本文介绍了无法让 OpenPrinter 工作的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我使用的是我从网上获取的代码.
I am using this code which I got off the net.
我正在尝试将 txt 文件发送到 Intermec PM4i 标签打印机，该打印机获取 RAW 数据并打印出标签.我已经加载了驱动程序并在机器上设置了打印机.我可以进入打印机和传真选择打印机并进入属性并将文件发送到打印机，它会打印出标签.所以我知道它有效.但是当我运行这段代码时，它以一个对话框开始询问 txt 文件.选择文件后，将在您选择打印机的位置打开另一个对话框.所有这些似乎都能正常工作.但是当代码进入 SendBytesToPrinter() 函数并到达 OpenPrinter(szPrinterName.Normalize(), hPrinter, IntPtr.Zero) 时， szPrinterName.Normalize() 具有正确的打印机名称.hPrinter 和 IntPtr.Zero 的值都为零.从这条线它直接转到如果 bSuccess = False 那么dwError = Marshal.GetLastWin32Error()万一而 Marshal.GetLastWin32Error() 的值为 87.就是这样，没有打印任何内容.请让我知道这是怎么回事?谢谢
I am trying to send a txt file to an Intermec PM4i label printer that takes RAW data and prints out labels. I have loaded the driver and have set up the printer on the machine. I can go into Printers and Faxes select the printer and go into the properties and send a file to the printer and it will print out the labels. So I know it works. But when I run this code it starts off with a dialog box asking for the txt file. Once file is chosen another dialog box opens where you chose the printer. All that seems to work correctly. But when the code goes into the SendBytesToPrinter() Function and gets to OpenPrinter(szPrinterName.Normalize(), hPrinter, IntPtr.Zero) the szPrinterName.Normalize() has the correct printer name.hPrinter and IntPtr.Zero both has values of Zero.From this line it goes directly toIf bSuccess = False Then dwError = Marshal.GetLastWin32Error()End IfAnd Marshal.GetLastWin32Error() has a value of 87.And that’s it and nothing is printed.Please let me know what is going on?Thank you
Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Linq
Imports System.Text
Imports System.Windows.Forms
Imports System.Drawing.Printing
Imports System.Runtime.InteropServices
Imports System.IO
Public Class Form1
' Structure and API declarions:
<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
Public Class DOCINFOA
<MarshalAs(UnmanagedType.LPStr)> _
Public pDocName As String
<MarshalAs(UnmanagedType.LPStr)> _
Public pOutputFile As String
<MarshalAs(UnmanagedType.LPStr)> _
Public pDataType As String
End Class
<DllImport("winspool.Drv", EntryPoint:="OpenPrinterA", SetLastError:=True, CharSet:=CharSet.Ansi, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function OpenPrinter(<MarshalAs(UnmanagedType.LPStr)> ByVal szPrinter As String, ByVal hPrinter As IntPtr, ByVal pd As IntPtr) As Boolean
End Function
<DllImport("winspool.Drv", EntryPoint:="ClosePrinter", SetLastError:=True, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function ClosePrinter(ByVal hPrinter As IntPtr) As Boolean
End Function
<DllImport("winspool.Drv", EntryPoint:="StartDocPrinterA", SetLastError:=True, CharSet:=CharSet.Ansi, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function StartDocPrinter(ByVal hPrinter As IntPtr, ByVal level As Int32, <[In](), MarshalAs(UnmanagedType.LPStruct)> ByVal di As DOCINFOA) As Boolean
End Function
<DllImport("winspool.Drv", EntryPoint:="EndDocPrinter", SetLastError:=True, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function EndDocPrinter(ByVal hPrinter As IntPtr) As Boolean
End Function
<DllImport("winspool.Drv", EntryPoint:="StartPagePrinter", SetLastError:=True, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function StartPagePrinter(ByVal hPrinter As IntPtr) As Boolean
End Function
<DllImport("winspool.Drv", EntryPoint:="EndPagePrinter", SetLastError:=True, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function EndPagePrinter(ByVal hPrinter As IntPtr) As Boolean
End Function
<DllImport("winspool.Drv", EntryPoint:="WritePrinter", SetLastError:=True, ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function WritePrinter(ByVal hPrinter As IntPtr, ByVal pBytes As IntPtr, ByVal dwCount As Int32, ByVal dwWritten As Int32) As Boolean
End Function
' SendBytesToPrinter()
' When the function is given a printer name and an unmanaged array
' of bytes, the function sends those bytes to the print queue.
' Returns true on success, false on failure.
Public Shared Function SendBytesToPrinter(ByVal szPrinterName As String, ByVal pBytes As IntPtr, ByVal dwCount As Int32) As Boolean
Dim dwError As Int32 = 0, dwWritten As Int32 = 0
Dim hPrinter As New IntPtr(0)
Dim di As New DOCINFOA()
Dim bSuccess As Boolean = False
' Assume failure unless you specifically succeed.
di.pDocName = "My C#.NET RAW Document"
di.pDataType = "RAW"
Try
' Open the printer.
If OpenPrinter(szPrinterName.Normalize(), hPrinter, IntPtr.Zero) Then
' Start a document.
If StartDocPrinter(hPrinter, 1, di) Then
' Start a page.
If StartPagePrinter(hPrinter) Then
' Write your bytes.
bSuccess = WritePrinter(hPrinter, pBytes, dwCount, dwWritten)
EndPagePrinter(hPrinter)
End If
EndDocPrinter(hPrinter)
End If
ClosePrinter(hPrinter)
End If
Catch ex As Exception
MsgBox("error")
End Try
' If you did not succeed, GetLastError may give more information
' about why not.
