Re: Threading problem

I attempted what you suggested and in my reduced application this problem
does not occur. This gives me some hints. I'll work on this some more and
post again if necessary.

Thanks again Alvin.

Regards
Chris Saunders

"Alvin Bruney" <www.lulu.com/owc> wrote in message
news:eWPnAMCiGHA.4864@xxxxxxxxxxxxxxxxxxxxxxx
I tried to run your project but it doesn't compile under 2.0. You need to
produce a short but complete program that demonstrates the problem. See
this definition for what a short but complete program is:
http://www.yoda.arachsys.com/csharp/complete.html

Basically, I or anyone else should be able to copy your code into a
project and run it successfully and see the problem. Newsgroupies don't
particularly like copying code and spending a day figuring out what
variables are and how to hack the program to get it to compile
successfully.

--

________________________
Warm regards,
Alvin Bruney [MVP ASP.NET]

[Shameless Author plug]
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The O.W.C. Black Book with .NET
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-------------------------------------------------------

"Chris Saunders" <evas@xxxxxxxxxxxxxxxxx> wrote in message
news:ez3%23zo3hGHA.4504@xxxxxxxxxxxxxxxxxxxxxxx
Ah, a response!!! I'm just learning about using multithreading in C#.
Actually fairly new to C#. I can assure you that this code is performing
with no apparent problems. The only problem that I know of is that
the thread runs twice before it stops. I'm not sure what you are
referring
to as regards "touching a windows resource" but I attempted to use
methods I found in the MSDN documentation for updating the UI
controls.

If you are knowledgeable in this area I would much appreciate a closer
look at the code. I know it is a bit much but I tried to minimize as
best
I could without missing anything relevant. I'm not even sure if my
approach to this is sensible.

Regards
Chris Saunders

"Alvin Bruney" <www.lulu.com/owc> wrote in message
news:%23tQ6zg2hGHA.4276@xxxxxxxxxxxxxxxxxxxxxxx
Chris,
What I don't get is why this call isn't failing. Backgroundworker
appears to be touching a windows resource (a quick eyeball of the code)

--

________________________
Warm regards,
Alvin Bruney [MVP ASP.NET]

[Shameless Author plug]
Professional VSTO.NET - Wrox/Wiley
The O.W.C. Black Book with .NET
www.lulu.com/owc, Amazon
Blog: http://www.msmvps.com/blogs/alvin
-------------------------------------------------------

"Chris Saunders" <evas@xxxxxxxxxxxxxxxxx> wrote in message
news:eIsHH5nhGHA.3572@xxxxxxxxxxxxxxxxxxxxxxx
I'm using System.ComponentModel.BackgroundWorker to do some drawing in
my application.
The thread seems to run fine but it runs twice and I can't see why.
I'm going to show my code with everything that I think is not relevant
removed.
Perhaps the drawBitmap function can be ignored, I just included it
because it is the
actual work the tread is performing. (It's just a test case.)
Can anyone help?

namespace Mandolin
{
public partial class MainForm : Form
{

public MainForm()
{
backgroundWorkerDraw.DoWork += new
DoWorkEventHandler(backgroundWorkerDraw_DoWork);
backgroundWorkerDraw.ProgressChanged += new
ProgressChangedEventHandler(backgroundWorkerDraw_ProgressChanged);
backgroundWorkerDraw.RunWorkerCompleted += new
RunWorkerCompletedEventHandler(backgroundWorkerDraw_RunWorkerCompleted);
}

private void goToolStripMenuItem_Click(object sender, EventArgs
e)
{
if (backgroundWorkerDraw.IsBusy == false)
{
backgroundWorkerDraw.RunWorkerAsync();
}
}

private void drawBitmap(BackgroundWorker worker, DoWorkEventArgs
e)
{
if (worker.CancellationPending)
e.Cancel = true;
else
{
for (int r = startRow; r < bitmapHeight; r++)
{
if (worker.CancellationPending)
e.Cancel = true;
else
{
for (int c = 0; c < bitmapWidth; c++)
{
mutex.WaitOne();
bitmap.SetPixel(c, r, Color.FromArgb(r *
c));
mutex.ReleaseMutex();
if (e.Cancel)
c = bitmapWidth;
}
}
worker.ReportProgress((int)(((double)r /
(double)bitmapHeight) * 100));
if (e.Cancel)
{
mutex.WaitOne();
if (pauseButtonPushed == true)
startRow = r;
if (stopButtonPushed == true)
startRow = 0;
r = bitmapHeight;
mutex.ReleaseMutex();
}
}
}
}

private void backgroundWorkerDraw_DoWork(object sender,
DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
drawBitmap(worker, e);
}

private void backgroundWorkerDraw_ProgressChanged(object sender,
ProgressChangedEventArgs e)
{
statusBar.Text = e.ProgressPercentage.ToString() + " percent
complete.";
Graphics g = CreateGraphics();
mutex.WaitOne();
g.DrawImage(bitmap, rect);
mutex.ReleaseMutex();
}

private void backgroundWorkerDraw_RunWorkerCompleted(object
sender, RunWorkerCompletedEventArgs e)
{
toolStripButtonPlay.Enabled = true;
toolStripButtonPause.Enabled = false;
toolStripButtonStop.Enabled = false;
goToolStripMenuItem.Enabled = true;
pauseToolStripMenuItem.Enabled = false;
stopToolStripMenuItem.Enabled = false;
statusBar.Text = statusBarReady;
}
}
}

Regards
Chris Saunders











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