Character size/font via RAW dot matrix printing

Mateus

Active member
Joined
Apr 16, 2010
Messages
27
Programming Experience
3-5
Hi All,

I'm using the code below to successfully print to a dot matrix printer. Only problem is, the character size is too big. I know it can be changed because I have third-party applications that print at a much smaller font.

I've searched this forum & the net for clues and I think I need an escape code to add to the byte string but I'm still lost. Any ideas?

Many thanks,
M.

VB.NET:
MatrixPrint.prt(sText, sLabelPrinter)

VB.NET:
Imports System.IO
Imports System.Drawing.Printing
Imports System.Runtime.InteropServices

Public Class MatrixPrinter
    ' Structure and API declarions:
    <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode)> Structure DOCINFOW
        <MarshalAs(UnmanagedType.LPWStr)> Public pDocName As String
        <MarshalAs(UnmanagedType.LPWStr)> Public pOutputFile As String
        <MarshalAs(UnmanagedType.LPWStr)> Public pDataType As String
    End Structure

    <DllImport("winspool.Drv", EntryPoint:="OpenPrinterW", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function OpenPrinter(ByVal src As String, ByRef hPrinter As IntPtr, ByVal pd As Long) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="ClosePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function ClosePrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="StartDocPrinterW", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function StartDocPrinter(ByVal hPrinter As IntPtr, ByVal level As Int32, ByRef pDI As DOCINFOW) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="EndDocPrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function EndDocPrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="StartPagePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function StartPagePrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="EndPagePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function EndPagePrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="WritePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function WritePrinter(ByVal hPrinter As IntPtr, ByVal pBytes As IntPtr, ByVal dwCount As Int32, ByRef dwWritten As Int32) As Boolean
    End Function

    ' When the function is given a string and a printer name,
    ' the function sends the string to the printer as raw bytes.
    'Public Shared Function SendStringToPrinter(ByVal szString As String, ByVal szPrinterName As String)
    Public Sub prt(ByVal szString As String, ByVal szPrinterName As String)
        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)
    End Sub

    ' 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 or False on failure.
    Public Shared Function SendBytesToPrinter(ByVal szPrinterName As String, ByVal pBytes As IntPtr, ByVal dwCount As Int32) As Boolean
        Dim hPrinter As IntPtr      ' The printer handle.
        Dim dwError As Int32        ' Last error - in case there was trouble.
        Dim di As DOCINFOW          ' Describes your document (name, port, data type).
        Dim dwWritten As Int32      ' The number of bytes written by WritePrinter().
        Dim bSuccess As Boolean     ' Your success code.

        ' Set up the DOCINFO structure.
        With di
            .pDocName = "Label"
            .pDataType = "RAW"
        End With
        ' Assume failure unless you specifically succeed.
        bSuccess = False
        If OpenPrinter(szPrinterName, hPrinter, 0) Then
            If StartDocPrinter(hPrinter, 1, di) Then
                If StartPagePrinter(hPrinter) Then
                    ' Write your printer-specific bytes to the printer.
                    bSuccess = WritePrinter(hPrinter, pBytes, dwCount, dwWritten)
                    EndPagePrinter(hPrinter)
                End If
                EndDocPrinter(hPrinter)
            End If
            ClosePrinter(hPrinter)
        End If
        ' 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 ' SendBytesToPrinter()
End Class
 
Last edited:

Mateus

Active member
Joined
Apr 16, 2010
Messages
27
Programming Experience
3-5
Think I've answered my own question. To find the escape codes, I redirecting RAW print data from a third-party application to a text file.

I noted the code characters in text file (shown below) and added them into my application code. Not ideal as I don't know exactly what these codes are saying and I feel I've cheated! But it does seem to work so far.

VB.NET:
M0

EDIT: The codes don't appear correctly above as I guess they're non-standard ASII characters; there's more than just 'M0'.
 
Last edited:
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