mvt_agg_transfn()

void mvt_agg_transfn

(

mvt_agg_context *

ctx

)

Aggregation step.

Parse a row, turn it into a feature, and add it to the layer.

Expands features array if needed by a factor of 2. Allocates a new feature, increment feature counter and encode geometry and properties into it.  

Definition at line 1032 of file mvt.c.

{
        bool isnull = false;
        Datum datum;
        GSERIALIZED *gs;
        LWGEOM *lwgeom;
        struct feature_builder feature_builder;
        VectorTile__Tile__Layer *layer = ctx->layer;
        POSTGIS_DEBUG(2, "mvt_agg_transfn called");
 
        /* geom_index is the cached index of the geometry. if missing, it needs to be initialized */
        if (ctx->geom_index == UINT32_MAX)
                parse_column_keys(ctx);
 
        /* Get the geometry column */
        datum = GetAttributeByNum(ctx->row, ctx->geom_index + 1, &isnull);
        if (isnull) /* Skip rows that have null geometry */
                return;
 
        /* Allocate a new feature object */
        feature_init(&feature_builder);
 
        /* Deserialize the geometry */
        gs = (GSERIALIZED *) PG_DETOAST_DATUM(datum);
        lwgeom = lwgeom_from_gserialized(gs);
 
        /* Set the geometry of the feature */
        encode_feature_geometry(&feature_builder, lwgeom);
        lwgeom_free(lwgeom);
        // TODO: free detoasted datum?
 
        /* Parse properties */
        parse_values(ctx, &feature_builder);
 
        /* Grow the features array of the layer */
        POSTGIS_DEBUGF(3, "mvt_agg_transfn encoded feature count: %zd", layer->n_features);
        if (layer->n_features >= ctx->features_capacity)
        {
                size_t new_capacity = ctx->features_capacity * 2;
                layer->features = repalloc(layer->features, new_capacity *
                        sizeof(*layer->features));
                ctx->features_capacity = new_capacity;
                POSTGIS_DEBUGF(3, "mvt_agg_transfn new_capacity: %zd", new_capacity);
        }
 
        /* Build and add the feature to the layer */
        layer->features[layer->n_features++] = feature_build(&feature_builder);
}

References encode_feature_geometry(), feature_build(), feature_init(), mvt_agg_context::features_capacity, mvt_agg_context::geom_index, mvt_agg_context::layer, lwgeom_free(), lwgeom_from_gserialized(), parse_column_keys(), parse_values(), mvt_agg_context::row, and UINT32_MAX.

Referenced by pgis_asmvt_transfn().

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