将 iTextSharp.text.pdf.BarcodeQRCode 转换为 System.Drawing.Image

Question

Looking for a way to convert iTextSharp.text.pdf.BarcodeQRCode to System.Drawing.Image

This is what I have so far...

public System.Drawing.Image GetQRCode(string content)
{
     iTextSharp.text.pdf.BarcodeQRCode qrcode = new iTextSharp.text.pdf.BarcodeQRCode(content, 115, 115, null);
     iTextSharp.text.Image img = qrcode.GetImage();
     MemoryStream ms = new MemoryStream(img.OriginalData);
     return System.Drawing.Image.FromStream(ms); 
}

In line 3 above using img.OriginalData returns null Using img.RawData on line 3 instead thows invalid parameter error on line 4.

Answer 1

I've googled some of the code samples on how to perform the thing you want and your code (the "OriginalData" approach) is basicaly the same: https://csharp.hotexamples.com/examples/iTextSharp.text.pdf/BarcodeQRCode/-/php-barcodeqrcode-class-examples.html .

However, I don't see how it could work. From my investigations of BarcodeQRCode#getImage it seems that OriginalData is not set while processing such a barcode, so it will always be null.

More than that, the code you mention belongs to iText 5, which is end of life and no longer maintained (with an exception of considerable security fixes), so it's recommended to update to iText 7.

As for iText 7, I do see how to achieve the same in Java, since barcode classes do have a createAwtImage method there. .NET, on the other hand, lacks such a functionality, so I'd day that one unfortunately couldn't do it in .NET.

There are some good reasons for that. iText's Image s (and a barcode could be easily converted to an iText's Image object as shown here: https://kb.itextpdf.com/home/it7kb/faq/how-to-generate-2d-barcode-as-vector-image ) represent a PDF's XObject. In PDF syntax, an image file (jpg, png, etc.) is an XObject with the raw image data stored inside. However, an XObject can also contain PDF syntaxt content (it is not just used for image files). So to render such a content one needs to process the data from PDF syntax to image syntax, which is not that easy. There are some means in Java's awt to do so, that's why it's implemented in Java. As for .NET, since there is no out-of-the-box means to convert PDF images to System.Drawing.Image, it was decided not to implement it.

To conclude, there is another iText product, pdfRender , which allows one to convert PDF files (and you could create a page just for a barcode) to images. Perhaps you might want to play with it: https://itextpdf.com/en/products/itext-7/convert-pdf-to-image-pdfrender