When use the UltraPrintPreviewControl to preview the content of the UltraWinGrid, close the form where the UltraPrintPreviewControl is in, System.NullReferenceException is thrown.

Exception trace is : 場所 Infragistics.Win.UltraWinGrid.RowColRegionIntersectionUIElement.OnAfterDraw(UIElementDrawParams& defaultDrawParams) 場所 Infragistics.Win.UIElement.DrawElement(UIElementDrawParams& defaultDrawParams) 場所 Infragistics.Win.UIElement.DrawChildElements(UIElementDrawParams& drawParams) 場所 Infragistics.Win.UIElement.DrawElement(UIElementDrawParams& defaultDrawParams) 場所 Infragistics.Win.UIElement.DrawChildElements(UIElementDrawParams& drawParams) 場所 Infragistics.Win.UIElement.DrawElement(UIElementDrawParams& defaultDrawParams) 場所 Infragistics.Win.UIElement.DrawHelper(Graphics graphics, Rectangle invalidRectangle, Boolean doubleBuffer, AlphaBlendMode alphaBlendMode, Boolean clipText, Boolean forceDrawAsFocused, Boolean preventAlphaBlendGraphics) 場所 Infragistics.Win.UIElement.Print(Graphics graphics, Boolean clipText) 場所 Infragistics.Win.UltraWinGrid.PrintManager.PrintPage(Object sender, PrintPageEventArgs ev) 場所 System.Drawing.Printing.PrintPageEventHandler.Invoke(Object sender, PrintPageEventArgs e) 場所 System.Drawing.Printing.PrintDocument.OnPrintPage(PrintPageEventArgs e) 場所 Infragistics.Win.Printing.UltraPrintDocument.OnPrintPageBody(PrintPageEventArgs e) 場所 Infragistics.Win.Printing.UltraPrintDocument.OnPrintPage(PrintPageEventArgs e) 場所 System.Drawing.Printing.PrintDocument._OnPrintPage(PrintPageEventArgs e) 場所 System.Drawing.Printing.PrintController.PrintLoop(PrintDocument document) 場所 System.Drawing.Printing.PrintController.Print(PrintDocument document) 場所 System.Drawing.Printing.PrintDocument.Print() 場所 Infragistics.Win.Printing.UltraPrintPreviewControl.GeneratePreviewHelper(Boolean synchronous) 場所 Infragistics.Win.Printing.UltraPrintPreviewControl.OnApplicationIdle(Object sender, EventArgs e) 場所 System.Windows.Forms.Application.ThreadContext.System.Windows.Forms.UnsafeNativeMethods.IMsoComponent.FDoIdle(Int32 grfidlef) 場所 System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) 場所 System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) 場所 System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) 場所 System.Windows.Forms.Application.Run(Form mainForm)

source:

UltraGridPrintDocument ugrpd; UltraPrintPreviewControl ultraPrintPreviewControl; ....... ultraPrintPreviewControl.Document = ugrpd; ultraPrintPreviewControl.InvalidatePreview(); ugrpd.PageHeaderPrinting += new HeaderFooterPrintingEventHandler(ugrpd_PageHeaderPrinting); // Preview status display private void ugrpd_PageHeaderPrinting(object sender, HeaderFooterPrintingEventArgs e) { ......... if (UserCloseForm()) // user can close the form. { { this.Dispose(); // form close. } } } How can I stop the print preview ,when in preview status display.