RASTER_dumpAsPolygons()

Datum RASTER_dumpAsPolygons

(

PG_FUNCTION_ARGS

)

Dump raster

Definition at line 194 of file rtpg_geometry.c.

                                              {
        FuncCallContext *funcctx;
        TupleDesc tupdesc;
        rt_geomval geomval;
        rt_geomval geomval2;
        int call_cntr;
        int max_calls;
 
        /* stuff done only on the first call of the function */
        if (SRF_IS_FIRSTCALL()) {
                MemoryContext oldcontext;
                int numbands;
                rt_pgraster *pgraster = NULL;
                rt_raster raster = NULL;
                int nband;
                bool exclude_nodata_value = TRUE;
                int nElements;
 
                POSTGIS_RT_DEBUG(2, "RASTER_dumpAsPolygons first call");
 
                /* create a function context for cross-call persistence */
                funcctx = SRF_FIRSTCALL_INIT();
 
                /* switch to memory context appropriate for multiple function calls */
                oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
 
                /* Get input arguments */
                if (PG_ARGISNULL(0)) {
                        MemoryContextSwitchTo(oldcontext);
                        SRF_RETURN_DONE(funcctx);
                }
                pgraster = (rt_pgraster *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
                raster = rt_raster_deserialize(pgraster, FALSE);
                if (!raster) {
                        PG_FREE_IF_COPY(pgraster, 0);
                        ereport(ERROR, (
                                errcode(ERRCODE_OUT_OF_MEMORY),
                                errmsg("Could not deserialize raster")
                        ));
                        MemoryContextSwitchTo(oldcontext);
                        SRF_RETURN_DONE(funcctx);
                }
 
                if (!PG_ARGISNULL(1))
                        nband = PG_GETARG_UINT32(1);
                else
                        nband = 1; /* By default, first band */
 
                POSTGIS_RT_DEBUGF(3, "band %d", nband);
                numbands = rt_raster_get_num_bands(raster);
 
                if (nband < 1 || nband > numbands) {
                        elog(NOTICE, "Invalid band index (must use 1-based). Returning empty set");
                        rt_raster_destroy(raster);
                        PG_FREE_IF_COPY(pgraster, 0);
                        MemoryContextSwitchTo(oldcontext);
                        SRF_RETURN_DONE(funcctx);
                }
 
                if (!PG_ARGISNULL(2))
                        exclude_nodata_value = PG_GETARG_BOOL(2);
 
                /* see if band is NODATA */
                if (rt_band_get_isnodata_flag(rt_raster_get_band(raster, nband - 1))) {
                        POSTGIS_RT_DEBUGF(3, "Band at index %d is NODATA. Returning empty set", nband);
                        rt_raster_destroy(raster);
                        PG_FREE_IF_COPY(pgraster, 0);
                        MemoryContextSwitchTo(oldcontext);
                        SRF_RETURN_DONE(funcctx);
                }
 
                /* Polygonize raster */
 
                geomval = rt_raster_gdal_polygonize(raster, nband - 1, exclude_nodata_value, &nElements);
                rt_raster_destroy(raster);
                PG_FREE_IF_COPY(pgraster, 0);
                if (NULL == geomval) {
                        ereport(ERROR, (
                                errcode(ERRCODE_NO_DATA_FOUND),
                                errmsg("Could not polygonize raster")
                        ));
                        MemoryContextSwitchTo(oldcontext);
                        SRF_RETURN_DONE(funcctx);
                }
 
                POSTGIS_RT_DEBUGF(3, "raster dump, %d elements returned", nElements);
 
                /* Store needed information */
                funcctx->user_fctx = geomval;
 
                /* total number of tuples to be returned */
                funcctx->max_calls = nElements;
 
                /* Build a tuple descriptor for our result type */
                if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) {
                        ereport(ERROR, (
                                errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                errmsg("function returning record called in context that cannot accept type record")
                        ));
                }
 
                BlessTupleDesc(tupdesc);
                funcctx->tuple_desc = tupdesc;
 
                MemoryContextSwitchTo(oldcontext);
        }
 
        /* stuff done on every call of the function */
        funcctx = SRF_PERCALL_SETUP();
 
        call_cntr = funcctx->call_cntr;
        max_calls = funcctx->max_calls;
        tupdesc = funcctx->tuple_desc;
        geomval2 = funcctx->user_fctx;
 
        /* do when there is more left to send */
        if (call_cntr < max_calls) {
                Datum values[VALUES_LENGTH];
                bool nulls[VALUES_LENGTH];
                HeapTuple    tuple;
                Datum        result;
 
                GSERIALIZED *gser = NULL;
                size_t gser_size = 0;
 
                POSTGIS_RT_DEBUGF(3, "call number %d", call_cntr);
 
                memset(nulls, FALSE, sizeof(bool) * VALUES_LENGTH);
 
                /* convert LWGEOM to GSERIALIZED */
                gser = gserialized_from_lwgeom(lwpoly_as_lwgeom(geomval2[call_cntr].geom), &gser_size);
                lwgeom_free(lwpoly_as_lwgeom(geomval2[call_cntr].geom));
 
                values[0] = PointerGetDatum(gser);
                values[1] = Float8GetDatum(geomval2[call_cntr].val);
 
                /* build a tuple */
                tuple = heap_form_tuple(tupdesc, values, nulls);
 
                /* make the tuple into a datum */
                result = HeapTupleGetDatum(tuple);
 
                SRF_RETURN_NEXT(funcctx, result);
        }
        /* do when there is no more left */
        else {
                pfree(geomval2);
                SRF_RETURN_DONE(funcctx);
        }
}

References FALSE, gserialized_from_lwgeom(), lwgeom_free(), lwpoly_as_lwgeom(), POSTGIS_RT_DEBUG, POSTGIS_RT_DEBUGF, result, rt_band_get_isnodata_flag(), rt_raster_deserialize(), rt_raster_destroy(), rt_raster_gdal_polygonize(), rt_raster_get_band(), rt_raster_get_num_bands(), TRUE, and VALUES_LENGTH.

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