postgres/src/backend/access/rtree/rtproc.c

/*-------------------------------------------------------------------------
 *
 * rtproc.c--
 *    pg_amproc entries for rtrees.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/access/rtree/Attic/rtproc.c,v 1.7 1997/04/22 17:31:23 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */

#include <postgres.h>

#include <utils/builtins.h>
#include <utils/geo_decls.h>
#ifndef HAVE_MEMMOVE
# include <regex/utils.h>
#else
# include <string.h>
#endif

BOX
*rt_box_union(BOX *a, BOX *b)
{
    BOX *n;
    
    if ((n = (BOX *) palloc(sizeof (*n))) == (BOX *) NULL)
	elog(WARN, "Cannot allocate box for union");
    
    n->high.x = Max(a->high.x, b->high.x);
    n->high.y = Max(a->high.y, b->high.y);
    n->low.x = Min(a->low.x, b->low.x);
    n->low.y = Min(a->low.y, b->low.y);
    
    return (n);
}

BOX *
rt_box_inter(BOX *a, BOX *b)
{
    BOX *n;
    
    if ((n = (BOX *) palloc(sizeof (*n))) == (BOX *) NULL)
	elog(WARN, "Cannot allocate box for union");
    
    n->high.x = Min(a->high.x, b->high.x);
    n->high.y = Min(a->high.y, b->high.y);
    n->low.x = Max(a->low.x, b->low.x);
    n->low.y = Max(a->low.y, b->low.y);
    
    if (n->high.x < n->low.x || n->high.y < n->low.y) {
	pfree(n);
	return ((BOX *) NULL);
    }
    
    return (n);
}

void
rt_box_size(BOX *a, float *size)
{
    if (a == (BOX *) NULL || a->high.x <= a->low.x || a->high.y <= a->low.y)
	*size = 0.0;
    else
	*size = (float) ((a->high.x - a->low.x) * (a->high.y - a->low.y));
    
    return;
}

/*
 *  rt_bigbox_size() -- Compute a size for big boxes.
 *
 *	In an earlier release of the system, this routine did something
 *	different from rt_box_size.  We now use floats, rather than ints,
 *	as the return type for the size routine, so we no longer need to
 *	have a special return type for big boxes.
 */
void
rt_bigbox_size(BOX *a, float *size)
{
    rt_box_size(a, size);
}

POLYGON *
rt_poly_union(POLYGON *a, POLYGON *b)
{
    POLYGON *p;
    
    p = (POLYGON *)PALLOCTYPE(POLYGON);
    
    if (!PointerIsValid(p))
	elog(WARN, "Cannot allocate polygon for union");
    
    memset((char *) p, 0, sizeof(POLYGON));	/* zero any holes */
    p->size = sizeof(POLYGON);
    p->npts = 0;
    p->boundbox.high.x = Max(a->boundbox.high.x, b->boundbox.high.x);
    p->boundbox.high.y = Max(a->boundbox.high.y, b->boundbox.high.y);
    p->boundbox.low.x = Min(a->boundbox.low.x, b->boundbox.low.x);
    p->boundbox.low.y = Min(a->boundbox.low.y, b->boundbox.low.y);
    return p;
}

void
rt_poly_size(POLYGON *a, float *size)
{
    double xdim, ydim;
    
    size = (float *) palloc(sizeof(float));
    if (a == (POLYGON *) NULL || 
	a->boundbox.high.x <= a->boundbox.low.x || 
	a->boundbox.high.y <= a->boundbox.low.y)
	*size = 0.0;
    else {
	xdim = (a->boundbox.high.x - a->boundbox.low.x);
	ydim = (a->boundbox.high.y - a->boundbox.low.y);
	
	*size = (float) (xdim * ydim);
    }
    
    return;
}

POLYGON *
rt_poly_inter(POLYGON *a, POLYGON *b)
{
    POLYGON *p;
    
    p = (POLYGON *) PALLOCTYPE(POLYGON);
    
    if (!PointerIsValid(p))
	elog(WARN, "Cannot allocate polygon for intersection");
    
    memset((char *) p, 0, sizeof(POLYGON));	/* zero any holes */
    p->size = sizeof(POLYGON);
    p->npts = 0;
    p->boundbox.high.x = Min(a->boundbox.high.x, b->boundbox.high.x);
    p->boundbox.high.y = Min(a->boundbox.high.y, b->boundbox.high.y);
    p->boundbox.low.x = Max(a->boundbox.low.x, b->boundbox.low.x);
    p->boundbox.low.y = Max(a->boundbox.low.y, b->boundbox.low.y);
    
    if (p->boundbox.high.x < p->boundbox.low.x || p->boundbox.high.y < p->boundbox.low.y)
	{
	    pfree(p);
	    return ((POLYGON *) NULL);
	}
    
    return (p);
}