Add itext fingerprints; update handling of producer info;

Author: pavel-alay

kernel/src/main/java/com/itextpdf/kernel/pdf/PdfDocument.java

@@ -1298,9 +1298,29 @@ protected void open(PdfVersion newPdfVersion) {
                     catalog = new PdfCatalog(this);
                     info = new PdfDocumentInfo(this).addCreationDate();
                     info.addModDate();
-                    info.setProducer(Version.getInstance().getVersion());
+                    info.getPdfObject().put(PdfName.Producer, new PdfString(Version.getInstance().getVersion()));
                 } else {
                     info.addModDate();
+                    String producer = null;
+                    if (info.getPdfObject().containsKey(PdfName.Producer)) {
+                        producer = info.getPdfObject().getAsString(PdfName.Producer).toUnicodeString();
+                    }
+                    Version version = Version.getInstance();
+                    if (producer == null || !version.getVersion().contains(version.getProduct())) {
+                        producer = version.getVersion();
+                    } else {
+                        int idx = producer.indexOf("; modified using");
+                        StringBuilder buf;
+                        if (idx == -1) {
+                            buf = new StringBuilder(producer);
+                        } else {
+                            buf = new StringBuilder(producer.substring(0, idx));
+                        }
+                        buf.append("; modified using ");
+                        buf.append(version.getVersion());
+                        producer = buf.toString();
+                    }
+                    info.getPdfObject().put(PdfName.Producer, new PdfString(producer));
                 }
                 trailer = new PdfDictionary();
                 trailer.put(PdfName.Root, catalog.getPdfObject().getIndirectReference());

kernel/src/main/java/com/itextpdf/kernel/pdf/PdfDocumentInfo.java

@@ -93,11 +93,6 @@ public PdfDocumentInfo setCreator(String creator) {
         return this;
     }
 
-    public PdfDocumentInfo setProducer(String creator) {
-        getPdfObject().put(PdfName.Producer, new PdfString(creator));
-        return this;
-    }
-
     public String getTitle() {
         return getStringValue(PdfName.Title);
     }

kernel/src/main/java/com/itextpdf/kernel/pdf/PdfXrefTable.java

@@ -46,6 +46,7 @@ This file is part of the iText (R) project.
 
 import com.itextpdf.io.source.ByteUtils;
 import com.itextpdf.kernel.PdfException;
+import com.itextpdf.kernel.Version;
 
 import java.io.IOException;
 import java.io.Serializable;
@@ -304,9 +305,10 @@ protected void writeXrefTableAndTrailer(PdfDocument document, PdfObject fileId,
                 trailer.put(PdfName.Prev, lastXref);
             }
             writer.write(document.getTrailer());
+            writer.write('\n');
         }
-
-        writer.writeString("\nstartxref\n").
+        writeKeyInfo(writer);
+        writer.writeString("startxref\n").
                 writeLong(startxref).
                 writeString("\n%%EOF\n");
         xref = null;
@@ -322,6 +324,14 @@ void clear() {
         count = 1;
     }
 
+    protected static void writeKeyInfo(PdfWriter writer) throws IOException {
+        Version version = Version.getInstance();
+        String k = version.getKey();
+        if (k == null) {
+            k = "iText";
+        }
+        writer.writeString(String.format("%%%s-%s\n", k, version.getRelease()));
+    }
 
     private void ensureCount(int count) {
         if (count >= xref.length) {