Forms application 'blanking out' while busy

**=?Utf-8?B?TW9ydGVuIFdlbm5ldmlrIFtDIyBNVlBd?=** · Mar 17 '08, 07:15 AM

RE: Forms application 'blanking out' while busy

Hi Chris

I apologize if this answer appears twice, but I got an error trying to post
the previous answer, so here goes.

When you do heavy processing inside the GUI thread (main thread in a windows
application) you won't have any processing time to perform GUI stuff. This
will cause a gray and/or non responsive interface.

You should move any heavy processing to a separate thread. The easiest way
to do this is by using a BackgroundWorke r object like Gilles points out.

Below is an example of how this can be done using a background worker that
reports progress as well as supports aborting. Add a progressbar control as
well as two buttons with their Click event attached to button1_Click and
button2_Click

private BackgroundWorke r worker;
public Form2()
{
InitializeCompo nent();

worker = new BackgroundWorke r();

// Needed to fire the progresschanged event
worker.WorkerRe portsProgress = true;

// Needed to be able to stop the processing
worker.WorkerSu pportsCancellat ion = true;

// Any heavy processing should spawn from this event
worker.DoWork += new DoWorkEventHand ler(worker_DoWo rk);

// This event fires when you want it to
worker.Progress Changed += new
ProgressChanged EventHandler(wo rker_ProgressCh anged);

// This event fires when the worker is done processing
worker.RunWorke rCompleted += new
RunWorkerComple tedEventHandler (worker_RunWork erCompleted);
}

private void button1_Click_1 (object sender, EventArgs e)
{
// Resett progressbar
progressBar1.Va lue = 0;

// Notify the worker object to start working
worker.RunWorke rAsync(@"C:\tem p");
// You can put anything as an argument to this method
}

private void button2_Click(o bject sender, EventArgs e)
{
// Stop working
if (worker.IsBusy)
worker.CancelAs ync();
}

void worker_DoWork(o bject sender, DoWorkEventArgs e)
{
DateTime start = DateTime.Now;

// This method is called when you use RunWorkerAsync

string path = e.Argument.ToSt ring();
// e.Argument can be anything, including a complex object

for (int i = 0; i < 100; i++)
{
// Did someone cancel the work?
if (worker.Cancell ationPending)
{
// if so, then simply return
return;
}

// Simulate processing of a single file
// which in this case would take 1 seconds
// to process.
System.Threadin g.Thread.Sleep( 1000);

// Report the number of files processed
worker.ReportPr ogress(i + 1);
// The parameter says intPercentage,
// but it can be any number you like
}

// the Result property can be used to provide information
e.Result = "100 files processed in " + (DateTime.Now -
start).TotalSec onds + " minutes";
}

void worker_Progress Changed(object sender, ProgressChanged EventArgs e)
{
// If the worker calls ReportProgress this method will be called.
progressBar1.Va lue = e.ProgressPerce ntage;
}

void worker_RunWorke rCompleted(obje ct sender, RunWorkerComple tedEventArgs e)
{
// This method will be called when the worker is done processing or
cancelled

if (e.Result == null)
MessageBox.Show ("Processing aborted");
else
MessageBox.Show (e.Result.ToStr ing());
}

--
Happy Coding!
Morten Wennevik [C# MVP]

"hardieca@hotma il.com" wrote:

Hi,
>
I'm building a forms app that parses thousands of text files. My boss
insisted it have a GUI, to which I added an information console and a
progress bar tracking the number of files parsed.
>
Everything is working fine, except that when the application is run,
it devotes itself entirely to the parsing, and the form with the
console and progress bar just blanks out until the application
finishes running.
>
I've done mostly web development, so I'm kinda flummoxed about this.
How do I rein my app in a little so that the form is continually
displaying useful information?
>
Regards,
>
Chris
>

Forms application 'blanking out' while busy

Forms application 'blanking out' while busy

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