Developer.com content and product recommendations are editorially independent. We may make money when you click on links to our partners. Learn More.
You can print from your program in a number of ways. One option, for example, is to automate Microsoft Word, edit a document in code, then programmatically print it out.
However, if you’re looking to print directly from your application, the .NET Framework provides a number of components to help you in the System.Drawing.Printing namespace.
The core component here is PrintDocument. At its simplest, printing involves instantiating a PrintDocument object, setting its properties, and calling the Print method. With each page to be printed, the PrintDocument raises a PrintPage event, to which you need to add your own printing logic. Other key classes in the same Printing namespace include PrinterSettings, PageSettings, and PrintPreviewControl.
As you can imagine, this is a large area and can get relatively complex. The following class attempts to simplify one of the most common uses: the simple printing of text. Simply add the following class code to your project and use as directed.
It’s worth noting that this class actually works, as opposed to the less-functional TextFilePrintDocument class bundled by Microsoft in the Windows Forms QuickStart tutorials, which cuts out as soon as a blank line is encountered in the passed text file, prints over the margin if a line is too large, plus only reads text from files. It is also neatly encapsulated and allows you to change its Font through a simple property, unlike Microsoft’s second attempt with its “101 VB.NET Samples”.
Here’s the code:
Public Class TextPrint
' Inherits all the functionality of a PrintDocument
Inherits Printing.PrintDocument
' Private variables to hold default font and text
Private fntPrintFont As Font
Private strText As String
Public Sub New(ByVal Text As String)
' Sets the file stream
MyBase.New()
strText = Text
End Sub
Public Property Text() As String
Get
Return strText
End Get
Set(ByVal Value As String)
strText = Value
End Set
End Property
Protected Overrides Sub OnBeginPrint(ByVal ev _
As Printing.PrintEventArgs)
' Run base code
MyBase.OnBeginPrint(ev)
' Sets the default font
If fntPrintFont Is Nothing Then
fntPrintFont = New Font("Times New Roman", 12)
End If
End Sub
Public Property Font() As Font
' Allows the user to override the default font
Get
Return fntPrintFont
End Get
Set(ByVal Value As Font)
fntPrintFont = Value
End Set
End Property
Protected Overrides Sub OnPrintPage(ByVal ev _
As Printing.PrintPageEventArgs)
' Provides the print logic for our document
' Run base code
MyBase.OnPrintPage(ev)
' Variables
Static intCurrentChar As Integer
Dim intPrintAreaHeight, intPrintAreaWidth, _
intMarginLeft, intMarginTop As Integer
' Set printing area boundaries and margin coordinates
With MyBase.DefaultPageSettings
intPrintAreaHeight = .PaperSize.Height - _
.Margins.Top - .Margins.Bottom
intPrintAreaWidth = .PaperSize.Width - _
.Margins.Left - .Margins.Right
intMarginLeft = .Margins.Left 'X
intMarginTop = .Margins.Top 'Y
End With
' If Landscape set, swap printing height/width
If MyBase.DefaultPageSettings.Landscape Then
Dim intTemp As Integer
intTemp = intPrintAreaHeight
intPrintAreaHeight = intPrintAreaWidth
intPrintAreaWidth = intTemp
End If
' Calculate total number of lines
Dim intLineCount As Int32 = _
CInt(intPrintAreaHeight / Font.Height)
' Initialise rectangle printing area
Dim rectPrintingArea As New RectangleF(intMarginLeft, _
intMarginTop, intPrintAreaWidth, intPrintAreaHeight)
' Initialise StringFormat class, for text layout
Dim objSF As New StringFormat(StringFormatFlags.LineLimit)
' Figure out how many lines will fit into rectangle
Dim intLinesFilled, intCharsFitted As Int32
ev.Graphics.MeasureString(Mid(strText, _
UpgradeZeros(intCurrentChar)), Font, _
New SizeF(intPrintAreaWidth, _
intPrintAreaHeight), objSF, _
intCharsFitted, intLinesFilled)
' Print the text to the page
ev.Graphics.DrawString(Mid(strText, _
UpgradeZeros(intCurrentChar)), Font, _
Brushes.Black, rectPrintingArea, objSF)
' Increase current char count
intCurrentChar += intCharsFitted
' Check whether we need to print more
If intCurrentChar < strText.Length Then
ev.HasMorePages = True
Else
ev.HasMorePages = False
intCurrentChar = 0
End If
End Sub
Public Function UpgradeZeros(ByVal Input As Integer) As Integer
' Upgrades all zeros to ones
' - used as opposed to defunct IIF or messy If statements
If Input = 0 Then
Return 1
Else
Return Input
End If
End Function
End Class
We could use this class as follows:
' Create object, passing in text
Dim MyPrintObject As New TextPrint(TextBox1.Text)
' Set font, if required
MyPrintObject.Font = New Font("Tahoma", 8)
' Issue print command
MyPrintObject.Print()
About the Author
Karl Moore (MCSD, MVP) is an experience author living in Yorkshire, England. He is author of numerous technology books, including the new Ultimate VB .NET and ASP.NET Code Book (ISBN 1-59059-106-2), plus regularly features at industry conferences and on BBC radio. Moore also runs his own creative consultancy, White Cliff Computing Ltd. Visit his official Web site at www.karlmoore.com.
# # #
