Graphics Problem

[Sunil Kumar Gupta]

Hi all

I am developing a solution to a small problem .

The problem is , i have to proof the (a+b)^3 using geometrical representation.

Since (a+b)^3 is a cuboid. i searched for java api for created cuboid.

But i did not find . what i did i created a cuboid using a combination of graphics drawLine() and drawRect() method.

But i have to change the shape of my cuboid depending on the values of a and b input by the user.

Since the cuboid is created using drawLine method. It's very difficult for me to change the shape of my cuboid by changing each line of the cuboid to map to a different x,y

Any idea??

Thanks

[Craig Wood]

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.event.*;
 
public class Cuboid extends JPanel
{
    GeneralPath path;
    int a, b, c;
    JSpinner xSpinner, ySpinner, zSpinner;
 
    public Cuboid()
    {
        a = 240;
        b = 60;
        c = 40;
    }
 
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        if(path == null)
            initPath();
        g2.setPaint(Color.blue);
        g2.draw(path);
    }
 
    private void initPath()
    {
        path = new GeneralPath();
        setSpinnerMaxima();
        setPath();
    }
 
    private void setPath()
    {
        path.reset();
        Point2D.Float origin = getOrigin();
        // front - start at lower left of face
        path.moveTo(origin.x, origin.y);
        path.lineTo(origin.x, origin.y-c);
        path.lineTo(origin.x+a, origin.y-c);
        path.lineTo(origin.x+a, origin.y);
        path.lineTo(origin.x, origin.y);
        // top
        double theta = Math.PI/6;
        path.moveTo(origin.x, origin.y-c);
        float x = (float)(origin.x     + b * Math.cos(theta));
        float y = (float)((origin.y-c) - b * Math.sin(theta));
        path.lineTo(x, y);
        path.lineTo(x+a, y);
        path.lineTo(origin.x+a, origin.y-c);
        // side
        path.moveTo(origin.x+a, origin.y);
        x = (float)((origin.x+a) + b * Math.cos(theta));
        y = (float)(origin.y     - b * Math.sin(theta));
        path.lineTo(x, y);
        path.lineTo(x, y-c);
    }
 
    private Point2D.Float getOrigin()
    {
        double w = getWidth();
        double h = getHeight();
        double theta = Math.PI/6;
        double width  = a + b * Math.cos(theta);
        double height = c + b * Math.sin(theta);
        double x = (w - width)/2;
        double y = (h + height)/2;
        return new Point2D.Float((float)x, (float)y);
    }
 
    private void setSpinnerMaxima()
    {
        final int PAD = 20;
        int w = getWidth() - PAD;
        int h = getHeight() - PAD;
        double theta = Math.PI/6;
        int width = (int)(w - b * Math.cos(theta));
        int depth = w - a;
        int height = (int)(h - b * Math.sin(theta));
        ((SpinnerNumberModel)xSpinner.getModel()).setMaximum(width);
        ((SpinnerNumberModel)ySpinner.getModel()).setMaximum(depth);
        ((SpinnerNumberModel)zSpinner.getModel()).setMaximum(height);
    }
 
    private JPanel getUIPanel()
    {
        SpinnerNumberModel xModel = new SpinnerNumberModel(a, 10, a, 1);
        xSpinner = new JSpinner(xModel);
        SpinnerNumberModel yModel = new SpinnerNumberModel(b, 10, b, 1);
        ySpinner = new JSpinner(yModel);
        SpinnerNumberModel zModel = new SpinnerNumberModel(c, 10, c, 1);
        zSpinner = new JSpinner(zModel);
        ChangeListener l = new ChangeListener()
        {
            public void stateChanged(ChangeEvent e)
            {
                JSpinner spinner = (JSpinner)e.getSource();
                int value = ((Integer)spinner.getValue()).intValue();
                if(spinner == xSpinner)
                    a = value;
                if(spinner == ySpinner)
                    b = value;
                if(spinner == zSpinner)
                    c = value;
                setPath();
                repaint();
            }
        };
        xSpinner.addChangeListener(l);
        ySpinner.addChangeListener(l);
        zSpinner.addChangeListener(l);
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(2,2,2,2);
        gbc.weightx = 1.0;
        addComponents(new JLabel("a"), xSpinner, panel, gbc);
        addComponents(new JLabel("b"), ySpinner, panel, gbc);
        addComponents(new JLabel("c"), zSpinner, panel, gbc);
        return panel;
    }
 
    private void addComponents(Component c1, Component c2, Container c,
                               GridBagConstraints gbc)
    {
        gbc.anchor = gbc.EAST;
        c.add(c1, gbc);
        gbc.anchor = gbc.WEST;
        c.add(c2, gbc);
    }
 
    public static void main(String[] args)
    {
        Cuboid cuboid = new Cuboid();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(cuboid);
        f.getContentPane().add(cuboid.getUIPanel(), "South");
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}

[Sunil Kumar Gupta]

Thanks Craig for your Reply.

It really helped me in my problem


Thanks again