lwgeom_out_mvt.c

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/**********************************************************************
 *
 * PostGIS - Spatial Types for PostgreSQL
 * http://postgis.net
 *
 * PostGIS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * PostGIS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with PostGIS.  If not, see <http://www.gnu.org/licenses/>.
 *
 **********************************************************************
 *
 * Copyright (C) 2016-2017 Björn Harrtell <bjorn@wololo.org>
 *
 **********************************************************************/
 
#include "postgres.h"
#include "utils/builtins.h"
#include "executor/spi.h"
#include "../postgis_config.h"
#include "lwgeom_pg.h"
#include "lwgeom_log.h"
#include "liblwgeom.h"
#include "mvt.h"
 
#ifdef HAVE_LIBPROTOBUF
#include "vector_tile.pb-c.h"
#endif  /* HAVE_LIBPROTOBUF */
 
PG_FUNCTION_INFO_V1(ST_AsMVTGeom);
Datum ST_AsMVTGeom(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBPROTOBUF
        elog(ERROR, "ST_AsMVTGeom: Compiled without protobuf-c support");
        PG_RETURN_NULL();
#else
        GBOX *bounds = NULL;
        int32_t extent = 0;
        int32_t buffer = 0;
        bool clip_geom = true;
        GSERIALIZED *geom_in, *geom_out;
        LWGEOM *lwgeom_in, *lwgeom_out;
        uint8_t type = 0;
 
        if (PG_ARGISNULL(0))
        {
                PG_RETURN_NULL();
        }
 
        if (PG_ARGISNULL(1))
        {
                elog(ERROR, "%s: Geometric bounds cannot be null", __func__);
                PG_RETURN_NULL();
        }
        bounds = (GBOX *)PG_GETARG_POINTER(1);
        if (bounds->xmax - bounds->xmin <= 0 || bounds->ymax - bounds->ymin <= 0)
        {
                elog(ERROR, "%s: Geometric bounds are too small", __func__);
                PG_RETURN_NULL();
        }
 
        extent = PG_ARGISNULL(2) ? 4096 : PG_GETARG_INT32(2);
        if (extent <= 0)
        {
                elog(ERROR, "%s: Extent must be greater than 0", __func__);
                PG_RETURN_NULL();
        }
 
        buffer = PG_ARGISNULL(3) ? 256 : PG_GETARG_INT32(3);
        clip_geom = PG_ARGISNULL(4) ? true : PG_GETARG_BOOL(4);
 
        geom_in = PG_GETARG_GSERIALIZED_P_COPY(0);
        type = gserialized_get_type(geom_in);
 
        /* If possible, peek into the bounding box before deserializing it to discard small geometries
         * We don't check COLLECTIONTYPE since that might be a collection of points */
        if (type == LINETYPE || type == POLYGONTYPE || type == MULTILINETYPE || type == MULTIPOLYGONTYPE)
        {
                GBOX gserialized_box;
                /* We only apply the optimization if the bounding box is available */
                if (gserialized_fast_gbox_p(geom_in, &gserialized_box) == LW_SUCCESS)
                {
                        /* Shortcut to drop geometries smaller than the resolution */
                        double geom_width = gserialized_box.xmax - gserialized_box.xmin;
                        double geom_height = gserialized_box.ymax - gserialized_box.ymin;
 
                        /* We use half of the square height and width as limit: We use this
                         * and not area so it works properly with lines */
                        double bounds_width = ((bounds->xmax - bounds->xmin) / extent) / 2.0;
                        double bounds_height = ((bounds->ymax - bounds->ymin) / extent) / 2.0;
                        if (geom_width < bounds_width && geom_height < bounds_height)
                        {
                                PG_RETURN_NULL();
                        }
                }
        }
 
        lwgeom_in = lwgeom_from_gserialized(geom_in);
 
        lwgeom_out = mvt_geom(lwgeom_in, bounds, extent, buffer, clip_geom);
        if (lwgeom_out == NULL)
                PG_RETURN_NULL();
 
        geom_out = geometry_serialize(lwgeom_out);
        lwgeom_free(lwgeom_out);
        PG_FREE_IF_COPY(geom_in, 0);
        PG_RETURN_POINTER(geom_out);
#endif
}
 
PG_FUNCTION_INFO_V1(pgis_asmvt_transfn);
Datum pgis_asmvt_transfn(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBPROTOBUF
        elog(ERROR, "ST_AsMVT: Compiled without protobuf-c support");
        PG_RETURN_NULL();
#else
        MemoryContext aggcontext, old_context;
        mvt_agg_context *ctx;
 
        /* We need to initialize the internal cache to access it later via postgis_oid() */
        postgis_initialize_cache();
 
        if (!AggCheckCallContext(fcinfo, &aggcontext))
                elog(ERROR, "%s called in non-aggregate context", __func__);
 
        if (PG_ARGISNULL(0)) {
                old_context = MemoryContextSwitchTo(aggcontext);
                ctx = palloc(sizeof(*ctx));
                ctx->name = "default";
                if (PG_NARGS() > 2 && !PG_ARGISNULL(2))
                        ctx->name = text_to_cstring(PG_GETARG_TEXT_P(2));
                ctx->extent = 4096;
                if (PG_NARGS() > 3 && !PG_ARGISNULL(3))
                        ctx->extent = PG_GETARG_INT32(3);
                ctx->geom_name = NULL;
                if (PG_NARGS() > 4 && !PG_ARGISNULL(4))
                        ctx->geom_name = text_to_cstring(PG_GETARG_TEXT_P(4));
                if (PG_NARGS() > 5 && !PG_ARGISNULL(5))
                        ctx->id_name = text_to_cstring(PG_GETARG_TEXT_P(5));
                else
                        ctx->id_name = NULL;
 
                ctx->trans_context = AllocSetContextCreate(aggcontext, "MVT transfn", ALLOCSET_DEFAULT_SIZES);
 
