animation

[Anandh Ramesh]

hi,

i have a text which i have to move from a point(x1,y1) to a point(x2,y2). How do i animate this motion?

any help is greatly appreciated.

[Craig Wood]

import java.awt.*;
import java.awt.font.*;
import java.awt.geom.Ellipse2D;
import javax.swing.*;
 
public class MovingText extends JPanel {
    Point p1, p2, loc;
    String text = "abc";
 
    public MovingText() {
        p1 = new Point(25, 25);
        p2 = new Point(350, 350);
        loc = p1.getLocation();
    }
 
    public void addNotify() {
        super.addNotify();
        Thread thread = new Thread(new Runner());
        thread.setPriority(Thread.NORM_PRIORITY);
        thread.start();
    }
 
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.red);
        g2.fill(new Ellipse2D.Double(p1.x-2, p1.y-2, 4, 4));
        g2.setPaint(Color.blue);
        g2.fill(new Ellipse2D.Double(p2.x-2, p2.y-2, 4, 4));
        g2.setPaint(Color.green.darker());
        Font font = g2.getFont().deriveFont(18f);
        g2.setFont(font);
        FontRenderContext frc = g2.getFontRenderContext();
        float width = (float)font.getStringBounds(text, frc).getWidth();
        LineMetrics lm = font.getLineMetrics(text, frc);
        float height = lm.getAscent() + lm.getDescent();
        float x = loc.x - width/2;
        float y = loc.y + height/2 - lm.getDescent();
        g2.drawString(text, x, y);
    }
 
    private class Runner implements Runnable {
        final int steps = 100;
        int step = 0;
 
        public void run() {
            while(step <= steps) {
                try {
                    Thread.sleep(100);
                } catch(InterruptedException e) {
                    System.out.println("interrupt");
                    break;
                }
                double distance = p1.distance(p2);
                double progress = step*(distance/steps);
                double dy = p2.y - p1.y;
                double dx = p2.x - p1.x;
                double theta = Math.atan2(dy, dx);
                int x = p1.x + (int)(progress*Math.cos(theta));
                int y = p1.y + (int)(progress*Math.sin(theta));
                loc.setLocation(x, y);
                repaint();
                step++;
            }
        }
    }
 
    public static void main(String[] args) {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new MovingText());
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}