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Using System.Drawing.Printing.PrintDocument in Service
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This message was discovered on ASPFriends.com 'ngfx-services' list.


Jeff Widmer
I am trying to print a document from a .net service that I have created. I
can create the System.Drawing.Printing.PrintDocument without a problem but
when I call the System.Drawing.Printing.PrintDocument.Print method, I get
the below two exceptions:

An unhandled exception of type
'System.Runtime.InteropServices.ExternalException' occurred in system.dll
Additional information: Failed to create system events window thread.

An unhandled exception of type 'System.TypeInitializationException' occurred
in system.drawing.dll
Additional information: The type initializer for
"System.Drawing.SafeNativeMethods" threw an exception.

I can print from an aspx page using the same code without a problem. But
when the code is moved into a service I get the exceptions above. Why would
there be a difference? Since the asp.net process is able to print, why
would my service not be able to?

-Jeff
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Jeff Widmer
Never mind. I figured it out. I had to allow the service to interact with
the desktop.
In the Services control panel > click on the service > choose properties >
choose the Log On tab > check the box Allow Service to Interact with Desktop

So now I know how to set this property manually to get my service to work,
but how do I set this property in my installer so that when it is installed,
it automatically has access to the desktop?

-Jeff

-----Original Message-----
From: Jeff Widmer [mailto:Click here to reveal e-mail address]
Sent: Wednesday, March 06, 2002 12:24 PM
To: ngfx-services
Subject: [ngfx-services] Using System.Drawing.Printing.PrintDocument in
Service

I am trying to print a document from a .net service that I have created. I
can create the System.Drawing.Printing.PrintDocument without a problem but
when I call the System.Drawing.Printing.PrintDocument.Print method, I get
the below two exceptions:

An unhandled exception of type
'System.Runtime.InteropServices.ExternalException' occurred in system.dll
Additional information: Failed to create system events window thread.

An unhandled exception of type 'System.TypeInitializationException' occurred
in system.drawing.dll
Additional information: The type initializer for
"System.Drawing.SafeNativeMethods" threw an exception.

I can print from an aspx page using the same code without a problem. But
when the code is moved into a service I get the exceptions above. Why would
there be a difference? Since the asp.net process is able to print, why
would my service not be able to?

-Jeff

| [ngfx-services] member Click here to reveal e-mail address = YOUR ID
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Reply to this message...
 
    
Todd Poston
Unfortunately the one thing about services that are not exposed by .NET is the Interact With Desktop setting. .NET team.. Hello??

I had to do the same thing and ended up pulling code directly from MSDN that uses the Win32 API to perform exactly this. The code is C, of which I know extremely little - but fortunately the code did what I needed it to without much tweaking. I wrapped it up in a console app, threw some argument handling on it, and then just executed the process with the command line arguments I needed (specifying the service I needed to modify) during the install of my application.

I don't have the link handy, but search MSDN on:
OpenSCManager
OpenService
ChangeServiceConfig
SERVICE_WIN32_SHARE_PROCESS | SERVICE_INTERACTIVE_PROCESS

you should be able to find the code pretty easily.

--------------------------------
From: Todd Poston
Reply to this message...
 
 
System.Drawing.Printing.PrintDocument
System.Runtime.InteropServices.ExternalException
System.TypeInitializationException




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