LWGEOM_setpoint_linestring()

Datum LWGEOM_setpoint_linestring

(

PG_FUNCTION_ARGS

)

Definition at line 2292 of file lwgeom_functions_basic.c.

{
        GSERIALIZED *pglwg1, *pglwg2, *result;
        LWGEOM *lwg;
        LWLINE *line;
        LWPOINT *lwpoint;
        POINT4D newpoint;
        int64_t which;
 
        POSTGIS_DEBUG(2, "LWGEOM_setpoint_linestring called.");
 
        /* we copy input as we're going to modify it */
        pglwg1 = PG_GETARG_GSERIALIZED_P_COPY(0);
 
        which = PG_GETARG_INT32(1);
        pglwg2 = PG_GETARG_GSERIALIZED_P(2);
 
        /* Extract a POINT4D from the point */
        lwg = lwgeom_from_gserialized(pglwg2);
        lwpoint = lwgeom_as_lwpoint(lwg);
        if (!lwpoint)
        {
                elog(ERROR, "Third argument must be a POINT");
                PG_RETURN_NULL();
        }
        getPoint4d_p(lwpoint->point, 0, &newpoint);
        lwpoint_free(lwpoint);
        PG_FREE_IF_COPY(pglwg2, 2);
 
        lwg = lwgeom_from_gserialized(pglwg1);
        line = lwgeom_as_lwline(lwg);
 
        if (!line)
        {
                elog(ERROR, "First argument must be a LINESTRING");
                PG_RETURN_NULL();
        }
 
        if ( line->points->npoints < 1 )        {
                elog(ERROR, "Line has no points");
                PG_RETURN_NULL();
        }
 
        if (which < 0)
        {
                /* Use backward indexing for negative values */
                which += (int64_t)line->points->npoints;
        }
        if ((uint32_t)which > line->points->npoints - 1)
        {
                elog(ERROR, "abs(Point index) out of range (-)(%u..%u)", 0, line->points->npoints - 1);
                PG_RETURN_NULL();
        }
 
        /*
         * This will change pointarray of the serialized pglwg1,
         */
        lwline_setPoint4d(line, (uint32_t)which, &newpoint);
        result = geometry_serialize((LWGEOM *)line);
 
        /* Release memory */
        lwline_free(line);
        pfree(pglwg1); /* we forced copy, POINARRAY is released now */
 
        PG_RETURN_POINTER(result);
}

References geometry_serialize(), getPoint4d_p(), lwgeom_as_lwline(), lwgeom_as_lwpoint(), lwgeom_from_gserialized(), lwline_free(), lwline_setPoint4d(), lwpoint_free(), POINTARRAY::npoints, LWPOINT::point, and LWLINE::points.

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