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Java image display

Answer 1

A:

If each of your panels were one of these ImagePanels, and you simply had it take another pair of ints as argument, your final paint method would simply paint your n different image panels onto the main graphics object:

public class Example extends JApplet{
     ImagePanel[] images;

//whatever code you want for the rest of your applet

     public void paint(){
         for(ImagePanel i : images)
              images.paintComponent();
         }
     }
 }

and you would fix ImagePanel to be:

@Override
public void paintComponent(Graphics g) {
    g.drawImage(img, x, y, this);
}

piggles 2009-12-28 01:04:53

this is an application, not an applet. will that affect the fact that you are overriding the paint() method?

Allen 2009-12-28 01:15:30

I don't believe so. The underlying idea is the same though. I only have JApplet code, but if you post your main class, I can give you some more help

piggles 2009-12-28 01:23:20

for the images themselves, there isn't really any logic to them, so events don't need to be handled. But i'm not sure WHERE code goes to update everything, and how to control the properties of the components being updated.

Allen 2009-12-28 02:20:27

Yeah. You should read some tutorials or play about (I learned by playing about). but your main problem is that you don't seem to have overridden the paint method. The signature is public void paint(Graphics g) -- either that or you need to be calling repaint. I'm not entirely sure.Also, it might be easier to be using a JApplet and then put that into a JFrame to make it an application

piggles 2009-12-28 02:24:11

Answer 2

A:

Use your ImagePanel to display the background image.

Then set the panel to use a null layout manager. Now you can add an ImageIcon to a JLabel and add the JLabel to the panel. Make sure you use:

label.setSize( label.getPreferredSize() );

otherwise the label won't appear. By default the label will appear at location (0, 0) although you can change this using the setLocation(...) method.

To do the animation you can use a Swing Timer and set it to fire every 5 seconds. When the Timer fires you move the image by changing its location.

If you don't know how to use a Timer, then read the section from the Swing tutorial on "How to Use Timers".

camickr 2009-12-28 04:35:00

They are being updated sporadically, not necessarily every x seconds. This is a game being written, so every time someone takes an action, the display needs to be updated.

Allen 2009-12-29 02:05:40

It doesn't change my answer of course some "event" has to happen for the image to move. That event could be regularly scheduled (by using a Timer), or is could be a user controlled event (by clicking a button for example). The point is whenever the event occurs you have to do "something". Without knowing the details of what you are doing, I'm just suggestion that "something" should be setting the location of the icon so it looks like its moving around the board from player to player.

camickr 2009-12-29 05:54:07

Answer 3

+1 A:

Hi Allen,

A better approach doing this would be by extending JComponent and overriding the paintComponent method to draw your custom Table and Chairs component.

You could use the foundations of Circle Trigonometry to calculate each circle dynamically. I have done a quick example to show you how this could be simple done using Java2D. There is a lot of performance tweaks that could be done such as caching, clipping, etc.

The reason why did this code is for you to understand how simple it is to draw them yourself. The reasons why to do this, you have more control over what is being drawn and the location its being drawn.

Example

public class JTableChairs extends JComponent {
  private final int TABLE_DIAMETER = 300;
  private final int CHAIR_DIAMETER = 50;
  private final int CHAIR_TABLE_BOUND = 50;
  private final int CANVAS_WIDTH = 500;
  private final int NUMBER_OF_CHAIRS = 10;

  private final int TABLE_X = (CANVAS_WIDTH - TABLE_DIAMETER) / 2;
  private final int TABLE_Y = TABLE_X;
  private final double TABLE_CENTER_X = TABLE_DIAMETER / 2.0 + TABLE_X;
  private final double TABLE_CENTER_Y = TABLE_DIAMETER / 2.0 + TABLE_Y;
  private final double TABLE_RADIUS = TABLE_DIAMETER / 2.0 + CHAIR_TABLE_BOUND;

  public JTableChairs() {
    super();
  }

  @Override
  public void paintComponent(Graphics g) {
    g.setColor(Color.WHITE);
    g.fillRect(0, 0, getSize().width, getSize().height);

    // Draw Table.
    g.setColor(Color.BLACK);
    g.fillOval(TABLE_X, TABLE_Y, TABLE_DIAMETER, TABLE_DIAMETER);

    // Draw each chair using normal circle trig functions.
    for (int i = 1; i <= NUMBER_OF_CHAIRS; i++) {
      Rectangle r = getSeatCoordinates(i);
      g.drawOval(r.x, r.y, r.width, r.height);
      g.drawString(String.valueOf(i), r.x, r.y);
    }
  }

  public Rectangle getSeatCoordinates(int seat) {
    // Clamp from 0 to number of chairs to make sure it doesn't
    // go over/under bounds.
    seat = seat < 1 ? 1 :
           (seat > NUMBER_OF_CHAIRS ? NUMBER_OF_CHAIRS : seat) - 1;

    // Calculate the coordinates using trig functions.
    double arcAngle = Math.toRadians(360 / NUMBER_OF_CHAIRS * seat);
    int x = (int)(TABLE_CENTER_X + TABLE_RADIUS * Math.cos(arcAngle) -
            CHAIR_DIAMETER / 2.0);
    int y = (int)(TABLE_CENTER_Y + TABLE_RADIUS * Math.sin(arcAngle) -
            CHAIR_DIAMETER / 2.0);
    return new Rectangle(new Point(x, y),
                         new Dimension(CHAIR_DIAMETER, CHAIR_DIAMETER));
  }
}

Say, you need to do some listener so when you press any circle, you want to highlight it. Using collision detection in 2D, you can do that. Note, the ugly way doing it is the following:

  public boolean setSeat(Point coord) {
    // Quick collision detection. This is bad performance since its
    // checking each point.
    for (int i = 1; i <= NUMBER_OF_CHAIRS; i++) {
      Rectangle r = getSeatCoordinates(i);
      if (r.contains(coord)) {
        Graphics g = getGraphics();
        g.setColor(Color.RED);
        g.drawRect(r.x, r.y, r.width, r.height);
        g.dispose();
        return true;
      }
    }
    return false;
  }

And in the constructor, you can add a mouse listener:

addMouseListener(new MouseAdapter() {
  @Override
  public void mouseReleased(MouseEvent e) {
    setSeat(e.getPoint());
  }
});

I hope you learned a thing or two :x

Mohamed Mansour 2009-12-28 06:32:02

Answer 4

+1 A:

just an idea: use an additional class for holding the images and corresponding coordinates, and put them into a list.

public class MyImage {    // or SubImage?
    private Image image;
    private int x;
    private int y;

    public MyImage(Image image, int x, int y) {
        this.image = image;
        this.x = x;
        this.y = y;
    }

    public void paint(Graphics g, ImageObserver obs) {
        g.drawImage(image, x, y, obs);
    }

    // getters and setters
}

public class ImagePanel extends JPanel {

    private Image img;
    private final List<MyImage> images = new ArrayList<MyImage>();

    // setImage methods

    public void addMyImage(MyImage image) {
        images.add(image);
    }
    // or/and
    public void addMyImage(Image image, int x, int y) {
        images.add(new MyImage(image, x, y));
    }

    @Override
    public void paintComponent(Graphics g) {
        g.drawImage(img, 0, 0, this);    // check if img is null?
        for (MyImage image : images) {
            image.paint(g, this);
    }
}

Carlos Heuberger 2009-12-28 10:35:51

Why the downvote? not much helpful downvoting without comment... or didn't you like the comment I did?

Carlos Heuberger 2009-12-30 17:45:00

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Java image display

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