判断打印机是否还有任务队列的方法~_怎么看根打印队列是否有残留-优快云博客

本文链接：https://blog.youkuaiyun.com/happybasic/article/details/8190450

本文将介绍如何确定打印机当前是否存在未完成的任务队列，包括Windows和Mac系统的操作步骤，帮助你了解打印机的工作状态。

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Private Structure PRINTER_DEFAULTS
  Dim pDatatype As String
  Dim pDevMode As Integer
  Dim DesiredAccess As Integer
End Structure

Private Const PRINTER_ACCESS_ADMINISTER As Integer = &H4
Private Declare Function OpenPrinter Lib "winspool.drv" Alias "OpenPrinterA" (ByVal pPrinterName As String, ByRef phPrinter As Integer, ByRef pDefault As PRINTER_DEFAULTS) As Integer

Private Declare Function EnumJobs Lib "winspool.drv" Alias "EnumJobsA" (ByVal hPrinter As Integer, ByVal FirstJob As Integer, ByVal NoJobs As Integer, ByVal Level As Integer, ByRef pJob As Byte, ByVal cdBuf As Integer, ByRef pcbNeeded As Integer, ByRef pcReturned As Integer) As Integer

Private Structure SYSTEMTIME
  Dim wYear As Short
  Dim wMonth As Short
  Dim wDayOfWeek As Short
  Dim wDay As Short
  Dim wHour As Short
  Dim wMinute As Short
  Dim wSecond As Short
  Dim wMilliseconds As Short
End Structure

Private Structure JOB_INFO_1
  Dim JobId As Integer
  Dim pPrinterName As Integer
  Dim pMachineName As Integer
  Dim pUserName As Integer
  Dim pDocument As Integer
  Dim pDatatype As Integer
  Dim pStatus As Integer
  Dim Status As Integer
  Dim Priority As Integer
  Dim Position As Integer
  Dim TotalPages As Integer
  Dim PagesPrinted As Integer
  Dim Submitted As SYSTEMTIME
End Structure

Private Declare Function ClosePrinter Lib "winspool.drv" (ByVal hPrinter As Integer) As Integer

Public Function HasJobs(ByVal PrinterName As String) As Integer
  Dim hPrinter As Integer
  Dim RetVal As Integer
  Dim pd As New PRINTER_DEFAULTS
  Dim aJi1() As Byte
  Dim dwBytesNeed As Integer
  Dim dwBytesRet As Integer
  Dim lngSize As Integer
  Dim JI_1 As JOB_INFO_1

  lngSize = Len(JI_1)
  pd.DesiredAccess = PRINTER_ACCESS_ADMINISTER
  RetVal = OpenPrinter(PrinterName, hPrinter, pd)
  ReDim aJi1(lngSize - 1)
  RetVal = EnumJobs(hPrinter, 0, 3, 1, aJi1(0), lngSize, dwBytesNeed, dwBytesRet)

  If RetVal = 0 And dwBytesNeed = 0 Then
    ClosePrinter(hPrinter)
    Return -1
  End If

  ClosePrinter(hPrinter)

  If dwBytesNeed = 0 Then
    Return 0
  Else
    Return 1
  End If

End Function

与前篇一样这个算是VB6时代的方法，如果你更好的基于.Net的方法，请赐教！ happybasic@163.com