List control, property change generates two events

Ignition
1

I have the following code in the property change event handler for a single select list:

if event.propertyName == 'selectedIndex':
    print event.source.selectedIndex

Two events are generated as I click on each item in the list box. Here is some sample output:

3
3
2
2
4
4

I think this issue has been highlighted before (“One other thing- working with Colby the other day, we found that the List.selectedIndex property change generates two events instead of one”). For details see:
http://www.inductiveautomation.com/forum/viewtopic.php?f=23&t=3974&p=7685&hilit=list+selectedIndex#p7685

Is this correct behaviour? If it is, can you suggest a simple workaround so I can get a single event for a single click?

We are using Ignition version 7.2.3 (b6630).

Thank you for your help,

2

You can work around this issue with a client property.

if event.propertyName == 'selectedIndex':
    if event.newValue != event.source.getClientProperty("LastIndex"):
        print event.source.selectedIndex
        event.source.putClientProperty("LastIndex",event.newValue)
3

Hello Kyle,

Thank you very much for the work around. My property change event is working perfectly now.

I can’t find any details of the methods:

event.source.getClientProperty
event.source.putClientProperty

…in the Ignition documentation. Is this working directly with dynamic properties?

Thank you again for your help,

Patrick

4

All the components in Ignition are extensions of JComponents.
http://download.oracle.com/javase/6/docs/api/javax/swing/JComponent.html

As such, most methods available to a JComponent will be available to Ignition Components, unless they are over-ridden.

Because the scripts we write are written in Jython, we can access the Java methods and constructors through Jython.

To list all the methods available to a certain component, you can do the following:

methods = event.source.parent.getComponent('Pie Chart').class.getMethods() data = [] for method in methods: data.append([method]) event.source.parent.getComponent('Table').data = system.dataset.toDataSet(["Methods"],data)

You can do the same for constructors, fields, etc.

5

Thank you again Kyle. I am sure this will be very useful in future.

I am interested to see if we can store an instance of a jython class in the client properties of a control. I will try it out as soon as I get some time.

6

Yeah, you can do something like that. For example, if I wanted to set a global reference to a Java Color or something else, you can do that like this

from java.awt import Color global testColor testColor = Color(255,255,255,0)

To use this in another script, you can do the following

Global testColor print testColor

Color, itself is a Java Object, so this will work for other things, such as JFrames, Ignition components, etc.