imgproc/src/shapedescr.cpp

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#include "precomp.hpp"

namespace cv
{

static int intersectLines( double x1, double dx1, double y1, double dy1,
                          double x2, double dx2, double y2, double dy2, double *t2 )
{
    double d = dx1 * dy2 - dx2 * dy1;
    int result = -1;

    if( d != 0 )
    {
        *t2 = ((x2 - x1) * dy1 - (y2 - y1) * dx1) / d;
        result = 0;
    }
    return result;
}

static bool findCircle( Point2f pt0, Point2f pt1, Point2f pt2,
                       Point2f* center, float* radius )
{
    double x1 = (pt0.x + pt1.x) * 0.5;
    double dy1 = pt0.x - pt1.x;
    double x2 = (pt1.x + pt2.x) * 0.5;
    double dy2 = pt1.x - pt2.x;
    double y1 = (pt0.y + pt1.y) * 0.5;
    double dx1 = pt1.y - pt0.y;
    double y2 = (pt1.y + pt2.y) * 0.5;
    double dx2 = pt2.y - pt1.y;
    double t = 0;

    if( intersectLines( x1, dx1, y1, dy1, x2, dx2, y2, dy2, &t ) >= 0 )
    {
        center->x = (float) (x2 + dx2 * t);
        center->y = (float) (y2 + dy2 * t);
        *radius = (float)norm(*center - pt0);
        return true;
    }

    center->x = center->y = 0.f;
    *radius = 0;
    return false;
}


static double pointInCircle( Point2f pt, Point2f center, float radius )
{
    double dx = pt.x - center.x;
    double dy = pt.y - center.y;
    return (double)radius*radius - dx*dx - dy*dy;
}


static int findEnslosingCicle4pts_32f( Point2f* pts, Point2f& _center, float& _radius )
{
    int shuffles[4][4] = { {0, 1, 2, 3}, {0, 1, 3, 2}, {2, 3, 0, 1}, {2, 3, 1, 0} };

    int idxs[4] = { 0, 1, 2, 3 };
    int i, j, k = 1, mi = 0;
    float max_dist = 0;
    Point2f center;
    Point2f min_center;
    float radius, min_radius = FLT_MAX;
    Point2f res_pts[4];

    center = min_center = pts[0];
    radius = 1.f;

    for( i = 0; i < 4; i++ )
        for( j = i + 1; j < 4; j++ )
        {
            float dist = (float)norm(pts[i] - pts[j]);

            if( max_dist < dist )
            {
                max_dist = dist;
                idxs[0] = i;
                idxs[1] = j;
            }
        }

    if( max_dist > 0 )
    {
        k = 2;
        for( i = 0; i < 4; i++ )
        {
            for( j = 0; j < k; j++ )
                if( i == idxs[j] )
                    break;
            if( j == k )
                idxs[k++] = i;
        }

        center = Point2f( (pts[idxs[0]].x + pts[idxs[1]].x)*0.5f,
                          (pts[idxs[0]].y + pts[idxs[1]].y)*0.5f );
        radius = (float)(norm(pts[idxs[0]] - center)*1.03);
        if( radius < 1.f )
            radius = 1.f;

        if( pointInCircle( pts[idxs[2]], center, radius ) >= 0 &&
            pointInCircle( pts[idxs[3]], center, radius ) >= 0 )
        {
            k = 2; //rand()%2+2;
        }
        else
        {
            mi = -1;
            for( i = 0; i < 4; i++ )
            {
                if( findCircle( pts[shuffles[i][0]], pts[shuffles[i][1]],
                                pts[shuffles[i][2]], &center, &radius ) )
                {
                    radius *= 1.03f;
                    if( radius < 2.f )
                        radius = 2.f;

                    if( pointInCircle( pts[shuffles[i][3]], center, radius ) >= 0 &&
                        min_radius > radius )
                    {
                        min_radius = radius;
                        min_center = center;
                        mi = i;
                    }
                }
            }
            CV_Assert( mi >= 0 );
            if( mi < 0 )
                mi = 0;
            k = 3;
            center = min_center;
            radius = min_radius;
            for( i = 0; i < 4; i++ )
                idxs[i] = shuffles[mi][i];
        }
    }

    _center = center;
    _radius = radius;

