ST_ClipByBox2d()

Datum ST_ClipByBox2d

(

PG_FUNCTION_ARGS

)

Definition at line 1527 of file postgis/lwgeom_geos.c.

{
        static const uint32_t geom_idx = 0;
        static const uint32_t box2d_idx = 1;
        GSERIALIZED *result;
        LWGEOM *lwgeom1, *lwresult ;
        GBOX bbox1 = {0};
        GBOX *bbox2;
        uint8_t type;
        int32_t srid;
        lwflags_t flags;
 
        if (!gserialized_datum_get_internals_p(PG_GETARG_DATUM(geom_idx), &bbox1, &flags, &type, &srid))
        {
                /* empty clips to empty, no matter rect */
                PG_RETURN_DATUM(PG_GETARG_DATUM(geom_idx));
        }
 
        /* WARNING: this is really a BOX2DF, use only xmin and ymin fields */
        bbox2 = (GBOX *)PG_GETARG_POINTER(box2d_idx);
        bbox2->flags = 0;
 
        /* If bbox1 is strictly contained by bbox2, return input geometry */
        if (bbox2->xmin < bbox1.xmin && bbox2->xmax > bbox1.xmax &&
            bbox2->ymin < bbox1.ymin && bbox2->ymax > bbox1.ymax)
        {
                PG_RETURN_DATUM(PG_GETARG_DATUM(geom_idx));
        }
 
        /* If bbox1 outside of bbox2, return empty */
        if (!gbox_overlaps_2d(&bbox1, bbox2))
        {
                /* Get type and srid from datum */
                lwresult = lwgeom_construct_empty(type, srid, 0, 0);
                result = geometry_serialize(lwresult) ;
                lwgeom_free(lwresult) ;
                PG_RETURN_POINTER(result);
        }
 
        lwgeom1 = lwgeom_from_gserialized(PG_GETARG_GSERIALIZED_P(geom_idx));
        lwresult = lwgeom_clip_by_rect(lwgeom1, bbox2->xmin, bbox2->ymin,
                                       bbox2->xmax, bbox2->ymax);
 
        lwgeom_free(lwgeom1);
 
        if (!lwresult)
                PG_RETURN_NULL();
 
        result = geometry_serialize(lwresult) ;
        PG_RETURN_POINTER(result);
}

References GBOX::flags, gbox_overlaps_2d(), gserialized_datum_get_internals_p(), lwgeom_clip_by_rect(), lwgeom_construct_empty(), lwgeom_free(), lwgeom_from_gserialized(), result, GBOX::xmax, GBOX::xmin, GBOX::ymax, and GBOX::ymin.

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