Function cvPtr2D

deps/opencv/modules/core/src/array.cpp:1743–1834

Returns pointer to specified element of 2d array

// Returns pointer to specified element of 2d array
CV_IMPL  uchar*
cvPtr2D( const CvArr* arr, int y, int x, int* _type )
{
    uchar* ptr = 0;
    if( CV_IS_MAT( arr ))
    {
        CvMat* mat = (CvMat*)arr;
        int type;

        if( (unsigned)y >= (unsigned)(mat->rows) ||
            (unsigned)x >= (unsigned)(mat->cols) )
            CV_Error( CV_StsOutOfRange, "index is out of range" );

        type = CV_MAT_TYPE(mat->type);
        if( _type )
            *_type = type;

        ptr = mat->data.ptr + (size_t)y*mat->step + x*CV_ELEM_SIZE(type);
    }
    else if( CV_IS_IMAGE( arr ))
    {
        IplImage* img = (IplImage*)arr;
        int pix_size = (img->depth & 255) >> 3;
        int width, height;
        ptr = (uchar*)img->imageData;

        if( img->dataOrder == 0 )
            pix_size *= img->nChannels;

        if( img->roi )
        {
            width = img->roi->width;
            height = img->roi->height;

            ptr += img->roi->yOffset*img->widthStep +
                   img->roi->xOffset*pix_size;

            if( img->dataOrder )
            {
                int coi = img->roi->coi;
                if( !coi )
                    CV_Error( CV_BadCOI,
                        "COI must be non-null in case of planar images" );
                ptr += (coi - 1)*img->imageSize;
            }
        }
        else
        {
            width = img->width;
            height = img->height;
        }

        if( (unsigned)y >= (unsigned)height ||
            (unsigned)x >= (unsigned)width )
            CV_Error( CV_StsOutOfRange, "index is out of range" );

        ptr += y*img->widthStep + x*pix_size;