package com.mindprod.image;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import javax.swing.JComponent;

/**
 * Component for viewing an Image. Simplified version of Symantec ImageViewer
 * displays an Image.  Does not resize the image, though may crop it.
 * Thus always maintains original magnification and aspect ratio.
 * Similar to IconImage.
 * @author Roedy Green
 */
public class ImageViewerSwing extends JComponent
   {
   /**
     * default Constructor
     */
   public ImageViewerSwing()
      {
      image = null;
      }

   /**
   * Constructor with Image.
   *
   * @param image the Image to be displayed .
   * See the Java glossary under Image for ways to create an Image from a file.
   */
   public ImageViewerSwing( Image image )
      {
      this();
      setImage( image );
      }

   /**
   * Set or change the current Image to display.
   * setImage does a MediaTracker to ensure the Image is loaded.
   * You don't have to.
   * If you don't plan to use the old image again you should
   * do a getImage().flush();
   *
   * @param image the new Image to be displayed.
   * If the image jpg may have recently changed, don't use
   * getImage to create it, use
   * URL.openConnection()
   * URLConnection.setUseCaches( false )
   * Connection.getContent
   * Component.createImage
   *
   */
   public void setImage( Image image )
      {
      // even if Image object is same, we use it since it may have changed state.

      this.image = image;

      if ( image != null )
         {
         MediaTracker tracker;
         try
            {
            // wait until image is fully loaded.
            // and so that paint will be instantaneous, rather than gradual as
            // the image arrives.
            // MediaTracker notifies of progress via our Component.ImageObsever interface
            tracker = new MediaTracker( this );
            tracker.addImage( image, 0 );
            tracker.waitForID( 0 );
            }
         catch ( InterruptedException e )
            {
            }
         }
      // image is now ready, let's paint it
      repaint();

      }

   /**
    * Get the Image currently being displayed.
    *
    * @return the Image currently displayed or null if no Image
    */
   public Image getImage()
      {
      return image;
      }

   /**
    * Paints this component using the given graphics context.
    * In Swing we override PaintComponent, not paint.
    *
    * @param g      Graphics context where to paint, e.g. to screen, printer, RAM.
    */
   public void paintComponent( Graphics g )
      {
      super.paintComponent( g );
      // get size of box we have to draw in
      Dimension dim = getSize();
      if ( image != null )
         {
         /* center Image in box, normally should exactly fill the box.
            If we overflow, no problem, drawImage will clip. */
         int imageWidth = image.getWidth( this );
         int imageHeight = image.getHeight( this );

         // this does not complete the job, just starts it.
         // We are notified of progress through our Component ImageObserver interface.
         g.drawImage ( image,                            /* Image to draw */
                       ( dim.width - imageWidth ) / 2,   /* x */
                       ( dim.height - imageHeight ) / 2, /* y */
                       imageWidth,                       /* width */
                       imageHeight,                      /* height */
                       this );                           /* this ImageViewerSwing component */

         }
      else
         {
         /*  we have no Image, clear the box */
         g.setColor( getBackground() );
         g.clearRect( 0, 0, dim.width, dim.height );
         }
      }

   /**
    * Preferred Layout size.
    *
    * @return the recommended dimensions to display the Image.
    */
   public Dimension getPreferredSize()
      {
      if ( image != null )
         {
         /* should just fit  the Image */
         return( new Dimension( image.getWidth(this), image.getHeight(this) ) );
         }
      else
         {  /* empty square as a placeholder */
         return new Dimension( 10, 10 );
         }
      }

   /**
    * Minimum layout size.
    *
    * @return he minimum dimensions to properly display the Image
    */
   public Dimension getMinimumSize()
      {
      return getPreferredSize();
      }

   /**
    * Image that this viewer is currently displaying.
    */
   private Image image;

   } // end class ImageViewerSwing