openpdf-renderer

OpenPDF-renderer

OpenPDF-renderer is a pure Java library for rendering PDF files as images using Java2D. It provides a lightweight, dependency-free way to convert PDF pages into BufferedImage objects suitable for display in Swing applications or saving to image files.

Features

• 🎨 Pure Java PDF Rendering - No native dependencies required
• 📄 PDF 1.4 Support - Renders subset of PDF 1.4 specification
• 🖼️ Multiple Image Formats - Convert to PNG, JPEG, or any ImageIO-supported format
• 🎯 Swing Integration - Direct rendering to Swing components
• 🔤 Font Support - TrueType, Type1, Type3, and CID fonts
• 🌈 Color Spaces - RGB, CMYK, Gray, and ICC-based color spaces
• 📝 Annotations - Basic support for PDF annotations
• 🎨 Patterns & Shaders - Advanced graphics rendering capabilities

Maven Dependency

Add OpenPDF Renderer to your project:

<dependency>
    <groupId>com.github.librepdf</groupId>
    <artifactId>openpdf-renderer</artifactId>
    <version>3.0.1-SNAPSHOT</version>
</dependency>

Quick Start

Basic PDF to Image Conversion

import org.openpdf.renderer.PDFFile;
import org.openpdf.renderer.PDFPage;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class PdfToImageExample {
    
    public static void main(String[] args) throws IOException {
        // Load PDF file
        File pdfFile = new File("document.pdf");
        try (RandomAccessFile raf = new RandomAccessFile(pdfFile, "r");
             FileChannel channel = raf.getChannel()) {
            
            ByteBuffer buf = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
            PDFFile pdf = new PDFFile(buf);
            
            // Get first page (1-based index)
            PDFPage page = pdf.getPage(1);
            
            // Create image from page
            Rectangle rect = new Rectangle(0, 0,
                    (int) page.getBBox().getWidth(),
                    (int) page.getBBox().getHeight());
            
            Image img = page.getImage(
                    rect.width, rect.height,  // image size
                    rect,                      // clip rectangle
                    null,                      // image observer
                    true,                      // fill background
                    true                       // block until done
            );
            
            // Convert to BufferedImage and save
            BufferedImage bufferedImage = new BufferedImage(
                    rect.width, rect.height, 
                    BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2 = bufferedImage.createGraphics();
            g2.drawImage(img, 0, 0, null);
            g2.dispose();
            
            ImageIO.write(bufferedImage, "png", new File("output.png"));
            System.out.println("PDF page rendered successfully!");
        }
    }
}

Examples

For complete working examples, see:

• ImageRendererTest.java - Basic PDF to image conversion
• PdfRendererGui.java - Interactive Swing PDF viewer

Building and Testing

Build the Project

mvn clean install

Run Tests

mvn test

Generate Javadoc

mvn javadoc:javadoc

Important Notes

• Package Naming: Classes have been renamed from com.sun.pdfview to org.openpdf.renderer
• Encryption: PDF decryption features have been removed from this module
• Page Indexing: Page numbers are 1-based (first page is index 1, not 0)
• Thread Safety: PDFFile and PDFPage objects are not thread-safe; synchronize access if needed

Supported PDF Features

Feature	Support Level
PDF 1.4 Specification	✅ Partial
Basic Text Rendering	✅ Full
TrueType Fonts	✅ Full
Type1 Fonts	✅ Full
CID Fonts	✅ Partial
RGB Color Space	✅ Full
CMYK Color Space	✅ Full
ICC Profiles	✅ Full
Images (JPEG, PNG)	✅ Full
Transparency	✅ Partial
Annotations	⚠️ Basic
Forms	⚠️ Limited
Encryption	❌ Removed

Troubleshooting

Common Issues

Issue: "ICC profile not found" error

Solution: Ensure all required ICC profile resources are in your classpath

Issue: Font rendering issues

Solution: Check that required font files are accessible and properly formatted

Issue: Out of memory errors with large PDFs

Solution: Increase JVM heap size with -Xmx flag (e.g., -Xmx2g)

Getting Help

• Report bugs: GitHub Issues
• Contribute: See CONTRIBUTING.md
• License: LGPL 2.1

Usage

Advanced: Rendering with Custom Resolution

import org.openpdf.renderer.PDFFile;
import org.openpdf.renderer.PDFPage;

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class HighResolutionRenderingExample {
    
    public static BufferedImage renderPageAtDPI(PDFFile pdf, int pageNum, int dpi) 
            throws IOException {
        PDFPage page = pdf.getPage(pageNum);
        
        // Calculate dimensions at desired DPI (default is 72 DPI)
        double scale = dpi / 72.0;
        int width = (int) (page.getBBox().getWidth() * scale);
        int height = (int) (page.getBBox().getHeight() * scale);
        
        Rectangle rect = new Rectangle(0, 0, width, height);
        Image img = page.getImage(width, height, rect, null, true, true);
        
        // Convert to BufferedImage
        BufferedImage bufferedImage = new BufferedImage(
                width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = bufferedImage.createGraphics();
        
        // Enable antialiasing for better quality
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, 
                            RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
        
        g2.drawImage(img, 0, 0, null);
        g2.dispose();
        
        return bufferedImage;
    }
}

License

This project is licensed under the GNU Lesser General Public License (LGPL) version 2.1.

OpenPDF-renderer is a fork from https://github.com/katjas/PDFrenderer (forked from http://java.net/projects/pdf-renderer) forked in june 2025, and is used in accordance with the license: https://github.com/katjas/PDFrenderer/blob/master/LICENSE.txt

PDFRenderer – Background & Origin

• Background – Sun Labs

  • Researchers at Sun Labs created the all-Java PDF Renderer to drive a lightweight PDF viewer for OpenOffice, rendering content via Java2D without needing full browser or native libraries.

• Open-Sourcing of the Project

  • When the internal needs waned, Sun Labs offered the project for open-source release. It was adopted and championed by Josh Marinacci and Richard Bair (of SwingLabs fame).
  • Tom Oke took lead in further development, and the first open-source release appeared publicly in December 2007, under the LGPL license.

• Key Motivations

  • Java lacked a built-in way to render PDFs. This project enabled:
    • Previewing PDFs in Swing applications,
    • Rendering pages as images for printing or embedding,
    • Using pure Java (Java2D) without external dependencies.

• Legacy & Influence

  • katjas/PDFrenderer is a modern GitHub-hosted fork of the java.net version. Its goal: fix bugs, improve functionality, and modernize the rendering pipeline.
  • Enhancements include:
    • Better colour space handling,
    • Support for more PDF features (annotations, fonts, JBIG2 decoding, etc.).