java/pokusy/_nodist/SketchPanel.java

   1 import java.awt.Container;
   2 import java.awt.Graphics;
   3 import java.awt.Point;
   4 import java.awt.event.KeyEvent;
   5 import java.awt.event.KeyListener;
   6 import java.awt.event.WindowAdapter;
   7 import java.awt.event.WindowEvent;
   8
   9 import javax.swing.JFrame;
  10 import javax.swing.JPanel;
  11
  12 public class SketchPanel extends JPanel implements KeyListener {
  13
  14   private Point startPoint = new Point(0, 0);
  15
  16   private Point endPoint = new Point(0, 0);
  17
  18   public SketchPanel() {
  19     addKeyListener(this);
  20   }
  21
  22   public void keyPressed(KeyEvent evt) {
  23     int keyCode = evt.getKeyCode();
  24     int d;
  25     if (evt.isShiftDown())
  26       d = 5;
  27     else
  28       d = 1;
  29     if (keyCode == KeyEvent.VK_LEFT)
  30       add(-d, 0);
  31     else if (keyCode == KeyEvent.VK_RIGHT)
  32       add(d, 0);
  33     else if (keyCode == KeyEvent.VK_UP)
  34       add(0, -d);
  35     else if (keyCode == KeyEvent.VK_DOWN)
  36       add(0, d);
  37   }
  38
  39   public void keyReleased(KeyEvent evt) {
  40   }
  41
  42   public void keyTyped(KeyEvent evt) {
  43   }
  44
  45   public boolean isFocusTraversable() {
  46     return true;
  47   }
  48
  49   public void add(int dx, int dy) {
  50     endPoint.x += dx;
  51     endPoint.y += dy;
  52     Graphics g = getGraphics();
  53     g.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
  54     g.dispose();
  55     startPoint.x = endPoint.x;
  56     startPoint.y = endPoint.y;
  57   }
  58
  59   public static void main(String[] args) {
  60     JFrame frame = new JFrame();
  61     frame.setTitle("Sketch");
  62     frame.setSize(300, 200);
  63     frame.addWindowListener(new WindowAdapter() {
  64       public void windowClosing(WindowEvent e) {
  65         System.exit(0);
  66       }
  67     });
  68
  69     Container contentPane = frame.getContentPane();
  70     contentPane.add(new SketchPanel());
  71
  72     frame.show();
  73   }
  74 }
  75