proj_api.cpp

projapi是一个关于GIS行业投影转换的程序库

// proj_api.cpp: implementation of the proj_api class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"

#define PJ_LIB__
#include "projects.h"
#ifndef UNICODE
#include <errno.h>
#endif
#include <math.h>

////////////////////////////////////////////////////////////////////
#define EPS 1.0e-12
C_NAMESPACE int pj_errno = 0;


///////////////////////////////////////////////////////////////////

int *pj_get_errno_ref()

{
    return &pj_errno;
}

/* forward projection entry */
XY pj_fwd(LP lp, PJ *P) 
{
	XY xy;
	double t;

	/* check for forward and latitude or longitude overange */
	if ((t = fabs(lp.phi)-HALFPI) > EPS || fabs(lp.lam) > 10.) 
	{
		xy.x = xy.y = HUGE_VAL;
		pj_errno = -14;
	} 
	else /* proceed with projection */
	{ 
		errno = pj_errno = 0;
		if (fabs(t) <= EPS)
			lp.phi = lp.phi < 0. ? -HALFPI : HALFPI;
		else if (P->geoc)
			lp.phi = atan(P->rone_es * tan(lp.phi));
		lp.lam -= P->lam0;	/* compute del lp.lam */
		if (!P->over)
			lp.lam = adjlon(lp.lam); /* adjust del longitude */
		xy = (*P->fwd)(lp, P); /* project */
		if (pj_errno || (pj_errno = errno))
			xy.x = xy.y = HUGE_VAL;
		/* adjust for major axis and easting/northings */
		else 
		{
			xy.x = P->fr_meter * (P->a * xy.x + P->x0);
			xy.y = P->fr_meter * (P->a * xy.y + P->y0);
		}
	}
	return xy;
}

/* inverse projection entry */
LP pj_inv(XY xy, PJ *P) 
{
	LP lp;

	/* can't do as much preliminary checking as with forward */
	if (xy.x == HUGE_VAL || xy.y == HUGE_VAL) 
	{
		lp.lam = lp.phi = HUGE_VAL;
		pj_errno = -15;
	}
	errno = pj_errno = 0;
	xy.x = (xy.x * P->to_meter - P->x0) * P->ra; /* descale and de-offset */
	xy.y = (xy.y * P->to_meter - P->y0) * P->ra;
	lp = (*P->inv)(xy, P); /* inverse project */
	if (pj_errno || (pj_errno = errno))
		lp.lam = lp.phi = HUGE_VAL;
	else 
	{
		lp.lam += P->lam0; /* reduce from del lp.lam */
		if (!P->over)
			lp.lam = adjlon(lp.lam); /* adjust longitude to CM */
		if (P->geoc && fabs(fabs(lp.phi)-HALFPI) > EPS)
			lp.phi = atan(P->one_es * tan(lp.phi));
	}

	return lp;
}

void * pj_malloc(size_t size) 
{
	return(malloc(size));
}
	
void pj_dalloc(void *ptr) 
{
	free(ptr);
}