private File convertPdfToPdfA(final InputStream source) throws IOException, DocumentException {
final File pdfAFile =
TempFileProvider.createTempFile("digitalSigning-" + System.currentTimeMillis(), ".pdf");
// Reads a PDF document.
PdfReader reader = new PdfReader(source);
// PdfStamper: Applies extra content to the pages of a PDF document. This extra content can be
// all the objects allowed in
// PdfContentByte including pages from other Pdfs.
PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(pdfAFile));
// A generic Document class.
Document document = new Document();
// we create a writer that listens to the document
PdfWriter writer = stamper.getWriter();
int numberPages = reader.getNumberOfPages();
writer.setPDFXConformance(PdfWriter.PDFA1A);
document.open();
// PdfDictionary:A dictionary is an associative table containing pairs of objects.
// The first element of each pair is called the key and the second element is called the value
// <CODE>PdfName</CODE> is an object that can be used as a name in a PDF-file
PdfDictionary outi = new PdfDictionary(PdfName.OUTPUTINTENT);
outi.put(PdfName.OUTPUTCONDITIONIDENTIFIER, new PdfString("sRGB IEC61966-2.1"));
outi.put(PdfName.INFO, new PdfString("sRGB IEC61966-2.1"));
outi.put(PdfName.S, PdfName.GTS_PDFA1);
writer.getExtraCatalog().put(PdfName.OUTPUTINTENTS, new PdfArray(outi));
// Add pages
PdfImportedPage p = null;
Image image;
for (int i = 0; i < numberPages; i++) {
p = writer.getImportedPage(reader, i + 1);
image = Image.getInstance(p);
document.add(image);
}
writer.createXmpMetadata();
document.close();
// Add Metadata from source pdf
HashMap<String, String> info = reader.getInfo();
stamper.setMoreInfo(info);
stamper.close();
return pdfAFile;
}
