How to use dot matrix printing in VB 6.0
In the first part of this tutorial we discussed the basics of printing in Vb 6.0. We discussed the lack of direct text
printing support in Windows. Now we will see the Win32 API functions used to print / emulate Dos mode text printing using
Visual Basic 6.0
First declare the following functions and types in your code. Better use a separate module to put these declarations.
Private Type DOCINFO
pDocname As String
pOutputFile As String
pDatatype As String
End Type
Private Declare Function ClosePrinter Lib "winspool.drv" (ByVal hPrinter As Long) As Long
Private Declare Function EndDocPrinter Lib "winspool.drv" (ByVal hPrinter As Long) As Long
Private Declare Function EndPagePrinter Lib "winspool.drv" (ByVal hPrinter As Long) As Long
Private Declare Function OpenPrinter Lib "winspool.drv" Alias "OpenPrinterA" (ByVal pPrinterName As String, phPrinter As
Long, ByVal pDefault As Long) As Long
Private Declare Function StartDocPrinter Lib "winspool.drv" Alias "StartDocPrinterA" (ByVal hPrinter As Long, ByVal Level As
Long, pDocInfo As DOCINFO) As Long
Private Declare Function StartPagePrinter Lib "winspool.drv" (ByVal hPrinter As Long) As Long
Private Declare Function WritePrinter Lib "winspool.drv" (ByVal hPrinter As Long, pBuf As Any, ByVal cdBuf As Long, pcWritten
As Long) As Long
Thats all about declarations.
Then write the following function
Public Function RawPrint(Optional FileToPrint As String) As Boolean
Dim lhPrinter As Long
Dim lReturn As Long
Dim lpcWritten As Long
Dim lDoc As Long
Dim sWrittenData As String
Dim MyDocInfo As DOCINFO
If Printers.Count <= 0 Then
MsgBox "No printer(s) found!"
Exit Function
End If
OpenTextFile ' Write a function to open the text file to be printed.
lReturn = OpenPrinter(Printer.DeviceName, lhPrinter, 0)
If lReturn = 0 Then
MsgBox "Printing failed!"
Exit Function
End If
MyDocInfo.pDocname = "Ultimate Solutions"
MyDocInfo.pOutputFile = vbNullString
MyDocInfo.pDatatype = "RAW"
lDoc = StartDocPrinter(lhPrinter, 1, MyDocInfo)
Call StartPagePrinter(lhPrinter)
sWrittenData = "Test printing"
While Not EOF(mRptPrint)
Line Input #mRptPrint, sWrittenData
sWrittenData = sWrittenData & vbLf
lReturn = WritePrinter(lhPrinter, ByVal sWrittenData, Len(sWrittenData), lpcWritten)
Wend
lReturn = EndPagePrinter(lhPrinter)
lReturn = EndDocPrinter(lhPrinter)
lReturn = ClosePrinter(lhPrinter)
Close #mRptPrint
End Function
This function takes a text file as parameter. It uses win32 printer functions declared above to print the text file line by
line. Because of RAW printing in text mode. The text will have standard size and will use standard printer font's like
courier, sans serif, etc. The bold, italic, underline as we do normally in a Ms-word file requires a bit of extra coding.
This requires control codes to be sent to the Dot Matrix printers.
You can also set CPI or characters per Inch. This will tell the printer to set the font width appropriately. You can also set
the paper size in inches or lines. A typical A4 size paper can hold about 72 lines.
To start bold printing use ESC + G (capital G) that is ASCII 27 + G, the actual code in VB is chr(27) +"M". This will the
tell the printer to start printing in bold letters. To stop bold printing just send chr(27) + "H"
sending means the WritePrinter function that sends output to printer. In the above printing function the sWrittenData
parameter should be set to this value (chr(27)+"H") for stop bold printing.
To set the characters per Inch,
To print 12 characters per Inch use Chr(27) + "g"
To print 17 characters per inch use Chr(27) + Chr(15) in VB
To Print 20 characters per inch use Chr(27) + "M" + Chr(27) + Chr(15)
To set paper size to 6 inch use Chr(27) + "C" + Chr(35)
For 8 inches use Chr(27) + "C" + Chr(47)
For 12 inch use Chr(27) + "C" + Chr(71)
For direct printing you can use another method instead of Win32 API. Just use the file IO in VB 6.0. Just open the printer port as if it were a file.
For file opening you will use the syntax.
Open 'filename' for output as 'filenumber'
This is the standard VB 6.0 syntax for opening a file for writing.
Commonly Dot matrix printers are connected to LPT ports. In most cases this will be LPT1:
so the following syntax can be used.
Open "LPT1:" for output as 1
to get the next available filenumber use FreeFile function.
Then use the Print FileNumber, Text syntax to print.
For example, Print 1, "HelloWorld!"
Then close the file using 'Close Filenumber' syntax, For example Close 1. Immediately after closing the file the printer will start printer whatever you printed using Print syntax. Thats all about Dot Matrix Fast printing using VB 6.0!
