Loading an image line by line Java

Question

So this is going to sound ridiculous but I am working on a project where I deliberately want to slow down the loading of an image down so that it loads line by line. Is there anyway I can do this? I currently have the image in an ImagePane which is just an extension of a JPanel:

public ImagePane() {
        initComponents();
        image = null;
        //this.setAutoscrolls(true);
    }
    public void setImage(String path) throws IOException {
        image = ImageIO.read(getClass().getResource(path));
    }

    @Override
    public void paintComponent(Graphics g)
    {
        //Graphics2D g2 = (Grahpics2D)g;
        g.drawImage(image, 0,0, this);
    }

And in my window that I'm trying to display this as:

ImagePane image = new ImagePane();
try {
    image.setImage("netscapelogo2.png");
}
catch (IOException e) {
    System.out.print("Failed to Set");
    e.printStackTrace();
}
//jScrollPane1.add(image);
jScrollPane1.setViewportView(image);

I imagine that i need to someone change my paintComponent method to do this but I'm not sure exactly how to do that.

If you want the 90's slow loading image experience, you'll have to get the raw pixel data and draw those row by row. See the javadocs for `Image/BufferedImage` (`getRGB()/getRaster()` etc.). — Kayaman, Jun 06 '16 at 19:40
I would simulate that the image is loading line by line by uncovering it gradually. — rodrigoap, Jun 06 '16 at 19:46

Martin Frank · Accepted Answer · 2016-06-07T09:42:13.133

2

this solution uses the premisse I would simulate that the image is loading line by line by uncovering it gradually. – rodrigoap so the image is loaded at once and only displayed as it would be read line by line!

a solution would be to create a thread and let the thread to the work...

Runnable r = new Runnable(){

    @Override
    run(){
        for(int i = 0; i < image.getHeight(); i++){
            // wait 100ms to 'slow down'
            Thread.sleep(100)// surround with try/catch, it may throw an exception
            line = line + 1; //increase amount of visible lines
            repaint(); //update the panel
        }
    }
}

//i don't know when you want to start the animation
new Thead(r).start(); //so trigger at free will

when you draw the image you just draw a the amount of lines, not the whole image at all...

@Override
public void paintComponent(Graphics g)
{
    super(g);
    int w = image.getWidth();
    int h = image.getHeight();
    g.drawImage(image, 0,0, w, line, 0,0,w,h,this);
}

the drawImage methode is a bit weird, see the docu for further help

of course you need to define the private int line = 0; at some place

edited Jun 07 '16 at 09:42

answered Jun 07 '16 at 09:36

Martin Frank

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hmm - i think you can also use a swing timer or something... i forgot about that, but this solution explains, how to solve the problem and can easily be adjustet to other time handler – Martin Frank Jun 07 '16 at 09:37
1

a timer will be a **much** better solution - dont *ever* simulate your own timing like that -- its unprecise, error-prone and merely a beginners' mistake. Use real timers, `ExecutorServices` and `Lambda` for enhanced readability. Also : use `static final AtomicInteger` instead of `int`, otherwise you **will** run into racing conditions, probably even a solid deadlock – specializt Jun 07 '16 at 09:47
1

@specializt i know i know - please modify the answer, i'm not very smart on that topic! i know they exists and are the better solution but haven't ever used one! shame on me! – Martin Frank Jun 07 '16 at 09:53
Thanks, this helped a lot – SDSMTKyzer Jun 07 '16 at 17:52

Loading an image line by line Java

1 Answers1