| 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 | |