OpenCV 图像旋转

RotateArbitrarilyAngle(Mat src, Mat &dst, float angle)
{
    float radian = (float)(angle / 180.0 * CV_PI);

    //填充图像
    int maxBorder = (int)(max(src.cols, src.rows)* 1.414); //即为sqrt(2)*max
    int dx = (maxBorder - src.cols) / 2;
    int dy = (maxBorder - src.rows) / 2;
    copyMakeBorder(src, dst, dy, dy, dx, dx, BORDER_CONSTANT);

    //旋转
    Point2f center((float)(dst.cols / 2), (float)(dst.rows / 2));
    Mat affine_matrix = getRotationMatrix2D(center, angle, 1.0);//求得旋转矩阵
    warpAffine(dst, dst, affine_matrix, dst.size());

    //计算图像旋转之后包含图像的最大的矩形
    float sinVal = abs(sin(radian));
    float cosVal = abs(cos(radian));
    Size targetSize((int)(src.cols * cosVal + src.rows * sinVal),
        (int)(src.cols * sinVal + src.rows * cosVal));

    //剪掉多余边框
    int x = (dst.cols - targetSize.width) / 2;
    int y = (dst.rows - targetSize.height) / 2;
    Rect rect(x, y, targetSize.width, targetSize.height);
    dst = Mat(dst, rect);
}