    /* reorder output points */
    for( i = 0; i < 4; i++ )
        res_pts[i] = pts[idxs[i]];

    for( i = 0; i < 4; i++ )
    {
        pts[i] = res_pts[i];
        CV_Assert( pointInCircle( pts[i], center, radius ) >= 0 );
    }

    return k;
}

}

void cv::minEnclosingCircle( InputArray _points, Point2f& _center, float& _radius )
{
    int max_iters = 100;
    const float eps = FLT_EPSILON*2;
    bool result = false;
    Mat points = _points.getMat();
    int i, j, k, count = points.checkVector(2);
    int depth = points.depth();
    Point2f center;
    float radius = 0.f;
    CV_Assert(count >= 0 && (depth == CV_32F || depth == CV_32S));

    _center.x = _center.y = 0.f;
    _radius = 0.f;

    if( count == 0 )
        return;

    bool is_float = depth == CV_32F;
    const Point* ptsi = points.ptr<Point>();
    const Point2f* ptsf = points.ptr<Point2f>();

    Point2f pt = is_float ? ptsf[0] : Point2f((float)ptsi[0].x,(float)ptsi[0].y);
    Point2f pts[4] = {pt, pt, pt, pt};

    for( i = 1; i < count; i++ )
    {
        pt = is_float ? ptsf[i] : Point2f((float)ptsi[i].x, (float)ptsi[i].y);

        if( pt.x < pts[0].x )
            pts[0] = pt;
        if( pt.x > pts[1].x )
            pts[1] = pt;
        if( pt.y < pts[2].y )
            pts[2] = pt;
        if( pt.y > pts[3].y )
            pts[3] = pt;
    }

    for( k = 0; k < max_iters; k++ )
    {
        double min_delta = 0, delta;
        Point2f farAway(0,0);
        /*only for first iteration because the alg is repared at the loop's foot*/
        if( k == 0 )
            findEnslosingCicle4pts_32f( pts, center, radius );

        for( i = 0; i < count; i++ )
        {
            pt = is_float ? ptsf[i] : Point2f((float)ptsi[i].x,(float)ptsi[i].y);

            delta = pointInCircle( pt, center, radius );
            if( delta < min_delta )
            {
                min_delta = delta;
                farAway = pt;
            }
        }
        result = min_delta >= 0;
        if( result )
            break;

        Point2f ptsCopy[4];
        // find good replacement partner for the point which is at most far away,
        // starting with the one that lays in the actual circle (i=3)
        for( i = 3; i >= 0; i-- )
        {
            for( j = 0; j < 4; j++ )
                ptsCopy[j] = i != j ? pts[j] : farAway;

            findEnslosingCicle4pts_32f( ptsCopy, center, radius );
            if( pointInCircle( pts[i], center, radius ) >= 0)
            {
                // replaced one again in the new circle?
                pts[i] = farAway;
                break;
            }
        }
    }

    if( !result )
    {
        radius = 0.f;
        for( i = 0; i < count; i++ )
        {
            pt = is_float ? ptsf[i] : Point2f((float)ptsi[i].x,(float)ptsi[i].y);
            float dx = center.x - pt.x, dy = center.y - pt.y;
            float t = dx*dx + dy*dy;
            radius = MAX(radius, t);
        }

        radius = (float)(std::sqrt(radius)*(1 + eps));
    }

    _center = center;
    _radius = radius;
}


// calculates length of a curve (e.g. contour perimeter)
double cv::arcLength( InputArray _curve, bool is_closed )
{
    Mat curve = _curve.getMat();
    int count = curve.checkVector(2);
    int depth = curve.depth();
    CV_Assert( count >= 0 && (depth == CV_32F || depth == CV_32S));
    double perimeter = 0;

    int i, j = 0;
    const int N = 16;
    float buf[N];

    if( count <= 1 )
        return 0.;

    bool is_float = depth == CV_32F;
    int last = is_closed ? count-1 : 0;
    const Point* pti = curve.ptr<Point>();
    const Point2f* ptf = curve.ptr<Point2f>();

