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about Custom Controlling and the Print Controller in GDI+.
Custom Controlling and the Print Controller in GDI+
At this point you must feel like a printer master and have the confidence you
need to write a printing application. We have covered almost every aspect of
printing in .NET, but guess what! There are still a few surprises hidden in
System.Drawing.Printing. You will probably never use the classes that we're
going to discuss in this section, but its' not a bad idea to know about them.
So far in this article we've created a PrintDocument object, created a PrintPage
event handler, and called the Print method of PrintDocument. PrintDocument took
care of everything internally for us. Now we will see how to control
PrintDocument objects handles printing.
The PrintController class represents print controllers in the .NET Framework
library. It's an abstract base class, so its functionality comes from its three
derived classes: PreviewPrintController, StandardPrintController, and
PrintControllerWithStatusDialog. PrintController and its derived classes are
shown schematically in Figure 11.28.
Normally PrintController is used by PrintDocument. When PrintDocument starts
printing by calling the Print method, it invokes the print controller's
OnStartPrint, OnEndPrint, OnStartPage, and OnEndPage methods, which determine
how a printer will print the document. Usually the OnStartPrint method of
PrintController is responsible for obtaining the Graphics object, which is later
used by the PrintPage event handler.
The StandardPrintController class is used to send pages to the printer. We set
the PrintController property of PrintDocument to PrintController. Standard-
PrintController.PrintControllerWithStatusDialog adds a status dialog to the
printing functionality. It shows the name of the document currently being
printed. To attach PrintControllerWithStatusDialog, we set PrintDocument's
PrintController property to Printcontroller.PrintControllerWithStatusDialog.
FIGURE 11.28: PrintController-derived classes
The PreviewPrintController class is used for generating previews of pages being
printed. Beside the methods defined in the PrintController class,
PreviewPrintController provides one property (UseAntiAlias) and one method (GetPreviewPageInfo).
The UseAntiAlias property indicates whether anti-aliasing will be used when the
print preview is being displayed.
The GetPreviewPageInfo method captures the pages of a document as a series of
images and returns them as an array called PreviewPageInfo. The PreviewPageInfo
class provides print preview information for a single page. This class has two
properties: Image and PhysicalSize. The Image property returns an Image object,
which represents an image of the printed page, and PhysicalSize represents the
size of the printed page in hundredths of an inch.
Let's write a sample application. We create a Windows application, and we add a
MainMenu control, and item and a StatusBar control to the form. Our final form
looks like Figure 11.29.
FIGURE 11.29: Print controller test form
Before adding any code to this form, we create a MyPrintcontroller class, which
is inherited from StandardPrintController. You can use the
PreviewPrintController or PrintControllerWithStatusDialog classes in the same
way. The code for the MyPrintController class is given in Listing 11.50. We
override all four methods: OnStartPrint, OnStartPage, OnEndPrint, and OnEndPage.
On these methods we notify the status bar about the status of the printing
process. This information could be useful for displaying page numbers or other
print status information when we're printing multipage documents.
LISTING 11.50: The MyPrintController class
'Print controller class
Class MyPrintController
Inherits StandardPrintController
Private statusBar
As StatusBar
Private str As
String = String.Empty
Public Sub
New(ByVal sBar
As StatusBar)
statusBar = sBar
End Sub
Public Overrides
Property OnStartPrint()
As Void
End Property
(PrintDocument printDoc,
Private
Function peArgs)() As
PrintEventArgs
statusBar.Text = "OnStartPrint Called"
MyBase.OnStartPrint(printDoc,
peArgs)
End Function
Public Overrides
Property OnStartPAge()
As Graphics
End Property
(printDocument printDoc,
Private
Function ppea)() As
PrintPageEventArgs
statusBar.Text = "OnStartPAget Called"
Return
MyBase.OnStartPage(printDoc, ppea)
End Function
Public
ovveride Property printDoc,()
As OnEndPage(PrintDocument
End
Property
Private
Function ppeArgs)() As
PrintPageEventArgs
statusBar.Text = "OnEndPage Called"
MyBase.OnEndPage(printDoc,
ppeArgs)
End Function
Public
Property OnEndPrint(PrintDocument()
As overrid
End Property
printDoc,PrintEventArgs peArgs)
{
statusBar.Text = "OnEndPrint Called"
statusBar.Text = str
MyBase.OnEndPrint
(printDoc, peArgs)
End Class
{
Private statusBar
As StatusBar
Private str As
String = String.Empty
Private
Function MyPrintController(ByVal
sBar As StatusBar) As
Public
statusBar = sBar
End Function
Public Overrides
Property OnStartPrint()
As Void
End Property
(PrintDocument printDoc,
Private
Function peArgs)() As
PrintEventArgs
statusBar.Text = "OnStartPrint Called"
MyBase.OnStartPrint(printDoc,
peArgs)
End Function
Public Overrides
Property OnStartPAge()
As Graphics
End Property
(printDocument printDoc,
Private
Function ppea)() As
PrintPageEventArgs
statusBar.Text = "OnStartPAget Called"
Return
MyBase.OnStartPage(printDoc, ppea)
End Function
Public
ovveride Property printDoc,()
As OnEndPage(PrintDocument
End
Property
Private
Function ppeArgs)() As
PrintPageEventArgs
statusBar.Text = "OnEndPage Called"
MyBase.OnEndPage(printDoc,
ppeArgs)
End Function
Public
Property OnEndPrint(PrintDocument()
As overrid
End Property
Private
Function peArgs)() As
printDoc,PrintEventArgs
statusBar.Text = "OnEndPrint Called"
statusBar.Text = str
MyBase.OnEndPrint(printDoc, peArgs)
End Function
To call the MyPrintController
class, we need to set the PrintController property of PrintDocument to invoke
MyPrintController's overridden methods. Let's write a menu click event handler
and set the create a PrintDocument object, set its DocumentName and
PrintController properties, enable the PrintPage event handler, and call Print
to print the document.
LISTING 11.51: Setting the PrintController property of PrintDocument
Private Sub
StandardPrintControllerMenu_Click(ByVal sender
As Object,
ByVal e As
System.EventArgs)
Dim printDoc As
New PrintDocument()
printDoc.DocumentName = "PrintController
Document"
printDoc.PrintController = New
MyPrintController(statusBar1)
printDoc.PrintPage += New
PrintPageEventHandler(PrintPageHandler)
printDoc.Print()
End Sub
Listing 11.52 gives the code for the PrintPage event handler which, just draws
some text on the printer.
LISTING 11.52: The PrintPage event handler
Private Sub
PrintPageHandler(ByVal obj
As Object,
ByVal ppeArgs As
PaintPageEventArgs)
Dim g As
Graphics = ppeArgs.Graphics
Dim brush As
solidBrush = New SolidBrush(Color.Red)
Dim verdana20Font
As New Font("Verdana",
20)
g.DrawString("Print Controller Test",
verdana20Font, brush, 20, 20)
End Sub
FIGURE 11.30: Print controller output
If we run the application and print, we will see that the status bar displays
the status of the printing process. The first event message is shown in Figure
11.30.
You can extend this functionality to write your own custom print controllers.
Conclusion
Hope the article would have helped you in understanding Custom Controlling and
the Print Controller in GDI+. Read other articles on GDI+ on the website.