Resizing a rectangle shape?

Question

In my drawing application the user uses the mouse to drag out a rectangle. When the rectangle is drawn it has four handles on it, so that the user can click on any one of these handles and resize it. I'm having great difficulties getting this to working properly, does anyone know of an open source example I could look at to see how to do this?
I have resizing a Line working perfectly, all I need now is the rectangle functionality.
Here is how I draw the handles on my rectangle:
public void drawHandles(Graphics2D aGraphics2D)
        aGraphics2D.setColor(Color.RED);
        // If the shape is selected then draw the handles
        if(isSelected())
            aGraphics2D.fillRect(getX1() - 2, getY1() - 2, 5, 5);
             aGraphics2D.fillRect(getX2() - 2, getY2() - 2, 5, 5);
             aGraphics2D.fillRect(getX1() - 2, getY2() - 2, 5, 5);
             aGraphics2D.fillRect(getX2() - 2, getY1() - 2, 5, 5);
    }I have also a method that returns which handle has been clicked.
Please help guys, I've spent too long trying to get this to work.
Thanks.

Answer 1

Probably you do custom painting. So do something like this:
class SuperClass extends JPanel implements MouseListener, MouseMotionListener {
private static final int NO_HANDLE_SELECTED = -1;
private static final int POINTS_COUNT = 4;
private Point[] points = new Point[POINTS_COUNT];
private int editedHandle = NO_HANDLE_SELECTED;
SuperClass(Rectangle rect) {
addMouseListener(this);
addMouseMotionListener(this);
points[0] = new Point(rect.x, rect.y);
points[1] = new Point(rect.x + rect.width, rect.y);
points[2] = new Point(rect.x, rect.y + rect.height);
points[3] = new Point(rect.x + rect.width, rect.y + rect.height);
public void paint(Graphics g) {
// Draw the "rectangle"
g.moveto(points[0]);
for (int i = 1; i < POINTS_COUNT; i++) {
g.lineto(points);
g.lineto(points[0]);
drawHandles(g); // This is your handle drawing routine
* A little bit altered
public void drawHandles(Graphics2D g) {
for (int i = 0; i < POINTS_COUNT; i++) {
g.fillRect(points[i].x - 2, points[i].y - 2, 5, 5);
public void mousePressed(MouseEvent m) {
editedHandle = getEditedHandle(m); // Your handle detecting routine.
// This should return 0 if the first point was clicked e.c.t. or NO_HANDLE_SELECTED
// if the user clicks in empty space.
public void mouseDragged(MouseEvent m) {
if (editedHandle != NO_HANDLE_SELECTED) {
points[editedHandle].x = m.getX();
points[editedHandle].y = m.getY();
repaint();
public void mouseReleased(MouseEvent m) {
editedHandle = NO_HANDLE_SELECTED;
1. Warning. This code was composed on the fly on an HTML browser and not in an IDE. It will probably not run. But with little debugging (1-5 mins) I am sure it will work.
2. This "algorithm" is nice because it paints and edits any polygon without holes, not only Rectangles.
3. This component is being based on JPanel as it is the most likely for you to use. You can adapt it to everything e.g. a JButton in order to edit its (Vectorized) icon when you double click over it! That would be fun!