Drawing vector images on PDF with PDFBox

Question

I would like to draw a vector image on a PDF with Apache PDFBox.

This is the code I use to draw regular images

PDPage page = (PDPage) document.getDocumentCatalog().getAllPages().get(1);
PDPageContentStream contentStream = new PDPageContentStream(document, page, true, true);

BufferedImage _prevImage = ImageIO.read(new FileInputStream("path/to/image.png"));
PDPixelMap prevImage = new PDPixelMap(document, _prevImage);
contentStream.drawXObject(prevImage, prevX, prevY, imageWidth, imageHeight);

If I use a svg or wmf image instead of png, the resulting PDF document comes corrupted.

The main reason I want the image to be a vector image is that with PNG or JPG the image looks horrible, I think it gets somehow compressed so it looks bad. With vector images this shouldn't happen (well, when I export svg paths as PDF in Inkscape it doesn't happen, vector paths are preserved).

Is there a way to draw a svg or wmf (or other vector) to PDF using Apache PDFBox?

I'm currently using PDFBox 1.8, if that matters.

Answer 1

See the library pdfbox-graphics2d, touted in this Jira.

You can draw the SVG, via Batik or Salamander or whatever, onto the class PdfBoxGraphics2D, which is parallel to iText's template.createGraphics(). See the GitHub page for samples.

PDDocument document = ...;
PDPage page = ...; // page whereon to draw

String svgXML = "<svg>...</svg>";
double leftX = ...;
double bottomY = ...; // PDFBox coordinates are oriented bottom-up!

// I set these to the SVG size, which I calculated via Salamander.
// Maybe it doesn't matter, as long as the SVG fits on the graphic.
float graphicsWidth = ...;
float graphicsHeight = ...;

// Draw the SVG onto temporary graphics.
var graphics = new PdfBoxGraphics2D(document, graphicsWidth, graphicsHeight);
try {
    int x = 0;
    int y = 0;
    drawSVG(svg, graphics, x, y); // with Batik, Salamander, or whatever you like
} finally {
    graphics.dispose();
}

// Graphics are not visible till a PDFormXObject is added.
var xform = graphics.getXFormObject();

try (var contentWriter = new PDPageContentStream(document, page, AppendMode.APPEND, false)) { // false = don't compress
    // XForm objects have to be placed via transform,
    // since they cannot be placed via coordinates like images.
    var transform = AffineTransform.getTranslateInstance(leftX, bottomY);
    xform.setMatrix(transform);

    // Now the graphics become visible.
    contentWriter.drawForm(xform);
}

And ... in case you want also to scale the SVG graphics to 25% size:

// Way 1: Scale the SVG beforehand
svgXML = String.format("<svg transform=\"scale(%f)\">%s</svg>", .25, svgXML);

// Way 2: Scale in the transform (before calling xform.setMatrix())
transform.concatenate(AffineTransform.getScaleInstance(.25, .25));

Answer 2

I do this, but not directly. In first transform your SVG documents in PDF documents with FOP librairy and Batik. https://xmlgraphics.apache.org/fop/dev/design/svg.html.

In second times, you can use LayerUtility in pdfbox to transform your new pdf document in PDXObjectForm. After that, just needs to include PDXObjectForm in your final pdf documents.

Answer 3

The final working solution for me that loads an SVG file and overlays it on a PDF file (this renders the SVG in a 500x500 box at (0,0) coordinate which is bottom left of the PDF document):

package com.example.svgadder;

import java.io.*;
import java.nio.*;

import org.apache.pdfbox.pdmodel.*;
import org.apache.pdfbox.pdmodel.PDPageContentStream.AppendMode;
import org.apache.pdfbox.pdmodel.graphics.form.PDFormXObject;

import de.rototor.pdfbox.graphics2d.PdfBoxGraphics2D;

import java.awt.geom.AffineTransform;

import com.kitfox.svg.SVGDiagram;
import com.kitfox.svg.SVGException;
import com.kitfox.svg.SVGUniverse;

public class App 
{
    public static void main( String[] args ) throws Exception {
        
        App app = new App();

    }

    public App() throws Exception {
        
        // loading PDF and SVG files

        File pdfFile = new File("input.pdf");
        File svgFile = new File("input.svg");

        PDDocument doc = PDDocument.load(pdfFile);
        PDPage page = doc.getPage(0);

        SVGUniverse svgUniverse = new SVGUniverse();
        SVGDiagram diagram = svgUniverse.getDiagram(svgUniverse.loadSVG(f.toURL()));
        
        PdfBoxGraphics2D graphics = new PdfBoxGraphics2D(doc, 500, 500);

        try {
            diagram.render(graphics);
        } finally {
            graphics.dispose();
        }

        PDFormXObject xform = graphics.getXFormObject();

        try (PDPageContentStream contentWriter = new PDPageContentStream(doc, page, AppendMode.APPEND, false)) {

            AffineTransform transform = AffineTransform.getTranslateInstance(0, 0);
            xform.setMatrix(transform);
            contentWriter.drawForm(xform);
        }

        doc.save("res.pdf");
        doc.close();
    }
}

Please use svgSalamander from here: https://github.com/mgarin/svgSalamander

Please use what Coemgenus suggested for scaling your final overlaid SVG. I tried the 2nd option and it works well.

Nirmal