source: trunk/gsdl/src/java/org/nzdl/gsdl/GsdlCollageApplet/DownloadImages.java@ 11647

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;
    boolean stopDownload;

  

    /** 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)
    {

    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{
           System.out.println( "   downloading ..."); 
           tracker.waitForID(num_of_downloads);
                System.out.println(Thread.currentThread().getName() + " get!!!"); 
           }
           catch (InterruptedException e){
            return 0;
         }
     
    downloaded_image  = new ImageUrlTriple(image,url,urlString,name);
    num_of_downloads++;

    if (num_of_downloads == app_.maxDownloads()){
        stopDownload = true;
            System.out.println("num_of_downloads "+num_of_downloads);

    }   
    //System.out.println("num_of_downloads "+num_of_downloads +" ");
    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 && !stopDownload){
        System.out.println(Thread.currentThread().getName() + " wait to get Collage image...");
        try{
        wait();
        }
        catch(InterruptedException e){
        //e.printStackTrace();  
        return null;
        }
    }

    collage_image = process(downloaded_image);
    downloaded_image = null;
       
        notify();
    System.out.println(Thread.currentThread().getName() + " get Collage image!!!");
        return collage_image;

    }

    public void stopDownload(){
        stopDownload = true;
    }

    private CollageImage process(ImageUrlTriple iutriple){
            Image image     = iutriple.image();
        String from_url = iutriple.urlString();
        String img_name = iutriple.name();
        URL url =  iutriple.url();
        
        CollageImage collage_image = new CollageImage(image,url,from_url,img_name);

        image = collage_image.image_;
        // images x and y dimensions
        int image_x_dim = image.getWidth(app_);
        int image_y_dim = image.getHeight(app_);

        if ((image_x_dim>0) && (image_y_dim>0))
        {
        collage_image.setDimensions(image_x_dim,image_y_dim);
        
        // places and sizes the image
        MyAffineTransform af = new MyAffineTransform(image_x_dim,image_y_dim);
        
        // sets location & size of collage image
        collage_image.setAffineTransform(af, isJava2_);
        
         if (isJava2_ ) {
            collage_image.image_ 
            = restoreAlpha(collage_image.image_, 0, 0, 
                       collage_image.image_x_dim_, collage_image.image_y_dim_); 
            
        }
            
            
        }
     
        collage_image.fresh = false;
        return collage_image;
    }

  /** Resets the alpha channel of an image so that it appears solid
     *
     *  @param img the image to restore
     *  @param x the x co-ordinate of the image
     *  @param y the y co-ordinate of the image
     *  @param w the width of the image
     *  @param h the height of the image */
    public Image restoreAlpha(Image img, int x, int y, int w, int h) {
      
    // declare an array to hold the pixels
    int[] pixels = new int[w * h];
    
    // get the pixels of the image into the pixels array
    PixelGrabber pg = new PixelGrabber(img, x, y, w, h, pixels, 0, w);
       
    try {
        System.err.println("  grab pixels....");
        pg.grabPixels();
        System.err.println("  got pixels");
    } catch (InterruptedException e) {
        System.err.println("interrupted waiting for pixels!");
        return img;
    }

      
    // check for any failures
    if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
        System.err.println(" image fetch aborted or errored");
        return img;
    }

    // loop through every pixel in the picture and handle it
       for (int j = 0; j < h; j++) {
           for (int i = 0; i < w; i++) {
           pixels[j * w + i] |= (255 << 24) & 0xff000000;
           }
       }
       
       // set the pixels of the whole picture to the pixels array
       pg.setPixels(0, 0, w, h, pg.getColorModel(), pixels, 0, w);
       // create the new image and return it
       return( app_.createImage(new MemoryImageSource(w, h, pixels, 0, w)) );
      
    
       
       
    }


}