/*
 *  File:  mInnerApplet.java
 *
 *  MouseEvents, movable objects, and inner classes
 *
 *  Note: The private modifier was removed from some of the
 *        variables so that the inner classes have access.  
 *        Evidently this is a longstanding bug in JDK 1.1
 *        (see page 103 of the tiger book).
 */

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

public class mInnerApplet extends Applet {
                          
  // Instance variables:
  /* private */ int numObj = 3;   // number of movable objects
  /* private */ 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:
  /* private */ int current = -1;
  /* private */ int hit = -1;
  /* private */ int xoffset = 0;
  /* private */ 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 MouseEvents via
    // an inner class (defined below):
    this.addMouseMotionListener( new MouseMotionHandler() );
    
    // Register the applet to listen for MouseEvents via
    // an *anonymous* inner class:
    this.addMouseListener(
      new MouseAdapter() {
  
        public void mousePressed( MouseEvent e ) {
          current = hit;
          if ( current != -1 ) {
            xoffset = object[ current ].getX() - e.getX();
            yoffset = object[ current ].getY() - e.getY();
          }
        }
      
        public void mouseReleased( MouseEvent e ) {
          current = -1;
        }
        
      }
    );
  
  }  // end method init()
  
  // A type of inner class called a "member class":
  class MouseMotionHandler extends MouseMotionAdapter {

    public void mouseMoved( MouseEvent e ) {
      // Determine which object contains the cursor (if any):
      hit = -1;
      for ( int i = 0; i < numObj; i++ ) {
        if ( object[i].isInside( e.getX(), e.getY() ) ) {
          hit = i;
          break;
        }
      }
      // Color all objects:
      Color color;
      for ( int i = 0; i < numObj; i++ ) {
        color = ( i == hit ) ? objColorSelect : objColor;
        object[i].setColor( color );
      }
      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();
      }
    }
    
  }

  // 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);
  }

}