Dynamic JPanel graphics within a JFame

Question

Dear Forum,
I have a class which extends JFrame. It calls two classes that each extend JPanel with paintComponent() overriden so that I can draw 2D graphics in each. The first JPanel class is a static arrangement of shapes. This class and the class that extends JFrame also implement a MouseListener so that when a MouseEvent occurs within the first JPanel class, it causes the second JPanel class to redraw in graphics. That's the hope.
I am able to do everything but get the second JPanel class to change (i.e. I can get a print statement to verify that my MouseEvent is creating the proper data structure in the JFrame class). However, I cannot figure a way around having the either JPanel class called statically.
Can this be done? It sounds simple enough. Rather than ask you all for code. Does anyone know the general approach to this problem?
Thanks,
Dan

Answer 1

import java.awt.*;
import java.awt.event.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;
public class Relay
    GeneralPanel generalPanel;
    DetailPanel detailPanel;
    int[][] data =
        { 60,  60, 60, 4 }, { 180, 120, 50, 3 },
        { 60, 300, 45, 7 }, { 165, 240, 60, 5 }
    private JPanel getContent()
        generalPanel = new GeneralPanel(this);
        generalPanel.setData(data);
        PolygonSelector selector = new PolygonSelector(this);
        generalPanel.addMouseListener(selector);
        detailPanel = new DetailPanel();
        JPanel panel = new JPanel(new GridLayout(1,0));
        panel.setOpaque(true);
        panel.add(generalPanel);
        panel.add(detailPanel);
        return panel;
    public void showDetails(Polygon p)
        detailPanel.showDetails(p);
    public static void main(String[] args)
        Relay relay = new Relay();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setContentPane(relay.getContent());
        f.setSize(500,400);
        f.setLocation(200,200);
        f.setVisible(true);
class GeneralPanel extends JPanel
    Relay relay;
    Polygon[] polygons;
    boolean haveSelection;
    public GeneralPanel(Relay relay)
        this.relay = relay;
        polygons = new Polygon[0];
        haveSelection = false;
    protected void paintComponent(Graphics g)
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.blue);
        for(int j = 0; j < polygons.length; j++)
            g2.draw(polygons[j]);
    public void setData(int[][] data)
        polygons = new Polygon[data.length];
        for(int j = 0; j < data.length; j++)
            int[][] xy = generateShapeArrays(data[j]);
            polygons[j] = new Polygon(xy[0], xy[1], data[j][3]);
        repaint();
    private int[][] generateShapeArrays(int[] data)
        int cx = data[0];
        int cy = data[1];
        int R = data[2];
        int sides = data[3];
        int radInc = 0;
        if(sides % 2 == 0)
            radInc = 1;
        int[] x = new int[sides];
        int[] y = new int[sides];
        for(int i = 0; i < sides; i++)
            x[i] = cx + (int)(R * Math.sin(radInc*Math.PI/sides));
            y[i] = cy - (int)(R * Math.cos(radInc*Math.PI/sides));
            radInc += 2;
        // keep base of triangle level
        if(sides == 3)
            y[2] = y[1];
        return new int[][] { x, y };
class DetailPanel extends JPanel
    String x;
    String y;
    Dimension size;
    String sides;
    boolean haveSelection;
    final int HPAD = 20;
    final int VPAD = 10;
    public DetailPanel()
        setBorder(BorderFactory.createLoweredBevelBorder());
        haveSelection = false;
    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();
        Font font = g2.getFont().deriveFont(16f);
        g2.setFont(font);
        FontRenderContext frc = g2.getFontRenderContext();
        String header = "Polygon Details";
        float width = (float)font.getStringBounds(header, frc).getWidth();
        LineMetrics lm = font.getLineMetrics(header, frc);
        float sx = (w - width)/2;
        float sy = VPAD + lm.getAscent();
        g2.drawString(header, sx, sy);
        if(haveSelection)
            String dim = String.valueOf(size.width) + ", " + size.height;
            String[] s =
                "x = " + x, "y = " + y, "size = " + dim, "sides = " + sides
            sx = HPAD;
            for(int j = 0; j < s.length; j++)
                sy += font.getLineMetrics(s[j], frc).getHeight();
                g2.drawString(s[j], sx, sy);
    public void showDetails(Polygon p)
        if(p == null)
            haveSelection = false;
        else
            Rectangle r = p.getBounds();
            size = r.getSize();
            Point loc = r.getLocation();
            x = String.valueOf(loc.x);
            y = String.valueOf(loc.y);
            sides = String.valueOf(p.npoints);
            haveSelection = true;
        repaint();
class PolygonSelector extends MouseAdapter
    Relay relay;
    public PolygonSelector(Relay relay)
        this.relay = relay;
    public void mouseClicked(MouseEvent e)
        GeneralPanel generalPanel = (GeneralPanel)e.getSource();
        Point p = e.getPoint();
        Polygon[] polygons = generalPanel.polygons;
        Polygon polygon = null;
        for(int j = 0; j < polygons.length; j++)
            if(polygons[j].contains(p))
                polygon = polygons[j];
                break;
        relay.showDetails(polygon);
}