How to apply rotation and transparency to background image?

8 Dec 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();
}