Re: Drawing line on ImageIcon on panel after getting data

bH wrote:


Others may comment on the worthiness of this example.

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import java.text.DecimalFormat;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.event.MouseInputAdapter;

public class Ruler
extends JPanel
implements Runnable
{
  private static final long serialVersionUID = 1L;
  private BufferedImage mapImage;
  private Point[] points = new Point[2];
  private int clickCount = 0;
  private static double factorPixelKilometer = 12.5;
  private double factorKilometerStatueMile = 0.62137;
  private double kilometers = 0.0;
  private double miles = 0.0;

  private Ruler()
  {
    try
    {
      mapImage = ImageIO.read(
        new URL("http://www.lib.utexas.edu/maps/" +
          "cia07/australia_sm_2007.gif"));
    }
    catch (IOException ioe)
    {
      ioe.printStackTrace();
    }
    setPreferredSize(new Dimension(
      mapImage.getWidth(),
      mapImage.getHeight()));
    MouseInputAdapter mouse = new Mouse();
    addMouseListener(mouse);
    addMouseMotionListener(mouse);
  }

  public static void main(String[] args)
  {
    Runnable r = new Runnable()
    {
      public void run()
      {
        Ruler ruler = new Ruler();
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(
            JFrame.EXIT_ON_CLOSE);
        frame.add(ruler);
        frame.pack();
        frame.setVisible(true);
        new Thread(ruler).start();
      }
    };
    EventQueue.invokeLater(r);
  }

  @Override
  public void run()
  {
    while (true){}
  }

  @Override
  public void paintComponent(Graphics g2D)
  {
    DecimalFormat f = new DecimalFormat();
    f.setMaximumFractionDigits(2);
    Graphics2D g = (Graphics2D)g2D;
    g.drawImage(mapImage,0,0,null);
    if(points[0] != null && points[1] != null)
    {
      g.drawLine(
        points[0].x,
        points[0].y,
        points[1].x,
        points[1].y);
      g.drawString(
        "Distance = " +
        f.format(kilometers) +
        " kilometers, " +
        f.format(miles) +
        " miles", 50, 50);
    }
  }

  private class Mouse
  extends MouseInputAdapter
  {
    @Override
    public void mouseClicked(MouseEvent e)
    {
      if(clickCount == 0)
      {
        points[clickCount] =
          new Point(e.getX(), e.getY());
        clickCount = 1;
        return;
      }
      if(clickCount == 1)
      {
        points[clickCount] =
          new Point(e.getX(), e.getY());
        clickCount = 0;
        calculate();
        repaint();
      }
    }

    @Override
    public void mouseMoved(MouseEvent e)
    {
      if(clickCount == 1)
      {
        points[1] =
          new Point(e.getX(), e.getY());
        calculate();
        repaint();
      }
    }

    private void calculate()
    {
      double deltaX = points[1].x - points[0].x;
      double deltaY = points[1].y - points[0].y;
      double pixelDistance = Math.pow(((deltaX * deltaX) +
          (deltaY * deltaY)), 0.5);
      kilometers = pixelDistance * factorPixelKilometer;
      miles = kilometers * factorKilometerStatueMile;
    }
  }
}