Progress Bar

Will · May 16th, 2010, 07:08 AM

I have got to the end of your Class chapters and you said to go away and create some programs before progressing so that is what I am doing. Currently I am working on a program which uses a web service to get some data, search that data, modify it if I find what I am looking for and then re-upload it.

I have done all of that fine but I wanted to tie in a progress bar to the UI so it doesn't look like the program has become unresponsive whilst it is performing this.

I am having trouble doing this, I need to get the bar running when I click a button to start the process now I can either get it to run *before* the method I wrote is called or *after* not during.

What do I need to look into to achieve this?

Will · May 16th, 2010, 08:06 AM

Ok I found that I should use something called the background worker...

Will · May 16th, 2010, 08:31 AM

Ok after doing some googling I have found that I should get the progress controlled by the main UI thread as it is part of the UI and use the Backgroundworker for my process.

I did this and it works great until I come to report the results back, the process returns an int which I update a label with to tell the user how many things were updated.

So I am getting the following exception:

"Cross-thread operation not valid: Control 'lblProgress' accessed from a thread other than the thread it was created on."

DrPurdum · May 17th, 2010, 08:59 AM

Threading is a useful technique to use when you expect a task to take a long time and there are other tasks to be done. However, it's not clear to me that you have other tasks to do, but rather you simply need to let the user know that the system is still working on the task at hand. If that's the case, the status bar is a control that will work. The online documentation shows how to use it.

If you really do need to use threading for some reason, that would require an answer that's a little too long to handle here. I would suggest you look at some other threading code examples (my guess is that your Invoke() method isn't being called correctly), such as you might find at CodeProject.com. For example:

http://www.codeproject.com/KB/cs/Fil...adManager.aspx

There's nothing wrong with looking (and learning) from other peoples' code.

Will · May 17th, 2010, 02:55 PM

You are right I only have one process, problem is it just takes awhile. I will look into the status bar and see how I get on.

Cheers