Searching for document signatures excluding external components

GroupDocs.Signature provides boolean property setSkipExternal of SearchOptions class to specify if searching process should exclude external signatures (external signatures are the signatures that were added with an 3rd party software and not with GroupDocs.Signature).

Since 20.3 version every time when document is being signed information about document signatures are stored in document’s metadata. Which means that all created signatures by GroupDocs.Signature can be distinguished from an actual document content and setSignature flag will be set as true. setSignature property specifies if document component (text/image/barcode/qr-code) is the actual signature or element of document content.

In order to convert signatures added by 3rd party software or by previous version of GroupDocs.Signature, just run searchwithsetSkipExternal property set to false (this is default value) and update setSignature for each signature returned by the search result.

There are few ways to manipulate with document signature search results:

  • If signature is no longer required it can be removed from the document by delete method;
  • Signature could be marked as document native content by setting up setSignature = false property,in this case setSkipExternal field will allow search method to skip this signature;
  • Signatures that were added before 20.3 are treated as non signatures because information about them are not yet stored in the document. Setting setSkipExternal flag to true will exclude these signatures from Searchresult.

Here are the steps to search for signatures and exclude external components of the document with GroupDocs.Signature:

Following example demonstrates usage of setSkipExternal   property for excluding non actual signatures from search result

Using SearchOptions SkipExternal property to exclude non actual signatures from search

Signature signature = new Signature("sample_signed.pdf");
TextSearchOptions options = new TextSearchOptions();
// search for text signatures in document
List<TextSignature> signatures =,options);
System.out.print("\nSource document contains following text signature(s).");
// enumerate all signature for output
//foreach to while statements conversion
    for (TextSignature sign : signatures)
        if (sign != null)
            System.out.print("Found Text signature at page "+sign.getPageNumber()+" with type ["+sign.getSignatureImplementation()+"] and text '"+sign.getText()+"'.");
            System.out.print("Location at "+sign.getLeft()+"-"+sign.getTop()+". Size is "+sign.getWidth()+"x"+sign.getHeight()+".");
catch (Exception ex) {
    System.out.print("System Exception: " + ex.getMessage());

Updating signatures from GroupDocs.Signature 20.3 and below

Following examples shows the way to mark signatures in document as actual signatures (setSignature = true)

How to mark signatures in document as actual signatures

 // initialize Signature instance 
Signature signature = new Signature("sample_signed.pdf");
// define few search options
BarcodeSearchOptions barcodeOptions = new BarcodeSearchOptions();
QrCodeSearchOptions qrCodeOptions = new QrCodeSearchOptions();
// add options to list
List<SearchOptions> listOptions = new ArrayList<SearchOptions>();
// search for signatures in document
SearchResult result =;
if (result.getSignatures().size() > 0)
    System.out.print("\nTrying to update all signatures...");
    // mark all signatures as actual Signatures
    for (BaseSignature baseSignature : result.getSignatures())
    // update all found signatures
    UpdateResult updateResult = signature.update(outputFilePath,result.getSignatures());
    if (updateResult.getSucceeded().size() == result.getSignatures().size())
        System.out.print("\nAll signatures were successfully updated!");
        System.out.print("Successfully updated signatures : "+updateResult.getSucceeded().size());
        System.out.print("Not updated signatures : "+updateResult.getFailed().size());
    System.out.print("\nList of updated signatures:");
    int number = 1;
    for (BaseSignature temp : updateResult.getSucceeded())
        System.out.print("Signature #"+ number++ +": Type: "+temp.getSignatureType()+" Id:"+temp.getSignatureId()+", Location: "+temp.getLeft()+"x"+temp.getTop()+". Size: "+temp.getWidth()+"x"+temp.getHeight());
    System.out.print("No one signature was found.");

More resources

GitHub Examples 

You may easily run the code above and see the feature in action in our GitHub examples:

Free Online App 

Along with full-featured .NET library we provide simple, but powerful free Apps.
You are welcome to eSign PDF, Word, Excel, PowerPoint documents with free to use online GroupDocs Signature App.