itextsharp合并具有形式的pdf文件

Question

I'm trying to use itextsharp to merge two PDF files (version 7), both having form fields. When I run the code I get this error message: "Cannot handle iref streams. The current implementation of PDFsharp cannot handle this PDF feature introduced with Acrobat 6." I tried different approaches but in my last I got the PDFs but instead of the original file contents, I got a file with the following info:

     Please wait... If this message is not eventually replaced by the proper contents of the document, your PDF viewer may not be able to
 display this type of document. You can upgrade to the latest version
 of Adobe Reader for Windows®, Mac, or Linux® by visiting
 http://www.adobe.com/go/reader_download. For more assistance with
 Adobe Reader visit http://www.adobe.com/go/acrreader. Windows is
 either a registered trademark or a trademark of Microsoft Corporation
 in the United States and/or other countries. Mac is a trademark of
 Apple Inc., registered in the United States and other countries. Linux
 is the registered trademark of Linus Torvalds in the U.S. and other
 countries.

Can anyone help me and post some working code method to concatenate two Pdfs of this kind. Thank you in advance.

Answer 1

You either have forms based on AcroForm technology. In this case the fields are described using PDF objects such as field dictionaries, widget annotation dictionaries, etc... These forms can easily be merged, regardless of the fact if they are PDF 1.7, 1.6,...

You can also have forms based on the XML Forms Architecture (XFA) in which case the PDF acts as a contained for an XML stream. Usually such a form starts from an XML schema.

Based on the "your PDF viewer may not be able to display this type of document" message, it seems that you are dealing with XFA forms.

If you want to merge pure XFA forms, you have the following options:

1. If the forms have the same schema, you extract the XML data from both forms, merge the XML data and fill an empty form with the merged data. This assumes that you know the XML schema and that you know how to merge the XML data.
2. If the forms don't have the same schema, it will be extremely difficult (if not impossible) to merge the forms and keep the forms interactive: you'd need to create a new schema for the data and basically create a new form from scratch.
3. You may be in luck if the forms are "hybrid". That is: if they contain a description of the form using both technologies next to each other. In that case, throw away the XFA part of the form, keep the AcroForm part and merge the AcroForm forms.
4. Finally, you could flatten the forms first (using our closed source XFA worker) and then merge the flattened PDFs. The end result will no longer be a form.

Bottom line: the answer to your question ranges from "you're trying to do something that is impossible if not done by a human" (merging two XFA forms based on a different XML schema) to "you're trying to do something that is really easy" (merging two AcroForm forms, possibly after removing the XFA counter-part).

A definitive answer can't be given as you are not giving us any details on the nature of the forms.