SVGReplacedElementFactory.java

package org.ggp.base.util.ui;

import java.awt.AlphaComposite;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.batik.dom.svg.SVGDOMImplementation;
import org.apache.batik.transcoder.TranscoderException;
import org.apache.batik.transcoder.TranscoderInput;
import org.apache.batik.transcoder.TranscoderOutput;
import org.apache.batik.transcoder.TranscodingHints;
import org.apache.batik.transcoder.image.ImageTranscoder;
import org.apache.batik.util.SVGConstants;
import org.ggp.base.util.files.FileUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xhtmlrenderer.extend.ReplacedElement;
import org.xhtmlrenderer.extend.ReplacedElementFactory;
import org.xhtmlrenderer.extend.UserAgentCallback;
import org.xhtmlrenderer.layout.LayoutContext;
import org.xhtmlrenderer.render.BlockBox;
import org.xhtmlrenderer.simple.extend.FormSubmissionListener;
import org.xhtmlrenderer.swing.ImageReplacedElement;

public class SVGReplacedElementFactory implements ReplacedElementFactory {
    @Override
    public ReplacedElement createReplacedElement(LayoutContext c, BlockBox box, UserAgentCallback uac, int cssWidth, int cssHeight) {
        Element element = box.getElement();
        if("svg".equals(element.getNodeName())) {
            DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder documentBuilder;

            try {
                documentBuilder = documentBuilderFactory.newDocumentBuilder();
            } catch (ParserConfigurationException e) {
                throw new RuntimeException(e);
            }
            Document svgDocument = documentBuilder.newDocument();
            Element svgElement = (Element) svgDocument.importNode(element, true);
            svgDocument.appendChild(svgElement);

            try {
                int width = box.getContentWidth() - 20;
                return new ImageReplacedElement(rasterize(svgDocument, width), width, width);
            } catch (IOException e) {
                return null;
            }
        }
        return null;
    }

    public static BufferedImage rasterize(Document dom, int width) throws IOException {

        final BufferedImage[] imagePointer = new BufferedImage[1];

        // Rendering hints can't be set programatically, so
        // we override defaults with a temporary stylesheet.
        String css = "svg {" +
                "shape-rendering: geometricPrecision;" +
                "text-rendering:  geometricPrecision;" +
                "color-rendering: optimizeQuality;" +
                "image-rendering: optimizeQuality;" +
                "}";
        File cssFile = File.createTempFile("batik-default-override-", ".css");
        FileUtils.writeStringToFile(cssFile, css);

        TranscodingHints transcoderHints = new TranscodingHints();
        transcoderHints.put(ImageTranscoder.KEY_XML_PARSER_VALIDATING, Boolean.FALSE);
        transcoderHints.put(ImageTranscoder.KEY_DOM_IMPLEMENTATION,
                SVGDOMImplementation.getDOMImplementation());
        transcoderHints.put(ImageTranscoder.KEY_DOCUMENT_ELEMENT_NAMESPACE_URI,
                SVGConstants.SVG_NAMESPACE_URI);
        transcoderHints.put(ImageTranscoder.KEY_DOCUMENT_ELEMENT, "svg");
        transcoderHints.put(ImageTranscoder.KEY_USER_STYLESHEET_URI, cssFile.toURI().toString());
        transcoderHints.put(ImageTranscoder.KEY_WIDTH, new Float(2 * width));
        transcoderHints.put(ImageTranscoder.KEY_HEIGHT, new Float(2 * width));
        transcoderHints.put(ImageTranscoder.KEY_MAX_HEIGHT, new Float(2 * width));
        transcoderHints.put(ImageTranscoder.KEY_MAX_WIDTH, new Float(2 * width));

        try {

            TranscoderInput input = new TranscoderInput(dom);

            ImageTranscoder t = new ImageTranscoder() {

                @Override
                public BufferedImage createImage(int w, int h) {
                    return new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
                }

                @Override
                public void writeImage(BufferedImage image, TranscoderOutput out)
                        throws TranscoderException {
                    int wd = image.getWidth() / 2;
                    int ht = image.getHeight() / 2;
                    BufferedImage resizedImage = new BufferedImage(wd, ht, BufferedImage.TYPE_INT_ARGB);
                    Graphics2D g = resizedImage.createGraphics();
                    g.setComposite(AlphaComposite.Src);
                    g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);
                    g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
                    g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
                    g.drawImage(image, 0, 0, wd, ht, null);
                    g.dispose();
                    imagePointer[0] = resizedImage;
                }
            };
            t.setTranscodingHints(transcoderHints);
            t.transcode(input, null);
        }
        catch (TranscoderException ex) {
            // Requires Java 6
            ex.printStackTrace();
            throw new IOException("Couldn't convert SVG");
        }
        finally {
            cssFile.delete();
        }

        return imagePointer[0];
    }
    @Override
    public void reset() {
    }

    @Override
    public void remove(Element e) {
    }

    @Override
    public void setFormSubmissionListener(FormSubmissionListener listener) {
    }
}