GetDefaultPrinter

  • Thread starter Thread starter mreisi
  • Start date Start date
M

mreisi

Hallo Leute,

ich habe vor kurzem schon einmal das Thema gestartet, wie man den
Standarddrucker unter .Net auslesen kann. Die API-Funktion
GetDefaultPrinter() ist mir dabei über den Weg gelaufen, leider habe
ich keine Ahnung, wie man sie richtig anwendet. Ich komme zwar
ursprünglich aus dem C bzw. C#--Bereich, jedoch lassen sich diese
Kenntnisse in .Net nicht so richtig verarbeiten. Folgende Fehlermeldung
tritt auf, wenn die Funktion versucht in die per Referenz übergebene
String-Variable zu schreiben. (Übrigens in VB.Net sowohl auch C#)

"Es wurde versucht, im geschützten Speicher zu lesen oder zu
schreiben. Dies ist häufig ein
Hinweis darauf, dass anderer Speicher beschädigt ist."

Es muss doch jemanden geben, der helfen kann. :-)

Vielen Dank im Voraus.
 
mreisi said:
ich habe vor kurzem schon einmal das Thema gestartet, wie man den
Standarddrucker unter .Net auslesen kann. Die API-Funktion
GetDefaultPrinter() ist mir dabei über den Weg gelaufen, leider habe
ich keine Ahnung, wie man sie richtig anwendet.
Click to expand...

Simple test call without error handling:

\\\
Private Declare Auto Function GetDefaultPrinter Lib "winspool.drv" ( _
ByVal pszBuffer As String, _
ByRef pcchBuffer As Int32 _
) As Boolean
....
Dim s As String = Space(128)
Dim n As Int32 = s.Length
If GetDefaultPrinter(s, n) Then
MsgBox(Strings.Left(s, n - 1))
Else
MsgBox("An error occured!")
End If
///
 
Herfried,

What was the problem?

Cor

Herfried K. Wagner said:
Simple test call without error handling:

\\\
Private Declare Auto Function GetDefaultPrinter Lib "winspool.drv" ( _
ByVal pszBuffer As String, _
ByRef pcchBuffer As Int32 _
) As Boolean
...
Dim s As String = Space(128)
Dim n As Int32 = s.Length
If GetDefaultPrinter(s, n) Then
MsgBox(Strings.Left(s, n - 1))
Else
MsgBox("An error occured!")
End If
///
Click to expand...
 
Cerebrus,
A Language problem, he he ! Ich verstehen deutsch nicht gut...
Click to expand...

I do, but that is no reason to answer it in that way without pointing on the
fact that not everybody does.

(For you misunderstand, I am sure that Herfried was thinking that he was
answering from a German language newsgroup)

:-)

Cor
 
Cor,

Cor Ligthert said:
What was the problem?
Click to expand...

The OP's question was how to use the 'GetDefaultPrinter' API function and/or
determine the name of the default printer.
 
Herfried,

I can easily read the German language, where I have always the problem with
those Data eieren. But it is not common to use that language here.

If you answer a question from an Op would you than not nicely write in the
message if the Op could use the next time not the German language before
you answer or even give a short translation of the text?

The Op does not know that, you do.

:-)

Cor
 
Addendum:

Extended version (supposed to work on Windows 2000/XP and later):

\\\

' <URL:http://dotnet.mvps.org/meta/terms/License.txt>
Public Class PrinterManager
Private Declare Auto Function GetDefaultPrinter Lib "winspool.drv" ( _
ByVal pszBuffer As String, _
ByRef pcchBuffer As Int32 _
) As Boolean

Private Const ERROR_FILE_NOT_FOUND As Int32 = 2
Private Const ERROR_INSUFFICIENT_BUFFER As Int32 = 122

Private Declare Auto Function SetDefaultPrinter_API _
Lib "winspool.drv" _
Alias "SetDefaultPrinter" _
( _
ByVal pszPrinter As String _
) As Boolean

Public Shared Sub SetDefaultPrinter(ByVal PrinterName As String)
If Not SetDefaultPrinter_API(PrinterName) Then
Throw New Win32Exception
End If
End Sub

Public Shared Function GetDefaultPrinter() As String
Dim s As String = Space(128)
Dim n As Int32 = s.Length
Dim Success As Boolean = GetDefaultPrinter(s, n)
If Success Then
Return Strings.Left(s, n - 1)
Else
Dim LastError As Integer = Marshal.GetLastWin32Error()
If LastError = ERROR_FILE_NOT_FOUND Then
Throw _
New Win32Exception( _
LastError, _
"There is no default printer." _
)
ElseIf LastError = ERROR_INSUFFICIENT_BUFFER Then
s = Space(n)
Success = GetDefaultPrinter(s, n)
If Success Then
Return Strings.Left(s, n - 1)
Else
Throw New Win32Exception
End If
Else
Throw New Win32Exception
End If
End If
End Function
End Class
///
 
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