lwproj_from_str()

LWPROJ* lwproj_from_str	(	const char *	str_in,
		const char *	str_out
	)

Allocate a new LWPROJ containing the reference to the PROJ's PJ If extra_geography_data is true, it will generate the following values for the source srs: is_latlong (geometric or not) and spheroid values.

Definition at line 50 of file liblwgeom/lwgeom_transform.c.

{
        uint8_t source_is_latlong = LW_FALSE;
        double semi_major_metre = DBL_MAX, semi_minor_metre = DBL_MAX;
 
        /* Usable inputs? */
        if (! (str_in && str_out))
                return NULL;
 
        PJ* pj = proj_create_crs_to_crs(PJ_DEFAULT_CTX, str_in, str_out, NULL);
        if (!pj)
                return NULL;
 
        /* Fill in geodetic parameter information when a null-transform */
        /* is passed, because that's how we signal we want to store */
        /* that info in the cache */
        if (strcmp(str_in, str_out) == 0)
        {
                PJ *pj_source_crs = proj_get_source_crs(PJ_DEFAULT_CTX, pj);
                PJ *pj_ellps;
                PJ_TYPE pj_type = proj_get_type(pj_source_crs);
                if (pj_type == PJ_TYPE_UNKNOWN)
                {
                        proj_destroy(pj);
                        lwerror("%s: unable to access source crs type", __func__);
                        return NULL;
                }
                source_is_latlong = (pj_type == PJ_TYPE_GEOGRAPHIC_2D_CRS) || (pj_type == PJ_TYPE_GEOGRAPHIC_3D_CRS);
 
                pj_ellps = proj_get_ellipsoid(PJ_DEFAULT_CTX, pj_source_crs);
                proj_destroy(pj_source_crs);
                if (!pj_ellps)
                {
                        proj_destroy(pj);
                        lwerror("%s: unable to access source crs ellipsoid", __func__);
                        return NULL;
                }
                if (!proj_ellipsoid_get_parameters(PJ_DEFAULT_CTX,
                                                   pj_ellps,
                                                   &semi_major_metre,
                                                   &semi_minor_metre,
                                                   NULL,
                                                   NULL))
                {
                        proj_destroy(pj_ellps);
                        proj_destroy(pj);
                        lwerror("%s: unable to access source crs ellipsoid parameters", __func__);
                        return NULL;
                }
                proj_destroy(pj_ellps);
        }
 
        /* Add in an axis swap if necessary */
        PJ* pj_norm = proj_normalize_for_visualization(PJ_DEFAULT_CTX, pj);
        /* Swap failed for some reason? Fall back to coordinate operation */
        if (!pj_norm)
                pj_norm = pj;
        /* Swap is not a copy of input? Clean up input */
        else if (pj != pj_norm)
                proj_destroy(pj);
 
        /* Allocate and populate return value */
        LWPROJ *lp = lwalloc(sizeof(LWPROJ));
        lp->pj = pj_norm; /* Caller is going to have to explicitly proj_destroy this */
        lp->pipeline_is_forward = true;
        lp->source_is_latlong = source_is_latlong;
        lp->source_semi_major_metre = semi_major_metre;
        lp->source_semi_minor_metre = semi_minor_metre;
        return lp;
}

References LW_FALSE, lwalloc(), lwerror(), LWPROJ::pipeline_is_forward, LWPROJ::pj, LWPROJ::source_is_latlong, LWPROJ::source_semi_major_metre, and LWPROJ::source_semi_minor_metre.

Referenced by gml_reproject_pa(), and lwgeom_transform_from_str().

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