OpenCV: rotate image(2)

Use Affin transform: cvWarpAffine()

#include "stdafx.h"
#include "cv.h"
#include "highgui.h"

int main( int argc, char** argv )
{
    IplImage* src;
    src = cvLoadImage("lena.jpg");
    IplImage* dst = cvCloneImage( src );
    int delta = 1;
    int angle = 0;
    
    cvNamedWindow( "src", 1 );
    cvShowImage( "src", src );

    for(;;)
    {
       float m[6];
       double factor = (cos(angle*CV_PI/180.) + 1.1)*3;
       CvMat M = cvMat( 2, 3, CV_32F, m );
       int w = src->width;
       int h = src->height;

       cv2DRotationMatrix( cvPoint2D32f(w*0.5f,h*0.5f), angle,
                           1./factor, &M );
       cvWarpAffine( src, dst, &M,
                     CV_INTER_LINEAR+CV_WARP_FILL_OUTLIERS, cvScalarAll(0));
       cvNamedWindow( "dst", 1 );
       cvShowImage( "dst", dst );
       if( cvWaitKey(5) == 27 )
                 break;
        angle = (angle + delta) % 360;
    }

    
    return 0;
}