How to: Set Page Orientation
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This example demonstrates how to set the orientation of worksheet pages via the WorksheetView.Orientation property of the worksheet view object that is accessed via the Worksheet.ActiveView. The PageOrientation enumerator lists available page orientation types.
A complete sample project is available at https://github.com/DevExpress-Examples/spreadsheet-document-server-api-e4339
// Set the page orientation to Landscape. workbook.Worksheets.ActiveView.Orientation = PageOrientation.Landscape;