1 /*
2 * File: MouseEvents.java
3 *
4 * MouseEvents and movable polygons
5 *
6 * Copyright: Northeast Parallel Architectures Center
7 *
8 */
9
10 import java.awt.*;
11 import java.awt.event.*;
12
13 public class MouseEvents extends java.applet.Applet
14 implements MouseListener, MouseMotionListener {
15
16 // Instance variables:
17 private final int numPoly = 3; // number of movable polygons
18 private MovablePolygon polygon[]; // array of movable polygons
19 private Image buffer; // image object for double buffering
20 private Graphics gOffScreen; // graphics object for double buffering
21
22 // Mouse handling variables:
23 private int current = -1; // index of polygon being dragged
24 private int hit = -1; // index of polygon containing cursor
25 private int xoffset = 0; // relative x-coordinate of mouse click
26 private int yoffset = 0; // relative y-coordinate of mouse click
27
28 // Default polygon color:
29 private final Color polyColor = Color.cyan;
30 // Selected polygon color:
31 private final Color polyColorSelect = Color.red;
32 // Applet colors:
33 private final Color bgColor = Color.black;
34 private final Color fgColor = Color.white;
35
36 public void init() {
37
38 setBackground( bgColor );
39 setForeground( fgColor );
40
41 // Instantiate polygon array:
42 polygon = new MovablePolygon[ numPoly ];
43
44 // Instantiate a square:
45 polygon[0] = new MovablePolygon( 75, 75, 50, 4 );
46 polygon[0] = ( MovablePolygon ) polygon[0].centerRotate( Math.PI/4 );
47 polygon[0].setDelta( 2, 3 );
48 polygon[0].setColor( Color.red );
49
50 // Instantiate a regular hexagon:
51 polygon[1] = new MovablePolygon( 250, 60, 50, 6 );
52 polygon[1].setDelta( -3, 2 );
53 polygon[1].setColor( Color.blue );
54
55 // Instantiate an equilateral triangle:
56 polygon[2] = new MovablePolygon( 60, 250, 50, 3 );
57 polygon[2].setDelta( -2, 2 );
58 polygon[2].setColor( Color.green );
59
60 // Create an off-screen image for double buffering:
61 buffer = createImage( getSize().width, getSize().height );
62 // Get off-screen graphics context:
63 gOffScreen = buffer.getGraphics();
64
65 // Register the applet to listen for ALL mouse events:
66 addMouseListener( this );
67 addMouseMotionListener( this );
68
69 } // end method init()
70
71 // Override java.awt.Component.update:
72 public void update( Graphics g ) {
73 // Fill background:
74 gOffScreen.setColor( getBackground() );
75 gOffScreen.fillRect( 1, 1, getSize().width - 2, getSize().height - 2 );
76 // Draw boundary:
77 gOffScreen.setColor( getForeground() );
78 gOffScreen.drawRect( 0, 0, getSize().width - 1, getSize().height - 1 );
79 paint( gOffScreen );
80
81 // Draw the buffer in the applet window:
82 g.drawImage( buffer, 0, 0, this );
83 }
84
85 // Override java.awt.Component.paint:
86 public void paint( Graphics g ) {
87 // Paint each polygon:
88 for ( int i = 0; i < numPoly; i++ ) {
89 polygon[i].fill(g);
90 }
91 }
92
93 // MouseMotionListener event handlers:
94 public void mouseMoved( MouseEvent e ) {
95 hit = -1;
96 for ( int i = 0; i < numPoly; i++ ) {
97 if ( polygon[i].contains( e.getX(), e.getY() ) ) {
98 hit = i; break;
99 }
100 }
101
102 for ( int i = 0; i < numPoly; i++ ) {
103 polygon[i].setColor( (i == hit) ? polyColorSelect : polyColor );
104 }
105 repaint();
106 }
107 public void mouseDragged( MouseEvent e ) {
108 if ( current != -1 ) {
109 int x = e.getX() + xoffset;
110 int y = e.getY() + yoffset;
111 polygon[current].translate( x, y );
112 repaint();
113 }
114 }
115
116 // MouseListener event handlers:
117 public void mousePressed( MouseEvent e ) {
118 current = hit;
119 if ( current != -1 ) {
120 xoffset = polygon[current].getBounds().x - e.getX();
121 yoffset = polygon[current].getBounds().y - e.getY();
122 }
123 }
124 public void mouseReleased( MouseEvent e ) {
125 current = -1;
126 }
127 public void mouseClicked( MouseEvent e ) { }
128 public void mouseEntered( MouseEvent e ) { }
129 public void mouseExited( MouseEvent e ) { }
130
131 } // end class MouseEvents
132