multitouch/src/trackers/tap.py

import time
from threading import Thread

from ..tracker import GestureTracker
from ..geometry import Positionable
from utils import PointGesture


class TapTracker(GestureTracker):
    __gesture_types__ = ['tap', 'single_tap', 'double_tap']

    __configurable__ = ['tap_distance', 'tap_time', 'double_tap_time',
                        'double_tap_distance', 'update_rate']

    def __init__(self, window=None):
        super(TapTracker, self).__init__(window)

        # Map of TUIO session id to tuple (timestamp, position) of point down
        self.reg = {}

        # Maximum radius in which a touch point can move in order to be a tap
        # event in pixels
        self.tap_distance = 20

        # Maximum time between 'down' and 'up' of a tap event in seconds
        self.tap_time = .2

        # Maximum time in seconds and distance in pixels between two taps to
        # count as double tap
        self.double_tap_time = .3
        self.double_tap_distance = 30

        # Times per second to detect single taps
        self.update_rate = 30

        self.reset_last_tap()
        self.single_tap_thread = Thread(target=self.detect_single_tap)
        self.single_tap_thread.daemon = True
        self.single_tap_thread.start()

    def detect_single_tap(self):
        """
        Iteration function for single-tap detection thread.
        """
        while True:
            time_diff = time.time() - self.last_tap_time

            if self.last_tap and time_diff > self.double_tap_time:
                # Last tap is too long ago to be a double tap, so trigger a
                # single tap
                self.trigger(SingleTapGesture(self.last_tap))
                self.reset_last_tap()

            time.sleep(1. / self.update_rate)

    def reset_last_tap(self):
        self.last_tap_time = 0
        self.last_tap = None

    def on_point_down(self, point):
        x, y = point.get_position()
        self.reg[point.sid] = time.time(), Positionable(x, y)

    def on_point_move(self, point):
        if point.sid not in self.reg:
            return

        # If a stationary point moves beyond a threshold, delete it so that the
        # 'up' event will not trigger a 'tap'
        t, initial_position = self.reg[point.sid]

        if point.distance_to(initial_position) > self.tap_distance:
            del self.reg[point.sid]

    def on_point_up(self, point):
        # Assert that the point has not been deleted by a 'move' event yet
        if point.sid not in self.reg:
            return

        down_time = self.reg[point.sid][0]
        del self.reg[point.sid]

        # Only trigger a tap event if the 'up' is triggered within a certain
        # time afer the 'down'
        current_time = time.time()

        if current_time - down_time > self.tap_time:
            return

        tap = TapGesture(point)
        self.trigger(tap)

        # Trigger double tap if the threshold has not not expired yet
        if self.last_tap:
            if self.last_tap.distance_to(tap) <= self.double_tap_distance:
                # Close enough to be a double tap
                self.trigger(DoubleTapGesture(self.last_tap))
                self.reset_last_tap()
                return

            # Generate a seperate single tap gesture for the last tap,
            # because the lat tap variable is overwritten now
            self.trigger(SingleTapGesture(self.last_tap))

        self.last_tap_time = current_time
        self.last_tap = tap


class TapGesture(PointGesture):
    """
    A tap gesture is triggered
    """
    __type__ = 'tap'


class SingleTapGesture(TapGesture):
    """
    A single tap gesture is triggered after a regular tap gesture, if no double
    tap is triggered for that gesture.
    """
    __type__ = 'single_tap'


class DoubleTapGesture(TapGesture):
    """
    A double tap gesture is triggered if two sequential taps are triggered
    within a certain time and distance of eachother.
    """
    __type__ = 'double_tap'