Draw on frame with keyboard
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class SketchPanel extends JPanel implements KeyListener {
private Point startPoint = new Point(0, 0);
private Point endPoint = new Point(0, 0);
public SketchPanel() {
addKeyListener(this);
}
public void keyPressed(KeyEvent evt) {
int keyCode = evt.getKeyCode();
int d;
if (evt.isShiftDown())
d = 5;
else
d = 1;
if (keyCode == KeyEvent.VK_LEFT)
add(-d, 0);
else if (keyCode == KeyEvent.VK_RIGHT)
add(d, 0);
else if (keyCode == KeyEvent.VK_UP)
add(0, -d);
else if (keyCode == KeyEvent.VK_DOWN)
add(0, d);
}
public void keyReleased(KeyEvent evt) {
}
public void keyTyped(KeyEvent evt) {
}
public boolean isFocusTraversable() {
return true;
}
public void add(int dx, int dy) {
endPoint.x += dx;
endPoint.y += dy;
Graphics g = getGraphics();
g.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
g.dispose();
startPoint.x = endPoint.x;
startPoint.y = endPoint.y;
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("Sketch");
frame.setSize(300, 200);
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
Container contentPane = frame.getContentPane();
contentPane.add(new SketchPanel());
frame.show();
}
}
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