How to get a list of all custom paper in windows system

Question

I know how to add a custom paper to windows (https://learn.microsoft.com/en-us/answers/questions/2116958/how-to-add-custom-paper-to-windows-system).

I thought that retrieving a list of all papers in windows will be easy... but.

I've tried with "EnumForms function" and found some examples in the web, but cannot force them to run properly.

Please help me. How (in VB.NET) list all papers in windows.

Answer 1

For example (adapted from ChatGPT...) :

        Dim sDefaultPrinterName As String = New PrinterSettings().PrinterName
        System.Diagnostics.Debug.WriteLine("Default Printer: " & sDefaultPrinterName)
        Dim hPrinter As IntPtr = IntPtr.Zero
        If Not OpenPrinter(sDefaultPrinterName, hPrinter, IntPtr.Zero) Then
            System.Diagnostics.Debug.WriteLine("Failed to open the default printer.")
            Exit Sub
        End If

        Dim pcbNeeded As UInteger = 0
        Dim pcReturned As UInteger = 0
        EnumForms(hPrinter, 1, IntPtr.Zero, 0, pcbNeeded, pcReturned)
        If pcbNeeded = 0 Then
            System.Diagnostics.Debug.WriteLine("No forms available.")
            ClosePrinter(hPrinter)
            Exit Sub
        End If
        Dim pFormInfo As IntPtr = Marshal.AllocHGlobal(CInt(pcbNeeded))
        If EnumForms(hPrinter, 1, pFormInfo, pcbNeeded, pcbNeeded, pcReturned) Then
            For i As Integer = 0 To CInt(pcReturned) - 1
                Dim formInfo As FORM_INFO_1 = Marshal.PtrToStructure(Of FORM_INFO_1)(pFormInfo + i * Marshal.SizeOf(Of FORM_INFO_1)())
                Dim formType As String = GetFormType(formInfo.Flags)
                Console.WriteLine($"Form Name: {formInfo.pName}, Type: {formType}")
            Next
        Else
            System.Diagnostics.Debug.WriteLine("Failed to enumerate forms.")
        End If
 
        Marshal.FreeHGlobal(pFormInfo)
        ClosePrinter(hPrinter)

with :

   <StructLayout(LayoutKind.Sequential)>
   Public Structure FORM_INFO_1
       Public Flags As UInteger
       <MarshalAs(UnmanagedType.LPWStr)>
       Public pName As String
       Public Size As SIZE
       Public ImageableArea As RECT
   End Structure

   <StructLayout(LayoutKind.Sequential)>
   Public Structure SIZE
       Public cx As Integer
       Public cy As Integer
   End Structure

   <StructLayout(LayoutKind.Sequential)>
   Public Structure RECT
       Public left As Integer
       Public top As Integer
       Public right As Integer
       Public bottom As Integer
   End Structure

   <DllImport("winspool.drv", SetLastError:=True, CharSet:=CharSet.Unicode)>
   Public Shared Function EnumForms(hPrinter As IntPtr, Level As UInteger, pForm As IntPtr, cbBuf As UInteger, ByRef pcbNeeded As UInteger, ByRef pcReturned As UInteger) As Boolean
   End Function

   <DllImport("winspool.drv", SetLastError:=True, CharSet:=CharSet.Unicode)>
   Public Shared Function OpenPrinter(pPrinterName As String, ByRef hPrinter As IntPtr, pDefault As IntPtr) As Boolean
   End Function

   <DllImport("winspool.drv", SetLastError:=True)>
   Public Shared Function ClosePrinter(hPrinter As IntPtr) As Boolean
   End Function

 Function GetFormType(flags As UInteger) As String
     Select Case flags
         Case 0
             Return "FORM_USER"
         Case 1
             Return "FORM_BUILTIN"
         Case 2
             Return "FORM_PRINTER"
         Case Else
             Return "Unknown"
     End Select
 End Function