Java - Add, hide or delete Layers in PDF

PDF layers allow documents to have content placed either above or below other content within the document. Individual layers within a PDF can be displayed or hidden by the user if needed. In this article, I am going to introduce how to add, hide or delete layers in a PDF document by using Spire.PDF for Java.

Below is a screenshot of the sample PDF file.

Installing Spire.Pdf.jar

If you create a Maven project, you can easily import the jar in your application using the following configurations. For non-Maven projects, download the jar file from this link and add it as a dependency in your application.

<repositories>
    <repository>
        <id>com.e-iceblue</id>
        <name>e-iceblue</name>
        <url>http://repo.e-iceblue.com/nexus/content/groups/public/</url>
    </repository>
</repositories>
<dependencies>
    <dependency>
        <groupId> e-iceblue</groupId>
        <artifactId>spire.pdf</artifactId>
        <verson>4.1.2</version>
    </dependency>
</dependencies>

Example 1. Add layers to PDF

import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfPageBase;
import com.spire.pdf.graphics.*;
import com.spire.pdf.graphics.layer.PdfLayer;

import java.awt.*;
import java.awt.geom.Dimension2D;
import java.io.IOException;

public class AddLayersToPdf {

    public static void main(String[] args) throws IOException {

        //Create a PdfDocument object and load the sample PDF file
        PdfDocument pdf = new PdfDocument();
        pdf.loadFromFile("C:\\Users\\Administrator\\Desktop\\sample.pdf");
        //Invoke AddLayerWatermark method to add a watermark layer
        AddLayerWatermark(pdf);
        //Invoke AddLayerHeader method to add a header layer
        AddLayerHeader(pdf);
        //Save to file
        pdf.saveToFile("AddLayers.pdf");
        pdf.close();

    }

    private static void AddLayerWatermark(PdfDocument doc) throws IOException {

        //Create a layer named "watermark"
        PdfLayer layer = doc.getLayers().addLayer("watermark");
        //Create a font
        PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Arial", Font.PLAIN,36),true);
        //Specify watermark text
        String watermarkText = "Internal use only";
        //Get text size
        Dimension2D fontSize = font.measureString(watermarkText);
        //Calculate two offsets
        float offset1 = (float)(fontSize.getWidth() * Math.sqrt(2) / 4);
        float offset2 = (float)(fontSize.getHeight() * Math.sqrt(2) / 4);
        //Get page count
        int pageCount = doc.getPages().getCount();
        //Declare two variables
        PdfPageBase page;
        PdfCanvas canvas;
        //Loop through the pages
        for (int i = 0; i < pageCount; i++) {
           
            page = doc.getPages().get(i);
            //Create a canvas from layer
            canvas = layer.createGraphics(page.getCanvas());
            canvas.translateTransform(canvas.getSize().getWidth() / 2 - offset1 - offset2, canvas.getSize().getHeight() / 2 + offset1 - offset2);
            canvas.setTransparency(0.4f);
            canvas.rotateTransform(-45);
            //Draw sting on the canvas of layer
            canvas.drawString(watermarkText, font, PdfBrushes.getDarkRed(), 0, 0);
        }
    }

    private static void AddLayerHeader(PdfDocument doc) {

        //Create a layer named "header"
        PdfLayer layer = doc.getLayers().addLayer("header");
        //Get page size
        Dimension2D size = doc.getPages().get(0).getSize();
        //Specify the initial values of X and y
        float x = 90;
        float y = 10;
        //Get page count
        int pageCount = doc.getPages().getCount();
        //Declare two variables
        PdfPageBase page;
        PdfCanvas canvas;
        //Loop through the pages
        for (int i = 0; i < pageCount; i++) {
           
            //Draw an image on the layer
            PdfImage pdfImage = PdfImage.fromFile("C:\\Users\\Administrator\\Desktop\\logo2.png");
            float width = pdfImage.getWidth();
            float height = pdfImage.getHeight();
            page = doc.getPages().get(i);
            canvas = layer.createGraphics(page.getCanvas());
            canvas.drawImage(pdfImage, x, y, width, height);
            //Draw a line on the layer
            PdfPen pen = new PdfPen(PdfBrushes.getDarkGray(), 3f);
            canvas.drawLine(pen, x, y + height + 5, size.getWidth() - x, y + height + 2);
        }
    }
}

Example 2. Set visibility of layer in PDF

import com.spire.pdf.FileFormat;
import com.spire.pdf.PdfDocument;
import com.spire.pdf.graphics.layer.PdfVisibility;

public class SetLayerVisibility {
    public static void main(String[] args) {

        //Create a PdfDocument object and load the sample PDF file
        PdfDocument pdf = new PdfDocument();
        pdf.loadFromFile("C:\\Users\\Administrator\\Desktop\\Layers.pdf");

        //Set the visibility of the first layer to off
        pdf.getLayers().get(0).setVisibility(PdfVisibility.Off);

        //Save to file
        pdf.saveToFile("HideLayer.pdf", FileFormat.PDF);
        pdf.dispose();
    }
}

Example 3. Delete layers from PDF

import com.spire.pdf.PdfDocument;

public class DeleteLayers {

    public static void main(String[] args) {

        //Create a PdfDocument object and load the sample PDF file
        PdfDocument pdf = new PdfDocument();
        pdf.loadFromFile("C:\\Users\\Administrator\\Desktop\\Layers.pdf");

        //Delete the specific layer by its name
        pdf.getLayers().removeLayer("watermark");

        //Save to file
        pdf.saveToFile("DeleteLayer.pdf");
        pdf.close();
    }
}