[PDFBOX-3751] Flattening a pdf with refreshAppearances set to true causes a NullPointerException

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.5
• Fix Version/s: 2.0.6, 3.0.0 PDFBox
• Component/s: AcroForm
• Assignee: Maruan Sahyoun
• Reporter: Travis Schneeberger
• Created: 12/Apr/17 13:11
• Updated: 08/Jun/17 16:08
• Resolved: 08/Jun/17 15:59

Description

Flattening a pdf with refreshAppearances set to true causes a NullPointerException. This is because some fields do not have a NormalAppearance set.

For example:

        try(PDDocument pdfDocument = PDDocument.load(new File("/Users/travis/Desktop/fdpAttachment2.pdf"))) {

            pdfDocument.getDocumentCatalog().getAcroForm().flatten(pdfDocument.getDocumentCatalog().getAcroForm().getFields(), true);
        }

causes:

Exception in thread "main" java.lang.NullPointerException
at org.apache.pdfbox.pdmodel.interactive.form.PDButton.updateByValue(PDButton.java:356)
at org.apache.pdfbox.pdmodel.interactive.form.PDButton.constructAppearances(PDButton.java:285)
at org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm.refreshAppearances(PDAcroForm.java:348)
at org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm.flatten(PDAcroForm.java:223)
at org.kuali.coeus.sys.pdf.FlattenException.main(FlattenException.java:13)

The workaround is pretty simple. Just make sure every widget without a NormalAppearance has one before calling flatten. I would think pdfbox could do a null check internally when trying to refresh appearance.

        pdfDocument.getDocumentCatalog().getAcroForm().getFields()
                .stream()
                .flatMap(f -> f.getWidgets().stream())
                .filter(w -> w.getAppearance() == null)
                .forEach(w -> {
                    final PDAppearanceDictionary appearance = new PDAppearanceDictionary(new COSDictionary());
                    appearance.setNormalAppearance(new PDAppearanceEntry(new COSDictionary()));
                    w.setAppearance(appearance);
                });