Viewing Window for Large Graphs

Question

Hi! I'm looking for pointers on how to develop a viewing window for large graphs, otherwise called 'reference maps' or 'reference diagrams'. For instance, you might have a very large diagram that does not fit in your screen with a very small version of it to one side. Over the small graph, there would be a square box that you move around to focus over to section of the graph. As you move the box, the large diagram on the other side moves around to show that "enlarged" area covered by the box. I'm trying to avoid reinventing the wheel. I've found plenty of information on graphs and diagrams, but nothing close to what I need. Please help? Thanks!

Answer 1

Here's something I played with for a while.import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;
public class Test extends JFrame {
    String text = "Hi! I'm looking for pointers on how to develop a viewing\n"+
            "window for large graphs, otherwise called 'reference maps'\n"+
            "or 'reference diagrams'. For instance, you might have a\n"+
            "very large diagram that does not fit in your screen with a\n"+
            "very small version of it to one side. Over the small graph\n"+
            ", there would be a square box that you move around to\n"+
            "focus over to section of the graph. As you move the box,\n"+
            "the large diagram on the other side moves around to show\n"+
            "that \"enlarged\" area covered by the box. I'm trying to\n"+
            "avoid reinventing the wheel. I've found plenty of\n"+
            "information on graphs and diagrams, but nothing close to\n"+
            "what I need. Please help? Thanks!";
    JTextArea jta = new JTextArea(text);
    JScrollPane jsp = new JScrollPane(jta);
    JPanel p = new ReferencePanel(jsp);
    public Test() {
     setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
     Container content = getContentPane();
     content.setLayout(new GridLayout(1,2));
     content.add(jsp);
     content.add(p);
     setSize(300,200);
     show();
    public static void main( String args[] ) { new Test(); }
class ReferencePanel extends JPanel {
    JScrollPane jsp;
    JScrollBar horiz, vert;
    Image img;
    public ReferencePanel(JScrollPane JSP) {
     jsp = JSP;
     horiz = jsp.getHorizontalScrollBar();
     vert = jsp.getVerticalScrollBar();
     jsp.getViewport().addChangeListener(new ChangeListener() {
         public void stateChanged(ChangeEvent ce) { updateView(); }
     jsp.getViewport().getView().addComponentListener(new ComponentAdapter() {
         public void componentShown(ComponentEvent ce) { updateView(); }
         public void componentResized(ComponentEvent ce) { updateView(); }
     addMouseListener(new MouseAdapter() {
         public void mousePressed(MouseEvent me) { setScrolls(me); }
    public void paint(Graphics g) {
     if (img!=null) g.drawImage(img, 0, 0, this);
    private void setScrolls(MouseEvent me) {
     vert.setValue(me.getY()*(vert.getMaximum()-vert.getVisibleAmount()/2)/getHeight());
     horiz.setValue(me.getX()*(horiz.getMaximum()-horiz.getVisibleAmount()/2)/getWidth());
    private void updateView() {
     Component c = jsp.getViewport().getView();
     if (c== null || c.getWidth()==0) return;
     Image i = c.createImage(c.getWidth(), c.getHeight());
     c.printAll(i.getGraphics());
     img = i.getScaledInstance(getWidth(), getHeight(), Image.SCALE_SMOOTH);
     repaint();
}