Generate signature preview

GroupDocs.Signature provides PreviewSignatureOptions class to specify different options to manage signatures preview generation process.

Here are the steps to generate signature preview with GroupDocs.Signature:

  • Instantiate the required SignOptions object with the settings you want to generate the preview
  • Instantiate the PreviewSignatureOptions object with:
  • delegate for signature stream creation (see event handler CreateSignatureStream);
  • image preview format - PNG / JPG / BMP,
  • unique signature identifier.

CreateSignatureStream delegate implementation

GroupDocs.Signature expects CreateSignatureStream delegate to obtain each signature stream for image preview generation process

private static CreateSignatureStream(PreviewSignatureOptions previewOptions)
{
    SignOptions signOptions = previewOptions.SignOptions;
    string imageFilePath = Path.Combine(Constants.OutputPath, "GenerateSignaturePreview", $"signature-{previewOptions.SignatureId}-{previewOptions.SignOptions.GetType().Name}.jpg");
    var folder = Path.GetDirectoryName(imageFilePath);
    if (!Directory.Exists(folder))
    {
        Directory.CreateDirectory(folder);
    }
    return new FileStream(imageFilePath, FileMode.Create);
}

ReleaseSignatureStream delegate implementation

private static void ReleaseSignatureStream(PreviewSignatureOptions previewOptions, Stream signatureStream)
{
     signatureStream.Dispose();
     Console.WriteLine($"Signature {previewOptions.SignatureId}-{previewOptions.SignOptions.GetType().Name} is ready for preview");
}

Generate signature preview

public static void GetPreview()
{
    // create options
    QrCodeSignOptions signOptions = new QrCodeSignOptions
    {
        EncodeType = QrCodeTypes.QR,
        // setup Data property with Address object
        Data = new GroupDocs.Signature.Domain.Extensions.Address()
        {
            Street = "221B Baker Street",
            City = "London",
            State = "NW",
            ZIP = "NW16XE",
            Country = "England"
        },
        // set right bottom corner
        HorizontalAlignment = HorizontalAlignment.Left,
        VerticalAlignment = VerticalAlignment.Center,
        Width = 100,
        Height = 100,
        Margin = new Padding(10)
    };

    // create signature preview options object
    PreviewSignatureOptions previewOption = new PreviewSignatureOptions(signOptions, CreateSignatureStream, ReleaseSignatureStream)
    {
        SignatureId = Guid.NewGuid().ToString(),
        PreviewFormat = PreviewSignatureOptions.PreviewFormats.JPEG,
    };
    // generate preview
    Signature.GenerateSignaturePreview(previewOption);
}

private static Stream CreateSignatureStream(PreviewSignatureOptions previewOptions)
{
    SignOptions signOptions = previewOptions.SignOptions;
    string imageFilePath = $"signature-{previewOptions.SignatureId}-{previewOptions.SignOptions.GetType().Name}.jpg";
    return new FileStream(imageFilePath, FileMode.Create);
}

private static void ReleaseSignatureStream(PreviewSignatureOptions previewOptions, Stream signatureStream)
{
    signatureStream.Dispose();
    Console.WriteLine($"Signature {previewOptions.SignatureId}-{previewOptions.SignOptions.GetType().Name} is ready for preview");
}

Advanced Usage Topics

To learn more about document eSign features, please refer to the advanced usage section.

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.

Generate document pages preview Update signatures in documents