at.ait.dme.yuma.server.image.ImageTilesetGenerator.java Source code

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Here is the source code for at.ait.dme.yuma.server.image.ImageTilesetGenerator.java

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/*
 * Copyright 2008-2010 Austrian Institute of Technology
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they
 * will be approved by the European Commission - subsequent
 * versions of the EUPL (the "Licence");
 * you may not use this work except in compliance with the
 * Licence.
 * You may obtain a copy of the Licence at:
 *
 * http://ec.europa.eu/idabc/eupl
 *
 * Unless required by applicable law or agreed to in
 * writing, software distributed under the Licence is
 * distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied.
 * See the Licence for the specific language governing
 * permissions and limitations under the Licence.
 */

package at.ait.dme.yuma.server.image;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.io.IOUtils;
import org.apache.log4j.Logger;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;

import at.ait.dme.yuma.client.map.Tileset;
import at.ait.dme.yuma.client.server.exception.TilesetGenerationException;

/**
 * This class uses gdal2tiles to generate TMS tiles for images
 * 
 * @author Christian Sadilek
 */
public class ImageTilesetGenerator {
    private static Logger logger = Logger.getLogger(ImageTilesetGenerator.class);

    private static String rootPath = null;
    private static String generationCommand = null;

    public static void init(String tilesRootPath, String tilesGenerationCommand) {
        rootPath = tilesRootPath;
        generationCommand = tilesGenerationCommand;
    }

    /**
     * generates TMS tiles for the given image. it starts a separate process and executes
     * the configured command (gdal2tiles).
     * 
     * @param url
     * @return tileset
     * @throws TilesetGenerationException
     */
    public Tileset generateTilesetFromUrl(String url) throws TilesetGenerationException {
        try {
            String tilesDir = rootPath + "/" + createPathForImage(url);
            if (new File(tilesDir).mkdir()) {
                String imageFile = storeImage(tilesDir, url);

                Process p = Runtime.getRuntime().exec(generationCommand + " " + imageFile + " " + tilesDir);

                // consume the input stream, so the process does not hang
                InputStream stderr = p.getInputStream();
                InputStreamReader isr = new InputStreamReader(stderr);
                BufferedReader br = new BufferedReader(isr);
                while ((br.readLine()) != null)
                    ;

                if (p.waitFor() != 0) {
                    String errorMessage = "";
                    InputStream errorStream = p.getErrorStream();
                    if (errorStream != null)
                        errorMessage = IOUtils.toString(errorStream, "UTF-8");

                    throw new TilesetGenerationException("failed to create tiles: " + errorMessage);
                }
            }
            return createTileset(url, tilesDir);
        } catch (Throwable t) {
            logger.fatal(t.getMessage(), t);
            throw new TilesetGenerationException(t);
        }
    }

    private String storeImage(String dir, String url) throws TilesetGenerationException {
        InputStream is = null;
        OutputStream os = null;
        try {
            GetMethod getImageMethod = new GetMethod(url);
            int statusCode = new HttpClient().executeMethod(getImageMethod);
            if (statusCode != HttpStatus.SC_OK)
                throw new TilesetGenerationException("GET " + url + " returned status code:" + statusCode);

            is = getImageMethod.getResponseBodyAsStream();
            File imageFile = new File(dir + "/" + url.substring(url.lastIndexOf("/")));
            os = new FileOutputStream(imageFile);

            byte buf[] = new byte[1024];
            int len;
            while ((len = is.read(buf)) > 0)
                os.write(buf, 0, len);

            return imageFile.getAbsolutePath();
        } catch (Throwable t) {
            logger.error("failed to store image from url:" + url, t);
            throw new TilesetGenerationException(t);
        } finally {
            try {
                if (os != null)
                    os.close();
                if (is != null)
                    is.close();
            } catch (IOException e) {
                logger.error("failed to close streams");
            }

        }
    }

    private Tileset createTileset(String url, String dir) throws JDOMException, IOException {
        Integer width = null, height = null, zoomlevel = null;

        Document doc = new SAXBuilder().build(new File(dir + "/tilemapresource.xml"));
        Element root = doc.getRootElement();
        if (root != null) {
            Element boundingBox = root.getChild("BoundingBox");
            if (boundingBox != null) {
                height = Math.round(Math.abs(boundingBox.getAttribute("minx").getFloatValue()));
                width = Math.round(Math.abs(boundingBox.getAttribute("maxy").getFloatValue()));
            }
            Element tileSets = root.getChild("TileSets");
            zoomlevel = tileSets.getChildren("TileSet").size();
        }
        return new Tileset("tiles/" + createPathForImage(url) + "/", height, width, zoomlevel);
    }

    /**
     * check if tiles exist for the given image
     * 
     * @param imageUrl
     * @return true, if tileset exists, otherwise false
     * @throws UnsupportedEncodingException 
     */
    public static boolean tilesetExists(String imageUrl) {
        return new File(rootPath + "/" + ImageTilesetGenerator.createPathForImage(imageUrl)).exists();
    }

    /**
     * creates the path name for an image.
     *  
     * @param imageUrl
     * @return
     */
    public static String createPathForImage(String imageUrl) {
        String path = imageUrl.replaceAll("[^(A-Za-z0-9)]+", "-");
        if (path.length() > 255)
            path = path.substring(path.length() - 255);

        return path;
    }

    /**
     * get root path of all tilesets
     * 
     * @return
     */
    public static String getRootPath() {
        return rootPath;
    }
}