从SVG文件创建一个非缓冲的java.awt.Image

Question

I have some existing code which looks a lot like the solution on Swing & Batik: Create an ImageIcon from an SVG file?

But the destination for my image is PDF, and it bugs me that when you zoom into the PDF, you see pixels. If the source and destination data are both vector graphics, it should be possible to render directly.

The library we're using (iText) takes a java.awt.Image, but I can't seem to figure out how to get a java.awt.Image which renders an SVG. Does Batik have some way to do that?

Answer 1

Well, here's what I ended up doing. java.awt.Image was certainly a dead-end. There was a solution in the form of wrapping up a PdfTemplate in an ImgTemplate so that it could be used as an iText Image .

(I had to have it in something which knew its size, because it's being used in a table and the layout would go completely crazy otherwise. An Image seems to know this.)

public class SvgHelper {
    private final SAXSVGDocumentFactory factory;
    private final GVTBuilder builder;
    private final BridgeContext bridgeContext;

    public SvgHelper() {
        factory = new SAXSVGDocumentFactory(
            XMLResourceDescriptor.getXMLParserClassName());
        UserAgent userAgent = new UserAgentAdapter();
        DocumentLoader loader = new DocumentLoader(userAgent);
        bridgeContext = new BridgeContext(userAgent, loader);
        bridgeContext.setDynamicState(BridgeContext.STATIC);
        builder = new GVTBuilder();
    }

    public Image createSvgImage(PdfContentByte contentByte, URL resource,
                                float maxPointWidth, float maxPointHeight) {
        Image image = drawUnscaledSvg(contentByte, resource);
        image.scaleToFit(maxPointWidth, maxPointHeight);
        return image;
    }

    public Image drawUnscaledSvg(PdfContentByte contentByte, URL resource) {
        GraphicsNode imageGraphics;
        try {
            SVGDocument imageDocument = factory.createSVGDocument(resource.toString());
            imageGraphics = builder.build(bridgeContext, imageDocument);
        } catch (IOException e) {
            throw new RuntimeException("Couldn't load SVG resource", e);
        }

        float width = (float) imageGraphics.getBounds().getWidth();
        float height = (float) imageGraphics.getBounds().getHeight();

        PdfTemplate template = contentByte.createTemplate(width, height);
        Graphics2D graphics = template.createGraphics(width, height);
        try {
            // SVGs can have their corner at coordinates other than (0,0).
            Rectangle2D bounds = imageGraphics.getBounds();

            //TODO: Is this in the right coordinate space even?
            graphics.translate(-bounds.getX(), -bounds.getY());

            imageGraphics.paint(graphics);

            return new ImgTemplate(template);
        } catch (BadElementException e) {
            throw new RuntimeException("Couldn't generate PDF from SVG", e);
        } finally {
            graphics.dispose();
        }
    }
}