void cv::warpAffine()

in modules/imgproc/src/imgwarp.cpp [5571:5692]
111 lines of code
53 McCabe index (conditional complexity)

void cv::warpAffine( InputArray _src, OutputArray _dst,
                     InputArray _M0, Size dsize,
                     int flags, int borderType, const Scalar& borderValue )
{
    CV_OCL_RUN(_src.dims() <= 2 && _dst.isUMat(),
               ocl_warpTransform(_src, _dst, _M0, dsize, flags, borderType,
                                 borderValue, OCL_OP_AFFINE))

    Mat src = _src.getMat(), M0 = _M0.getMat();
    _dst.create( dsize.area() == 0 ? src.size() : dsize, src.type() );
    Mat dst = _dst.getMat();
    CV_Assert( src.cols > 0 && src.rows > 0 );
    if( dst.data == src.data )
        src = src.clone();

    double M[6];
    Mat matM(2, 3, CV_64F, M);
    int interpolation = flags & INTER_MAX;
    if( interpolation == INTER_AREA )
        interpolation = INTER_LINEAR;

    CV_Assert( (M0.type() == CV_32F || M0.type() == CV_64F) && M0.rows == 2 && M0.cols == 3 );
    M0.convertTo(matM, matM.type());

#ifdef HAVE_TEGRA_OPTIMIZATION
    if( tegra::useTegra() && tegra::warpAffine(src, dst, M, flags, borderType, borderValue) )
        return;
#endif

    if( !(flags & WARP_INVERSE_MAP) )
    {
        double D = M[0]*M[4] - M[1]*M[3];
        D = D != 0 ? 1./D : 0;
        double A11 = M[4]*D, A22=M[0]*D;
        M[0] = A11; M[1] *= -D;
        M[3] *= -D; M[4] = A22;
        double b1 = -M[0]*M[2] - M[1]*M[5];
        double b2 = -M[3]*M[2] - M[4]*M[5];
        M[2] = b1; M[5] = b2;
    }

    int x;
    AutoBuffer<int> _abdelta(dst.cols*2);
    int* adelta = &_abdelta[0], *bdelta = adelta + dst.cols;
    const int AB_BITS = MAX(10, (int)INTER_BITS);
    const int AB_SCALE = 1 << AB_BITS;

#if defined (HAVE_IPP) && IPP_VERSION_MAJOR * 100 + IPP_VERSION_MINOR >= 801 && 0
    CV_IPP_CHECK()
    {
        int type = src.type(), depth = CV_MAT_DEPTH(type), cn = CV_MAT_CN(type);
        if( ( depth == CV_8U || depth == CV_16U || depth == CV_32F ) &&
           ( cn == 1 || cn == 3 || cn == 4 ) &&
           ( interpolation == INTER_NEAREST || interpolation == INTER_LINEAR || interpolation == INTER_CUBIC) &&
           ( borderType == cv::BORDER_TRANSPARENT || borderType == cv::BORDER_CONSTANT) )
        {
            ippiWarpAffineBackFunc ippFunc = 0;
            if ((flags & WARP_INVERSE_MAP) != 0)
            {
                ippFunc =
                type == CV_8UC1 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_8u_C1R :
                type == CV_8UC3 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_8u_C3R :
                type == CV_8UC4 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_8u_C4R :
                type == CV_16UC1 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_16u_C1R :
                type == CV_16UC3 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_16u_C3R :
                type == CV_16UC4 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_16u_C4R :
                type == CV_32FC1 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_32f_C1R :
                type == CV_32FC3 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_32f_C3R :
                type == CV_32FC4 ? (ippiWarpAffineBackFunc)ippiWarpAffineBack_32f_C4R :
                0;
            }
            else
            {
                ippFunc =
                type == CV_8UC1 ? (ippiWarpAffineBackFunc)ippiWarpAffine_8u_C1R :
                type == CV_8UC3 ? (ippiWarpAffineBackFunc)ippiWarpAffine_8u_C3R :
                type == CV_8UC4 ? (ippiWarpAffineBackFunc)ippiWarpAffine_8u_C4R :
                type == CV_16UC1 ? (ippiWarpAffineBackFunc)ippiWarpAffine_16u_C1R :
                type == CV_16UC3 ? (ippiWarpAffineBackFunc)ippiWarpAffine_16u_C3R :
                type == CV_16UC4 ? (ippiWarpAffineBackFunc)ippiWarpAffine_16u_C4R :
                type == CV_32FC1 ? (ippiWarpAffineBackFunc)ippiWarpAffine_32f_C1R :
                type == CV_32FC3 ? (ippiWarpAffineBackFunc)ippiWarpAffine_32f_C3R :
                type == CV_32FC4 ? (ippiWarpAffineBackFunc)ippiWarpAffine_32f_C4R :
                0;
            }
            int mode =
            interpolation == INTER_LINEAR ? IPPI_INTER_LINEAR :
            interpolation == INTER_NEAREST ? IPPI_INTER_NN :
            interpolation == INTER_CUBIC ? IPPI_INTER_CUBIC :
            0;
            CV_Assert(mode && ippFunc);

            double coeffs[2][3];
            for( int i = 0; i < 2; i++ )
                for( int j = 0; j < 3; j++ )
                    coeffs[i][j] = matM.at<double>(i, j);

            bool ok;
            Range range(0, dst.rows);
            IPPWarpAffineInvoker invoker(src, dst, coeffs, mode, borderType, borderValue, ippFunc, &ok);
            parallel_for_(range, invoker, dst.total()/(double)(1<<16));
            if( ok )
            {
                CV_IMPL_ADD(CV_IMPL_IPP|CV_IMPL_MT);
                return;
            }
            setIppErrorStatus();
        }
    }
#endif

    for( x = 0; x < dst.cols; x++ )
    {
        adelta[x] = saturate_cast<int>(M[0]*x*AB_SCALE);
        bdelta[x] = saturate_cast<int>(M[3]*x*AB_SCALE);
    }

    Range range(0, dst.rows);
    WarpAffineInvoker invoker(src, dst, interpolation, borderType,
                              borderValue, adelta, bdelta, M);
    parallel_for_(range, invoker, dst.total()/(double)(1<<16));
}