pj_utils.cpp

projapi是一个关于GIS行业投影转换的程序库

#include "stdafx.h"

#define PJ_LIB__

#include "projects.h"
#include <string.h>
#include <math.h>

/************************************************************************/
/*                           pj_is_latlong()                            */
/*                                                                      */
/*      Returns TRUE if this coordinate system object is                */
/*      geographic.                                                     */
/************************************************************************/

int pj_is_latlong( PJ *pj )

{
    return pj == NULL || pj->is_latlong;
}

/************************************************************************/
/*                           pj_is_geocent()                            */
/*                                                                      */
/*      Returns TRUE if this coordinate system object is geocentric.    */
/************************************************************************/

int pj_is_geocent( PJ *pj )

{
    return pj != NULL && pj->is_geocent;
}

/************************************************************************/
/*                        pj_latlong_from_proj()                        */
/*                                                                      */
/*      Return a PJ* definition defining the lat/long coordinate        */
/*      system on which a projection is based.  If the coordinate       */
/*      system passed in is latlong, a clone of the same will be        */
/*      returned.                                                       */
/************************************************************************/

PJ *pj_latlong_from_proj( PJ *pj_in )

{
    char	defn[512];
    int		got_datum = FALSE;

    pj_errno = 0;
    strcpy( defn, "+proj=latlong" );

    if( pj_param(pj_in->params, "tdatum").i )
    {
        got_datum = TRUE;
        sprintf( defn+strlen(defn), " +datum=%s", 
                 pj_param(pj_in->params,"sdatum").s );
    }
    else if( pj_param(pj_in->params, "tellps").i )
    {
        sprintf( defn+strlen(defn), " +ellps=%s", 
                 pj_param(pj_in->params,"sellps").s );
    }
    else if( pj_param(pj_in->params, "ta").i )
    {
        sprintf( defn+strlen(defn), " +a=%s", 
                 pj_param(pj_in->params,"sa").s );
            
        if( pj_param(pj_in->params, "tb").i )
            sprintf( defn+strlen(defn), " +b=%s", 
                     pj_param(pj_in->params,"sb").s );
        else if( pj_param(pj_in->params, "tes").i )
            sprintf( defn+strlen(defn), " +es=%s", 
                     pj_param(pj_in->params,"ses").s );
        else if( pj_param(pj_in->params, "tf").i )
            sprintf( defn+strlen(defn), " +f=%s", 
                     pj_param(pj_in->params,"sf").s );
        else
            sprintf( defn+strlen(defn), " +es=%.4f", 
                     pj_in->es );
    }
    else
    {
        pj_errno = -13;

        return NULL;
    }

    if( !got_datum )
    {
        if( pj_param(pj_in->params, "ttowgs84").i )
            sprintf( defn+strlen(defn), " +towgs84=%s", 
                     pj_param(pj_in->params,"stowgs84").s );

        if( pj_param(pj_in->params, "ttowgs84").i )
            sprintf( defn+strlen(defn), " +towgs84=%s", 
                     pj_param(pj_in->params,"stowgs84").s );

        if( pj_param(pj_in->params, "tnadgrids").i )
            sprintf( defn+strlen(defn), " +nadgrids=%s", 
                     pj_param(pj_in->params,"snadgrids").s );
    }

    /* copy over some other information related to ellipsoid */
    if( pj_param(pj_in->params, "tR").i )
        sprintf( defn+strlen(defn), " +R=%s", 
                 pj_param(pj_in->params,"sR").s );

    if( pj_param(pj_in->params, "tR_A").i )
        sprintf( defn+strlen(defn), " +R_A" );

    if( pj_param(pj_in->params, "tR_V").i )
        sprintf( defn+strlen(defn), " +R_V" );

    if( pj_param(pj_in->params, "tR_a").i )
        sprintf( defn+strlen(defn), " +R_a" );

    if( pj_param(pj_in->params, "tR_lat_a").i )
        sprintf( defn+strlen(defn), " +R_lat_a=%s", 
                 pj_param(pj_in->params,"sR_lat_a").s );

    if( pj_param(pj_in->params, "tR_lat_g").i )
        sprintf( defn+strlen(defn), " +R_lat_g=%s", 
                 pj_param(pj_in->params,"sR_lat_g").s );

    /* copy over prime meridian */
    if( pj_param(pj_in->params, "tpm").i )
        sprintf( defn+strlen(defn), " +pm=%s", 
                 pj_param(pj_in->params,"spm").s );

    return pj_init_plus( defn );
}