The MediaTracker inneficient w/o the ImageObserver ? (RE:)

Quote from: broumbroum

Hi!
I was wondering if someone's already checked this statement that says : Innefficiency of MediaTracker w/o ImageObserver and vice-versa.
Because of some reasons, some web articles (http://www.sdv.fr/pages/casa/html/java-image.html and other posts in various forums) discussed this topic and but miss-spelled the relationship between these 2 Java Classes, as the MediaTracker's would be used in place of ImageObserver's.
I'd rather state that nor the MT nor the IObs can be used standing alone. They are related ! As someone says, they're cousins and they can't live one w/o each other.
Do you agree ? Huh

Hence, buffered painting becomes easier only if BOTH of these classes are linked together with the SAME component. Let's have a unit test : (...)
hence this be an assertion rule : the MediaTracker target (ImageObserver) must be equal to the Graphics ImageObserver otherwise painting will fail with no picture rendered. Can someone get this validated, too ?

Tested code is :

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import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.awt.event.*;
import javax.swing.*;
class MainBufferedPainting {
    class ImageComponent extends JComponent {
        public Component obs;
        public MediaTracker mt;
        public Image[] img;
        public void paint(Graphics g) {
            try {
                int rowIndex = 0;                        // wait on mediaTracker
                for(int index = 0; index < img.length; index++) {
                    if(img[index].getWidth(obs) != getWidth() || img[index].getHeight(obs) != (int)Math.floor((float)getHeight() / (float)img.length)) {
                        BufferedImage bi = new BufferedImage(getWidth(), (int)Math.floor((float)getHeight() / (float)img.length), BufferedImage.TYPE_INT_ARGB);
                        mt.addImage(img[index], index, getWidth(), (int)Math.floor((float)getHeight() / (float)img.length));
                        mt.waitForID(index);
                        bi.createGraphics().drawImage(
                                img[index],
                                AffineTransform.getScaleInstance((float)getWidth() / (float)img[index].getWidth(obs), Math.floor((float)getHeight() / (float)img.length) / (float)img[index].getHeight(obs)),
                                obs
                                );
                        mt.removeImage(img[index]);
                        img[index] = bi;
                        mt.addImage(img[index], index);
                    }
                    mt.waitForID(index); // wait on mediaTracker
                    try{
                        Graphics gI = img[index].getGraphics();
                        gI.setColor(Color.RED);
                        gI.drawOval(0, 0, img[index].getWidth(obs), img[index].getHeight(obs));
                    } catch(Exception e) {e.printStackTrace();} finally {
                        Point pos = new Point(
                                (int)((float)(getWidth() - img[index].getWidth(obs)) / 2.0),
                                rowIndex
                                );
                        g.drawImage(img[index], pos.x, pos.y, obs);
                        rowIndex += img[index].getHeight(obs);
                    }
                }
            } catch(InterruptedException e) { e.printStackTrace();}
        }
    }
    public ImageComponent getComponent() {
        return new ImageComponent();
    }
    public static void main(String[] args) {
        JFrame f = new JFrame("Buffered Painting");
        MainBufferedPainting.ImageComponent comp = new MainBufferedPainting().getComponent();
// our test is out of three different image implementations
        String picture = "";
        if(args != null) {
            if(args.length > 0)
                picture = args[0];
        }
        
        comp.setPreferredSize(new Dimension(150,300));
        f.getContentPane().removeAll();
        f.getContentPane().add(comp);
        f.pack();
        f.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) {
            System.exit(0);
        }});
        f.setLocationRelativeTo(null);
        f.setVisible(true);
        try {
            while(true) {
                comp.img = new Image[]{
                    new BufferedImage(50,50, BufferedImage.TYPE_INT_ARGB),
                    Toolkit.getDefaultToolkit().getImage(picture),
                    GraphicsEnvironment. getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration().createCompatibleVolatileImage(50, 50)
                };
                
// for a given component c which we want to paint on
                MediaTracker mt = new MediaTracker(f); // cannot be null ! best is to give the exact component on which all images will be drawn
                comp.obs = f;//f;//null;//new JLabel("virtual"); // here we can say that the ImageObserver is kinda unused in new impl.'s
                comp.mt = mt;                
                for(int i = 0; i < comp.img.length; i++)
                    mt.addImage(comp.img[i], i);
                Thread.sleep(100);
                f.repaint();
            }
        } catch(InterruptedException e) { e.printStackTrace(); System.exit(0); }
    }
}

If the MediaTracker has no Component as a target, no loading can be done. But ImageObserver's impl. must be EXACT for the Component you give as target.
ImageObserver's are indeed quite unused in the drawImage() impl. but are best used WITH the MediaTracker, especially if you scale the images. Grin