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01 package examples.moveongrid;
02
03 import java.awt.Point;
04
05 import fang.*;
06
07 /**This example shows how to move
08 * a circle smoothly on a 5 x 5 grid.
09 * @author Jam Jenkins
10 */
11 public class MoveOnGrid
12 extends Game
13 {
14 /**this is the circle which moves
15 * around with the mouse*/
16 private Sprite piece;
17
18 private GridTracker gridTracker;
19
20 /**adds the grid to the background
21 * and the circle in front*/
22 public void setup()
23 {
24 Grid grid=new Grid(5, 5, 0.1);
25 grid.setScale(1);
26 grid.setLocation(0.5, 0.5);
27 addSprite(grid);
28
29 piece=new OvalSprite(0.1, 0.1);
30 piece.setLocation(0.1, 0.1);
31 piece.setColor(getColor("yellow"));
32 addSprite(piece);
33
34 gridTracker=new GridTracker(5, 5);
35 gridTracker.setMoveTime(1);
36 piece.addTransformer(gridTracker);
37
38 setHelp("resources/MoveOnGridHelp.txt");
39 }
40
41 /**gets the snapped to grid location
42 * @param point the horizontal and vertical
43 * screen location
44 * @return the snapped to grid column
45 * and row. These are numbered 0...4.
46 */
47 public Point getCell(Location2D point)
48 {
49 int x=(int)Math.min(4, point.x*5);
50 int y=(int)Math.min(4, point.y*5);
51 return new Point(x, y);
52 }
53
54 /**moves the circle with the mouse. When
55 * the user clicks, a circle is deposited
56 * in the nearest cell.
57 */
58 public void advance()
59 {
60 //gets the position of a click
61 Location2D click=getClick2D();
62
63 //a null click position means the
64 //user did not click
65 if(click!=null)
66 {
67 Point target=getCell(click);
68 Point source=getCell(piece.getLocation());
69
70 gridTracker.move(target.y-source.y,
71 target.x-source.x);
72 }
73 }
74
75 /**runs SnapToGrid as an application
76 * @param args not used
77 */
78 public static void main(String[] args)
79 {
80 new MoveOnGrid().runAsApplication();
81 }
82
83 }
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