    Point2f prev = is_float ? ptf[last] : Point2f((float)pti[last].x,(float)pti[last].y);

    for( i = 0; i < count; i++ )
    {
        Point2f p = is_float ? ptf[i] : Point2f((float)pti[i].x,(float)pti[i].y);
        float dx = p.x - prev.x, dy = p.y - prev.y;
        buf[j] = dx*dx + dy*dy;

        if( ++j == N || i == count-1 )
        {
            Mat bufmat(1, j, CV_32F, buf);
            sqrt(bufmat, bufmat);
            for( ; j > 0; j-- )
                perimeter += buf[j-1];
        }
        prev = p;
    }

    return perimeter;
}

// area of a whole sequence
double cv::contourArea( InputArray _contour, bool oriented )
{
    Mat contour = _contour.getMat();
    int npoints = contour.checkVector(2);
    int depth = contour.depth();
    CV_Assert(npoints >= 0 && (depth == CV_32F || depth == CV_32S));

    if( npoints == 0 )
        return 0.;

    double a00 = 0;
    bool is_float = depth == CV_32F;
    const Point* ptsi = contour.ptr<Point>();
    const Point2f* ptsf = contour.ptr<Point2f>();
    Point2f prev = is_float ? ptsf[npoints-1] : Point2f((float)ptsi[npoints-1].x, (float)ptsi[npoints-1].y);

    for( int i = 0; i < npoints; i++ )
    {
        Point2f p = is_float ? ptsf[i] : Point2f((float)ptsi[i].x, (float)ptsi[i].y);
        a00 += (double)prev.x * p.y - (double)prev.y * p.x;
        prev = p;
    }

    a00 *= 0.5;
    if( !oriented )
        a00 = fabs(a00);

    return a00;
}


cv::RotatedRect cv::fitEllipse( InputArray _points )
{
    Mat points = _points.getMat();
    int i, n = points.checkVector(2);
    int depth = points.depth();
    CV_Assert( n >= 0 && (depth == CV_32F || depth == CV_32S));

    RotatedRect box;

    if( n < 5 )
        CV_Error( CV_StsBadSize, "There should be at least 5 points to fit the ellipse" );

    // New fitellipse algorithm, contributed by Dr. Daniel Weiss
    Point2f c(0,0);
    double gfp[5], rp[5], t;
    const double min_eps = 1e-8;
    bool is_float = depth == CV_32F;
    const Point* ptsi = points.ptr<Point>();
    const Point2f* ptsf = points.ptr<Point2f>();

    AutoBuffer<double> _Ad(n*5), _bd(n);
    double *Ad = _Ad, *bd = _bd;

    // first fit for parameters A - E
    Mat A( n, 5, CV_64F, Ad );
    Mat b( n, 1, CV_64F, bd );
    Mat x( 5, 1, CV_64F, gfp );

    for( i = 0; i < n; i++ )
    {
        Point2f p = is_float ? ptsf[i] : Point2f((float)ptsi[i].x, (float)ptsi[i].y);
        c += p;
    }
    c.x /= n;
    c.y /= n;

    for( i = 0; i < n; i++ )
    {
        Point2f p = is_float ? ptsf[i] : Point2f((float)ptsi[i].x, (float)ptsi[i].y);
        p -= c;

        bd[i] = 10000.0; // 1.0?
        Ad[i*5] = -(double)p.x * p.x; // A - C signs inverted as proposed by APP
        Ad[i*5 + 1] = -(double)p.y * p.y;
        Ad[i*5 + 2] = -(double)p.x * p.y;
        Ad[i*5 + 3] = p.x;
        Ad[i*5 + 4] = p.y;
    }

    solve(A, b, x, DECOMP_SVD);

    // now use general-form parameters A - E to find the ellipse center:
    // differentiate general form wrt x/y to get two equations for cx and cy
    A = Mat( 2, 2, CV_64F, Ad );
    b = Mat( 2, 1, CV_64F, bd );
    x = Mat( 2, 1, CV_64F, rp );
    Ad[0] = 2 * gfp[0];
    Ad[1] = Ad[2] = gfp[2];
    Ad[3] = 2 * gfp[1];
    bd[0] = gfp[3];
    bd[1] = gfp[4];
    solve( A, b, x, DECOMP_SVD );

