Watermark Annotations using Java

Add a watermark annotation

1. Open the input PDF and define the rectangle where the watermark annotation will be placed.
2. Create the WatermarkAnnotation, add it to the page, and configure the watermark text state and opacity.
3. Apply the watermark text lines and save the modified PDF.

public static void watermarkAdd(Path inputFile, Path outputFile) {
    try (Document document = new Document(inputFile.toString())) {
        WatermarkAnnotation watermarkAnnotation = new WatermarkAnnotation(
                document.getPages().get_Item(1), new Rectangle(100, 0, 400, 100, true));

        document.getPages().get_Item(1).getAnnotations().add(watermarkAnnotation);

        TextState textState = new TextState();
        textState.setForegroundColor(Color.getBlue());
        textState.setFontSize(25);
        textState.setFont(FontRepository.findFont("Arial"));

        watermarkAnnotation.setOpacity(0.5);
        watermarkAnnotation.setTextAndState(new String[]{"HELLO", "Line 1", "Line 2"}, textState);

        document.save(outputFile.toString());
    }
}