[Java] java实现图片任意角度旋转

/**
   * 图像旋转
   * @param src
   * @param angel
   * @return
*/
  public static bufferedimage rotate(image src, double angel) {
  int src_width = src.getwidth(null);
  int src_height = src.getheight(null);
  // calculate the new image size
  rectangle rect_des = calcrotatedsize(new rectangle(new dimension(
    src_width, src_height)), angel);
 
  bufferedimage res = null;
  res = new bufferedimage(rect_des.width, rect_des.height,
    bufferedimage.type_3byte_bgr);
  graphics2d g2 = res.creategraphics();
  // transform
  g2.translate((rect_des.width - src_width) / 2,
    (rect_des.height - src_height) / 2);
  g2.rotate(math.toradians(angel), src_width / 2, src_height / 2);
 
  g2.drawimage(src, null, null);
  return res;
  }
 
  public static rectangle calcrotatedsize(rectangle src, double angel) {
  // if angel is greater than 90 degree, we need to do some conversion
  if (angel >= 90) {
    if(angel / 90 % 2 == 1){
    int temp = src.height;
    src.height = src.width;
    src.width = temp;
    }
    angel = angel % 90;
  }
 
  double r = math.sqrt(src.height * src.height + src.width * src.width) / 2;
  double len = 2 * math.sin(math.toradians(angel) / 2) * r;
  double angel_alpha = (math.pi - math.toradians(angel)) / 2;
  double angel_dalta_width = math.atan((double) src.height / src.width);
  double angel_dalta_height = math.atan((double) src.width / src.height);
 
  int len_dalta_width = (int) (len * math.cos(math.pi - angel_alpha
    - angel_dalta_width));
  len_dalta_width=len_dalta_width>0?len_dalta_width:-len_dalta_width;
 
  int len_dalta_height = (int) (len * math.cos(math.pi - angel_alpha
    - angel_dalta_height));
  len_dalta_height=len_dalta_height>0?len_dalta_height:-len_dalta_height;
 
  int des_width = src.width + len_dalta_width * 2;
  int des_height = src.height + len_dalta_height * 2;
  des_width=des_width>0?des_width:-des_width;
  des_height=des_height>0?des_height:-des_height;
  return new java.awt.rectangle(new dimension(des_width, des_height));
}

/**
   * opencv实现图片旋转
   * @param splitimage
   * @param angle
   * @return
*/
  public static mat rotate3(mat splitimage, double angle)
  {
  double thera = angle * math.pi / 180;
  double a = math.sin(thera);
  double b = math.cos(thera);
 
  int wsrc = splitimage.width();
  int hsrc = splitimage.height();
 
  int wdst = (int) (hsrc * math.abs(a) + wsrc * math.abs(b));
  int hdst = (int) (wsrc * math.abs(a) + hsrc * math.abs(b));
  mat imgdst = new mat(hdst, wdst, splitimage.type());
 
  point pt = new point(splitimage.cols() / 2, splitimage.rows() / 2);
  // 获取仿射变换矩阵
  mat affinetrans = imgproc.getrotationmatrix2d(pt, angle, 1.0);
 
  system.out.println(affinetrans.dump());
  // 改变变换矩阵第三列的值
  affinetrans.put(0, 2, affinetrans.get(0, 2)[0] + (wdst - wsrc) / 2);
  affinetrans.put(1, 2, affinetrans.get(1, 2)[0] + (hdst - hsrc) / 2);
 
  imgproc.warpaffine(splitimage, imgdst, affinetrans, imgdst.size(),
    imgproc.inter_cubic | imgproc.warp_fill_outliers);
  return imgdst;
}