Enlarged view of a part of an image

Question

Hi folks I am preparing a project on "GPS vehile tracking system" and thats why I want to know a procedure to get an enlarged view of a part of an image.

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.AffineTransform;
import java.awt.image.*;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.*;
public class Magnifier
    BufferedImage image;
    SourcePanel sourcePanel;
    JLabel magLabel;
    double scale;
    public Magnifier(BufferedImage image)
        this.image = image;
        sourcePanel = new SourcePanel(image);
        ClipMover mover = new ClipMover(this, sourcePanel);
        sourcePanel.addMouseListener(mover);
        sourcePanel.addMouseMotionListener(mover);
        scale = 2.0;
    public void setImage()
        ImageIcon icon = new ImageIcon(getMagnifiedImage());
        magLabel.setIcon(icon);
    private BufferedImage getMagnifiedImage()
        Rectangle r = sourcePanel.clip;
        int x = r.x - sourcePanel.imageBounds.x;
        int y = r.y - sourcePanel.imageBounds.y;
        BufferedImage clipped = null;
        try
            clipped = image.getSubimage(x, y, r.width, r.height);
        catch(RasterFormatException rfe)
            System.out.println("r out of bounds: " + rfe.getMessage() + "\n" +
                               "\tx = " + x + "\t" +
                               "(x + w) = " + (x + r.width) + "\n" +
                               "\ty = " + y + "\t" +
                               "(y + h) = " + (y + r.height));
            return clipped;
        int w = (int)(scale * r.width);
        int h = (int)(scale * r.height);
        BufferedImage scaled = new BufferedImage(w, h, image.getType());
        Graphics2D g2 = scaled.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                            RenderingHints.VALUE_INTERPOLATION_BICUBIC);
        AffineTransform at = AffineTransform.getScaleInstance(scale, scale);
        g2.drawRenderedImage(clipped, at);
        g2.dispose();
        return scaled;
    private JPanel getCenter()
        magLabel = new JLabel();
        magLabel.setHorizontalAlignment(JLabel.CENTER);
        JPanel magPanel = new JPanel(new BorderLayout());
        magPanel.add(magLabel);
        JPanel panel = new JPanel(new GridLayout(1,0));
        panel.add(new JScrollPane(sourcePanel));
        panel.add(new JScrollPane(magPanel));
        return panel;
    private JPanel getSouth()
        final JLabel scaleLabel = new JLabel("scale = " + scale, JLabel.CENTER);
        int value = (int)(scale * 2);
        final JSlider slider = new JSlider(JSlider.HORIZONTAL, 1, 8, value);
        slider.setSnapToTicks(true);
        slider.addChangeListener(new ChangeListener()
            public void stateChanged(ChangeEvent e)
                scale = slider.getValue()/2.0;
                scaleLabel.setText("scale = " + scale);
                setImage();
        JPanel panel = new JPanel(new GridLayout(1,0));
        panel.add(slider);
        panel.add(scaleLabel);
        return panel;
    public static void main(String[] args) throws IOException
        String path = "images/cougar.jpg";
        BufferedImage bi = ImageIO.read(Magnifier.class.getResource(path));
        Magnifier magnifier = new Magnifier(bi);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(magnifier.getCenter());
        f.getContentPane().add(magnifier.getSouth(), "South");
        f.setSize(500,400);
        f.setLocation(200,200);
        f.setVisible(true);
class SourcePanel extends JPanel
    BufferedImage image;
    Rectangle clip;
    Rectangle imageBounds;
    public SourcePanel(BufferedImage image)
        this.image = image;
        imageBounds = new Rectangle(image.getWidth(), image.getHeight());
    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 x = (w - imageBounds.width)/2;
        int y = (h - imageBounds.height)/2;
        g2.drawImage(image, x, y, this);
        g2.setPaint(Color.red);
        if(clip == null)
            clip = new Rectangle(x, y, 75, 125);
            imageBounds.x = x;
            imageBounds.y = y;
        g2.draw(clip);
    public void setClip(int x, int y)
        Point p = getLegalLocation(x, y);
        clip.setLocation(p.x, p.y);
        repaint();
    private Point getLegalLocation(int x, int y)
        if(x < imageBounds.x)
            x = imageBounds.x;
        if(x + clip.width > imageBounds.x + imageBounds.width)
            x = imageBounds.x + imageBounds.width - clip.width;
        if(y < imageBounds.y)
            y = imageBounds.y;
        if(y + clip.height > imageBounds.y + imageBounds.height)
            y = imageBounds.y + imageBounds.height - clip.height;
        return new Point(x, y);
    public Dimension getPreferredSize()
        return new Dimension(imageBounds.width, imageBounds.height);
class ClipMover extends MouseInputAdapter
    Magnifier magnifier;
    SourcePanel sourcePanel;
    Point offset;
    boolean dragging;
    public ClipMover(Magnifier m, SourcePanel sp)
        magnifier = m;
        sourcePanel = sp;
        offset = new Point();
        dragging = true;
    public void mousePressed(MouseEvent e)
        Point p = e.getPoint();
        if(sourcePanel.clip.contains(p))
            offset.x = p.x - sourcePanel.clip.x;
            offset.y = p.y - sourcePanel.clip.y;
            dragging = true;
    public void mouseReleased(MouseEvent e)
        dragging = false;
        magnifier.setImage();
    public void mouseDragged(MouseEvent e)
        if(dragging)
            int x = e.getX() - offset.x;
            int y = e.getY() - offset.y;
            sourcePanel.setClip(x, y);
}