Extract Vector Data from a PDF file using Java

Access vector data from a PDF document

Use GraphicsAbsorber to inspect vector graphic elements on a page and write their basic geometry to a text file.

1. Open the source PDF in a Document instance.
2. Create a GraphicsAbsorber and visit the target Page to collect vector graphics operations.
3. Iterate through the extracted GraphicElement objects and read their rectangle, position, and operator collections.
4. Build the output text with geometry and operator-count details for each element.
5. Write the extracted vector data to the output file.

public static void extractGraphicsElements(Path inputFile, Path outputFile) throws Exception {
    try (Document document = new Document(inputFile.toString())) {
        GraphicsAbsorber absorber = new GraphicsAbsorber();
        absorber.visit(document.getPages().get_Item(1));

        StringBuilder text = new StringBuilder();
        int index = 1;
        for (GraphicElement element : absorber.getElements()) {
            text.append("Element ").append(index)
                    .append(": Rectangle = ").append(element.getRectangle())
                    .append(", Position = ").append(element.getPosition())
                    .append(", Operators = ").append(element.getOperators().size())
                    .append("\n");
            index++;
        }
        Files.writeString(outputFile, text.toString());
    }
}

Save page vector graphics to SVG

1. Open the source PDF in a Document instance.
2. Get the target Page from the document.
3. Call page.trySaveVectorGraphics(outputFile.toString()) to export the vector graphics content of that page directly to SVG.

public static void saveVectorGraphicsToSvg(Path inputFile, Path outputFile) {
    try (Document document = new Document(inputFile.toString())) {
        Page page = document.getPages().get_Item(1);
        page.trySaveVectorGraphics(outputFile.toString());
    }
}

Save each extracted element to a separate SVG

1. Open the source PDF in a Document instance.
2. Create a GraphicsAbsorber and visit the target Page.
3. Create the output directory for the extracted subpaths before writing any files.
4. Iterate through the extracted GraphicElement objects and call saveToSvg(...) for each element.
5. Save every extracted element to a separate SVG file.

public static void extractSubpathsToSvgs(Path inputFile, Path outputDir) throws Exception {
    try (Document document = new Document(inputFile.toString())) {
        GraphicsAbsorber absorber = new GraphicsAbsorber();
        absorber.visit(document.getPages().get_Item(1));
        Path subpathsDir = outputDir.resolve("subpaths");
        Files.createDirectories(subpathsDir);

        int index = 1;
        for (GraphicElement element : absorber.getElements()) {
            element.saveToSvg(subpathsDir.resolve("subpath_" + index + ".svg").toString());
            index++;
        }
    }
}

Combine extracted elements into a single SVG

1. Open the source PDF in a Document instance.
2. Create a GraphicsAbsorber and visit the target Page.
3. Create the SVG wrapper markup that will contain the combined vector fragments.
4. Iterate through the extracted GraphicElement objects and append each generated SVG fragment.
5. Write the combined SVG output to the target file.

public static void extractListOfElementsToSingleImage(Path inputFile, Path outputFile) throws Exception {
    try (Document document = new Document(inputFile.toString())) {
        GraphicsAbsorber absorber = new GraphicsAbsorber();
        absorber.visit(document.getPages().get_Item(1));

        StringBuilder svg = new StringBuilder();
        svg.append("<svg xmlns=\"http://www.w3.org/2000/svg\">\n");
        for (GraphicElement element : absorber.getElements()) {
            svg.append(element.saveToSvg()).append("\n");
        }
        svg.append("</svg>\n");
        Files.writeString(outputFile, svg.toString());
    }
}

Extract a single vector element

1. Open the source PDF in a Document instance.
2. Create a GraphicsAbsorber and visit the target Page.
3. Get the required GraphicElement from the extracted elements collection.
4. Check whether the selected element is an XFormPlacement and descend into its nested elements when needed.
5. Save the selected vector element to the output SVG file.

public static void extractSingleVectorElement(Path inputFile, Path outputFile) {
    try (Document document = new Document(inputFile.toString())) {
        GraphicsAbsorber graphicsAbsorber = new GraphicsAbsorber();
        Page page = document.getPages().get_Item(1);
        graphicsAbsorber.visit(page);
        if (graphicsAbsorber.getElements().size() > 1) {
            GraphicElement xformPlacement = graphicsAbsorber.getElements().get_Item(1);
            if (xformPlacement instanceof XFormPlacement) {
                XFormPlacement placement = (XFormPlacement) xformPlacement;
                if (placement.getElements().size() > 2) {
                    placement.getElements().get_Item(2).saveToSvg(outputFile.toString());
                }
            } else {
                xformPlacement.saveToSvg(outputFile.toString());
            }
        }
    }
}