/*
 *  File:  MouseEvents.java
 *
 *  MouseEvents and movable polygons
 *
 *  Copyright:  Northeast Parallel Architectures Center
 *
 */

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

public class MouseEvents extends java.applet.Applet 
                         implements MouseListener, MouseMotionListener {
                          
  // Instance variables:
  private final int numPoly = 3;     // number of movable polygons
  private MovablePolygon polygon[];  // array of movable polygons
  private Image buffer;              // image object for double buffering
  private Graphics gOffScreen;       // graphics object for double buffering
  
  // Mouse handling variables:
  private int current = -1;        // index of polygon being dragged
  private int hit = -1;            // index of polygon containing cursor
  private int xoffset = 0;         // relative x-coordinate of mouse click
  private int yoffset = 0;         // relative y-coordinate of mouse click
  
  // Default polygon color:
  private final Color polyColor = Color.cyan;
  // Selected polygon color:
  private final Color polyColorSelect = Color.red;
  // Applet colors:
  private final Color bgColor = Color.black;
  private final Color fgColor = Color.white;

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

    // Instantiate polygon array:
    polygon = new MovablePolygon[ numPoly ];

    // Instantiate a square:
    polygon[0] = new MovablePolygon( 75, 75, 50, 4 );
    polygon[0] = ( MovablePolygon ) polygon[0].centerRotate( Math.PI/4 );
    polygon[0].setDelta( 2, 3 );
    polygon[0].setColor( Color.red );

    // Instantiate a regular hexagon:
    polygon[1] = new MovablePolygon( 250, 60, 50, 6 );
    polygon[1].setDelta( -3, 2 );
    polygon[1].setColor( Color.blue );

    // Instantiate an equilateral triangle:
    polygon[2] = new MovablePolygon( 60, 250, 50, 3 );
    polygon[2].setDelta( -2, 2 );
    polygon[2].setColor( Color.green );

    // 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:
    addMouseListener( this );
    addMouseMotionListener( this );
    
  }  // end method init()

  // 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 polygon:
    for ( int i = 0; i < numPoly; i++ ) {
      polygon[i].fill(g);
    }
  }

  // MouseMotionListener event handlers:
  public void mouseMoved( MouseEvent e ) {
    hit = -1;
    for ( int i = 0; i < numPoly; i++ ) {
      if ( polygon[i].contains( e.getX(), e.getY() ) ) {
        hit = i; break;
      }
    }
    
    for ( int i = 0; i < numPoly; i++ ) {
      polygon[i].setColor( (i == hit) ? polyColorSelect : polyColor );
    }
    repaint();
  }
  public void mouseDragged( MouseEvent e ) {
    if ( current != -1 ) {
      int x = e.getX() + xoffset;
      int y = e.getY() + yoffset;
      polygon[current].translate( x, y );
      repaint();
    }
  }

  // MouseListener event handlers:
  public void mousePressed( MouseEvent e ) {
    current = hit;
    if ( current != -1 ) {
      xoffset = polygon[current].getBounds().x - e.getX();
      yoffset = polygon[current].getBounds().y - e.getY();
    }
  }
  public void mouseReleased( MouseEvent e ) {
    current = -1;
  }
  public void mouseClicked( MouseEvent e ) { }
  public void mouseEntered( MouseEvent e ) { }
  public void mouseExited( MouseEvent e ) { }

}  // end class MouseEvents