                MemoryContextSwitchTo(ctx->trans_context);
                mvt_agg_init_context(ctx);
                MemoryContextSwitchTo(old_context);
        } else {
                ctx = (mvt_agg_context *) PG_GETARG_POINTER(0);
        }
 
        if (!type_is_rowtype(get_fn_expr_argtype(fcinfo->flinfo, 1)))
                elog(ERROR, "%s: parameter row cannot be other than a rowtype", __func__);
        ctx->row = PG_GETARG_HEAPTUPLEHEADER(1);
 
        old_context = MemoryContextSwitchTo(ctx->trans_context);
        mvt_agg_transfn(ctx);
        MemoryContextSwitchTo(old_context);
 
        PG_FREE_IF_COPY(ctx->row, 1);
        PG_RETURN_POINTER(ctx);
#endif
}
 
PG_FUNCTION_INFO_V1(pgis_asmvt_finalfn);
Datum pgis_asmvt_finalfn(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBPROTOBUF
        elog(ERROR, "ST_AsMVT: Compiled without protobuf-c support");
        PG_RETURN_NULL();
#else
        mvt_agg_context *ctx;
        bytea *buf;
        elog(DEBUG2, "%s called", __func__);
        if (!AggCheckCallContext(fcinfo, NULL))
                elog(ERROR, "%s called in non-aggregate context", __func__);
 
        if (PG_ARGISNULL(0))
        {
                bytea *emptybuf = palloc(VARHDRSZ);
                SET_VARSIZE(emptybuf, VARHDRSZ);
                PG_RETURN_BYTEA_P(emptybuf);
        }
 
        ctx = (mvt_agg_context *) PG_GETARG_POINTER(0);
        buf = mvt_agg_finalfn(ctx);
        PG_RETURN_BYTEA_P(buf);
#endif
}
 
PG_FUNCTION_INFO_V1(pgis_asmvt_serialfn);
Datum pgis_asmvt_serialfn(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBPROTOBUF
        elog(ERROR, "ST_AsMVT: Compiled without protobuf-c support");
        PG_RETURN_NULL();
#else
        mvt_agg_context *ctx;
        bytea *result;
        elog(DEBUG2, "%s called", __func__);
        if (!AggCheckCallContext(fcinfo, NULL))
                elog(ERROR, "%s called in non-aggregate context", __func__);
 
        if (PG_ARGISNULL(0))
        {
                bytea *emptybuf = palloc(VARHDRSZ);
                SET_VARSIZE(emptybuf, VARHDRSZ);
                PG_RETURN_BYTEA_P(emptybuf);
        }
 
        ctx = (mvt_agg_context *) PG_GETARG_POINTER(0);
        result = mvt_ctx_serialize(ctx);
        if (ctx->trans_context)
                MemoryContextDelete(ctx->trans_context);
        ctx->trans_context = NULL;
        PG_RETURN_BYTEA_P(result);
#endif
}
 
 
PG_FUNCTION_INFO_V1(pgis_asmvt_deserialfn);
Datum pgis_asmvt_deserialfn(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBPROTOBUF
        elog(ERROR, "ST_AsMVT: Compiled without protobuf-c support");
        PG_RETURN_NULL();
#else
        MemoryContext aggcontext, oldcontext;
        mvt_agg_context *ctx;
        elog(DEBUG2, "%s called", __func__);
        if (!AggCheckCallContext(fcinfo, &aggcontext))
                elog(ERROR, "%s called in non-aggregate context", __func__);
 
        oldcontext = MemoryContextSwitchTo(aggcontext);
        ctx = mvt_ctx_deserialize(PG_GETARG_BYTEA_P(0));
        MemoryContextSwitchTo(oldcontext);
 
        PG_RETURN_POINTER(ctx);
#endif
}
 
PG_FUNCTION_INFO_V1(pgis_asmvt_combinefn);
Datum pgis_asmvt_combinefn(PG_FUNCTION_ARGS)
{
#ifndef HAVE_LIBPROTOBUF
        elog(ERROR, "ST_AsMVT: Compiled without protobuf-c support");
        PG_RETURN_NULL();
#else
        MemoryContext aggcontext, oldcontext;
        mvt_agg_context *ctx, *ctx1, *ctx2;
        elog(DEBUG2, "%s called", __func__);
        if (!AggCheckCallContext(fcinfo, &aggcontext))
                elog(ERROR, "%s called in non-aggregate context", __func__);
 
        ctx1 = (mvt_agg_context*)PG_GETARG_POINTER(0);
        ctx2 = (mvt_agg_context*)PG_GETARG_POINTER(1);
        oldcontext = MemoryContextSwitchTo(aggcontext);
        ctx = mvt_ctx_combine(ctx1, ctx2);
        MemoryContextSwitchTo(oldcontext);
        PG_RETURN_POINTER(ctx);
#endif
}