multitouch/src/tracker.py

from logger import Logger


class GestureTracker(Logger):
    """
    Abstract class for gesture tracker definitions. Contains methods for
    changing the state of touch points.
    """
    # Supported gesture types
    gesture_types = []

    # Configurable properties (see configure() method)
    configurable = []

    def __init__(self, window=None):
        # Hashmap of gesture types
        self.handlers = {}

        if window:
            window.add_tracker(self)

    def bind(self, gesture_type, handler, *args, **kwargs):
        """
        Bind a handler to a gesture type. Multiple handlers can be bound to a
        single gesture type. Optionally, (keyword) arguments that will be
        passed to the handler along with a Gesture object can be specified.
        """
        if gesture_type not in self.gesture_types:
            raise ValueError('Unsupported gesture type "%s".' % gesture_type)

        h = handler, args, kwargs

        if gesture_type not in self.handlers:
            self.handlers[gesture_type] = [h]
        else:
            self.handlers[gesture_type].append(h)

    def trigger(self, gesture):
        if gesture._type not in self.handlers:
            self.debug('Triggered "%s", but no handlers are bound.'
                       % gesture._type)
            return

        self.info('Triggered %s.' % gesture)

        for handler, args, kwargs in self.handlers[gesture._type]:
            handler(gesture, *args, **kwargs)

    def is_type_bound(self, gesture_type):
        return gesture_type in self.handlers

    def on_point_down(self, point):
        pass

    def on_point_move(self, point):
        pass

    def on_point_up(self, point):
        pass

    def configure(self, **kwargs):
        for name, value in kwargs.iteritems():
            if name not in self.configurable:
                raise ValueError('%s.%s is not a configurable property.'
                                 % (self.__class__.__name__, name))

            setattr(self, name, value)

    def __getattr__(self, name):
        """
        Allow calls like:
        tracker.gesture(...)
        instead of:
        tracker.bind('gesture', ...)
        """
        if name not in self.gesture_types:
            raise AttributeError("'%s' has no attribute '%s'"
                                 % (self.__class__.__name__, name))

        return lambda handler: self.bind(name, handler)


class Gesture(object):
    """
    Abstract class that represents a triggered gesture.
    """
    pass