    // re-fit for parameters A - C with those center coordinates
    A = Mat( n, 3, CV_64F, Ad );
    b = Mat( n, 1, CV_64F, bd );
    x = Mat( 3, 1, CV_64F, gfp );
    for( i = 0; i < n; i++ )
    {
        Point2f p = is_float ? ptsf[i] : Point2f((float)ptsi[i].x, (float)ptsi[i].y);
        p -= c;
        bd[i] = 1.0;
        Ad[i * 3] = (p.x - rp[0]) * (p.x - rp[0]);
        Ad[i * 3 + 1] = (p.y - rp[1]) * (p.y - rp[1]);
        Ad[i * 3 + 2] = (p.x - rp[0]) * (p.y - rp[1]);
    }
    solve(A, b, x, DECOMP_SVD);

    // store angle and radii
    rp[4] = -0.5 * atan2(gfp[2], gfp[1] - gfp[0]); // convert from APP angle usage
    if( fabs(gfp[2]) > min_eps )
        t = gfp[2]/sin(-2.0 * rp[4]);
    else // ellipse is rotated by an integer multiple of pi/2
        t = gfp[1] - gfp[0];
    rp[2] = fabs(gfp[0] + gfp[1] - t);
    if( rp[2] > min_eps )
        rp[2] = std::sqrt(2.0 / rp[2]);
    rp[3] = fabs(gfp[0] + gfp[1] + t);
    if( rp[3] > min_eps )
        rp[3] = std::sqrt(2.0 / rp[3]);

    box.center.x = (float)rp[0] + c.x;
    box.center.y = (float)rp[1] + c.y;
    box.size.width = (float)(rp[2]*2);
    box.size.height = (float)(rp[3]*2);
    if( box.size.width > box.size.height )
    {
        float tmp;
        CV_SWAP( box.size.width, box.size.height, tmp );
        box.angle = (float)(90 + rp[4]*180/CV_PI);
    }
    if( box.angle < -180 )
        box.angle += 360;
    if( box.angle > 360 )
        box.angle -= 360;

    return box;
}


namespace cv
{

// Calculates bounding rectagnle of a point set or retrieves already calculated
static Rect pointSetBoundingRect( const Mat& points )
{
    int npoints = points.checkVector(2);
    int depth = points.depth();
    CV_Assert(npoints >= 0 && (depth == CV_32F || depth == CV_32S));

    int  xmin = 0, ymin = 0, xmax = -1, ymax = -1, i;
    bool is_float = depth == CV_32F;

    if( npoints == 0 )
        return Rect();

    const Point* pts = points.ptr<Point>();
    Point pt = pts[0];

#if CV_SSE4_2
    if(cv::checkHardwareSupport(CV_CPU_SSE4_2))
    {
        if( !is_float )
        {
            __m128i minval, maxval;
            minval = maxval = _mm_loadl_epi64((const __m128i*)(&pt)); //min[0]=pt.x, min[1]=pt.y

            for( i = 1; i < npoints; i++ )
            {
                __m128i ptXY = _mm_loadl_epi64((const __m128i*)&pts[i]);
                minval = _mm_min_epi32(ptXY, minval);
                maxval = _mm_max_epi32(ptXY, maxval);
            }
            xmin = _mm_cvtsi128_si32(minval);
            ymin = _mm_cvtsi128_si32(_mm_srli_si128(minval, 4));
            xmax = _mm_cvtsi128_si32(maxval);
            ymax = _mm_cvtsi128_si32(_mm_srli_si128(maxval, 4));
        }
        else
        {
            __m128 minvalf, maxvalf, z = _mm_setzero_ps(), ptXY = _mm_setzero_ps();
            minvalf = maxvalf = _mm_loadl_pi(z, (const __m64*)(&pt));

            for( i = 1; i < npoints; i++ )
            {
                ptXY = _mm_loadl_pi(ptXY, (const __m64*)&pts[i]);

                minvalf = _mm_min_ps(minvalf, ptXY);
                maxvalf = _mm_max_ps(maxvalf, ptXY);
            }

            float xyminf[2], xymaxf[2];
            _mm_storel_pi((__m64*)xyminf, minvalf);
            _mm_storel_pi((__m64*)xymaxf, maxvalf);
            xmin = cvFloor(xyminf[0]);
            ymin = cvFloor(xyminf[1]);
            xmax = cvFloor(xymaxf[0]);
            ymax = cvFloor(xymaxf[1]);
        }
    }
    else
#endif
    {
        if( !is_float )
        {
            xmin = xmax = pt.x;
            ymin = ymax = pt.y;

