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# Copyright (C) 2009, Tutorius.org
# Copyright (C) 2009, Vincent Vinet <vince.vinet@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import gobject
from sugar.tutorius.gtkutils import find_widget
class EventFilter(object):
"""
Base class for an event filter
"""
def __init__(self, next_state):
"""
Constructor.
@param next_state name of the next state
"""
self._next_state = next_state
self._callback = None
def get_next_state(self):
"""
Getter for the next state
"""
return self._next_state
def set_next_state(self, new_next_name):
"""
Setter for the next state. Should only be used during construction of
the event_fitler, not while the tutorial is running.
"""
self._next_state = new_next_name
def install_handlers(self, callback, **kwargs):
"""
install_handlers is called for eventfilters to setup all
necessary event handlers to be able to catch the desired
event.
@param callback the callback function that will be called
with the event filter as an argument when the event is catched
and validated.
@param **kwargs unused by this handler for now, allows subclasses
to receive information about the context when installing
Subclasses must call this super method to setup the callback if they
feel like cooperating
"""
self._callback = callback
def remove_handlers(self):
"""
remove_handlers is called when a state is done so that all
event filters can cleanup any handlers they have installed
This function will also clear the callback function so that any
leftover handler that is triggered will not be able to change the
application state.
subclasses must call this super method to cleanup the callback if they
collaborate and use this classe's do_callback()
"""
self._callback = None
def do_callback(self, *args, **kwargs):
"""
Default callback function that calls the event filter callback
with the event filter as only argument.
"""
if self._callback:
self._callback(self)
class TimerEvent(EventFilter):
"""
TimerEvent is a special EventFilter that uses gobject
timeouts to trigger a state change after a specified amount
of time. It must be used inside a gobject main loop to work.
"""
def __init__(self,next_state,timeout_s):
"""Constructor.
@param next_state default EventFilter param, passed on to EventFilter
@param timeout_s timeout in seconds
"""
super(TimerEvent,self).__init__(next_state)
self._timeout = timeout_s
self._handler_id = None
def install_handlers(self, callback, **kwargs):
"""install_handlers creates the timer and starts it"""
super(TimerEvent,self).install_handlers(callback, **kwargs)
#Create the timer
self._handler_id = gobject.timeout_add_seconds(self._timeout, self._timeout_cb)
def remove_handlers(self):
"""remove handler removes the timer"""
super(TimerEvent,self).remove_handlers()
if self._handler_id:
try:
#XXX What happens if this was already triggered?
#remove the timer
gobject.source_remove(self._handler_id)
except:
pass
def _timeout_cb(self):
"""
_timeout_cb triggers the eventfilter callback.
It is necessary because gobject timers only stop if the callback they
trigger returns False
"""
self.do_callback()
return False #Stops timeout
class GtkWidgetEventFilter(EventFilter):
"""
Basic Event filter for Gtk widget events
"""
def __init__(self, next_state, object_id, event_name):
"""Constructor
@param next_state default EventFilter param, passed on to EventFilter
@param object_id object fqdn-style identifier
@param event_name event to attach to
"""
super(GtkWidgetEventFilter,self).__init__(next_state)
self._callback = None
self._object_id = object_id
self._event_name = event_name
self._widget = None
self._handler_id = None
def install_handlers(self, callback, **kwargs):
"""install handlers
@param callback default EventFilter callback arg
@param activity keyword argument activity must be present to install
the event handler into the activity's widget hierarchy
"""
super(GtkWidgetEventFilter, self).install_handlers(callback, **kwargs)
if not "activity" in kwargs:
raise TypeError("activity argument is Mandatory")
#find the widget and connect to its event
self._widget = find_widget(kwargs["activity"], self._object_id)
self._handler_id = self._widget.connect( \
self._event_name, self.do_callback )
def remove_handlers(self):
"""remove handlers"""
super(GtkWidgetEventFilter, self).remove_handlers()
#if an event was connected, disconnect it
if self._handler_id:
self._widget.handler_disconnect(self._handler_id)
self._handler_id=None
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