#!/usr/bin/env python
#############################################################################
##
# This file is part of Taurus
##
# http://taurus-scada.org
##
# Copyright 2011 CELLS / ALBA Synchrotron, Bellaterra, Spain
##
# Taurus is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
##
# Taurus 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 Lesser General Public License for more details.
##
# You should have received a copy of the GNU Lesser General Public License
# along with Taurus. If not, see <http://www.gnu.org/licenses/>.
##
#############################################################################
""""""
from __future__ import print_function
__all__ = ["QTaurusBaseListener", "QObjectTaurusListener"]
__docformat__ = 'restructuredtext'
from taurus.qt.qtcore.util import baseSignal
from taurus.core.util.log import deprecation_decorator
from taurus.core.tauruslistener import TaurusListener
from taurus.external.qt import Qt
[docs]class QTaurusBaseListener(TaurusListener):
"""Base class for QObjects listening to taurus events.
.. note::
:meth:`getSignaller` is now unused and deprecated. This is because
`taurusEvent` is implemented using :func:`baseSignal`, that doesn't
require the class to inherit from QObject.
"""
taurusEvent = baseSignal('taurusEvent', object, object, object)
def __init__(self, name=None, parent=None):
if name is None:
name = self.__class__.__name__
super(QTaurusBaseListener, self).__init__(name, parent=parent)
self._eventFilters = []
self.taurusEvent.connect(self.filterEvent)
#-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
# Event handling chain
#-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
[docs] def eventReceived(self, evt_src, evt_type, evt_value):
"""The basic implementation of the event handling chain is as
follows:
- eventReceived just calls :meth:`fireEvent` which emits a "taurusEvent"
PyQt signal that is connected (by :meth:`preAttach`) to the
:meth:`filterEvent` method.
- After filtering, :meth:`handleEvent` is invoked with the resulting
filtered event
.. note::
in the earlier steps of the chain (i.e., in :meth:`eventReceived`/:meth:`fireEvent`),
the code is executed in a Python thread, while from eventFilter
ahead, the code is executed in a Qt thread.
When writing widgets, one should normally work on the Qt thread
(i.e. reimplementing :meth:`handleEvent`)
:param evt_src: (object) object that triggered the event
:param evt_type: (taurus.core.taurusbasetypes.TaurusEventType) type of event
:param evt_value: (object) event value
"""
self.fireEvent(evt_src, evt_type, evt_value)
[docs] def fireEvent(self, evt_src=None, evt_type=None, evt_value=None):
"""Emits a "taurusEvent" signal.
It is unlikely that you may need to reimplement this method in subclasses.
Consider reimplementing :meth:`eventReceived` or :meth:`handleEvent`
instead depending on whether you need to execute code in the python
or Qt threads, respectively
:param evt_src: (object or None) object that triggered the event
:param evt_type: (taurus.core.taurusbasetypes.TaurusEventType or None) type of event
:param evt_value: (object or None) event value
"""
try:
self.taurusEvent.emit(evt_src, evt_type, evt_value)
except:
pass
[docs] def filterEvent(self, evt_src=-1, evt_type=-1, evt_value=-1):
"""The event is processed by each and all filters in strict order
unless one of them returns None (in which case the event is discarded)
:param evt_src: (object) object that triggered the event
:param evt_type: (taurus.core.taurusbasetypes.TaurusEventType) type of event
:param evt_value: (object) event value
"""
r = evt_src, evt_type, evt_value
if r == (-1, -1, -1):
# @todo In an ideal world the signature of this method should be
# (evt_src, evt_type, evt_value). However there's a bug in PyQt:
# If a signal is disconnected between the moment it is emitted and
# the moment the slot is called, then the slot is called without
# parameters (!?). We added this default values to detect if
# this is the case without printing an error message each time.
# If this gets fixed, we should remove this line.
return
for f in self._eventFilters:
r = f(*r)
if r is None:
return
self.handleEvent(*r)
[docs] def handleEvent(self, evt_src, evt_type, evt_value):
"""Event handling. Default implementation does nothing.
Reimplement as necessary
:param evt_src: (object or None) object that triggered the event
:param evt_type: (taurus.core.taurusbasetypes.TaurusEventType or None) type of event
:param evt_value: (object or None) event value
"""
pass
[docs] def setEventFilters(self, filters=None):
"""sets the taurus event filters list.
The filters are run in order, using each output to feed the next filter.
A filter must be a function that accepts 3 arguments ``(evt_src, evt_type, evt_value)``
If the event is to be ignored, the filter must return None.
If the event is not to be ignored, filter must return a
``(evt_src, evt_type, evt_value)`` tuple which may (or not) differ from the input.
For a library of common filters, see taurus/core/util/eventfilters.py
:param filters: (sequence) a sequence of filters
See also: insertEventFilter
"""
if filters is None:
filters = []
self._eventFilters = list(filters)
[docs] def getEventFilters(self):
"""Returns the list of event filters for this widget
:return: (sequence<callable>) the event filters
"""
return self._eventFilters
[docs] def insertEventFilter(self, filter, index=-1):
"""insert a filter in a given position
:param filter: (callable(evt_src, evt_type, evt_value)) a filter
:param index: (int) index to place the filter (default = -1 meaning place at the end)
See also: setEventFilters
"""
self._eventFilters.insert(index, filter)
@deprecation_decorator(rel='4.0')
def getSignaller(self):
return self
[docs]class QObjectTaurusListener(Qt.QObject, QTaurusBaseListener):
def __init__(self, name=None, parent=None):
self.call__init__wo_kw(Qt.QObject, parent)
self.call__init__(QTaurusBaseListener, name=name)
[docs]class ListenerDemo(QObjectTaurusListener):
[docs] def eventReceived(self, evt_src, evt_type, evt_value):
self.info("New %s event from %s",
taurus.core.taurusbasetypes.TaurusEventType[evt_type], evt_src)
return super(ListenerDemo, self).eventReceived(evt_src, evt_type, evt_value)
[docs] def handleEvent(self, evt_src, evt_type, evt_value):
self.info("New %s event from %s",
taurus.core.taurusbasetypes.TaurusEventType[evt_type], evt_src)
if __name__ == "__main__":
import time
import taurus
qlistener = ListenerDemo(name="DemoObject")
attr = taurus.Attribute("sys/tg_test/1/double_scalar")
attr.addListener(qlistener)
try:
while True:
time.sleep(1)
except KeyboardInterrupt:
print("Finished!")