If bSuccess = False Then
dwError = Marshal.GetLastWin32Error()
End If
Return bSuccess
End Function
Public Shared Function SendFileToPrinter(ByVal szPrinterName As String, ByVal szFileName As String) As Boolean
' Open the file.
Dim fs As New FileStream(szFileName, FileMode.Open)
' Create a BinaryReader on the file.
Dim br As New BinaryReader(fs)
' Dim an array of bytes big enough to hold the file's contents.
Dim bytes As [Byte]() = New [Byte](fs.Length - 1) {}
Dim bSuccess As Boolean = False
' Your unmanaged pointer.
Dim pUnmanagedBytes As New IntPtr(0)
Dim nLength As Integer
nLength = Convert.ToInt32(fs.Length)
' Read the contents of the file into the array.
bytes = br.ReadBytes(nLength)
' Allocate some unmanaged memory for those bytes.
pUnmanagedBytes = Marshal.AllocCoTaskMem(nLength)
' Copy the managed byte array into the unmanaged array.
Marshal.Copy(bytes, 0, pUnmanagedBytes, nLength)
' Send the unmanaged bytes to the printer.
bSuccess = SendBytesToPrinter(szPrinterName, pUnmanagedBytes, nLength)
' Free the unmanaged memory that you allocated earlier.
Marshal.FreeCoTaskMem(pUnmanagedBytes)
Return bSuccess
End Function
Public Shared Function SendStringToPrinter(ByVal szPrinterName As String, ByVal szString As String) As Boolean
Dim pBytes As IntPtr
Dim dwCount As Int32
' How many characters are in the string?
dwCount = szString.Length
' Assume that the printer is expecting ANSI text, and then convert
' the string to ANSI text.
pBytes = Marshal.StringToCoTaskMemAnsi(szString)
' Send the converted ANSI string to the printer.
SendBytesToPrinter(szPrinterName, pBytes, dwCount)
Marshal.FreeCoTaskMem(pBytes)
Return True
End Function
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
If True Then
' Allow the user to select a file.
Dim ofd As New OpenFileDialog()
If DialogResult.OK = ofd.ShowDialog(Me) Then
' Allow the user to select a printer.
Dim pd As New PrintDialog()
pd.PrinterSettings = New PrinterSettings()
If DialogResult.OK = pd.ShowDialog(Me) Then
' Print the file to the printer.
SendFileToPrinter(pd.PrinterSettings.PrinterName, ofd.FileName)
End If
End If
End If
End Sub
End Class
推荐答案
我有一些用于 OpenPrinter 的 C# 代码，应该很容易翻译.
I have some C# code for the OpenPrinter, should be easy enough to translate.
[DllImport("winspool.drv", EntryPoint = "OpenPrinter", SetLastError = true)]
internal static extern bool OpenPrinter(string pPrinterName, ref IntPtr phPrinter, PRINTER_DEFAULTS pDefault);
[DllImport("winspool.drv", EntryPoint = "ClosePrinter", SetLastError = true)]
internal static extern int ClosePrinter(IntPtr hPrinter);
[StructLayout(LayoutKind.Sequential)]
public class PRINTER_DEFAULTS
{
public string pDatatype;
public IntPtr pDevMode;
public int DesiredAccess;
}
public struct OpenPrinterAccessCodes
{
public const int DELETE = 0x10000; // DELETE - Allowed to delete printers
public const int READ_CONTROL = 0x20000; // READ_CONTROL - Allowed to read printer information
public const int WRITE_DAC = 0x40000; // WRITE_DAC - Allowed to write device access control info
public const int WRITE_OWNER = 0x80000; // WRITE_OWNER - Allowed to change the object owner
public const int SERVER_ACCESS_ADMINISTER = 0x1;
public const int SERVER_ACCESS_ENUMERATE = 0x2;
public const int PRINTER_ACCESS_ADMINISTER = 0x4;
public const int PRINTER_ACCESS_USE = 0x8;
public const int STANDARD_RIGHTS_REQUIRED = 0xF0000;
public const int PRINTER_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED | PRINTER_ACCESS_ADMINISTER | PRINTER_ACCESS_USE);
public const int SERVER_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED | SERVER_ACCESS_ADMINISTER | SERVER_ACCESS_ENUMERATE);
public const int MAX_PORTNAME_LEN = 64;
public const int MAX_NETWORKNAME_LEN = 49;
public const int MAX_SNMP_COMMUNITY_STR_LEN = 33;
public const int MAX_QUEUENAME_LEN = 33;
public const int MAX_IPADDR_STR_LEN = 16;
public const int ERROR_INSUFFICIENT_BUFFER = 122;
public const int ERROR_INVALID_FLAGS = 1004;
}
public IntPtr OpenPrinterHandle(string printerName)
{
var def = new PRINTER_DEFAULTS { pDatatype = null, pDevMode = IntPtr.Zero, DesiredAccess = OpenPrinterAccessCodes.PRINTER_ALL_ACCESS };
var hPrinter = IntPtr.Zero;
if (!OpenPrinter(printerName, ref hPrinter, def))
{
var lastWin32Error = new Win32Exception(Marshal.GetLastWin32Error());
Logger.Log("Failed open Printer: " + lastWin32Error.Message);
throw lastWin32Error;
}
return hPrinter;
}
public void ClosePrinterHandle(IntPtr hPrinter)
{
ClosePrinter(hPrinter);
}
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