ICommandHandler.HandleCommand(PrintingSystemCommand, Object[], IPrintControl, ref Boolean) Method

If implemented by a class, allows you to handle Printing System commands (listed in the PrintingSystemCommand enumeration).

Namespace: DevExpress.XtraPrinting

Assembly: DevExpress.Printing.v24.2.Core.dll

Declaration

C#

void HandleCommand(
    PrintingSystemCommand command,
    object[] args,
    IPrintControl printControl,
    ref bool handled
)

VB.NET

Sub HandleCommand(
    command As PrintingSystemCommand,
    args As Object(),
    printControl As IPrintControl,
    ByRef handled As Boolean
)

Parameters

Name	Type	Description
command	PrintingSystemCommand	A PrintingSystemCommand enumeration value.
args	Object[]	An array of Object values, specifying the command arguments.
printControl	IPrintControl	An object implementing the IPrintControl interface (typically, this is a PrintControl instance).
handled	Boolean	true, if the command has been handled; otherwise, false.

Remarks

Exceptions thrown from within a user’s handler are not allowed to bubble up to the main application thread.

Example

This example illustrates how to override a Printing System command.

A custom command handler must implement the ICommandHandler interface. You can add it to a Printing System’s list of handlers using the PrintingSystemBase.AddCommandHandler method.

C#

using DevExpress.XtraPrinting;
using DevExpress.XtraReports.UI;
// ...

private void button1_Click(object sender, System.EventArgs e) {
    // Create a Print Tool with an assigned report instance.
    ReportPrintTool printTool = new ReportPrintTool(new XtraReport1());

    // Generate the report's document to be able to access its Printing System.
    printTool.Report.CreateDocument(false);

    // Override the ExportGraphic command.
    printTool.PrintingSystem.AddCommandHandler(new ExportToImageCommandHandler());

    // Show the report's Print Preview in a dialog window.
    printTool.ShowPreviewDialog();

}

public class ExportToImageCommandHandler : ICommandHandler {
    public virtual void HandleCommand(PrintingSystemCommand command,
    object[] args, IPrintControl printControl, ref bool handled) {
        if (!CanHandleCommand(command, printControl)) return;

        // Export the document to PNG.
        printControl.PrintingSystem.ExportToImage("C:\\Report.png", System.Drawing.Imaging.ImageFormat.Png);

        // Prevent the default exporting procedure from being called.
        handled = true;
    }

    public virtual bool CanHandleCommand(PrintingSystemCommand command, IPrintControl printControl) {
        return command == PrintingSystemCommand.ExportGraphic;
    }
}

VB.NET

Imports DevExpress.XtraPrinting
Imports DevExpress.XtraReports.UI
' ...

Private Sub button1_Click(sender As Object, e As System.EventArgs)
    ' Create a Print Tool with an assigned report instance.
    Dim printTool As New ReportPrintTool(New XtraReport1())

    ' Generate the report's document to be able to access its Printing System.
    printTool.Report.CreateDocument(False)

    ' Override the ExportGraphic command.
    printTool.PrintingSystem.AddCommandHandler(New ExportToImageCommandHandler())

    ' Show the report's Print Preview in a dialog window.
    printTool.ShowPreviewDialog()

End Sub

Public Class ExportToImageCommandHandler
    Implements ICommandHandler
    Public Overridable Sub HandleCommand(command As PrintingSystemCommand, args As Object(), _ 
    printControl As IPrintControl, ByRef handled As Boolean)
        If Not CanHandleCommand(command, printControl) Then
            Return
        End If

        ' Export the document to PNG.
        printControl.PrintingSystem.ExportToImage("C:\Report.png", System.Drawing.Imaging.ImageFormat.Png)

        ' Prevent the default exporting procedure from being called.
        handled = True
    End Sub

    Public Overridable Function CanHandleCommand(command As PrintingSystemCommand, _ 
    printControl As IPrintControl) As Boolean
        Return command = PrintingSystemCommand.ExportGraphic
    End Function
End Class