Introduction
In versions of iText 7 Core prior to 7.1.12 it was possible that a link could occupy more than two areas. If this occurred, the result would be that a link occupying more than two areas would throw a NullPointerException.
After further investigation we found the source of the bug was caused due to a link annotation being copied and applied only on the draw method.
Solution
Our solution to this problem was to do the following:
1. Copy the link annotation on split.
2. Change the value of LINK_ANNOTATION property on each split (important for links which occupy more than two areas.)
This is because when we update the second instance of a link, the content of the first one will be flushed.
Example Code
Below is some example code that demonstrates that the bug has been fixed and is working:
package LinkExample;
import com.itextpdf.kernel.colors.ColorConstants;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.action.PdfAction;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.Div;
import java.io.FileNotFoundException;
public class LinkExample {
public static void main(String[] args) throws FileNotFoundException {
createPdf();
}
public static void createPdf() throws FileNotFoundException {
//get ouput path for pdf file
String outFileName = System.getProperty("user.dir")+"\\output.pdf";
// create Pdfdocument with pdfwriter
PdfDocument pdfDocument = new PdfDocument(new PdfWriter(outFileName));
//add to doc
Document doc = new Document(pdfDocument);
//create link
PdfAction action = PdfAction.createURI("http://itextpdf.com");
//create div with height 2000 will expand to three pdf pages
Div div = new Div()
.setHeight(2000)
.setBackgroundColor(ColorConstants.RED);
//add link to pdf
div.setAction(action);
//add div to document
doc.add(div);
//close document
doc.close();
}
}
using iText.Kernel.Colors;
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Action;
using iText.Layout;
using iText.Layout.Element;
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
namespace ConsoleApp1
{
class MutipleLinkExample{
public static void Main(String[]args)
{
CreatePdf();
}
public static void CreatePdf()
{
// path to output pdf
String outFileName = Directory.GetCurrentDirectory()+ "\\output.pdf";
// create Pdfdocument with pdfwriter
PdfDocument pdfDocument = new PdfDocument(new PdfWriter(outFileName));
//add to doc
Document doc = new Document(pdfDocument);
//create link
PdfAction action = PdfAction.CreateURI("http://itextpdf.com");
//create div with height 2000 will expand to three pdf pages
Div div = new Div()
.SetHeight(2000)
.SetBackgroundColor(ColorConstants.RED);
//add link to pdf
div.SetAction(action);
//add div to document
doc.Add(div);
//close document
doc.Close();
}
}
}