How to apply rotation and transparency to background image?

25 May 20231 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
  FileStream inputStream = new FileStream("Sample.xlsx", FileMode.Open, FileAccess.Read);
  IWorkbook workbook = application.Workbooks.Open(inputStream);
  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
  FileStream outputStream = new FileStream("Output.xlsx", FileMode.Create, FileAccess.Write);
  workbook.SaveAs(outputStream);
  #endregion

  //Dispose streams
  outputStream.Dispose();
  inputStream.Dispose();
}