com.tdclighthouse.prototype.servlets.JLatexServlet.java Source code

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Here is the source code for com.tdclighthouse.prototype.servlets.JLatexServlet.java

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/*
 *  Copyright 2012 Finalist B.V.
 * 
 *  Licensed under the Apache License, Version 2.0 (the "License")
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 * 
 *       http://www.apache.org/licenses/LICENSE-2.0
 * 
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package com.tdclighthouse.prototype.servlets;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.swing.JLabel;

import org.apache.commons.lang3.StringEscapeUtils;
import org.scilab.forge.jlatexmath.TeXConstants;
import org.scilab.forge.jlatexmath.TeXFormula;
import org.scilab.forge.jlatexmath.TeXIcon;

/**
 * @author Ebrahim Aharpour
 *
 */
public class JLatexServlet extends HttpServlet {

    private static final String IMAGE_TYPE = "png";
    private static final String MIME_TYPE = "image/png";
    private static final String LATEX_PARAM = "latex";
    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String latexExpression = req.getParameter(LATEX_PARAM);
        latexExpression = StringEscapeUtils.unescapeXml(latexExpression);

        if (latexExpression != null && !"".equals(latexExpression)) {
            BufferedImage image = generateImage(latexExpression);
            resp.setContentType(MIME_TYPE);
            ImageIO.write(image, IMAGE_TYPE, resp.getOutputStream());
        } else {
            resp.setStatus(HttpServletResponse.SC_NOT_FOUND);
        }
    }

    private synchronized BufferedImage generateImage(String latex) {
        TeXFormula formula = new TeXFormula(latex);
        TeXIcon icon = formula.createTeXIcon(TeXConstants.STYLE_DISPLAY, 20);
        icon.setInsets(new Insets(5, 5, 5, 5));

        BufferedImage image = new BufferedImage(icon.getIconWidth(), icon.getIconHeight(),
                BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2 = image.createGraphics();
        g2.setColor(Color.white);
        g2.fillRect(0, 0, icon.getIconWidth(), icon.getIconHeight());
        JLabel jl = new JLabel();
        jl.setForeground(new Color(0, 0, 0));
        icon.paintIcon(jl, g2, 0, 0);
        return image;
    }

}