plantuml/src/net/sourceforge/plantuml/math/AsciiMath.java

package net.sourceforge.plantuml.math;

import java.awt.geom.Dimension2D;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import javax.imageio.ImageIO;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import net.sourceforge.plantuml.Dimension2DDouble;

import org.w3c.dom.Document;
import org.w3c.dom.Node;

public class AsciiMath {

	private static final String ASCIIMATH_PARSER_JS_LOCATION = "/net/sourceforge/plantuml/math/";

	private static String JAVASCRIPT_CODE;

	static {
		try {
			final BufferedReader br = new BufferedReader(new InputStreamReader(
					AsciiMath.class.getResourceAsStream(ASCIIMATH_PARSER_JS_LOCATION + "AsciiMathParser.js"), "UTF-8"));
			final StringBuilder sb = new StringBuilder();
			String s = null;
			while ((s = br.readLine()) != null) {
				sb.append(s);
				sb.append("\n");
			}
			br.close();
			JAVASCRIPT_CODE = sb.toString();
		} catch (Exception e) {
			e.printStackTrace();
		}

	}

	private final Node mathML;

	public AsciiMath(String form) throws IOException, ScriptException, ParserConfigurationException,
			NoSuchMethodException {
		final ScriptEngine engine = new ScriptEngineManager().getEngineByName("JavaScript");
		engine.eval(JAVASCRIPT_CODE);
		final Invocable inv = (Invocable) engine;
		final Document dom = createDocument();
		mathML = (Node) inv.invokeFunction("plantuml", dom, form);
	}

	public static void main(String[] args) throws IOException, NoSuchMethodException, ScriptException,
			ParserConfigurationException, ClassNotFoundException, SecurityException, IllegalAccessException,
			IllegalArgumentException, InvocationTargetException, NoSuchFieldException {
		AsciiMath math = new AsciiMath("sum_(i=1)^n i^3=((n(n+1))/2)^2");
		PrintWriter pw = new PrintWriter(new File("math2.svg"));
		pw.println(math.getSvg());
		pw.close();
		ImageIO.write(math.getImage(), "png", new File("math2.png"));
	}

	private Document createDocument() throws ParserConfigurationException {
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		dbf.setNamespaceAware(true);
		DocumentBuilder db = dbf.newDocumentBuilder();
		Document document = db.newDocument();
		return document;
	}

	private Dimension2D dim;

	public String getSvg() throws IOException, ClassNotFoundException, NoSuchMethodException, SecurityException,
			IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchFieldException {
		final ByteArrayOutputStream baos = new ByteArrayOutputStream();
		final Class<?> clConverter = Class.forName("net.sourceforge.jeuclid.converter.Converter");
		final Method getInstance = clConverter.getMethod("getInstance");
		final Object conv = getInstance.invoke(null);
		final Method convert = clConverter.getMethod("convert", Node.class, OutputStream.class, String.class,
				Class.forName("net.sourceforge.jeuclid.LayoutContext"));
		dim = (Dimension2D) convert.invoke(conv, mathML, baos, "image/svg+xml", getLayout());
		return new String(baos.toByteArray());
	}

	public BufferedImage getImage() throws IOException, ClassNotFoundException, NoSuchMethodException,
			SecurityException, IllegalAccessException, IllegalArgumentException, InvocationTargetException,
			NoSuchFieldException {
		final Class<?> clConverter = Class.forName("net.sourceforge.jeuclid.converter.Converter");
		final Method getInstance = clConverter.getMethod("getInstance");
		final Object conv = getInstance.invoke(null);
		// final LayoutContext layoutContext = LayoutContextImpl.getDefaultLayoutContext();

		final Method render = clConverter.getMethod("render", Node.class,
				Class.forName("net.sourceforge.jeuclid.LayoutContext"));

		final BufferedImage result = (BufferedImage) render.invoke(conv, mathML, getLayout());
		dim = new Dimension2DDouble(result.getWidth(), result.getHeight());
		return result;
	}

	private Object getLayout() throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException,
			InvocationTargetException, IllegalArgumentException, NoSuchFieldException, SecurityException {
		final Class<?> clLayoutContextIml = Class.forName("net.sourceforge.jeuclid.context.LayoutContextImpl");
		final Class<?> clParameter = Class.forName("net.sourceforge.jeuclid.context.Parameter");
		final Method getDefaultLayoutContext = clLayoutContextIml.getMethod("getDefaultLayoutContext");
		final Object layoutContext = getDefaultLayoutContext.invoke(null);

		final Method setParameter = clLayoutContextIml.getMethod("setParameter", clParameter, Object.class);
		setParameter.invoke(layoutContext, clParameter.getDeclaredField("SCRIPTSIZEMULTIPLIER").get(null), (float) 2);
		return layoutContext;
	}

	public Dimension2D getDimension() {
		return dim;
	}

}