source: tags/gsdl-2_70u-distribution/gsdl/src/java/org/nzdl/gsdl/GsdlCollageApplet/DownloadImages.java@ 11745

package org.nzdl.gsdl.GsdlCollageApplet;

import java.awt.*;
import java.io.*;
import java.net.*;
import java.util.*;
import java.awt.image.*;
import java.awt.geom.*;

/** 
 *  @author Katrina Edgar
 *  @author David Bainbridge
 *
 *  Stores images that are downloaded but have not yet been displayed
 *  in the applet. Provides methods to add to and remove from this list
 *  and check it's size. It uses an inner class to store the data for these
 *  images, comprising of three parts: the image itself, it's source url
 *  and the name of the image */
public class DownloadImages {

    /** Data structure to store an image that has been downloaded and is
     *  waiting to be used. */
    public class ImageUrlTriple {

    Image image_;
    String urlString_;
    String name_;
        URL url_;

    /** Constructs a downloaded image structure from the given parameters
     *  @param image the graphical image
     *  @param url the source url for this image
     *  @param name the name of the image file */
    public ImageUrlTriple (Image image, URL url, String urlString, String name)
    {
        image_ = image;
        url_ = url;
            urlString_ = urlString; 
        name_ = name;
    }

    Image image() {
        return image_;
    }

    String urlString() {
        return urlString_;
    }

    String name() {
        return name_;
    }

    URL url(){
        return url_;
    }

    }

   
    ImageUrlTriple downloaded_image;
    CollageImage collage_image; 

    /** Refers to applet */
    GsdlCollageApplet app_ = null;
    boolean isJava2_;
    int num_of_downloads = 1;
    boolean stopDownload;

    MediaTracker tracker_;

    /** Initialises an empty vector to store downloaded images in and sets
     *  the verbosity for this class */
    public DownloadImages(GsdlCollageApplet app, int verbosity, boolean isJava2)
    {
    
        app_=app;
        isJava2_= isJava2;
    }

    /** Push a new image into the vector of downloaded images
     *  @param image the graphical image to add
     *  @param url the source url of the image
     *  @param name the name of the image to add */
    public  synchronized int downloadImage(MediaTracker tracker, URL url, String urlString, String name)
    {
    
    tracker_= tracker;

    while (downloaded_image != null ){
        System.out.println(Thread.currentThread().getName() + " wait to download..."); 
        try{
        wait();
        }
        catch(InterruptedException e){
        return 0;
        }

    }
      
    Image image = Toolkit.getDefaultToolkit().getImage(url);
    tracker_.addImage(image,num_of_downloads);

    try{
        tracker_.waitForID(num_of_downloads);
    }
    catch (InterruptedException e){
        notify();
        return num_of_downloads;
    }
    

    downloaded_image  = new ImageUrlTriple(image,url,urlString,name);

    notify();
       
    return num_of_downloads ;
    }
 
 
    /** Remove the image from the specified position in the array of downloaded images
     *  @return an ImageUrlTriple containing the image, url and image name */
    public synchronized CollageImage getCollageImage()
    {
    if (stopDownload)  return null;   

    while (downloaded_image == null){
        System.out.println(Thread.currentThread().getName() + " wait to get Collage image...");
        try{
        wait();
        }
        catch(InterruptedException e){
        //e.printStackTrace();
        downloaded_image = null;
        notify();
        return null;
        }
    }
         
        if (tracker_.statusID(num_of_downloads, false) == MediaTracker.COMPLETE){
        collage_image = new CollageImage(app_,isJava2_,downloaded_image);
        downloaded_image = null; 
        num_of_downloads++;
        notify();
        return collage_image;
    }
    else{
        if ((tracker_.statusAll(false) & MediaTracker.ERRORED) != 0){
        //System.out.println(downloaded_image.name_);
        downloaded_image = null;
        num_of_downloads++;
        notify();
        return null;
        }
    }
    
    return null;

    }

    public void stopDownload(){
        stopDownload = true;
    }

 
}