Pythonaddins combobox advanced functionality

Question

I made an Add-in for ArcMap that shows important news for our company. It is actually a toolbar with combobox and refresh button. It loads news from a text file located in our server and as every user has an access to it, this toolbar loads lines from this file. Finally it looks like this:

Here is a part of code

class gc_cmb(object):
"""Implementation for GC_NewsToolbar_addin.combobox (ComboBox)"""
def __init__(self):
    file_txt =  u'\\\SRV-03\\Projects\\UTILS\\AddIns\\\\news.txt'
    list_news = []
    with open(file_txt, 'r') as myfile:
        list_news=myfile.read().split('\n')

    self.value = list_news[0]
    self.items = list_news
    self.editable = True
    self.enabled = True
    self.dropdownWidth = 'WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW'
    self.width = 'WWWWWWWWWWWWWWWWW'

User can see the latest new in a combobox's window here self.value = list_news[0]. Other news are in a dropdown list. The refresh button updates this list. But there one thing I would like to add:

Auto-update - It would be much better if news are refreshng automtically after text file is edited. Looks like writing some kind of timer but it probably can interrupt geoprocessing tools if they are launch.

Any thoughts?

Answer 1

I've not had much call in developing Python AddIns but what you were asking is something I would have approached in VB .net using an extension with an event firing on something specific.

If you look at the help file you can create a Python add-in application extension. This can hook into various events, an obvious one is on openDocument() or possibly contentsChanged(); you could get the combobox to refresh on that.

Below is a basic outline of me adding things to the list, in your case you would use your code to read from your text file. I hook into 3 events to improve the regular updating of the combobox.

import arcpy
import pythonaddins


class myComboBoxClass(object):
    """Implementation for PythonAddIns_addin.combobox (ComboBox)"""
    def __init__(self):
        self.items = ["item1", "item2"]
        self.editable = True
        self.enabled = True
        self.dropdownWidth = 'WWWWWW'
        self.width = 'WWWWWW'
    def onSelChange(self, selection):
        pass
    def onEditChange(self, text):
        pass
    def onFocus(self, focused):
        # Add text to list on click of control as suggested by Kadir
        if focused:
            self.items.append("Click me!")
    def onEnter(self):
        pass
    def refresh(self):
        pass

class myExtensionClass(object):
    """Implementation for PythonAddIns_addin.extension2 (Extension)"""

    # Note to access the combobox I use the name after the full stop in PythonAddIns_addin.combobox, so combobox
    def __init__(self):
        # For performance considerations, please remove all unused methods in this class.
        self.enabled = True
    def openDocument(self):
        combobox.items.append("FUNKY")
    def contentsChanged(self):
        combobox.items.append("WOMBAT")
    def itemAdded(self, new_item):
        combobox.items.append("ROBOT")

Answer 2

I doubt you can use timer in addin seamlessly. If possible, I want to learn, too. However, you can use onFocus() function of combobox. This is not a perfect solution, but it might be helpful.

class gc_cmb(object):

    def __init__(self):
        self.editable = True
        self.enabled = True
        self.dropdownWidth = 'WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW'
        self.width = 'WWWWWWWWWWWWWWWWW'
        self.getNews() ####

    def onFocus(self, focused):
        if focused:
            self.getNews() ####

    def getNews(self): ####
        file_txt =  u'\\\SRV-03\\Projects\\UTILS\\AddIns\\\\news.txt'
        list_news = []
        with open(file_txt, 'r') as myfile:
            list_news = myfile.read().split('\n')

        self.value = list_news[0]
        self.items = list_news

In that way, when combobox gets focus by any user, content of combobox changes.