ST_ClipByBox2d()

Datum ST_ClipByBox2d

(

PG_FUNCTION_ARGS

)

Definition at line 1294 of file postgis/lwgeom_geos.c.

{
        GSERIALIZED *geom1;
        GSERIALIZED *result;
        LWGEOM *lwgeom1, *lwresult ;
        const GBOX *bbox1;
        GBOX *bbox2;
 
        geom1 = PG_GETARG_GSERIALIZED_P(0);
        lwgeom1 = lwgeom_from_gserialized(geom1) ;
 
        bbox1 = lwgeom_get_bbox(lwgeom1);
        if ( ! bbox1 )
        {
                /* empty clips to empty, no matter rect */
                lwgeom_free(lwgeom1);
                PG_RETURN_POINTER(geom1);
        }
 
        /* WARNING: this is really a BOX2DF, use only xmin and ymin fields */
        bbox2 = (GBOX *)PG_GETARG_POINTER(1);
        bbox2->flags = 0;
 
        /* If bbox1 outside of bbox2, return empty */
        if ( ! gbox_overlaps_2d(bbox1, bbox2) )
        {
                lwresult = lwgeom_construct_empty(lwgeom1->type, lwgeom1->srid, 0, 0);
                lwgeom_free(lwgeom1);
                PG_FREE_IF_COPY(geom1, 0);
                result = geometry_serialize(lwresult) ;
                lwgeom_free(lwresult) ;
                PG_RETURN_POINTER(result);
        }
 
        /* if bbox1 is covered by bbox2, return lwgeom1 */
        if ( gbox_contains_2d(bbox2, bbox1) )
        {
                lwgeom_free(lwgeom1);
                PG_RETURN_POINTER(geom1);
        }
 
        lwresult = lwgeom_clip_by_rect(lwgeom1, bbox2->xmin, bbox2->ymin,
                                       bbox2->xmax, bbox2->ymax);
 
        lwgeom_free(lwgeom1);
        PG_FREE_IF_COPY(geom1, 0);
 
        if (!lwresult) PG_RETURN_NULL();
 
        result = geometry_serialize(lwresult) ;
        lwgeom_free(lwresult) ;
        PG_RETURN_POINTER(result);
}

References GBOX::flags, gbox_contains_2d(), gbox_overlaps_2d(), geometry_serialize(), lwgeom_clip_by_rect(), lwgeom_construct_empty(), lwgeom_free(), lwgeom_from_gserialized(), lwgeom_get_bbox(), LWGEOM::srid, LWGEOM::type, GBOX::xmax, GBOX::xmin, GBOX::ymax, and GBOX::ymin.

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