How to apply rotation and transparency to background image?

4 Nov 20251 minute to read

Syncfusion® XlsIO do not have direct support to apply rotation and transparency to background image. But this can be achieved through below workaround.

C# [Cross-platform]

using (ExcelEngine excelEngine = new ExcelEngine())
{
  IApplication application = excelEngine.Excel;

  //Load an existing Excel file into IWorkbook
  IWorkbook workbook = application.Workbooks.Open("Sample.xlsx");
  IWorksheet worksheet = workbook.Worksheets[0];

  System.Drawing.Image image = System.Drawing.Image.FromFile("image.png");
  Bitmap bitmap = new Bitmap(image);

  //Rotate the image
  bitmap.RotateFlip(System.Drawing.RotateFlipType.Rotate90FlipNone);

  //Apply transparency
  bitmap.MakeTransparent(System.Drawing.Color.Black);

  bitmap.Save("image_M.png", ImageFormat.Png);

  FileStream imageStream = new FileStream("image_M.png", FileMode.Open, FileAccess.Read);
  worksheet.PageSetup.BackgoundImage = Syncfusion.Drawing.Image.FromStream(imageStream);

  #region Save
  //Saving the workbook
  workbook.SaveAs("Output.xlsx");
  #endregion
}