ST_Scale()

Datum ST_Scale

(

PG_FUNCTION_ARGS

)

Definition at line 3163 of file lwgeom_functions_basic.c.

{
        GSERIALIZED *geom;
        GSERIALIZED *geom_scale = PG_GETARG_GSERIALIZED_P(1);
        GSERIALIZED *geom_origin = NULL;
        LWGEOM *lwg, *lwg_scale, *lwg_origin;
        LWPOINT *lwpt_scale, *lwpt_origin;
        POINT4D origin;
        POINT4D factors;
        bool translate = false;
        GSERIALIZED *ret;
        AFFINE aff;
 
        /* Make sure we have a valid scale input */
        lwg_scale = lwgeom_from_gserialized(geom_scale);
        lwpt_scale = lwgeom_as_lwpoint(lwg_scale);
        if (!lwpt_scale)
        {
                lwgeom_free(lwg_scale);
                PG_FREE_IF_COPY(geom_scale, 1);
                lwpgerror("Scale factor geometry parameter must be a point");
                PG_RETURN_NULL();
        }
 
        /* Geom Will be modified in place, so take a copy */
        geom = PG_GETARG_GSERIALIZED_P_COPY(0);
        lwg = lwgeom_from_gserialized(geom);
 
        /* Empty point, return input untouched */
        if (lwgeom_is_empty(lwg))
        {
                lwgeom_free(lwg_scale);
                lwgeom_free(lwg);
                PG_FREE_IF_COPY(geom_scale, 1);
                PG_RETURN_POINTER(geom);
        }
 
        /* Once we read the scale data into local static point, we can */
        /* free the lwgeom */
        lwpoint_getPoint4d_p(lwpt_scale, &factors);
        if (!lwgeom_has_z(lwg_scale))
                factors.z = 1.0;
        if (!lwgeom_has_m(lwg_scale))
                factors.m = 1.0;
        lwgeom_free(lwg_scale);
 
        /* Do we have the optional false origin? */
        if (PG_NARGS() > 2 && !PG_ARGISNULL(2))
        {
                geom_origin = PG_GETARG_GSERIALIZED_P(2);
                lwg_origin = lwgeom_from_gserialized(geom_origin);
                lwpt_origin = lwgeom_as_lwpoint(lwg_origin);
                if (lwpt_origin)
                {
                        lwpoint_getPoint4d_p(lwpt_origin, &origin);
                        translate = true;
                }
                /* Free the false origin inputs */
                lwgeom_free(lwg_origin);
                PG_FREE_IF_COPY(geom_origin, 2);
        }
 
        /* If we have false origin, translate to it before scaling */
        if (translate)
        {
                /* Initialize affine */
                memset(&aff, 0, sizeof(AFFINE));
                /* Set rotation/scale/sheer matrix to no-op */
                aff.afac = aff.efac = aff.ifac = 1.0;
                /* Strip false origin from all coordinates */
                aff.xoff = -1 * origin.x;
                aff.yoff = -1 * origin.y;
                aff.zoff = -1 * origin.z;
                lwgeom_affine(lwg, &aff);
        }
 
        lwgeom_scale(lwg, &factors);
 
        /* Return to original origin after scaling */
        if (translate)
        {
                aff.xoff *= -1;
                aff.yoff *= -1;
                aff.zoff *= -1;
                lwgeom_affine(lwg, &aff);
        }
 
        /* Cleanup and return */
        ret = geometry_serialize(lwg);
        lwgeom_free(lwg);
        PG_FREE_IF_COPY(geom, 0);
        PG_FREE_IF_COPY(geom_scale, 1);
        PG_RETURN_POINTER(ret);
}

References AFFINE::afac, AFFINE::efac, AFFINE::ifac, lwgeom_affine(), lwgeom_as_lwpoint(), lwgeom_free(), lwgeom_from_gserialized(), lwgeom_has_m(), lwgeom_has_z(), lwgeom_is_empty(), lwgeom_scale(), lwpoint_getPoint4d_p(), POINT4D::m, POINT4D::x, AFFINE::xoff, POINT4D::y, AFFINE::yoff, POINT4D::z, and AFFINE::zoff.

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