Tagged PDF: Adding Alt to the Structure Tree

This is a code example of iText PDF, discover more.

31st May 2016
iText PDF
AddAltTags.java
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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2019 iText Group NV
    Authors: iText Software.
 
    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
/*
 * This example was written in answer to the following question:
 * http://stackoverflow.com/questions/34036200
 */
package com.itextpdf.samples.sandbox.pdfa;
 
import com.itextpdf.kernel.pdf.*;
import com.itextpdf.samples.GenericTest;
import com.itextpdf.test.annotations.type.SampleTest;
 
import org.junit.experimental.categories.Category;
 
import java.io.File;
import java.io.IOException;
 
@Category(SampleTest.class)
public class AddAltTags extends GenericTest {
    public static final String DEST = "./target/test/resources/sandbox/pdfa/add_alt_tags.pdf";
    public static final String SRC = "./src/test/resources/pdfs/no_alt_attribute.pdf";
 
    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();
        new AddAltTags().manipulatePdf(DEST);
    }
 
    public void manipulatePdf(String dest) throws IOException {
        PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));
        PdfDictionary catalog = pdfDoc.getCatalog().getPdfObject();
        PdfDictionary structTreeRoot = catalog.getAsDictionary(PdfName.StructTreeRoot);
        manipulate(structTreeRoot);
        pdfDoc.close();
    }
 
    public void manipulate(PdfDictionary element) {
        if (element == null) {
            return;
        }
        if (PdfName.Figure.equals(element.get(PdfName.S))) {
            element.put(PdfName.Alt, new PdfString("Figure without an Alt description"));
        }
        PdfArray kids = element.getAsArray(PdfName.K);
        if (kids == null) {
            return;
        }
        for (int i = 0; i < kids.size(); i++) {
            manipulate(kids.getAsDictionary(i));
        }
    }
}

Click the following link to see the legacy example for iText 5. Except for security fixes, iText 5 is no longer being developed.



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