How rotate rectangle around corner on applet?

Question

I want to rotate the rectangle around one of corner, but I don't now how determine the new coordinates of corners. Rotation may be around any corner. May be exists another method of rotation?

Can someone help me?

screenshot of my applet

import java.applet.*;
import java.awt.*;

public class MainApplet extends Applet implements Runnable {

int width, height;
int i = 0;
Thread t = null;
boolean threadSuspended;

public void init() {
    width = getSize().width;
    height = getSize().height;
    setBackground(Color.black);
}

public void destroy() {}


public void start() {
    if (t == null) {
        t = new Thread(this);
        threadSuspended = false;
        t.start();
    } else {
        if (threadSuspended) {
            threadSuspended = false;
            synchronized (this) {
                notify();
            }
        }
    }
}

public void stop() {
    threadSuspended = true;
}

public void run() {
    try {
        while (true) {
            ++i;
            if (i == 359) {
                i = 0;
            }
            showStatus("i is " + i);

            if (threadSuspended) {
                synchronized (this) {
                    while (threadSuspended) {
                        wait();
                    }
                }
            }
            repaint();
            t.sleep(100);  // interval given in milliseconds
        }
    } catch (InterruptedException e) {
    }
}

public void paint(Graphics g) {
    g.setColor(Color.green);

    g.drawRect(200,150, (int) (50*Math.cos(i)-100*Math.sin(i)+200-200*Math.cos(i)+150*Math.sin(i)),
                        (int) (50*Math.sin(i)+100*Math.cos(i)+150-200*Math.sin(i)-150*Math.cos(i)));
}
}

Answer 1

You can use Graphics2D 's .rotate(theta, double x, double y) method.

public void paint(Graphics g){
  //Create Graphics2D object:
  Graphics2D g2d = (Graphics2D) g.create();

  //Create rectangle of origin (0,0), w=30, h=50
  Rectangle rectangle = new Rectangle();
  rectangle.setBounds(0,0,30,50);

  //Rotate rectangle by 1 radian(Math.PI) from the bottom corner
  g2d.rotate(Math.PI, rectangle.x + rectangle.width/2, rectangle.y + rectangle.height/2);

  //Draw rectangle
  g2d.draw(rectangle);
}