Code Sample: Getting links from a PDF

Links are saved as part of the annotations in a PDF document even though they are not really considered annotations.

Links in a PDF document do not specifically have a destination.  Instead, they are more general, they hold a list of actions that can really be anything.

We define actions that we support in the com.qoppa.android.pdfViewer.actions package.  You can get the list of actions for an annotation by calling:

annot.getActions();
This returns a List object that will hold objects that extend

com.qoppa.android.pdfViewer.actions.Action

Most inks will normally have a single action in the list and it will be one of these type:

  •   GotoPageAction – Go to a page within the same document
  •   GotoPageRemoteAction – Go to a page in another document
  •   URLAction – Open a web browser to a URL

Each of these classes has methods to get to the relevant data. i.e. the URLAction class has a method called getURL() that returns the target URL.

The java code sample below shows how to loop through the annotations in a PDF document and print out the URL for all links found.

import com.qoppa.pdf.annotations.Annotation;
import com.qoppa.pdf.annotations.Link;
import com.qoppa.pdfProcess.PDFDocument;
import com.qoppa.pdfProcess.PDFPage;
import com.qoppa.pdfViewer.actions.Action;
import com.qoppa.pdfViewer.actions.URLAction;

…

// Load the document
PDFDocument pdfDoc = new PDFDocument (“input.pdf”, null);

// Loop through pages
for(int count = 0; count < pdfDoc.getPageCount(); count++)
{

PDFPage page = pdfDoc.getPage(count);
if(page != null)
{
// Get list of annotations
Vector annots = page.getAnnotations();

// Write the annotations
if(annots != null)
{
for (int aCount = 0; aCount < annots.size(); ++aCount )
{
Annotation annot = (Annotation) annots.get (aCount);
if(annot != null)
{
if((annot instanceof Link) == false)
{
java.util.List actions = ((Link) annot).getActions();
if(actions != null)
{
for (int j = 0; count < actions.size(); ++j)
{
Action action = (Action)actions.get (j);
if (action instanceof URLAction)
{
String url = ((URLAction)action).getURL();
System.out.println(url);
}
}
}
}
}
}
}
}
}