BOX2D_to_LWGEOM()

Datum BOX2D_to_LWGEOM

(

PG_FUNCTION_ARGS

)

Definition at line 470 of file lwgeom_box.c.

{
        GBOX *box = (GBOX *)PG_GETARG_POINTER(0);
        POINTARRAY *pa = ptarray_construct_empty(0, 0, 5);
        POINT4D pt;
        GSERIALIZED *result;
 
 
        /*
         * Alter BOX2D cast so that a valid geometry is always
         * returned depending upon the size of the BOX2D. The
         * code makes the following assumptions:
         *     - If the BOX2D is a single point then return a
         *     POINT geometry
         *     - If the BOX2D represents either a horizontal or
         *     vertical line, return a LINESTRING geometry
         *     - Otherwise return a POLYGON
         */
 
        if ( (box->xmin == box->xmax) && (box->ymin == box->ymax) )
        {
                /* Construct and serialize point */
                LWPOINT *point = lwpoint_make2d(SRID_UNKNOWN, box->xmin, box->ymin);
                result = geometry_serialize(lwpoint_as_lwgeom(point));
                lwpoint_free(point);
        }
        else if ( (box->xmin == box->xmax) || (box->ymin == box->ymax) )
        {
                LWLINE *line;
 
                /* Assign coordinates to point array */
                pt.x = box->xmin;
                pt.y = box->ymin;
                ptarray_append_point(pa, &pt, LW_TRUE);
                pt.x = box->xmax;
                pt.y = box->ymax;
                ptarray_append_point(pa, &pt, LW_TRUE);
 
                /* Construct and serialize linestring */
                line = lwline_construct(SRID_UNKNOWN, NULL, pa);
                result = geometry_serialize(lwline_as_lwgeom(line));
                lwline_free(line);
        }
        else
        {
                POINT4D points[4];
                LWPOLY *poly;
 
                /* Initialize the 4 vertices of the polygon */
                points[0] = (POINT4D) { box->xmin, box->ymin, 0.0, 0.0 };
                points[1] = (POINT4D) { box->xmin, box->ymax, 0.0, 0.0 };
                points[2] = (POINT4D) { box->xmax, box->ymax, 0.0, 0.0 };
                points[3] = (POINT4D) { box->xmax, box->ymin, 0.0, 0.0 };
 
                /* Construct polygon */
                poly = lwpoly_construct_rectangle(LW_FALSE, LW_FALSE, &points[0], &points[1],
                                &points[2], &points[3]);
                result = geometry_serialize(lwpoly_as_lwgeom(poly));
                lwpoly_free(poly);
        }
 
        PG_RETURN_POINTER(result);
}

References geometry_serialize(), LW_FALSE, LW_TRUE, lwline_as_lwgeom(), lwline_construct(), lwline_free(), lwpoint_as_lwgeom(), lwpoint_free(), lwpoint_make2d(), lwpoly_as_lwgeom(), lwpoly_construct_rectangle(), lwpoly_free(), ptarray_append_point(), ptarray_construct_empty(), SRID_UNKNOWN, POINT4D::x, GBOX::xmax, GBOX::xmin, POINT4D::y, GBOX::ymax, and GBOX::ymin.

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