<repositories>
    <repository>
        <id>com.e-iceblue</id>
        <name>e-iceblue</name>
        <url>https://repo.e-iceblue.com/nexus/content/groups/public/</url>
    </repository>
</repositories>
<dependencies>
    <dependency>
        <groupId>e-iceblue</groupId>
        <artifactId>spire.pdf</artifactId>
        <version>10.6.2</version>
    </dependency>
</dependencies>
    

import com.spire.pdf.*;
import com.spire.pdf.annotations.*;
import com.spire.pdf.annotations.appearance.*;
import com.spire.pdf.graphics.*;
import java.awt.*;
import java.awt.geom.*;

public class AddWatermarkInPDF {
    public static void main(String[] args) {
        // Create a PdfDocument object
        PdfDocument pdfDocument = new PdfDocument();

        // Load the PDF document from a file
        pdfDocument.loadFromFile("Sample1.pdf");

        // Set the font style
        Font font = new Font("Arial", Font.PLAIN, 22);

        // Create a PdfTrueTypeFont object for subsequent text rendering
        PdfTrueTypeFont trueTypeFont = new PdfTrueTypeFont(font);

        // Get the page object
        PdfPageBase page;

        // Define the watermark text
        String watermarkAnnotationText = "ID_0";

        // Create a size object
        Dimension2D dimension2D = new Dimension();

        // Create a rectangle object
        Rectangle2D loRect = new Rectangle2D.Float();

        // Iterate through each page in the PDF
        for (int i = 0; i < pdfDocument.getPages().getCount(); i++) {
            // Get the current page
            page = pdfDocument.getPages().get(i);

            // Set the size object to the size of the current page
            dimension2D.setSize(page.getClientSize().getWidth(), page.getClientSize().getHeight());

            // Set the rectangle object frame, which is the entire page range
            loRect.setFrame(new Point2D.Float(0, 0), dimension2D);

            // Create a PdfTemplate object to draw the watermark
            PdfTemplate template = new PdfTemplate(page.getClientSize().getWidth(), page.getClientSize().getHeight());

            // Insert the watermark
            insertWatermark(template, trueTypeFont, "Non Editable");

            // Create a PdfWatermarkAnnotation object to define the watermark position
            PdfWatermarkAnnotation watermarkAnnotation = new PdfWatermarkAnnotation(loRect);

            // Create a PdfAppearance object to set the watermark appearance
            PdfAppearance appearance = new PdfAppearance(watermarkAnnotation);

            // Set the normal state template of the watermark
            appearance.setNormal(template);

            // Set the appearance to the watermark object
            watermarkAnnotation.setAppearance(appearance);

            // Set the watermark text
            watermarkAnnotation.setText(watermarkAnnotationText);

            // Set the watermark print matrix to control the watermark's position and size
            watermarkAnnotation.getFixedPrint().setMatrix(new float[]{1, 0, 0, 1, 0, 0});

            // Set the horizontal offset
            watermarkAnnotation.getFixedPrint().setHorizontalTranslation(0.5f);

            // Set the vertical offset
            watermarkAnnotation.getFixedPrint().setVerticalTranslation(0.5f);

            // Add the watermark to the page's annotation widget
            page.getAnnotationsWidget().add(watermarkAnnotation);
        }

        // Save the PDF document to a file
        pdfDocument.saveToFile("AddWatermark.pdf");

        // Close and release the PDF document resources
        pdfDocument.dispose();
    }

    static void insertWatermark(PdfTemplate template, PdfTrueTypeFont font, String watermark) {
        // Create a Dimension2D object to set the size of the watermark
        Dimension2D dimension2D = new Dimension();

        // Set the size of the watermark to half the width and one third the height of the template
        dimension2D.setSize(template.getWidth() / 2, template.getHeight() / 3);

        // Create a PdfTilingBrush object for repeating pattern fill of the watermark
        PdfTilingBrush brush = new PdfTilingBrush(dimension2D);

        // Set the transparency of the watermark to 0.3
        brush.getGraphics().setTransparency(0.3F);

        // Start a group of graphic state saves
        brush.getGraphics().save();

        // Translate the graphics context so its center aligns with the center of the watermark tile
        brush.getGraphics().translateTransform((float) brush.getSize().getWidth() / 2, (float) brush.getSize().getHeight() / 2);

        // Rotate the graphics context to tilt the watermark at 45 degrees
        brush.getGraphics().rotateTransform(-45);

        // Draw the watermark text in the graphics context using the specified font, color, and centered alignment
        brush.getGraphics().drawString(watermark, font, PdfBrushes.getGray(), 0, 0, new PdfStringFormat(PdfTextAlignment.Center));

        // End the group of graphic state saves and restore
        brush.getGraphics().restore();

        // Reset the watermark transparency to 1, i.e., completely opaque
        brush.getGraphics().setTransparency(1);

        // Create a Rectangle2D object to define the area for filling the watermark
        Rectangle2D loRect = new Rectangle2D.Float();

        // Set the fill area for the watermark to cover the entire size of the template
        loRect.setFrame(new Point2D.Float(0, 0), template.getSize());

        // Draw the watermark on the template using the watermark tile
        template.getGraphics().drawRectangle(brush, loRect);
    }
}

import com.spire.pdf.*;
import com.spire.pdf.annotations.*;

public class RemoveWatermarkFromPDF {
    public static void main(String[] args) {
        // Create a PdfDocument object
        PdfDocument pdfDocument = new PdfDocument();

        // Load the PDF document from a file
        pdfDocument.loadFromFile("Sample2.pdf");

        // Define a string ID to match and remove a specific watermark
        String id = "ID_0";

        // Iterate through every page in the PDF document
        for (int i = 0; i < pdfDocument.getPages().getCount(); i++) {
            // Get all annotations on the current page
            PdfAnnotationCollection annotationWidget = pdfDocument.getPages().get(i).getAnnotationsWidget();

            // Iterate through all annotations on the current page
            for (int j = 0; j < annotationWidget.getCount(); j++) {
                // Check if the current annotation is a watermark annotation
                if (annotationWidget.get(j) instanceof PdfWatermarkAnnotationWidget) {
                    // If the watermark text equals the ID, remove the watermark
                    if (annotationWidget.get(j).getText().equals(id)) {
                        annotationWidget.remove(annotationWidget.get(j));
                    }
                }
            }
        }

        // Save the modified PDF document to a new file
        pdfDocument.saveToFile("RemoveWatermark.pdf");

        // Dispose of the PdfDocument object resources
        pdfDocument.dispose();
    }
}