Printing

Previous to .NET, printing with Visual Basic involved either using the common print dialog control and/or the Win32 API. The former did not always provide enough flexibility and the later sapped the productivity level to which VB developers have become accustomed. System.Drawing.Printing to the rescue! This namespace provides us with a ton of flexibility while encapsulating the low-level stuff that can often bog down programmers.

Sending Output to the Printer

Printing in Windows involves a printer device context. The good news is that this context can be used the same way as any other device context. All the drawing functions presented in the following chapter, for instance, work the same way for printers as they do for display devices. This is one of the reasons you find the Printing namespace tucked under Drawing. This device independence is one of the powerful features that Windows provides. It is possible to render output to either the screen or the printer just by switching device contexts.

Typically, programmers execute the following basic steps when writing printing functionality using the .NET Class Library:

Dim printDocument As New System.Drawing.Printing.PrintDocument

'tell the print document object the name of the printer
printDocument.PrinterSettings.PrinterName = _
    "Epson Stylus COLOR 640 ESC/P 2"

'set the page orientation to landscape
printDocument.PrinterSettings.DefaultPageSettings.Landscape = False

AddHandler printDocument.PrintPage, AddressOf Me.printPage_handler

printDocument.Print()

Private Sub printPage_handler(ByVal sender As Object, _
    ByVal ev As System.Drawing.Printing.PrintPageEventArgs)

      'draw the string to the printer device
    ev.Graphics.DrawString(s:="Hello World!", _
     font:= New Font("Arial", 10), brush:=Brushes.Black, _
     x:= ev.MarginBounds.Left, y:=ev.MarginBounds.Top, _
     format:=New StringFormat())

End Sub

Printer Configuration

The Printing namespace provides a number of enumerations that enable us to manage various printer configuration settings. This section provides an overview of what is available. It is arranged into a number of tables that describe the enumerations and their members.

Table 6.7 lists the Duplex enumeration members. This enables you to read and write the printer's duplex setting. Duplex, in printing, describes how printers print on both sides of the paper. This enumeration provides values for the PrinterSettings class's Duplex property. A PrinterSettings instance is used to control how a printer is configured to send output.

PaperKind refers to the physical type of paper loaded into the printer. The enumeration is used by the PaperSize class for its Kind property. PaperSize itself is used by the PrinterSettings class when specifying the PaperSizes property. The PaperSizes property is a collection of PaperSize objects that indicate the various sizes of paper the given printer supports. Table 6.8 lists some of the key PaperKind members most commonly used in the United States.

Table 6.9 documents the PaperSourceKind enumeration members. Paper sources can be thought of as paper trays and the like on a physical printer. The enumeration is used by the PaperSource class for its Kind property. This property is used to both return and to set the source of the paper used when printing. PaperSource itself is used by the PrinterSettings class when specifying the PaperSources property. The PaperSources property is a collection of PaperSource objects that indicates the various paper sources a given printer supports. The most common setting is AutomaticFeed, which tells most printers that they should handle the source from where the paper comes.

Table 6.10 lists the various printer resolution settings that are available to your applications. The PrinterResolutionKind enumeration members enable you to tell the printer to output documents based on some standard resolutions. The enumeration is used by the PrinterResoultion class for its Kind property. PrinterResoultion itself is used by the PrinterSettings class when specifying the PrinterResolutions property. The PrinterResolutions property is a collection of PrinterResolution objects that indicate the various resolutions supported by a given printer. These properties are handy when users want a quick version, or draft, of their documents for proofing, or a slower, but high-quality version for release.

Table 6.11 lists the PrintRange enumeration members. The enumeration is used to represent the portions of the document that should be output to the printer. This enumeration is used by the PrinterSettings class to indicate the range that should be printed.

Previewing Documents Prior to Printing

Before sending documents to the printer, users often need to see how their output is going to look. This saves paper, ink, and time. For instance, Microsoft Word provides the print previewing functionality. .NET exposes two classes that enable developers to simulate this functionality. The PreviewPrintController class is a print controller that displays documents to the screen as a series of images. This class makes extensive use of the PreviewPageInfo class. The PreviewPageInfo class represents the print preview information of one specific page. The following is a step-by-step walkthrough of adding print preview capabilities to your application:

Dim printDocument As System.Drawing.Printing.PrintDocument
Dim previewController As System.Drawing.Printing.PreviewPrintController
Dim pageInfoArray() As System.Drawing.Printing.PreviewPageInfo
Dim i As Integer

printDocument = New System.Drawing.Printing.PrintDocument()

previewController = New System.Drawing.Printing.PreviewPrintController()

printDocument.PrintController = previewController

AddHandler printDocument.PrintPage, AddressOf Me.printPage_handler

printDocument.Print()

'return an array of PreviewPageInfo objects from the print controller
pageInfoArray = previewController.GetPreviewPageInfo()

'loop through the array and display each image
For i = 0 To UBound(pageInfoArray)
     Me.pictureBoxPreview.Image = pageInfoArray(i).Image
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