Problem in rotating picturebox

public static Bitmap RotateImage1(Image image, float angle, Form f)
{
   if (image == null)
      throw new ArgumentNullException("image");

   const double pi2 = Math.PI / 2.0;
   double oldWidth = Convert.ToDouble(420);
   double oldHeight = Convert.ToDouble(420);
   double theta = ((double)angle) * Math.PI / 180.0;
   double locked_theta = theta;
   while (locked_theta < 0.0)
      locked_theta += 2 * Math.PI;

   double newWidth, newHeight;
   int nWidth, nHeight; 
   double adjacentTop, oppositeTop;
   double adjacentBottom, oppositeBottom;
   if ((locked_theta >= 0.0 && locked_theta < pi2) ||
       (locked_theta >= Math.PI && locked_theta < (Math.PI + pi2)))
   {
      adjacentTop = Math.Abs(Math.Cos(locked_theta)) * oldWidth;
      oppositeTop = Math.Abs(Math.Sin(locked_theta)) * oldWidth;

      adjacentBottom = Math.Abs(Math.Cos(locked_theta)) * oldHeight;
      oppositeBottom = Math.Abs(Math.Sin(locked_theta)) * oldHeight;
   }
   else
   {
      adjacentTop = Math.Abs(Math.Sin(locked_theta)) * oldHeight;
      oppositeTop = Math.Abs(Math.Cos(locked_theta)) * oldHeight;

      adjacentBottom = Math.Abs(Math.Sin(locked_theta)) * oldWidth;
      oppositeBottom = Math.Abs(Math.Cos(locked_theta)) * oldWidth;
   }

   newWidth = adjacentTop + oppositeBottom;
   newHeight = adjacentBottom + oppositeTop;

   nWidth = (int)Math.Ceiling(newWidth);
   nHeight = (int)Math.Ceiling(newHeight);

   Bitmap rotatedBmp;
          
   rotatedBmp = new Bitmap(nWidth, nHeight);
                       
   using (Graphics g = Graphics.FromImage(rotatedBmp))
   {
      // This array will be used to pass in the three points that 
      // make up the rotated image
      Point[] points;
      if (locked_theta >= 0.0 && locked_theta < pi2)
      {
         points = new Point[]
         { 
            new Point( (int) oppositeBottom, 0 ), 
            new Point( nWidth, (int) oppositeTop ),
            new Point( 0, (int) adjacentBottom )
         };
      }
      else if (locked_theta >= pi2 && locked_theta < Math.PI)
      {
         points = new Point[]
         { 
            new Point( nWidth, (int) oppositeTop ),
            new Point( (int) adjacentTop, nHeight ),
            new Point( (int) oppositeBottom, 0 )
         };
      }
      else if (locked_theta >= Math.PI && locked_theta < (Math.PI + pi2))
      {
         points = new Point[]
         {
            new Point( (int) adjacentTop, nHeight ), 
            new Point( 0, (int) adjacentBottom ),
            new Point( nWidth, (int) oppositeTop )
         };
      }
      else
      {
         points = new Point[]
         { 
            new Point( 0, (int) adjacentBottom ), 
            new Point( (int) oppositeBottom, 0 ),
            new Point( (int) adjacentTop, nHeight )		
         };
      }

      g.DrawImage((Image)image.Clone(), points);
   }

   return rotatedBmp;
}