2Dgraphics object

[Ken Ng]

hi all,
I have created a graphic object using the drawPolygon().
The object is drawn on a frame.
Is it possible to save that 2D graphic object in some image file format
so that when i open the file, that image will appear in the frame.
Something similar to a workspace for u to load your document in it.

AWT newbie need help!

[Craig Wood]

If you check the JFileChooser page in the java tutorial you will find some fancy bells and whistles to add to your file chooser. This one is the stripped down model.

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;
 
public class GraphicsImaging
{
    public static void main(String[] args)
    {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        GraphicImagingPanel gip = new GraphicImagingPanel();
        ImagingAction action = new ImagingAction(gip, f);
        f.setJMenuBar(action.getMenuBar());
        f.getContentPane().add(gip);
        f.setSize(400,300);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}
 
/**
 * Graphics2D component that can save its graphic to png image.
 */
class GraphicImagingPanel extends JPanel
{
    public GraphicImagingPanel()
    {
        setBackground(Color.white);
    }
 
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        int width = getWidth();
        int height = getHeight();
        int cx = width/2;
        int cy = height/2;
        int dia = Math.min(width, height)/4;
        int strut = Math.min(width, height)*3/4;
        g2.setPaint(Color.blue);
        g2.draw(new Rectangle2D.Double(width/16, height/16, width*7/8, height*7/8));
        int R = (int)(strut / (4 * Math.cos(Math.PI/5) * Math.sin(Math.PI/5)));
        int[][] xy = generateShapeArrays(R, 5, cx, cy);
        Polygon pentagon = new Polygon(xy[0], xy[1], 5);
        g2.setPaint(Color.magenta);
        g2.draw(pentagon);
        g2.setPaint(Color.green);
        g2.fill(new Ellipse2D.Double(cx - dia/2, cy - dia/2, dia, dia));
        g2.setPaint(Color.yellow);
        g2.draw(new Line2D.Double(width/8, height/8, width*7/8, height*7/8));
    }
 
    private int[][] generateShapeArrays(int R, int sides, int cx, int cy)
    {
        int[] x = new int[sides];
        int[] y = new int[sides];
        int radInc = 0;
        if(sides % 2 == 0)
            radInc = 1;
        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;
        }
        return new int[][] {x,y};
    }
 
    /**
     * Saves this components graphics as file image.
     * Called from save item in file menu.
     */
    public void saveAsImage()
    {
        int w = getWidth();
        int h = getHeight();
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = image.createGraphics();
        paint(g2);
        g2.dispose();
        try
        {
            ImageIO.write(image, "png", new File(getClass().getName() + ".png"));
        }
        catch(IOException ioe)
        {
            System.out.println("Unable to write: " + ioe.getMessage());
        }
    }
}
 
/**
 * Handles menu events for saving a graphics component
 * and for opening a JFileChooser open dialog.
 */
class ImagingAction
{
    GraphicImagingPanel gip;
    JFrame frame;
    JFileChooser fileChooser;
    JMenuBar menuBar;
 
    public ImagingAction(GraphicImagingPanel component, JFrame f)
    {
        gip = component;
        frame = f;
        fileChooser = new JFileChooser();
   
        JMenu fileMenu = new JMenu("file");
        final JMenuItem openItem = new JMenuItem("open");
        final JMenuItem saveItem = new JMenuItem("save");
        ActionListener l = new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                JMenuItem item = (JMenuItem)e.getSource();
                if(item == openItem)
                    openDialog();
 
                if(item == saveItem)
                    gip.saveAsImage();
            }
        };
        openItem.addActionListener(l);
        saveItem.addActionListener(l);
        fileMenu.add(openItem);
        fileMenu.add(saveItem);
        menuBar = new JMenuBar();
        menuBar.add(fileMenu);
    }
 
    private void openDialog()
    {
        int returnVal = fileChooser.showOpenDialog(frame);
        if(returnVal == JFileChooser.APPROVE_OPTION)
        {
            File file = fileChooser.getSelectedFile();
            if(!isImage(file))
                return;
            ImageIcon icon = new ImageIcon(file.getAbsolutePath());
            JLabel label = new JLabel(icon);
            frame.getContentPane().removeAll();
            frame.getContentPane().add(label);
            frame.validate();
            frame.repaint();
        }
    }
 
    /**
     * Filters files for jpg and png extensions
     */
    private boolean isImage(File file)
    {
        String extension = file.getPath().toLowerCase();
        if(extension.indexOf("jpg") != -1 || extension.indexOf("png") != -1)
            return true;
        return false;
    }
 
    public JMenuBar getMenuBar()
    {
        return menuBar;
    }
}