            for( i = 1; i < npoints; i++ )
            {
                pt = pts[i];

                if( xmin > pt.x )
                    xmin = pt.x;

                if( xmax < pt.x )
                    xmax = pt.x;

                if( ymin > pt.y )
                    ymin = pt.y;

                if( ymax < pt.y )
                    ymax = pt.y;
            }
        }
        else
        {
            Cv32suf v;
            // init values
            xmin = xmax = CV_TOGGLE_FLT(pt.x);
            ymin = ymax = CV_TOGGLE_FLT(pt.y);

            for( i = 1; i < npoints; i++ )
            {
                pt = pts[i];
                pt.x = CV_TOGGLE_FLT(pt.x);
                pt.y = CV_TOGGLE_FLT(pt.y);

                if( xmin > pt.x )
                    xmin = pt.x;

                if( xmax < pt.x )
                    xmax = pt.x;

                if( ymin > pt.y )
                    ymin = pt.y;

                if( ymax < pt.y )
                    ymax = pt.y;
            }

            v.i = CV_TOGGLE_FLT(xmin); xmin = cvFloor(v.f);
            v.i = CV_TOGGLE_FLT(ymin); ymin = cvFloor(v.f);
            // because right and bottom sides of the bounding rectangle are not inclusive
            // (note +1 in width and height calculation below), cvFloor is used here instead of cvCeil
            v.i = CV_TOGGLE_FLT(xmax); xmax = cvFloor(v.f);
            v.i = CV_TOGGLE_FLT(ymax); ymax = cvFloor(v.f);
        }
    }

    return Rect(xmin, ymin, xmax - xmin + 1, ymax - ymin + 1);
}


static Rect maskBoundingRect( const Mat& img )
{
    CV_Assert( img.depth() <= CV_8S && img.channels() == 1 );

    Size size = img.size();
    int xmin = size.width, ymin = -1, xmax = -1, ymax = -1, i, j, k;

    for( i = 0; i < size.height; i++ )
    {
        const uchar* _ptr = img.ptr(i);
        const uchar* ptr = (const uchar*)alignPtr(_ptr, 4);
        int have_nz = 0, k_min, offset = (int)(ptr - _ptr);
        j = 0;
        offset = MIN(offset, size.width);
        for( ; j < offset; j++ )
            if( _ptr[j] )
            {
                have_nz = 1;
                break;
            }
        if( j < offset )
        {
            if( j < xmin )
                xmin = j;
            if( j > xmax )
                xmax = j;
        }
        if( offset < size.width )
        {
            xmin -= offset;
            xmax -= offset;
            size.width -= offset;
            j = 0;
            for( ; j <= xmin - 4; j += 4 )
                if( *((int*)(ptr+j)) )
                    break;
            for( ; j < xmin; j++ )
                if( ptr[j] )
                {
                    xmin = j;
                    if( j > xmax )
                        xmax = j;
                    have_nz = 1;
                    break;
                }
            k_min = MAX(j-1, xmax);
            k = size.width - 1;
            for( ; k > k_min && (k&3) != 3; k-- )
                if( ptr[k] )
                    break;
            if( k > k_min && (k&3) == 3 )
            {
                for( ; k > k_min+3; k -= 4 )
                    if( *((int*)(ptr+k-3)) )
                        break;
            }
            for( ; k > k_min; k-- )
                if( ptr[k] )
                {
                    xmax = k;
                    have_nz = 1;
                    break;
                }
            if( !have_nz )
            {
                j &= ~3;
                for( ; j <= k - 3; j += 4 )
                    if( *((int*)(ptr+j)) )
                        break;
                for( ; j <= k; j++ )
                    if( ptr[j] )
                    {
                        have_nz = 1;
                        break;
                    }
            }
            xmin += offset;
            xmax += offset;
            size.width += offset;
        }
        if( have_nz )
        {
            if( ymin < 0 )
                ymin = i;
            ymax = i;
        }
    }

    if( xmin >= size.width )
        xmin = ymin = 0;
    return Rect(xmin, ymin, xmax - xmin + 1, ymax - ymin + 1);
}

}

cv::Rect cv::boundingRect(InputArray array)
{
    Mat m = array.getMat();
    return m.depth() <= CV_8U ? maskBoundingRect(m) : pointSetBoundingRect(m);
}

