1. GroupDocs Documentation
    2. /
    3. GroupDocs.Signature Product Family
    4. /
    5. GroupDocs.Signature for Java
    6. /
    7. Developer Guide
    8. /
    9. Basic usage
    10. /
    11. Generate signature preview

    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:

    Note
    Stream that were created by createSignatureStream delegate will be disposed automatically once after generation of preview image. If you need to implement custom image preview stream disposing you have to pass additional argument closeSignatureStream to clean up resources.

    CreateSignatureStream delegate implementation

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

    private static OutputStream createSignatureStream(PreviewSignatureOptions previewOptions)
    {
        try {
            Path path = Paths.get("C:\\Output\\GenerateSignaturePreviewAdvanced\\");
            if (!Files.exists(path)) {

                Files.createDirectory(path);
                System.out.println("Directory created");
            } else {

                System.out.println("Directory already exists");
            }
            File imageFilePath = new File(path+"\\signature"+previewOptions.getSignatureId()+"-"+previewOptions.getSignOptions().getSignatureType()+".jpg");
            return new FileOutputStream(imageFilePath);
        }catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }

    }

    ReleaseSignatureStream delegate implementation 

     private static void releaseSignatureStream(PreviewSignatureOptions previewOptions, OutputStream signatureStream)
    {
        try {
            signatureStream.close();
            String imageFilePath = new File("C:\\Output\\GenerateSignaturePreviewAdvanced\\\\signature"+previewOptions.getSignatureId()+"-"+previewOptions.getSignOptions().getSignatureType()+".jpg").getPath();
            System.out.print("Image file "+imageFilePath+" is ready for preview");
        }catch (Exception e){
            throw new RuntimeException(e.getMessage());
        }
    }

    Generate signature preview 

    public static void GetPreview()
{
    // create options
    QrCodeSignOptions signOptions = new QrCodeSignOptions();
        {
            signOptions.setEncodeType(QrCodeTypes.QR);
                // setup Data property with Address object
            Address address = new Address();
            address.setStreet("221B Baker Street");
            address.setCity("London");
            address.setState("NW");
            address.setZIP("NW16XE");
            address.setCountry("England");
            signOptions.setData(address);
                // set right bottom corner
            signOptions.setHorizontalAlignment(HorizontalAlignment.Left);
            signOptions.setVerticalAlignment(VerticalAlignment.Center);
            signOptions.setWidth(100);
            signOptions.setHeight(100);
            signOptions.setMargin(new Padding(10));
        };

        // create signature preview options object
        PreviewSignatureOptions previewOption = new PreviewSignatureOptions(signOptions, new PageSignatureStreamFactory() {
            @Override
            public OutputStream createSignatureStream(PreviewSignatureOptions previewOptions) {
                return generateSignatureStream(previewOptions);
            }

            @Override
            public void closeSignatureStream(PreviewSignatureOptions previewOptions, OutputStream pageStream) {
                releaseSignatureStream(previewOptions, pageStream);
            }
        });
        previewOption.setSignatureId(UUID.randomUUID().toString());
        previewOption.setPreviewFormat(PreviewFormats.JPEG);

        // generate preview
        Signature.generateSignaturePreview(previewOption);
}

    private static OutputStream generateSignatureStream(PreviewSignatureOptions previewOptions)
    {
        try {
            Path path = Paths.get(Constants.OutputPath, "\\GenerateSignaturePreviewAdvanced\\");
            if (!Files.exists(path)) {

                Files.createDirectory(path);
                System.out.println("Directory created");
            } else {

                System.out.println("Directory already exists");
            }
            File imageFilePath = new File(path+"\\signature"+previewOptions.getSignatureId()+"-"+previewOptions.getSignOptions().getSignatureType()+".jpg");
            return new FileOutputStream(imageFilePath);
        }catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
    }

    private static void releaseSignatureStream(PreviewSignatureOptions previewOptions, OutputStream signatureStream)
    {
        try {
            signatureStream.close();
            String imageFilePath = new File(Constants.OutputPath + "\\GeneratePreviewHideSignatures\\signature"+previewOptions.getSignatureId()+"-"+previewOptions.getSignOptions().getSignatureType()+".jpg").getPath();
            System.out.print("Image file "+imageFilePath+" is ready for preview");
        }catch (Exception e){
            throw new RuntimeException(e.getMessage());
        }
    }

    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.

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