Monday, November 15, 2004

Appointment label Colour Changing Event Sink

[2/2/2005 updated this post and script to use named property instead the custom Mapi prop]

One of the cool features that was implemented in Outlook 2002 was the ability to change the colour of appointment labels to help distinguish between different types of appointments. (see http://www.slipstick.com/calendar/colorcal.htm for a good description of this feature). But because of the laziness factor I find that I rarely use this feature because I usually forget to set it. One of the things that I really wanted this to do also was be able to show me at a glace which meetings in my calendar where internal meeting (only contained internal attendees) and which meeting contained external attendees (this can be usefull in the morning). Putting this into an event sink turned out to be a really easy solution. All I needed was some code that would go though the attendees collection of a appointment object when the appointment was created and check each of the address's of the attendees to see if they where local address's or external. I leaned on the side of low tech and just decided to go for a match against one local domain. The property that controls the appointment colour is http://schemas.microsoft.com/mapi/id/{00062002-0000-0000-C000-000000000046}/0x8214 and there are 10 integers (data type needs to be long) you can pass to it representing the different colours available in Outlook. I decided to go for blue for external meeting and green for internal meeting. The other check the code performs is to check the number of attendees in the appointment this is because I only wanted it to work on meeting or appointments where someone else other then me was attending. NOTE: I’ve restricted this sink so it only takes action on newly created appointments this is because a sink that updates properties on an existing message can be pretty dangerous. If you look at the logic when the sink fires it updates properties on the message and saves that message which then causes the sink to fire again and again and before you know it your transaction logs are full and the store is dismounted (Doh!)

The appointment label text provides a bit more of a challenge its located in the http://schemas.microsoft.com/mapi/proptag/0x36DC0102 property in an undocumented binary form, although on first look it doesn’t appear that daunting it looks like its just in byte format padded with a few zeros but this is a challenge for another day.
The code for the sink looks like this, Ive posted a copy up here


<SCRIPT LANGUAGE="VBScript">

Sub ExStoreEvents_OnSave(pEventInfo, bstrURLItem, lFlags)

Const EVT_NEW_ITEM = 1
Const EVT_IS_DELIVERED = 8

If (lFlags And EVT_IS_DELIVERED) Or (lFlags And EVT_NEW_ITEM) Then

chgappt = 0
LocalSearchdomain = "@yourdomain.com"
set apptobj = createobject("CDO.Appointment")
apptobj.datasource.open bstrURLItem,,3
cval = apptobj.fields("http://schemas.microsoft.com/mapi/id/{00062002-0000-0000-C000-000000000046}/0x8214")
if apptobj.Attendees.count > 1 then
for each attend in apptobj.Attendees
if instr(lcase(attend.address),LocalSearchdomain) = 0 then
chgappt = 1
end if
next
if chgappt = 1 then
if cavl <> 2 then
apptobj.fields("http://schemas.microsoft.com/mapi/id/{00062002-0000-0000-C000-000000000046}/0x8214") = clng(2)
apptobj.fields.update
apptobj.datasource.save
end if
else
if cavl <> 3 then
apptobj.fields("http://schemas.microsoft.com/mapi/id/{00062002-0000-0000-C000-000000000046}/0x8214") = clng(3)
apptobj.fields.update
apptobj.datasource.save
end if
end if
end if
apptobj = nothing

end if

End Sub

</SCRIPT>