Deleting Image signatures - advanced

GroupDocs.Signature provides ImageSignature class to manipulate image signatures and delete them from the documents over Delete method.

Please be aware that Delete method modifies the same document that was passed to constructor of Signature class.

Here are the steps to delete Image signature from the document with GroupDocs.Signature:

  • Create new instance of Signature class and pass source document path as a constructor parameter;
  • Instantiate ImageSearchOptions object with desired properties;
  • Call Search method to obtain list of ImageSignature;
  • Select from list ImageSignature object(s) that should be removed from the document;
  • Call Signature object Delete method and pass one or several signatures to it.
  • Analyze DeleteResult result to check whether signatures were updated or not.

Here are the alternative steps to delete Image signature from the document with GroupDocs.Signature. This approach is based on saved signatures Id after Search or Sign methods.

  • Create new instance of Signature class and pass source document path as a constructor parameter;
  • Instantiate one or several ImageSignature objects with signature Id(s) passed to constructor;
  • Call Signature class object Delete method and pass one or several signatures to it;
  • Analyze DeleteResult result to check whether signatures were updated or not.

This example shows how to delete Image signature that was found using Search method.

// initialize Signature instance
using (Signature signature = new Signature("signed.docx"))
{
    ImageSearchOptions options = new ImageSearchOptions();
    List<ImageSignature> signatures = signature.Search<ImageSignature>(options);
    List<BaseSignature> signaturesToDelete = new List<BaseSignature>();
    // collect signatures to delete
    foreach (ImageSignature temp in signatures)
    {
        if (temp.Size > 100000)
        {
            signaturesToDelete.Add(temp);
        }
    }
    // delete signatures
    DeleteResult deleteResult = signature.Delete(signaturesToDelete);
    if (deleteResult.Succeeded.Count == signaturesToDelete.Count)
    {
        Console.WriteLine("All signatures were successfully deleted!");
    }
    else
    {
        Console.WriteLine($"Successfully deleted signatures : {deleteResult.Succeeded.Count}");
        Console.WriteLine($"Not deleted signatures : {deleteResult.Failed.Count}");
    }
    Console.WriteLine("List of deleted signatures:");
    foreach (BaseSignature temp in deleteResult.Succeeded)
    {
        Console.WriteLine($"Signature# Id:{temp.SignatureId}, Location: {temp.Left}x{temp.Top}. Size: {temp.Width}x{temp.Height}");
    }
}

Delete Image signature from the document by known signature Identifier

This example shows how to delete Image signature in the document by known signature Id (that was obtained by Search or Sign method previously).

// initialize Signature instance
using (Signature signature = new Signature("signed.docx"))
{
    // read from some data source signature Id value
    string[] signatureIdList = new string[]
    {
        "1dd21cf3-b904-4da9-9413-1ff1dab51974",
        "9e386726-a773-4971-b2fc-eaadfce65ffd"
    };
    // create list of Image Signature by known SignatureId
    List<BaseSignature> signatures = new List<BaseSignature>();
    signatureIdList.ToList().ForEach(p => signatures.Add(new ImageSignature(p)));
    // delete required signatures
    DeleteResult deleteResult = signature.Delete(signatures);
    if (deleteResult.Succeeded.Count == signatures.Count)
    {
        Console.WriteLine("All signatures were successfully deleted!");
    }
    else
    {
        Console.WriteLine($"Successfully deleted signatures : {deleteResult.Succeeded.Count}");
        Console.WriteLine($"Not deleted signatures : {deleteResult.Failed.Count}");
    }
    Console.WriteLine("List of deleted signatures:");
    foreach (BaseSignature temp in deleteResult.Succeeded)
    {
        Console.WriteLine($"Signature# Id:{temp.SignatureId}, Location: {temp.Left}x{temp.Top}. Size: {temp.Width}x{temp.Height}");
    }
}

More resources

GitHub Examples

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

Free Online App

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You are welcome to eSign PDF, Word, Excel, PowerPoint documents with free to use online GroupDocs Signature App.