Why is batik can't save .svg file using OutputStream?

Question

I want to manipulate with existing .svg file from file system using library Batik by Apache. My goal is load .svg file, draw some shapes on it and than save final result on file system.

Now I have two classes. First class is able to load file .svg and draw shape on it, but don't able to save result. Second class is able to draw shape on new canvas and save result on file system.

This first class. I try to save final result using OutputStream, but it didn't work.

import org.apache.batik.svggen.SVGGraphics2D;
import org.apache.batik.svggen.SVGGraphics2DIOException;
import org.apache.batik.swing.JSVGCanvas;
import org.apache.batik.swing.svg.GVTTreeBuilderAdapter;
import org.apache.batik.swing.svg.GVTTreeBuilderEvent;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.net.MalformedURLException;
import java.util.concurrent.atomic.AtomicBoolean;

public class RedrawingSVG extends JFrame {

    protected AtomicBoolean shown = new AtomicBoolean(false);

    public static void main(String[] args) throws MalformedURLException, InterruptedException, FileNotFoundException, UnsupportedEncodingException, SVGGraphics2DIOException {
        RedrawingSVG redrawingSVG = new RedrawingSVG();
        redrawingSVG.drawSvg();
    }

    public void drawSvg() throws MalformedURLException, InterruptedException, FileNotFoundException, UnsupportedEncodingException, SVGGraphics2DIOException {
        final JSVGCanvas canvas = new JSVGCanvas();
        canvas.setDocumentState(JSVGCanvas.ALWAYS_DYNAMIC); // to update it
        canvas.setURI(new File("/home/ekuntsevich/Downloads/img.svg").toURI().toURL().toString());

        canvas.addGVTTreeBuilderListener(new GVTTreeBuilderAdapter() {
            public void gvtBuildCompleted(GVTTreeBuilderEvent e) {
                synchronized (shown) {
                    shown.set(true); // No modifications be fore!!
                    shown.notifyAll();
                }
            }
        });
        getContentPane().add(canvas);

        setSize(800, 400);
        setVisible(true);

        synchronized (shown) { // Strictly required to wait
            while (shown.get() == false) {
                try {
                    shown.wait(0);
                } catch (Exception e) {
                }
            }
        }
        Document doc = canvas.getSVGDocument();

        SVGGraphics2D svgGenerator = new SVGGraphics2D(doc);
        svgGenerator.setPaint(Color.red);
        svgGenerator.fill(new Rectangle(100, 100, 1000, 1000));

        Element root = doc.getDocumentElement();
        svgGenerator.getRoot(root);

        Writer out;
        try {
            OutputStream outputStream = new FileOutputStream(new File("img2.svg"));
            out = new OutputStreamWriter(outputStream, "UTF-8");
            svgGenerator.stream(out, true);
            outputStream.flush();
            outputStream.close();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (SVGGraphics2DIOException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

This second class.

import java.awt.Rectangle;
import java.awt.Graphics2D;
import java.awt.Color;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.io.IOException;

import org.apache.batik.svggen.SVGGraphics2D;
import org.apache.batik.dom.GenericDOMImplementation;

import org.apache.batik.svggen.SVGGraphics2DIOException;
import org.w3c.dom.Document;
import org.w3c.dom.DOMImplementation;

public class TestSVGGen {

    public void paint(Graphics2D g2d) {
        g2d.setPaint(Color.red);
        g2d.fill(new Rectangle(10, 10, 100, 100));
    }

    public static void main(String[] args) throws IOException {

        // Get a DOMImplementation.
        DOMImplementation domImpl = GenericDOMImplementation.getDOMImplementation();

        // Create an instance of org.w3c.dom.Document.
        String svgNS = "http://www.w3.org/2000/svg";
        Document document = domImpl.createDocument(svgNS, "svg", null);

        // Create an instance of the SVG Generator.
        SVGGraphics2D svgGenerator = new SVGGraphics2D(document);

        // Ask the test to render into the SVG Graphics2D implementation.
        TestSVGGen test = new TestSVGGen();
        test.paint(svgGenerator);

        // Finally, stream out SVG to the standard output using
        // UTF-8 encoding.
        boolean useCSS = true; // we want to use CSS style attributes
        Writer out;
        try {
            OutputStream outputStream = new FileOutputStream(new File("img3.svg"));
            out = new OutputStreamWriter(outputStream, "UTF-8");
            svgGenerator.stream(out, useCSS);
            outputStream.flush();
            outputStream.close();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (SVGGraphics2DIOException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Finally I want to combine capabilities this two classes. I want to have code for: loading .svg image -> drawing something over this image -> save result as .svg image on file system.

Answer 1

I resolved my issue. I looked through different signatures for method stream from class SVGGraphics2D and found out that there is has method with parameters suitable for my case. I used next method stream(Element svgRoot, Writer writer) for saving .svg image. Finally, instead svgGenerator.stream(out, true); I used svgGenerator.stream(root, out);. It works for me.