import java.awt.*;
 import javax.swing.*;
 import java.awt.image.*;
 /**
  * An ImagePanel is a Swing component that can display an OFImage.
  * It is constructed as a subclass of JComponent with the added functionality
  * of setting an OFImage that will be displayed on the surface of this
  * component.
  *
  * @author Michael Kolling and David J. Barnes
  * @version 1.0
  */
 public class ImagePanel extends JComponent
 {
   // The current width and height of this panel
   private int width, height;
   // An internal image buffer that is used for painting. For
   // actual display, this image buffer is then copied to screen.
   private OFImage panelImage;
   /**
    * Create a new, empty ImagePanel.
    */
   public ImagePanel()
   {
     width = 360;  // arbitrary size for empty panel
     height = 240;
     panelImage = null;
   }
   /**
    * Set the image that this panel should show.
    *
    * @param image The image to be displayed.
    */
   public void setImage(OFImage image)
   {
     if(image != null) {
       width = image.getWidth();
       height = image.getHeight();
       panelImage = image;
       repaint();
     }
   }
   /**
    * Clear the image on this panel.
    */
   public void clearImage()
   {
     Graphics imageGraphics = panelImage.getGraphics();
     imageGraphics.setColor(Color.LIGHT_GRAY);
     imageGraphics.fillRect(0, 0, width, height);
     repaint();
   }
   // The following methods are redefinitions of methods
   // inherited from superclasses.
   /**
    * Tell the layout manager how big we would like to be.
    * (This method gets called by layout managers for placing
    * the components.)
    *
    * @return The preferred dimension for this component.
    */
   public Dimension getPreferredSize()
   {
     return new Dimension(width, height);
   }
   /**
    * This component needs to be redisplayed. Copy the internal image
    * to screen. (This method gets called by the Swing screen painter
    * every time it want this component displayed.)
    *
    * @param g The graphics context that can be used to draw on this component.
    */
   public void paintComponent(Graphics g)
   {
     Dimension size = getSize();
     g.clearRect(0, 0, size.width, size.height);
     if(panelImage != null) {
       g.drawImage(panelImage, 0, 0, null);
     }
   }
 }