opencv 旋转图片

没什么好说的，直接上代码

旋转
参数：
	angle  旋转的角度
	clockwise = false 逆时针旋转
	          = true  顺时针旋转
*/
// clockwise 为true则顺时针旋转，否则为逆时针旋转
IplImage* CPreprocessImage::rotateImage(const IplImage* src, int angle, bool clockwise)
{
	angle = abs(angle) % 180;
	if (angle > 90)
	{
		angle = 90 - (angle % 90);
	}
	IplImage* dst = NULL;
	int width =
		(double)(src->height * sin(angle * CV_PI / 180.0)) +
		(double)(src->width * cos(angle * CV_PI / 180.0 )) + 1;
	int height =
		(double)(src->height * cos(angle * CV_PI / 180.0)) +
		(double)(src->width * sin(angle * CV_PI / 180.0 )) + 1;
	int tempLength = sqrt(double(src->width * src->width + src->height * src->height)) + 10;
	int tempX = (tempLength + 1) / 2 - src->width / 2;
	int tempY = (tempLength + 1) / 2 - src->height / 2;
	int flag = -1;

	dst = cvCreateImage(cvSize(width, height), src->depth, src->nChannels);
	cvZero(dst);
	IplImage* temp = cvCreateImage(cvSize(tempLength, tempLength), src->depth, src->nChannels);
	cvZero(temp);

	cvSetImageROI(temp, cvRect(tempX, tempY, src->width, src->height));
	cvCopy(src, temp, NULL);
	cvResetImageROI(temp);

	if (clockwise)
		flag = 1;

	float m[6];
	int w = temp->width;
	int h = temp->height;
	m[0] = (float) cos(flag * angle * CV_PI / 180.);
	m[1] = (float) sin(flag * angle * CV_PI / 180.);
	m[3] = -m[1];
	m[4] = m[0];
	// 将旋转中心移至图像中间
	m[2] = w * 0.5f;
	m[5] = h * 0.5f;
	//
	CvMat M = cvMat(2, 3, CV_32F, m);
	cvGetQuadrangleSubPix(temp, dst, &M);
	cvReleaseImage(&temp);
	return dst;
}