////////////////////////////////////////////// C API ///////////////////////////////////////////

CV_IMPL int
cvMinEnclosingCircle( const void* array, CvPoint2D32f * _center, float *_radius )
{
    cv::AutoBuffer<double> abuf;
    cv::Mat points = cv::cvarrToMat(array, false, false, 0, &abuf);
    cv::Point2f center;
    float radius;

    cv::minEnclosingCircle(points, center, radius);
    if(_center)
        *_center = center;
    if(_radius)
        *_radius = radius;
    return 1;
}

static void
icvMemCopy( double **buf1, double **buf2, double **buf3, int *b_max )
{
    CV_Assert( (*buf1 != NULL || *buf2 != NULL) && *buf3 != NULL );

    int bb = *b_max;
    if( *buf2 == NULL )
    {
        *b_max = 2 * (*b_max);
        *buf2 = (double *)cvAlloc( (*b_max) * sizeof( double ));

        memcpy( *buf2, *buf3, bb * sizeof( double ));

        *buf3 = *buf2;
        cvFree( buf1 );
        *buf1 = NULL;
    }
    else
    {
        *b_max = 2 * (*b_max);
        *buf1 = (double *) cvAlloc( (*b_max) * sizeof( double ));

        memcpy( *buf1, *buf3, bb * sizeof( double ));

        *buf3 = *buf1;
        cvFree( buf2 );
        *buf2 = NULL;
    }
}


/* area of a contour sector */
static double icvContourSecArea( CvSeq * contour, CvSlice slice )
{
    CvPoint pt;                 /*  pointer to points   */
    CvPoint pt_s, pt_e;         /*  first and last points  */
    CvSeqReader reader;         /*  points reader of contour   */

    int p_max = 2, p_ind;
    int lpt, flag, i;
    double a00;                 /* unnormalized moments m00    */
    double xi, yi, xi_1, yi_1, x0, y0, dxy, sk, sk1, t;
    double x_s, y_s, nx, ny, dx, dy, du, dv;
    double eps = 1.e-5;
    double *p_are1, *p_are2, *p_are;
    double area = 0;

    CV_Assert( contour != NULL && CV_IS_SEQ_POINT_SET( contour ));

    lpt = cvSliceLength( slice, contour );
    /*if( n2 >= n1 )
        lpt = n2 - n1 + 1;
    else
        lpt = contour->total - n1 + n2 + 1;*/

    if( contour->total <= 0 || lpt <= 2 )
        return 0.;

    a00 = x0 = y0 = xi_1 = yi_1 = 0;
    sk1 = 0;
    flag = 0;
    dxy = 0;
    p_are1 = (double *) cvAlloc( p_max * sizeof( double ));

    p_are = p_are1;
    p_are2 = NULL;

    cvStartReadSeq( contour, &reader, 0 );
    cvSetSeqReaderPos( &reader, slice.start_index );
    CV_READ_SEQ_ELEM( pt_s, reader );
    p_ind = 0;
    cvSetSeqReaderPos( &reader, slice.end_index );
    CV_READ_SEQ_ELEM( pt_e, reader );

/*    normal coefficients    */
    nx = pt_s.y - pt_e.y;
    ny = pt_e.x - pt_s.x;
    cvSetSeqReaderPos( &reader, slice.start_index );

    while( lpt-- > 0 )
    {
        CV_READ_SEQ_ELEM( pt, reader );

        if( flag == 0 )
        {
            xi_1 = (double) pt.x;
            yi_1 = (double) pt.y;
            x0 = xi_1;
            y0 = yi_1;
            sk1 = 0;
            flag = 1;
        }
        else
        {
            xi = (double) pt.x;
            yi = (double) pt.y;

