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Twain32Native.DsUserInterface results always AccessViolationAcception #5

Open GoogleCodeExporter opened 8 years ago

GoogleCodeExporter commented 8 years ago 
What steps will reproduce the problem?
1. Start to debug
2. Select a webcam as source
3. click Acquire and then the exception is launched.

OS is vista. IDE is VS2008, target framework  is .net 2.0.

Original issue reported on code.google.com by carl...@hotmail.com on 20 Sep 2009 at 3:24

GoogleCodeExporter commented 8 years ago 
[deleted comment]
GoogleCodeExporter commented 8 years ago 
[deleted comment]
GoogleCodeExporter commented 8 years ago 
[deleted comment]
GoogleCodeExporter commented 8 years ago 
if the sample source, from TWAIN Developer Toolkit, is selected as virrual 
scanner, 
the scanning process will be finished in success.
and if use Twacker, from TWAIN Developer Toolkit, to select my webcam to take a 
picture, act as scan, it can be finished in success.

Original comment by carl...@hotmail.com on 21 Sep 2009 at 3:40

GoogleCodeExporter commented 8 years ago 
I tested this source successfully with scanner EPSON Perfection1260.

It seems the AccessViolationException is relative to .Net 2.0. maybe the 
DllImport 
mechanism for .net 2.0 is different with 1.0.

if searched 'AccessViolationException' in forum 
of 'http://www.codeproject.com/KB/dotnet/twaindotnet.aspx ', there is somebody 
else 
facing similar problem.

In most case, it is impossible to use a webcam as scanner, but I sincerely wish 
this 
problem can be resolved technically.

I can run Demo app from http://www.codeproject.com/KB/dotnet/twaindotnet.aspx 
successfully with my webcam. The demo app seems built (compiled and linked) 
upon .net 1.1 or before. 
But if I run the Source from 
http://www.codeproject.com/KB/dotnet/twaindotnet.aspx 
under VS2008 target to .net 2.0+, the AccessViolationException is launched 
definitely.

I also searched the web, and from leadtool's forum, it seems resolved by the 
leadtools. But the details about 'how to' can't be gotten.

for you reference.

Original comment by carl...@hotmail.com on 24 Sep 2009 at 4:47

GoogleCodeExporter commented 8 years ago 
Hi Carl,

What sort of webcam do you have? I tried with my webcam and I can't even get it 
to 
appear in the TWAIN sources.

Cheers,

Luke

Original comment by luke.qui...@gmail.com on 29 Sep 2009 at 1:11

GoogleCodeExporter commented 8 years ago 

The webcam I used is 'Logitech QuickCam'.

Thanks.

Original comment by carl...@hotmail.com on 2 Oct 2009 at 12:32

GoogleCodeExporter commented 8 years ago 
Hi Carl,

I finally got hold of a QuickCam and I still can't reproduce the problem. 
Basically 
the device doesn't show up in my list of sources. Looking at the Logitech 
forums it 
seems like they no longer support TWAIN or WIA: 

http://forums.logitech.com/t5/Webcams/WIA-TWAIN-issue-with-QuickCam-Communicate-
STX/m-p/187527#M38768

Do you have the latest version of the drivers?

Cheers,

Luke

Original comment by luke.qui...@gmail.com on 27 Oct 2009 at 2:33