source: trunk/gsdl/src/java/org/nzdl/gsdl/GsdlCollageApplet/GsdlCollageApplet.java@ 6816

package org.nzdl.gsdl.GsdlCollageApplet;

import java.applet.*;
import java.awt.*;
import java.net.*;

/**
 * 
 *  @author Katrina Edgar
 *  @author David Bainbridge
 *
 * Main class for the GsdlCollageApplet<br>
 * Processes the parameters passed through the Applet<br>
 * Builds an appropriate starting url from these parameters<br>
 * Creates a storage class for downloaded images<br>
 * Starts thread to download images and their associated url<br>
 * Starts thread to display downloaded images on the applet screen<br>
 */
 
public class GsdlCollageApplet extends Applet {


    /** Amount of error checking output produced <br>
     *  Ranges from 0 - no output to 3 - maximum output */ 
    protected int verbosity_     = 0;
    /** Indicates whether java2 functionality should be used <br>
     *  If true will allow advanced image processing techniques to occur, 
     *  such as fading and colouring using pixel manipulation <br>
     *  If false, images will maintain an alpha value of 1 (appear solid), 
     *  newer images will simply be pasted on top of existing images <br> */
    protected boolean is_java2_  = true;
    /** Number of nested links to follow
     *  When used with greenstone, controls to which level of the document links will be followed
     *  For example a maximum depth of 1 will mean only the top page of a document will be examined,
     *  while a depth of 2 will include sections within this document, 3 includes sections within 
     *  sections, and so on */
    protected int max_depth_     = 1;
    /** Maximum number of downloaded images to stored <br>
     *  Prevents applet from using excessive amounts of bandwidth by downloading too many images simulataneously*/
    protected int max_downloads_ = Integer.MAX_VALUE;
    /** Types of images permitted in the collage, for example gif, jpg, png... */
    protected String image_type;
    /** Background color of applet screen */
    protected Color bgcolor_     = new Color(150, 193, 155);

    /** Time lapse between repainting of the applet */
    protected int refresh_delay_ = 1500;
    
    /** Stores an image and url pair and provides associated methods */
    protected DownloadImages download_images_ = null;
    /** Downloads images from a starting url, recursively follows nested links */
    protected DownloadUrls download_thread_   = null;
    /** Image processing and placement on applet screen */
    protected DisplayImages display_thread_   = null;

    protected Display display_ = null;

    /** Gets verbosity */
    public int verbosity()    { return verbosity_; }
    /** Gets maximum depth for nested links */
    public int maxDepth()     { return max_depth_; }
    /** Gets maximum number of images to store during downloading */
    public int maxDownloads() { return max_downloads_; }
    /** Gets the refresh delay used between repaint */
    public int refreshDelay() { return refresh_delay_; }

    /** Gets parameters from the applet code and stores locally<br>
     * Forms a starting url for image retrieval to begin from<br>
     * The starting url is formed either by: <br>
     * Using the image_url parameter as provided, which is assumed to be a complete url<br>
     * If this parameter does not exist, the assumption is that the collage is being incorporated
     * with the Greenstone Digital Library Software. The starting url is formed by concatenating
     * the gwcgi, collection and classifier parameters as provided.<br>
     * Then starts downloading and displaying images */
    public void init() 
    {

    // gets the parameters specified
    String verbosity_param      = getParameter("verbosity");
    String is_java2_param       = getParameter("isJava2");
    String max_depth_param      = getParameter("maxDepth");
    String max_downloads_param  = getParameter("maxDownloads");
    String refresh_delay_param  = getParameter("refreshDelay");
    String image_type_param     = getParameter("imageType");
    String bgcolor_param        = getParameter("bgcolor");

    if (bgcolor_param != null) {
        String [] c = bgcolor_param.split(",");
        if (c.length == 3)
        bgcolor_ = new Color(Integer.parseInt(c[0]), Integer.parseInt(c[1]), Integer.parseInt(c[2]));
    }

    if (image_type_param != null) {
        image_type = image_type_param;
    }

    if (verbosity_param!=null)
    {
        verbosity_  = Integer.parseInt(verbosity_param);
    }

    if (is_java2_param == null || is_java2_param.equals("auto"))
    {
        String version = System.getProperty("java.version");
        version = version.substring(0, version.lastIndexOf("."));
        System.err.println("VERSION:" + version);
        float ver = (new Float(version)).floatValue();
        is_java2_ = (ver >= 1.2) ? true : false;
    }
    else {
        is_java2_ = (is_java2_param.equals("true")) ? true : false;
    }

    if (max_depth_param!=null)
    {
        max_depth_ = Integer.parseInt(max_depth_param);
    }
    if (max_downloads_param!=null)
    {
        max_downloads_ = Integer.parseInt(max_downloads_param);
    }

    if (refresh_delay_param!=null)
    {
        refresh_delay_ = Integer.parseInt(refresh_delay_param);
    }

