java实现图片旋转

方法一：普通方法实现图片旋转

     /**
     * 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));
    }

方法二：opencv实现图片旋转

     /**
     * 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;
    }