import java.awt.geom.AffineTransform;

// angle is in our system (clockwise, 0 is north)
// rx, ry is rotation point in painted image space
static BufferedImage drawRotatedImageOnImage(BufferedImage img, BufferedImage canvas, int x, int y, double angle, double rx, double ry) {
  Graphics2D g = createGraphics(canvas);
  g.setTransform(AffineTransform.getRotateInstance(angle*pi()/180, rx, ry));
  g.drawImage(img, x, y, null);
  ret canvas;
}