Solved

Is Subclassing Required In Order To Do This?

Posted on 1998-06-01
5
175 Views
Last Modified: 2010-05-03
I have two VB applications(call them A and B), and I want A to be notified when B gets focus(and A loses focus).  Is there a VB event within application A I can generate when this happens?  Do I have to use windows subclassing?  I would like to avoid subclassing if I can.  

Furthermore, if I have to subclass, what's the best way to do this? I know that the message I need to subclass is WM_ACTIVATEAPP or WM_ACTIVATE.  Do I need to purchase a third party OCX?  

Please Advise,

Thanks.
0
Comment
Question by:debbyt
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 
LVL 6

Expert Comment

by:clifABB
ID: 1462249
Well, you don't *really* have to subclass.

You could let B write to an ini file when it changes focus and have A constantly poll (through a timer control) the ini file for a change in B's focus.

But subclassing is so much easier on the resources.
0
 

Author Comment

by:debbyt
ID: 1462250
I know I can use a timer to poll for the name of the foreground window with an API call, but this is very wasteful especially when there's no way to know when the focus will change.

So is subclassing the only reasonable way?
0
 
LVL 7

Accepted Solution

by:
kamall earned 100 total points
ID: 1462251
debbyt,
One way is to use DDE between the two applications. (I am not good in DDE), but you should find some examples in the VB samples directory.
The second way is to use a timer in application A, and check for its Title. In app. B, you can simply use the SetWindowText API  to change the title of the A application (for example, append a space to the end of the title). Now reading the title of A in its timer event, you get the notification, and reset its title.
Hope that helps.
Regards
0
 
LVL 7

Expert Comment

by:kamall
ID: 1462252
The
"In app. B, you can simply use the SetWindowText API  to change the title of the A application"
means
"When app B gets the focus (your form in app. B), you can simply...."
0
 
LVL 6

Expert Comment

by:clifABB
ID: 1462253
Yep.  That's why I said it was easier on the resources.

I did some tests and, apparently, you'll have to have a third-party control such as MessageBlaster (a shareware ocx available at various shareware sites) or Spyworks (available from Desaware - www.desaware.com)

Once you retrieve one of these, let us know if you need some help subclassing.
0

Featured Post

Salesforce Has Never Been Easier

Improve and reinforce salesforce training & adoption using WalkMe's digital adoption platform. Start saving on costly employee training by creating fast intuitive Walk-Thrus for Salesforce. Claim your Free Account Now

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I’ve seen a number of people looking for examples of how to access web services from VB6.  I’ve been using a test harness I built in VB6 (using many resources I found online) that I use for small projects to work out how to communicate with web serv…
I was working on a PowerPoint add-in the other day and a client asked me "can you implement a feature which processes a chart when it's pasted into a slide from another deck?". It got me wondering how to hook into built-in ribbon events in Office.
Get people started with the utilization of class modules. Class modules can be a powerful tool in Microsoft Access. They allow you to create self-contained objects that encapsulate functionality. They can easily hide the complexity of a process from…
This lesson covers basic error handling code in Microsoft Excel using VBA. This is the first lesson in a 3-part series that uses code to loop through an Excel spreadsheet in VBA and then fix errors, taking advantage of error handling code. This l…
Suggested Courses
Course of the Month5 days, 13 hours left to enroll

627 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question