图片旋转算法实现

图片旋转则是将现有的图片，以中心位置为圆心，进行一定角度的旋转。

 

 

核心代码如下：

@Component(value = "revolveFilter")
public class RevolvePictureFilter extends AbstractPictureFilter {

    private double angle = 30;
    /**
     * log
     **/
    private static final Log log = LogFactory.getLog(RevolvePictureFilter.class);

    /**
     * 对像素color 进行处理
     *
     * @param color 原color
     * @return 新color
     */
    @Override
    protected Color filterColor(Color color) {
        return null;
    }

    /**
     * 对图片增加滤镜
     *
     * @param image 图片
     * @return 增加滤镜之后的图片
     * 默认30度
     */
    @Override
    public BufferedImage pictureAddFilter(BufferedImage image) {
        int srcWidth = image.getWidth();
        int srcHeight = image.getHeight();
        // calculate the new image size
        Rectangle rectDes = calcRotatedSize(new Rectangle(new Dimension(
                srcWidth, srcHeight)), angle);

        BufferedImage res = null;
        res = new BufferedImage(rectDes.width, rectDes.height,
                BufferedImage.TYPE_3BYTE_BGR);
        Graphics2D g2 = res.createGraphics();
        // transform
        g2.translate((rectDes.width - srcWidth) / 2,
                (rectDes.height - srcHeight) / 2);
        g2.rotate(Math.toRadians(angle), srcWidth / 2, srcHeight / 2);

        g2.drawImage(image, 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 angelAlpha = (Math.PI - Math.toRadians(angel)) / 2;
        double angelDaltaWidth = Math.atan((double) src.height / src.width);
        double angelDaltaHeight = Math.atan((double) src.width / src.height);

        int lenDaltaWidth = (int) (len * Math.cos(Math.PI - angelAlpha
                - angelDaltaWidth));
        lenDaltaWidth=lenDaltaWidth>0?lenDaltaWidth:-lenDaltaWidth;

        int lenDaltaHeight = (int) (len * Math.cos(Math.PI - angelAlpha
                - angelDaltaHeight));
        lenDaltaHeight=lenDaltaHeight>0?lenDaltaHeight:-lenDaltaHeight;

        int desWidth = src.width + lenDaltaWidth * 2;
        int desHeight = src.height + lenDaltaHeight * 2;
        desWidth=desWidth>0?desWidth:-desWidth;
        desHeight=desHeight>0?desHeight:-desHeight;
        return new java.awt.Rectangle(new Dimension(desWidth, desHeight));
    }
}