废话不多说，直接上代码：

/*****************************************
*inputim:要旋转的图像
*tempImg:结果图像
*angle:旋转角度，（逆时针为正，顺时针为负）
*/
void warpFfine (Mat &inputIm,Mat &tempImg,float angle)
{

       CV_Assert(!inputIm.empty());
       Mat inputImg;
       inputIm.copyTo(inputImg);
  
       float radian = (float) (angle /180.0 * CV_PI);

       //填充图像使其符合旋转要求
       int uniSize =(int) ( max(inputImg.cols, inputImg.rows)* 1.414 );
       int dx = (int) (uniSize - inputImg.cols)/2;
       int dy = (int) (uniSize - inputImg.rows)/2;

       copyMakeBorder(inputImg, tempImg, dy, dy, dx, dx, BORDER_CONSTANT);

       //旋轉中心
       Point2f center( (float)(tempImg.cols/2) , (float) (tempImg.rows/2));
       Mat affine_matrix = getRotationMatrix2D( center, angle, 1.0 );

       //旋轉
       warpAffine(tempImg, tempImg, affine_matrix, tempImg.size());

       //旋轉后的圖像大小
       float sinVal = fabs(sin(radian));
       float cosVal = fabs(cos(radian));

       Size targetSize( (int)(inputImg.cols * cosVal + inputImg.rows * sinVal),
               (int)(inputImg.cols * sinVal + inputImg.rows * cosVal) );

       //剪掉四周边框
       int x = (tempImg.cols - targetSize.width) / 2;
       int y = (tempImg.rows - targetSize.height) / 2;

       Rect rect(x, y, targetSize.width, targetSize.height);
       tempImg = Mat(tempImg, rect);
}