package com.mxgraph.examples.web;

import java.awt.Color;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.io.OutputStream;

import java.io.StringReader;

import java.net.URLDecoder;

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.xml.parsers.ParserConfigurationException;

import org.mortbay.jetty.Request;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import com.mxgraph.reader.mxGraphViewImageReader;

/**

* This servlet may be used to create bitmap versions of the graphs

* using a high-level description of the visual appearance so there

* is no need to create an object representation of the model on

* the server-side. The description even allows the server to create

* the bitmaps using a SAX parser. A DOM parser is not required.

*

* To integrate the image handler with a client application, the client

* application must be setup to use this servlet. This can be done by

* setting mxEditor.urlImage programmatically or using a config file.

*/

public class Export extends HttpServlet

{

/**

*

*/

private static final long serialVersionUID = -4951624126588618796L;

/**

*

*/

protected void doPost(HttpServletRequest request,

HttpServletResponse response) throws ServletException, IOException

{

String xml = URLDecoder.decode(request.getParameter("xml"), "UTF-8").replace("\n", "
");

try

{

// Set the clip on the mxGraphViewImageReader or use

// image.getSubimage to create multiple image files

response.setContentType("image/png");

response.setHeader("Content-Disposition",

"attachment; filename=diagram.png");

response.setStatus(HttpServletResponse.SC_OK);

streamImage(Color.WHITE, xml, response.getOutputStream());

((Request) request).setHandled(true);

}

catch (Exception e)

{

throw new ServletException(e);

}

}

/**

* Streams the given XML string as a PNG image into the given stream.

*

* @param xml

* @param stream

* @throws IOException

* @throws SAXException

* @throws ParserConfigurationException

*/

protected void streamImage(Color bg, String xml, OutputStream stream)

throws ParserConfigurationException, SAXException, IOException

{

mxGraphViewImageReader reader = new mxGraphViewImageReader(bg, 4, true,

true);

InputSource inputSource = new InputSource(new StringReader(xml));

BufferedImage image = mxGraphViewImageReader.convert(inputSource,

reader);

ImageIO.write(image, "png", stream);

}

}