Hi Peter,
Thanks for the info. However, I did *not* assume that the Save method was
thread-safe. I only call Save once, from one thread for any given instance
of the Bitmap class. Perhaps some more info would be useful here. This is
the basic flow of events involving the Bitmap.
I have a loop running in a worker thread which rebuilds scenes and then adds
them to a control and list of controls which render copies of the images in
the main GUI thread of the application. Here is a cut-down version of the
thread which does the image generating and the other simply sets the values
of PictureBox's Image property and lets them repaint themselves (indirectly
through the ThumbnailControl class):
public void ProcessScenes()
{
foreach (Scene s in scenes)
{
renderer.CurrentScene = s;
renderer.RebuildSceneImage();
// ... (non-image related stuff)
string file = FILENAME;
try
{
Image sceneImage = new Bitmap(renderer.SceneImage);
sceneImage.Save(file, ImageFormat.Png); // <-- HERE IS THE GENERIC
ERROR
sceneImage.Dispose();
}
catch (Exception ex)
{
Trace.WriteLine(ex);
// ... (handle error)
}
Bitmap oldImage = thumbnailControl.SourceImage;
thumbnailControlCurrent.SourceImage = new Bitmap(renderer.SceneImage);
if (oldImage != null)
{
oldImage.Dispose();
}
thumbnailPageControl1.AddThumbnail(new ThumbnailPageControl(new
Bitmap(renderer.SceneImage)));
}
}
What could be going on here? Any ideas?
Thanks,
Michael
"Peter Huang [MSFT]" <v-******@online.microsoft.com> wrote in message
news:Bb**************@cpmsftngxa06.phx.gbl...
Hi Michael,
The save method of Image class is not thread safe.
Here is what MSDN said,
Any public static (Shared in Visual Basic) members of this type are safe
for multithreaded operations. Any instance members are not guaranteed to
be thread safe.
For more information, you may refer to the link below.
http://msdn.microsoft.com/library/de...us/cpref/html/ frlrfsystemdrawingimageclasssavetopic.asp
So I think you may try to invoke the Save method in one thread, which will
avoid the problem.
Regards,
Peter Huang
Microsoft Online Partner Support
Get Secure! www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.
--------------------From: "Michael Kennedy [UB]" <mk******@REMOVETHIS.unitedbinary.com>
Subject: Generic GDI+ Error when saving bitmaps
Date: Wed, 10 Sep 2003 11:04:08 -0700
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Organization: United Binary, LLC.
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Hi Everyone,
I have this multithreaded C# windows forms application which does a lot
ofimage processing. Occasionally, I get the following error:
A generic error occurred in GDI+.
System.Runtime.InteropServices.ExternalExceptio n: A generic error
occurredin GDI+.
at System.Drawing.Image.Save(String filename, ImageCodecInfo encoder,
EncoderParameters encoderParams)
at System.Drawing.Image.Save(String filename, ImageFormat format)
It's very strange. Most of the time it works without a problem. But
sometimes I get this error. It can happen with the same source image
whichjust worked previously and will work next time.
Does anyone know what's causing this? "A generic error" is quiet
unhelpfultracking this down.
Thanks for any help.
Regards,
Michael
Michael Kennedy
http://www.unittesting.com
