What you need to do, is save the previously drawn rectangle in some sort of data structure, so you can draw it again later.
This code (sorry about the length, will do something similar to what you are describing.
To use it, just slap the JPanel
inside of a JFrame
.
public class DrawPane extends JPanel {
private List<DrawnShape> drawings;
private DrawnShape curShape;
public DrawPane() {
drawings = new ArrayList<DrawnShape>();
setBackground(Color.WHITE);
setPreferredSize(new Dimension(300, 300));
addMouseListener(clickListener);
addMouseMotionListener(moveListener);
}
@Override
protected void paintComponent(Graphics g2) {
super.paintComponent(g2);
Graphics2D g = (Graphics2D) g2;
for (DrawnShape s : drawings) {
s.draw(g);
}
g.setColor(Color.BLACK);
g.setStroke(new BasicStroke(2));
if (curShape == null)
return;
curShape.draw(g);
}
private MouseListener clickListener = new MouseAdapter() {
@Override
public void mousePressed(MouseEvent e) {
curShape = new DrawnShape(e.getPoint(), e.getPoint());
}
@Override
public void mouseReleased(MouseEvent e) {
drawings.add(new DrawnShape(curShape.getClickP(), e.getPoint()));
curShape = null;
}
};
private MouseMotionListener moveListener = new MouseMotionListener() {
@Override
public void mouseDragged(MouseEvent e) {
curShape = new DrawnShape(curShape.getClickP(), e.getPoint());
repaint();
}
@Override
public void mouseMoved(MouseEvent e) {
}
};
}
class DrawnShape {
private Point p1, p2;
public DrawnShape(Point p1, Point p2) {
this.p1 = p1;
this.p2 = p2;
}
public Point getClickP() {
return p1;
}
public void draw(Graphics2D g) {
g.drawLine(p1.x, p1.y, p2.x, p1.y);
g.drawLine(p1.x, p1.y, p1.x, p2.y);
g.drawLine(p2.x, p2.y, p2.x, p1.y);
g.drawLine(p2.x, p2.y, p1.x, p2.y);
}
}