    String image_url  = getParameter("imageURL"); 
    String image_ignore  = getParameter("imageIgnorePrefix"); 
    String href_musthave  = getParameter("hrefMustHave"); 
    String image_mustnothave = getParameter("imageMustNotHave");

    // builds starting url when incorporated with Greenstone
    if (image_url==null)
    {
        String gwcgi_param  = getParameter("gwcgi");
        gwcgi_param = tidy_URL(gwcgi_param, true);
    
        String collection_param  = getParameter("collection");
        String classifier_param  = getParameter("classifier");

        image_url = gwcgi_param + "a=d";
        image_url += "&c=" + collection_param;
        image_url += "&cl=" + classifier_param;
    }

    // creates a class to store the image and it's associated url
    download_images_ = new DownloadImages(verbosity_);
    // starts the download image thread with the starting url
    download_thread_ = new DownloadUrls(this, download_images_, 
                        image_url, href_musthave, image_mustnothave, 
                        image_ignore, image_type);
    // starts the display image thread with the currently downloaded images
    display_thread_ = new DisplayImages(this,download_images_,is_java2_, bgcolor_);
    display_ = new Display(this);
    }

    /** Goes to the url associated with the image that is clicked on screen<br>
     *  Displays the url containing the image in a new window */
    public boolean mouseDown(Event event, int x, int y)
    {
    // determines which image was clicked on
    CollageImage cimage = display_thread_.clickedOnImage(x,y);
    // if they were clicking on an image (as opposed to background)
    if (cimage != null)
    {
        //System.err.println("Click on image: from url = " + cimage.from_url_);
        try {
        // displays the associated url in a new window
        URL from_url = new URL(cimage.from_url_  + "#" + cimage.name_);
        getAppletContext().showDocument(from_url,"gsdlDoc");
        } 
        catch (MalformedURLException e) {
        e.printStackTrace();
        }

    }
        return true;
    }
    
    /** Start threads for downloading and displaying images */
    public void start() 
    {
    download_thread_.start();
    display_thread_.start();
    display_.start();
    }

    /** Stops threads for downloading and displaying images */
    public void stop() 
    {
    download_thread_.stop();
    display_thread_.stop();
    display_.stop();

    download_thread_ = null;
    display_thread_ = null;
    display_ = null;
    }

    /** Destroys threads for downloading and displaying images */
    public void destroyed() 
    {
    download_thread_ = null;
    display_thread_ = null;
    display_ = null;
    }

    /** Repaints the applet */
    public void update(Graphics g) 
    { 
    // System.err.println("Update called");
    paint(g); 
    } 
        
    /** Repaints the applet using the paint method of the thread that is currently displaying images */
    public void paint(Graphics g) {
    if (display_thread_!=null)
    {
        //display_thread_.display_collage();
        display_thread_.paint(g);
    }
    else
    {
        System.err.println("Applet still trying to paint!!");
    }
    }


    
    /** Ensures a URL address (as string) has a protocol, host, and file.
     *
     * If the URL is a CGI script URL, it should be tidied up so that it is
     * appropriate to tage attrib=value pairs on the end.  This means it
     * must either end with a "?" or (if it contains a question-mark
     * internally) end with a "&". */
    String tidy_URL(String address, boolean isCGI) {

    // System.err.println("tidy URL: " + address);
    
    // make sure the URL has protocol, host, and file
    if (address.startsWith("http")) {
        // the address has all the necessary components
    } else if (address.startsWith("/")) {
        // there is not protocol and host
        URL document = getDocumentBase();
        String port = "";
        if (document.getPort()!=-1) {
        port = ":" + document.getPort();
        }
        address = "http://" + document.getHost() + port  + address;
    } else {
        // this URL is relative to the directory the document is in
        URL document = getDocumentBase();
        String directory = document.getFile();
        int end = directory.lastIndexOf('/');
        String port = "";
        if (document.getPort()!=-1) {
        port = ":" + document.getPort();
        }
        directory = directory.substring(0,end + 1);
        address = "http://" + document.getHost() + port + directory + address;

    }

    // if the URL is a cgi script, make sure it has a "?" in ti,
    // and that it ends with a "?" or "&"
    if (isCGI) {
        if (address.indexOf((int) '?') == -1) { 
        address = address + "?";
        } else if (!address.endsWith("?")) {
        address = address + "&";
        }
    }

    return address;
    }


}