Question about placing an image in swing

import java.awt.*;

import java.awt.event.*;

import java.awt.geom.*;

import java.awt.image.BufferedImage;

import java.io.*;

import javax.imageio.ImageIO;

import javax.imageio.stream.ImageInputStream;

import javax.swing.*;

public class MovingImages extends JPanel

{

BufferedImage image;

Ellipse2D e;

Point2D.Double loc;

public MovingImages(BufferedImage bi)

{

image = bi;

}

protected void paintComponent(Graphics g)

{

super.paintComponent(g);

Graphics2D g2 = (Graphics2D)g;

g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,

RenderingHints.VALUE_ANTIALIAS_ON);

int w = getWidth();

int h = getHeight();

int diameter = Math.min(w,h)*3/4;

g2.setPaint(Color.blue);

e = new Ellipse2D.Double(w/2-diameter/2, h/2-diameter/2, diameter, diameter);

if(loc == null)

loc = new Point2D.Double(w/2, h/2+diameter/2);

g2.draw(e);

g2.draw(new Line2D.Double(w/2, 0, w/2, h/2-diameter/2));

g2.draw(new Line2D.Double(0, h/2, w/2-diameter/2, h/2));

g2.draw(new Line2D.Double(w/2, h, w/2, h/2+diameter/2));

g2.draw(new Line2D.Double(w, h/2, w/2+diameter/2, h/2));

int x = (int)(loc.x - image.getWidth()/2);

int y = (int)(loc.y - image.getHeight()/2);

g2.drawImage(image, x, y, this);

}

protected void stepAhead()

{

PathIterator pit = e.getPathIterator(null, 0.01); // 0.01 ~ 512

double[] coords = new double[6];

Point2D.Double[] marker = { new Point2D.Double(), new Point2D.Double() };

double minDistance = Double.MAX_VALUE;

boolean foundMinimum = false;

while(!pit.isDone())

{

pit.currentSegment(coords);

double distance = loc.distance(coords[0], coords[1]);

if(foundMinimum)

{

// saving this point following the last minimum

marker[1].x = coords[0];

marker[1].y = coords[1];

foundMinimum = false;

}

if(distance < minDistance)

{

// save the point closest to member "loc"

minDistance = distance;

marker[0].x = coords[0];

marker[0].y = coords[1];

foundMinimum = true;// record the next point

}

pit.next();

}

loc.x = marker[1].x;

loc.y = marker[1].y;

repaint();

}

public static void main(String[] args) throws IOException

{

ImageInputStream iis =

ImageIO.createImageInputStream(new File("images/Bird.gif"));

BufferedImage bi = ImageIO.read(iis);

MovingImages movingImages = new MovingImages(bi);

movingImages.addMouseListener(new Animator(movingImages));

JFrame f = new JFrame("click me");

f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

f.setContentPane(movingImages);

f.setSize(400,400);

f.setLocation(200,200);

f.setVisible(true);

}

}

class Animator extends MouseAdapter implements Runnable

{

MovingImages movingImages;

Thread thread;

boolean keepGoing;

public Animator(MovingImages mi)

{

movingImages = mi;

keepGoing = false;

}

public void mousePressed(MouseEvent e)

{

if(!keepGoing)

{

keepGoing = true;

thread = new Thread(this);

thread.setPriority(Thread.NORM_PRIORITY);

thread.start();

}

else if(keepGoing)

{

keepGoing = false;

thread = null;

}

}

public void run()

{

while(keepGoing)

{

try

{

Thread.sleep(40);

}

catch(InterruptedException ie)

{

System.out.printf("interruptus %s\n", ie.getMessage());

keepGoing = false;

}

movingImages.stepAhead();

}

}

}

74philipa at 2007-7-14 0:57:16 >