source: qtprobe-demo/traits_probe.py @ 858

#!/usr/bin/env python

########### SVN repository information ###################
# $Date: 2012-05-31 20:01:30 +0000 (Thu, 31 May 2012) $
# $Author: jemian $
# $Revision: 858 $
# $URL: qtprobe-demo/traits_probe.py $
# $Id: traits_probe.py 858 2012-05-31 20:01:30Z jemian $
########### SVN repository information ###################

'''
EPICS PvProbe built using Enthought Traits

*pvProbe* is one of the simplest EPICS user GUI tools.
It is used to watch the value of an EPICS Process Variable.

This version is based on the Enthought Traits user interface toolkit.

USAGE::

    [jemian@gov]$ ./pvProbe.py -h
    usage: pvProbe.py [-h] [pv]
    
    pvProbe: EPICS Traits-based version of Probe
    
    positional arguments:
      pv          EPICS PV name
    
    optional arguments:
      -h, --help  show this help message and exit


SEE ALSO:

For more information about Python version of pvProbe, see
this presentation from the 2012 EPICS Collaboration Meeting:
https://subversion.xor.aps.anl.gov/bcdaext/qtprobe-demo/docs/build/html/index.html

This code is the work entitled *traits_probe.py*.
'''

__description__ = "EPICS Traits-based version of pvProbe"


import argparse
import epics
import sys                  #@UnusedImport


choose_Qt4 = True
choose_Qt4 = False
from traits.etsconfig.api import ETSConfig
if choose_Qt4:
    ETSConfig.toolkit = 'qt4'
else:
    ETSConfig.toolkit = 'wx'

from traits.api import *    #@UnusedWildImport
from traitsui.api import *  #@UnusedWildImport
from traitsui.key_bindings \
    import KeyBinding, KeyBindings


key_bindings = KeyBindings(
    KeyBinding( binding1    = 'Enter',
                description = 'Connect to new PV',
                method_name = 'connect' ),
    KeyBinding( binding1    = 'Return',
                description = 'Connect to new PV',
                method_name = 'connect' ),
)


# 
class CodeHandler ( Handler ):
    '''TraitsUI Handler class for bound methods
    '''
    
    def connect ( self, info ):
        '''handle a request to connect with an EPICS PV
        '''
        info.object.do_connect()
        if len(info.object.name) > 0:
            # FIXME: This is not working
            info.object.title = "pvProbe: " + str(info.object.name)


class Probe( HasTraits ):
    '''EPICS PvProbe built using Enthought Traits
    '''
    name = Str
    value = Str
    _chid = Instance( epics.PV, value = None )

    def do_callback(self, value=None, **kwds):
        """simple monitor callback"""
        self.value = str(value)

    traits_view = View(
        Item('name'),
        Readonly('value'),
        resizable=True,
        width = 250,
        title='pvProbe',
        key_bindings = key_bindings,
        handler   = CodeHandler()
    )
    
    def do_connect(self):
        '''connect this GUI with an EPICS Process Variable
           and set up a Channel Access monitor to update ``value``
           whenever the PV changes.
        '''
        if len(self.name) > 0:
            try:
                if self._chid is not None:
                    self._chid.cancel_callback()
                    self._chid.disconnect()
            except:
                pass
            self._chid = epics.PV(str(self.name), 
                                  callback=self.do_callback)
    
    def __init__(self, name=""):
        HasTraits.__init__(self)
        self.name = name
        self.do_connect()


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description=__description__)
    parser.add_argument('pv', 
                        action='store', 
                        nargs='?', 
                        help="EPICS PV name", 
                        default="EpicsDemo1")
    results = parser.parse_args()

    probe = Probe(name=results.pv)
    probe.configure_traits()