.NET Core PdfPage Save As Image Using Streams Fails

.NET Core PdfPage Save As Image Using Streams Fails

Posted by: andy.baker on 6 March 2020, 8:20 am EST

• 

  andy.baker

  • Post Options:
  • Link
    Copy
  • Jump To Answer

  Posted 6 March 2020, 8:20 am EST

  I have a Web API that accepts uploaded files where I need to rasterize each page. I need to keep the images as byte arrays as I cannot write these files to disk (if I could this wouldn’t be an issue). I’ve tried the different image types Bmp, Jpeg, etc… without success.

  foreach (var pdfPage in pdfDocument.Pages)
                  {
                      Stream s = new MemoryStream();
                      pdfPage.SaveAsPng(s);
  
                      Byte[] pageBytes = new byte[s.Length];
                      s.Read(pageBytes, 0, (int)s.Length);
                      s.Dispose();
  
                      // This fails
                      System.IO.File.WriteAllBytes("C:\\TEMP\\BadPage " + (pdfPage.Index + 1).ToString() + ".png", pageBytes);
  
                      // This works
                      pdfPage.SaveAsPng("C:\\TEMP\\GoodPage " + (pdfPage.Index + 1).ToString() + ".png");
  }
  

  When using the PdfPage.SaveAsPng() it saves the image to disk exactly as it should.

  When using the PdfPage.SaveAsPng() overload it seems the image is corrupt and I can never render it.

• 

  andy.baker

  • Post Options:
  • Link
    Copy

  Posted 8 March 2020, 10:35 pm EST

  Solved…

  Required a slightly different approach to the code, but here is what worked.

  
  foreach (var pdfPage in pdfDocument.Pages)
  {
  	MemoryStream s = new MemoryStream();
          pdfPage.SaveAsPng(s);
  
  	// This was the new approach that loaded the array correctly
          Byte[] pageBytes = s.ToArray();
  	s.Dispose();
  }