edisonqkj / pyaddin-interval-caller

Base Extension class to add an onTimer method to Python Add-In Extensions in ArcGIS 10.1+.

Interval-Callable ArcGIS Extension

This library extends your Extension classes in ArcGIS Add-Ins (in Python) to have an onTimer() event, which is called at configurable intervals.

Installing

Install locally on your machine using setup.py:

C:\gitprojects\pyaddin-interval-caller> C:\Python27\ArcGIS10.2\Python setup.py install

Or copy the tickextension folder into your Add-In's Install\ folder.

Using this Dingus

Make an python add-in with at least one extension class. Import tickextension near the top of your Whatever_addin.py file. If you opted for the copy-into-Install\ option over using setup.py, you'll do it like this:

import imp
import os
tickextension_info = imp.find_module('tickextension',
                                     [os.path.dirname(
                                         os.path.abspath(__file__))])
tickextension = imp.load_module('tickextension', *tickextension_info)

If you did the setup.py it's just import tickextension like always.

Then make these changes to your extension class:

• Inherit from tickextension.TickExtension.
• Add a onTimer(self): event. No arguments.
• If you have a startup method, add a super call if it so the TickExtension's startup is also called.
• Set a self.interval attribute. It will be a float which is the interval, in seconds, in which the onTimer method is called.

Here is a visual example of what you'll need to do:

import imp
import os
tickextension_info = imp.find_module('tickextension',
                                     [os.path.dirname(
                                         os.path.abspath(__file__))])
tickextension = imp.load_module('tickextension', *tickextension_info)

import arcpy
import pythonaddins

class MyNewAndShinyExtensionClass(tickextension.TickExtension):
    def __init__(self):
        self.interval = 0.5 # Call every half second
    def startup(self):
        super(MyNewAndShinyExtensionClass, self).startup()
    def onTimer(self):
        print "Tick"

The timer will turn itself off automatically when the extension is disabled. To turn it off manually, del self.interval. No interval set = no interval calls. If you wish to start it up again, set self.interval to a valid interval again and call self.startTimer().

Be careful, try to follow the simple built-in enabled/disabled workflow if you can. If the interval ticker sticks around after the extension is deactivated, it will never be garbage collected and will hang the program.

How It Works

Win32. Injecting a timer event into Arc*.exe's Windows event loop via ::SetTimer. Check out the CallQueue class in call_later.py for all the gory, pedantic, confusing details. You could also take that class to do other horrible timer-based ugliness in Python in Arc*.exe for your own amusement/profit.

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

[](Esri: Python Add-In Timed Call Extension) [](Esri Language: Python)