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/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2025 Artem Pavlenko
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*****************************************************************************/
#ifndef OGR_LAYER_PTR_HPP
#define OGR_LAYER_PTR_HPP
// mapnik
#include <mapnik/debug.hpp>
// stl
#include <stdexcept>
// gdal
#include <ogrsf_frmts.h>
using gdal_dataset_type = GDALDataset*;
class ogr_layer_ptr
{
public:
ogr_layer_ptr()
: datasource_(nullptr),
layer_(nullptr),
owns_layer_(false),
is_valid_(false)
{}
~ogr_layer_ptr() { free_layer(); }
void free_layer()
{
if (owns_layer_ && layer_ != nullptr && datasource_ != nullptr)
{
datasource_->ReleaseResultSet(layer_);
}
datasource_ = nullptr;
layer_ = nullptr;
layer_name_ = "";
owns_layer_ = false;
is_valid_ = false;
}
void layer_by_name(gdal_dataset_type const datasource, std::string const& layer_name)
{
free_layer();
datasource_ = datasource;
OGRLayer* ogr_layer = datasource_->GetLayerByName(layer_name.c_str());
if (ogr_layer)
{
layer_name_ = layer_name;
layer_ = ogr_layer;
is_valid_ = true;
MAPNIK_LOG_DEBUG(ogr) << "ogr_layer_ptr: layer_from_name layer=" << layer_name_;
}
#ifdef MAPNIK_LOG
debug_print_last_error();
#endif
}
void layer_by_index(gdal_dataset_type const datasource, int layer_index)
{
free_layer();
datasource_ = datasource;
OGRLayer* ogr_layer = datasource_->GetLayer(layer_index);
if (ogr_layer)
{
OGRFeatureDefn* def = ogr_layer->GetLayerDefn();
if (def != 0)
{
layer_ = ogr_layer;
layer_name_ = def->GetName();
is_valid_ = true;
MAPNIK_LOG_DEBUG(ogr) << "ogr_layer_ptr: layer_from_index layer=" << layer_name_;
}
}
#ifdef MAPNIK_LOG
debug_print_last_error();
#endif
}
void layer_by_sql(gdal_dataset_type const datasource, std::string const& layer_sql)
{
free_layer();
datasource_ = datasource;
owns_layer_ = true;
// TODO - actually filter fields!
// http://trac.osgeo.org/gdal/wiki/rfc29_desired_fields
// http://trac.osgeo.org/gdal/wiki/rfc28_sqlfunc
OGRGeometry* spatial_filter = nullptr;
char const* sql_dialect = nullptr;
OGRLayer* ogr_layer = datasource_->ExecuteSQL(layer_sql.c_str(), spatial_filter, sql_dialect);
if (ogr_layer)
{
OGRFeatureDefn* def = ogr_layer->GetLayerDefn();
if (def != 0)
{
layer_ = ogr_layer;
layer_name_ = def->GetName();
is_valid_ = true;
MAPNIK_LOG_DEBUG(ogr) << "ogr_layer_ptr: layer_from_sql layer=" << layer_name_;
}
}
#ifdef MAPNIK_LOG
debug_print_last_error();
#endif
}
std::string const& layer_name() const { return layer_name_; }
OGRLayer* layer() const { return layer_; }
bool is_valid() const { return is_valid_; }
private:
#ifdef MAPNIK_LOG
void debug_print_last_error()
{
if (!is_valid_)
{
std::string const err = CPLGetLastErrorMsg();
if (err.size() == 0)
{
MAPNIK_LOG_DEBUG(ogr) << "ogr_layer_ptr: Error getting layer";
}
else
{
MAPNIK_LOG_DEBUG(ogr) << "ogr_layer_ptr: " << err;
}
}
}
#endif
gdal_dataset_type datasource_;
OGRLayer* layer_;
std::string layer_name_;
bool owns_layer_;
bool is_valid_;
};
#endif // OGR_LAYER_PTR_HPP
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