/****************   edges intersection examination   **************************/
            sk = nx * (xi - pt_s.x) + ny * (yi - pt_s.y);
            if( (fabs( sk ) < eps && lpt > 0) || sk * sk1 < -eps )
            {
                if( fabs( sk ) < eps )
                {
                    dxy = xi_1 * yi - xi * yi_1;
                    a00 = a00 + dxy;
                    dxy = xi * y0 - x0 * yi;
                    a00 = a00 + dxy;

                    if( p_ind >= p_max )
                        icvMemCopy( &p_are1, &p_are2, &p_are, &p_max );

                    p_are[p_ind] = a00 / 2.;
                    p_ind++;
                    a00 = 0;
                    sk1 = 0;
                    x0 = xi;
                    y0 = yi;
                    dxy = 0;
                }
                else
                {
/*  define intersection point    */
                    dv = yi - yi_1;
                    du = xi - xi_1;
                    dx = ny;
                    dy = -nx;
                    if( fabs( du ) > eps )
                        t = ((yi_1 - pt_s.y) * du + dv * (pt_s.x - xi_1)) /
                            (du * dy - dx * dv);
                    else
                        t = (xi_1 - pt_s.x) / dx;
                    if( t > eps && t < 1 - eps )
                    {
                        x_s = pt_s.x + t * dx;
                        y_s = pt_s.y + t * dy;
                        dxy = xi_1 * y_s - x_s * yi_1;
                        a00 += dxy;
                        dxy = x_s * y0 - x0 * y_s;
                        a00 += dxy;
                        if( p_ind >= p_max )
                            icvMemCopy( &p_are1, &p_are2, &p_are, &p_max );

                        p_are[p_ind] = a00 / 2.;
                        p_ind++;

                        a00 = 0;
                        sk1 = 0;
                        x0 = x_s;
                        y0 = y_s;
                        dxy = x_s * yi - xi * y_s;
                    }
                }
            }
            else
                dxy = xi_1 * yi - xi * yi_1;

            a00 += dxy;
            xi_1 = xi;
            yi_1 = yi;
            sk1 = sk;

        }
    }

    xi = x0;
    yi = y0;
    dxy = xi_1 * yi - xi * yi_1;

    a00 += dxy;

    if( p_ind >= p_max )
        icvMemCopy( &p_are1, &p_are2, &p_are, &p_max );

    p_are[p_ind] = a00 / 2.;
    p_ind++;

    // common area calculation
    area = 0;
    for( i = 0; i < p_ind; i++ )
        area += fabs( p_are[i] );

    if( p_are1 != NULL )
        cvFree( &p_are1 );
    else if( p_are2 != NULL )
        cvFree( &p_are2 );

    return area;
}


/* external contour area function */
CV_IMPL double
cvContourArea( const void *array, CvSlice slice, int oriented )
{
    double area = 0;

    CvContour contour_header;
    CvSeq* contour = 0;
    CvSeqBlock block;

    if( CV_IS_SEQ( array ))
    {
        contour = (CvSeq*)array;
        if( !CV_IS_SEQ_POLYLINE( contour ))
            CV_Error( CV_StsBadArg, "Unsupported sequence type" );
    }
    else
    {
        contour = cvPointSeqFromMat( CV_SEQ_KIND_CURVE, array, &contour_header, &block );
    }

    if( cvSliceLength( slice, contour ) == contour->total )
    {
        cv::AutoBuffer<double> abuf;
        cv::Mat points = cv::cvarrToMat(contour, false, false, 0, &abuf);
        return cv::contourArea( points, oriented !=0 );
    }

    if( CV_SEQ_ELTYPE( contour ) != CV_32SC2 )
        CV_Error( CV_StsUnsupportedFormat,
        "Only curves with integer coordinates are supported in case of contour slice" );
    area = icvContourSecArea( contour, slice );
    return oriented ? area : fabs(area);
}


/* calculates length of a curve (e.g. contour perimeter) */
CV_IMPL  double
cvArcLength( const void *array, CvSlice slice, int is_closed )
{
    double perimeter = 0;

    int i, j = 0, count;
    const int N = 16;
    float buf[N];
    CvMat buffer = cvMat( 1, N, CV_32F, buf );
    CvSeqReader reader;
    CvContour contour_header;
    CvSeq* contour = 0;
    CvSeqBlock block;

    if( CV_IS_SEQ( array ))
    {
        contour = (CvSeq*)array;
        if( !CV_IS_SEQ_POLYLINE( contour ))
            CV_Error( CV_StsBadArg, "Unsupported sequence type" );
        if( is_closed < 0 )
            is_closed = CV_IS_SEQ_CLOSED( contour );
    }
    else
    {
        is_closed = is_closed > 0;
        contour = cvPointSeqFromMat(
                                    CV_SEQ_KIND_CURVE | (is_closed ? CV_SEQ_FLAG_CLOSED : 0),
                                    array, &contour_header, &block );
    }

    if( contour->total > 1 )
    {
        int is_float = CV_SEQ_ELTYPE( contour ) == CV_32FC2;

        cvStartReadSeq( contour, &reader, 0 );
        cvSetSeqReaderPos( &reader, slice.start_index );
        count = cvSliceLength( slice, contour );

        count -= !is_closed && count == contour->total;

