/*
 *  File:  mAdapterApplet.java
 *
 *  MouseEvents, movable objects, and adapter classes
 *
 *  Note: The private modifier was removed from some of the
 *        variables so that the adapter class has access.  
 */

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class mAdapterApplet extends Applet 
                            implements MouseMotionListener {
                          
  // Instance variables:
  private int numObj = 3;       // number of movable objects
  mPoint object[];              // array of movable objects
  private Image buffer;         // image object for double buffering
  private Graphics gOffScreen;  // graphics object for double buffering
  
  // Mouse handling variables:
  int current = -1;
  int hit = -1;
  int xoffset = 0;
  int yoffset = 0;
  
  // Colors:
  private Color objColor = Color.cyan;
  private Color objColorSelect = Color.red;
  private Color bgColor = Color.black;
  private Color fgColor = Color.white;

  public void init() {
    setBackground( bgColor );
    setForeground( fgColor );

    // Instantiate object array:
    object = new mPoint[ numObj ];

    // Instantiate a rectangle:
    object[0] = new mRectangle( 10, 10, 100, 100 );
    object[0].setColor( objColor );

    // Instantiate a circle:
    object[1] = new mOval( 200, 10, 100, 100 );
    object[1].setColor( objColor );

    // Instantiate a triangle:
    object[2] = new mTriangle( 10, 200, 100, 100 );
    object[2].setColor( objColor );

    // Create an off-screen image for double buffering:
    buffer = createImage( getSize().width, getSize().height );
    // Get off-screen graphics context:
    gOffScreen = buffer.getGraphics(); 

    // Register the applet to listen for ALL mouse events:
    this.addMouseListener( new MouseHandler( this ) );
    this.addMouseMotionListener( this );
  }

  // Override java.awt.Component.update:
  public void update( Graphics g ) {
    // Fill background:
    gOffScreen.setColor( getBackground() );
    gOffScreen.fillRect( 1, 1, getSize().width - 2, getSize().height - 2 );
    // Draw boundary:
    gOffScreen.setColor( getForeground() );
    gOffScreen.drawRect( 0, 0, getSize().width - 1, getSize().height - 1 );
    paint( gOffScreen );
    
    // Draw the buffer in the applet window:
    g.drawImage( buffer, 0, 0, this );
  }
  
  // Override java.awt.Component.paint:
  public void paint( Graphics g ) {
    // Paint each object:
    for ( int i = 0; i < numObj; i++ ) {
      object[i].paint(g);
    }
  }

  /*
   *  MouseMotionListener event handlers
   */
  
  public void mouseMoved( MouseEvent e ) {
    hit = -1;
    for ( int i = 0; i < numObj; i++ ) {
      if ( object[i].isInside( e.getX(), e.getY() ) ) {
        hit = i; break;
      }
    }
    
    for ( int i = 0; i < numObj; i++ ) {
      object[i].setColor( (i == hit) ? objColorSelect : objColor );
    }
    repaint();
  }

  public void mouseDragged( MouseEvent e ) {
    if ( current != -1 ) {
      int x = e.getX() + xoffset;
      int y = e.getY() + yoffset;
      object[current].setPoint( x, y );
      repaint();
    }
  }

}

// Extend the MouseAdapter class, which is a trivial implementation
// of the MouseListener interface:
class MouseHandler extends MouseAdapter {

  private mAdapterApplet applet;

  public MouseHandler( mAdapterApplet a ) { applet = a; }
  
  public void mousePressed( MouseEvent e ) {
    int i = applet.current = applet.hit;
    if ( i != -1 ) {
      applet.xoffset = applet.object[i].getX() - e.getX();
      applet.yoffset = applet.object[i].getY() - e.getY();
    }
  }

  public void mouseReleased( MouseEvent e ) {
    applet.current = -1;
  }

}