveGesture, FingerUpGesture]

    configurable = ['max_finger_distance']

    def __init__(self, area):
        super(HandTracker, self).__init__(area)

        # Map of finger id's to corresponding hand objects
        self.finger_hands = {}

        # All hands being tracked
        self.hands = []

        # Maximum distance between two fingers to be assigned to the same hand
        self.max_finger_distance = 300

    def find_hand(self, finger):
        min_dist = hand = None

        for h in self.hands:
            dist = finger.distance_to(h.get_centroid())

            if min_dist is None or dist < min_dist:
                min_dist = dist
                hand = h

        if not hand or min_dist > self.max_finger_distance:
            hand = Hand()
            self.hands.append(hand)

        self.finger_hands[finger.get_id()] = hand
        hand.add_finger(finger)

        if len(hand) == 1:
            self.trigger(HandDownGesture(hand))

        return hand

    def on_point_down(self, event):
        finger = event.get_touch_object()
        hand = self.find_hand(finger)
        self.trigger(FingerDownGesture(hand, finger))

    def on_point_move(self, event):
        finger = event.get_touch_object()

        if finger.get_id() not in self.finger_hands:
            return

        hand = self.finger_hands[finger.get_id()]
        hand.update_centroid()

        if finger.distance_to(hand.get_centroid()) > self.max_finger_distance:
            hand.remove_finger(finger)

            if not len(hand):
                self.hands.remove(hand)
                self.trigger(HandUpGesture(hand))

            hand = self.find_hand(finger)

        self.trigger(FingerMoveGesture(hand, finger))

    def on_point_up(self, event):
        finger = event.get_touch_object()
        finger_id = finger.get_id()

        if finger_id not in self.finger_hands:
            return

        hand = self.finger_hands[finger_id]
        del self.finger_hands[finger_id]
        hand.remove_finger(finger)
        self.trigger(FingerUpGesture(hand, finger))

        if not len(hand):
            self.hands.remove(hand)
            self.trigger(HandUpGesture(hand))