        // scroll the reader by 1 point
        reader.prev_elem = reader.ptr;
        CV_NEXT_SEQ_ELEM( sizeof(CvPoint), reader );

        for( i = 0; i < count; i++ )
        {
            float dx, dy;

            if( !is_float )
            {
                CvPoint* pt = (CvPoint*)reader.ptr;
                CvPoint* prev_pt = (CvPoint*)reader.prev_elem;

                dx = (float)pt->x - (float)prev_pt->x;
                dy = (float)pt->y - (float)prev_pt->y;
            }
            else
            {
                CvPoint2D32f* pt = (CvPoint2D32f*)reader.ptr;
                CvPoint2D32f* prev_pt = (CvPoint2D32f*)reader.prev_elem;

                dx = pt->x - prev_pt->x;
                dy = pt->y - prev_pt->y;
            }

            reader.prev_elem = reader.ptr;
            CV_NEXT_SEQ_ELEM( contour->elem_size, reader );
            // Bugfix by Axel at rubico.com 2010-03-22, affects closed slices only
            // wraparound not handled by CV_NEXT_SEQ_ELEM
            if( is_closed && i == count - 2 )
                cvSetSeqReaderPos( &reader, slice.start_index );

            buffer.data.fl[j] = dx * dx + dy * dy;
            if( ++j == N || i == count - 1 )
            {
                buffer.cols = j;
                cvPow( &buffer, &buffer, 0.5 );
                for( ; j > 0; j-- )
                    perimeter += buffer.data.fl[j-1];
            }
        }
    }

    return perimeter;
}


CV_IMPL CvBox2D
cvFitEllipse2( const CvArr* array )
{
    cv::AutoBuffer<double> abuf;
    cv::Mat points = cv::cvarrToMat(array, false, false, 0, &abuf);
    return cv::fitEllipse(points);
}

/* Calculates bounding rectagnle of a point set or retrieves already calculated */
CV_IMPL  CvRect
cvBoundingRect( CvArr* array, int update )
{
    CvRect  rect;
    CvContour contour_header;
    CvSeq* ptseq = 0;
    CvSeqBlock block;

    CvMat stub, *mat = 0;
    int calculate = update;

    if( CV_IS_SEQ( array ))
    {
        ptseq = (CvSeq*)array;
        if( !CV_IS_SEQ_POINT_SET( ptseq ))
            CV_Error( CV_StsBadArg, "Unsupported sequence type" );

        if( ptseq->header_size < (int)sizeof(CvContour))
        {
            update = 0;
            calculate = 1;
        }
    }
    else
    {
        mat = cvGetMat( array, &stub );
        if( CV_MAT_TYPE(mat->type) == CV_32SC2 ||
            CV_MAT_TYPE(mat->type) == CV_32FC2 )
        {
            ptseq = cvPointSeqFromMat(CV_SEQ_KIND_GENERIC, mat, &contour_header, &block);
            mat = 0;
        }
        else if( CV_MAT_TYPE(mat->type) != CV_8UC1 &&
                CV_MAT_TYPE(mat->type) != CV_8SC1 )
            CV_Error( CV_StsUnsupportedFormat,
                "The image/matrix format is not supported by the function" );
        update = 0;
        calculate = 1;
    }

    if( !calculate )
        return ((CvContour*)ptseq)->rect;

    if( mat )
    {
        rect = cv::maskBoundingRect(cv::cvarrToMat(mat));
    }
    else if( ptseq->total )
    {
        cv::AutoBuffer<double> abuf;
        rect = cv::pointSetBoundingRect(cv::cvarrToMat(ptseq, false, false, 0, &abuf));
    }
    if( update )
        ((CvContour*)ptseq)->rect = rect;
    return rect;
}


/* End of file. */