Hi,
I am writing a small console/systray application to monitor a database and spool off "documents" generated via the .NET printing API and I keep running into this exception.Is there a limitation with System.Drawing.Printing and theading or is it a limitation of the Win32 printing API?
I would find this strange as I've seen MSDN articles on printing in the background which would seem to negate this. The entire print process does not span a thread. That is I create the PrintDocument object and all it's settings withone one thread. I just may have multiple PrintDocuments queueing each in their own Thread. Initially I did this using ThreadPool but have also tried it using one "thread per printer" in case there was some conflict over the same printer being spooled to by different threads.
Usually the "handle is invalid" exception is the result of a stack-trace from OnStartPrint
Unhandled Exception: System.ComponentModel.Win32Exception: The handle is invalid
at System.Drawing.Printing.StandardPrintController.OnStartPrint(PrintDocument
document, PrintEventArgs e)
at System.Drawing.Printing.PrintController.Print(PrintDocument document)
at System.Drawing.Printing.PrintDocument.Print()
But it has occured from System.Drawing.Printing.StandardPrintController.OnEndPrint, or sometimes within PrintSettings.
Via Reflection I've noticed that the System.Drawing.Printing API uses HandleRef for operating system handles. Is this a problem that was noted previously in regard to operating system handles and .NET and solved by SafeHandle?
Is there anything I can do to solve this issue? Thanks,
Joe