_boxblur.h

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/* === S T A R T =========================================================== */

#ifndef __ETL__BOXBLUR_H
#define __ETL__BOXBLUR_H

/* === H E A D E R S ======================================================= */

/* === M A C R O S ========================================================= */

/* === T Y P E D E F S ===================================================== */

/* === C L A S S E S & S T R U C T S ======================================= */

_ETL_BEGIN_NAMESPACE

template<typename T1,typename T2> void
hbox_blur(T1 pen,int w, int h, int length, T2 outpen)
{
    int x,y;
    typename T1::iterator_x iter, end;

    length=std::min(w,length);
    const float divisor(1.0f/(length*2+1));

    for(y=0;y<h;y++,pen.inc_y(),outpen.inc_y())
    {
        iter=pen.x();
        end=pen.end_x();

        typename T1::accumulator_type tot((typename T1::accumulator_type)(*iter)*(length+1));

        for (x=0;x<length && iter!=end;x++,++iter) tot+=*iter;
        iter=pen.x();

        for (x=0;x<w && iter!=end;x++,++iter,outpen.inc_x())
        {
            tot -= (x>length) ?
                (typename T1::accumulator_type)(iter[-length-1]) :
                (typename T1::accumulator_type)(*pen.x());
            tot += ((x+length)<w) ?
                (typename T1::accumulator_type)(iter[length]) :
                (typename T1::accumulator_type)(end[-1]);
                                      
            outpen.put_value((typename T2::value_type)(tot*divisor));
        }
        outpen.dec_x(x);
    }
}

#if 1
template<typename T1,typename T2> void
vbox_blur(T1 pen,const int w, const int h, int length, T2 outpen)
{
    int x,y;
    typename T1::iterator_y iter, end;

    length=std::min(h,length);
    const float divisor(1.0f/(length*2+1));

    for(x=0;x<w;x++,pen.inc_x(),outpen.inc_x())
    {
        iter=pen.y();
        end=pen.end_y();

        typename T1::accumulator_type tot((typename T1::accumulator_type)(*iter)*(length+1));

        for (y=0;y<length && iter!=end;y++,++iter) tot+=*iter;
        iter=pen.y();

        for (y=0;y<h && iter!=end;y++,++iter,outpen.inc_y())
        {
            tot -= (y>length) ?
            (typename T1::accumulator_type)(iter[-length-1]) :
            (typename T1::accumulator_type)(*pen.y());
            tot += ((y+length)<h) ?
            (typename T1::accumulator_type)(iter[length]) :
            (typename T1::accumulator_type)(end[-1]);

            outpen.put_value((typename T2::value_type)(tot*divisor));
        }
        outpen.dec_y(y);
    }
}

#else

template<typename T1,typename T2> void
vbox_blur(T1 pen,int w, int h, int length,T2 outpen)
{
    int x,y;
    typename T1::iterator_y iter, end, biter,eiter;

    //print out the info I need to figure out if this is somehow a buffer overrun...
    /*char *beginptr=0,*endptr=0;
    {
        T1 ypen = pen;
        T1 endpen = pen;
        endpen.move(w,h);
        ypen.inc_y();

        T2  open = outpen,
            oepen = outpen;
        oepen.move(w,h);
        printf("V Blur (%d,%d,s-%d) in(%p,%p,st %d) out(%p,%p)\n",
                w,h,length,(char*)pen.x(),(char*)endpen.x(),(char*)ypen.x()-(char*)pen.x(),
                (char*)open.x(),(char*)oepen.x());
    }*/
    length=min(h-1,length);

    const float divisor(1.0f/(length*2+1));
    //const int div = (length*2+1);

    //since the filter range is 2*length+1 we need h-1
    for(x=0;x<w;x++,pen.inc_x(),outpen.inc_x())
    {
        iter=pen.y();
        end=pen.end_y();

        const typename T1::value_type bval = *iter;
        const typename T1::value_type eval = end[-1];

        typename T1::accumulator_type tot(bval*(length+1));
        //beginptr = (char*)&*iter; endptr = (char*)&*end;

        //printf("\nx line %d (%p,%p)\n",x,beginptr,endptr);

        //printf("Init %.3f - ",tot);
        for (y=0;y<length && iter!=end;y++)
        {
            tot+=iter[y];
            //printf("(%d,%p,+%.3f->%.3f),",y,&iter[y],iter[y],tot);
        }
        iter=pen.y();

        //printf(" tot=%.3f\n",tot);

        biter = iter+(-length-1); //get the first one...
        eiter = iter+length;

        //y will always be > length
        //T2 open = outpen;
        for (y=0;y<h && iter!=end;y++,++iter,++biter,++eiter,outpen.inc_y())
        {
            //printf("y line %d - (%f) ",y,tot);

            if (y>length)
            {
                typename T1::value_type &v = *biter;
                /*if( (char*)&v < beginptr ||
                    (char*)&v >= endptr)
                    printf("crap! %d (%p off %p)\n",y,(char*)&v,(char*)&*iter);*/
                tot -= v;
                //printf("[%.3f,",v);
            }
            else
            {
                tot -= bval;
                //printf("[%.3f,",bval);
            }

            if (y+length<h)
            {
                typename T1::value_type &v = *eiter;
                /*if( (char*)&v < beginptr ||
                    (char*)&v >= endptr)
                    printf("crap! %d (%p off %p)\n",y,(char*)&v,(char*)&*iter);*/
                tot += v;
                //printf("%.3f]",v);
            }
            else
            {
                tot += eval;
                //printf("%.3f]",eval);
            }

            //test handled in the previous case...
            //tot -= (y>length) ? *biter : bval;
            //tot += (y+length<h) ? *eiter : eval;

            //printf(" - %.3f\n",tot);
            outpen.put_value(tot*divisor);
        }
        outpen.dec_y(y);
    }
}
#endif

template<typename T1,typename T2> void
box_blur(T1 pen,int w, int h, int blur_w, int blur_h, T2 outpen)
    { hbox_blur(pen,w,h,blur_w,outpen); vbox_blur(pen,w,h,blur_h,outpen); }

template<typename T1,typename T2> void
box_blur(T1 pen,int w, int h, int size, T2 outpen)
    { hbox_blur(pen,w,h,size,outpen); vbox_blur(pen,w,h,size,outpen); }

template<typename T1,typename T2> void
hbox_blur(T1 begin,T1 end, int len,T2 outpen)
{
    typename T1::difference_type size(end-begin);
    hbox_blur(begin,size.x,size.y,len,outpen);
}

template<typename T1,typename T2> void
vbox_blur(T1 begin,T1 end, int len,T2 outpen)
{
    typename T1::difference_type size(end-begin);
    vbox_blur(begin,size.x,size.y,len,outpen);
}

template<typename T1,typename T2> void
box_blur(T1 begin,T1 end, int blur_w, int blur_h,T2 outpen)
{
    typename T1::difference_type size(end-begin);
    hbox_blur(begin,size.x,size.y,blur_w,outpen); vbox_blur(begin,size.x,size.y,blur_h,outpen);
}

template<typename T1,typename T2> void
box_blur(T1 begin,T1 end, int blursize,T2 outpen)
{
    typename T1::difference_type size(end-begin);
    hbox_blur(begin,size.x,size.y,blursize,outpen); vbox_blur(begin,size.x,size.y,blursize,outpen);
}

_ETL_END_NAMESPACE

/* === E X T E R N S ======================================================= */

/* === E N D =============================================================== */

#endif