static bool detect_extent(boost::shared_ptr<sqlite_connection> ds,
bool has_spatial_index,
mapnik::box2d<double> & extent,
std::string const& index_table,
std::string const& metadata,
std::string const& geometry_field,
std::string const& geometry_table,
std::string const& key_field,
std::string const& table
)
{
if (has_spatial_index)
{
std::ostringstream s;
s << "SELECT MIN(xmin), MIN(ymin), MAX(xmax), MAX(ymax) FROM "
<< index_table;
boost::shared_ptr<sqlite_resultset> rs(ds->execute_query(s.str()));
if (rs->is_valid() && rs->step_next())
{
if (! rs->column_isnull(0))
{
double xmin = rs->column_double(0);
double ymin = rs->column_double(1);
double xmax = rs->column_double(2);
double ymax = rs->column_double(3);
extent.init (xmin, ymin, xmax, ymax);
return true;
}
}
}
else if (! metadata.empty())
{
std::ostringstream s;
s << "SELECT xmin, ymin, xmax, ymax FROM " << metadata;
s << " WHERE LOWER(f_table_name) = LOWER('" << geometry_table << "')";
boost::shared_ptr<sqlite_resultset> rs(ds->execute_query(s.str()));
if (rs->is_valid() && rs->step_next())
{
double xmin = rs->column_double(0);
double ymin = rs->column_double(1);
double xmax = rs->column_double(2);
double ymax = rs->column_double(3);
extent.init (xmin, ymin, xmax, ymax);
return true;
}
}
else if (! key_field.empty())
{
std::ostringstream s;
s << "SELECT " << geometry_field << "," << key_field
<< " FROM (" << table << ")";
boost::shared_ptr<sqlite_resultset> rs(ds->execute_query(s.str()));
sqlite_utils::query_extent(rs,extent);
return true;
}
return false;
}
void shape_io::read_bbox(shape_file::record_type & record, mapnik::box2d<double> & bbox)
{
double lox = record.read_double();
double loy = record.read_double();
double hix = record.read_double();
double hiy = record.read_double();
bbox.init(lox, loy, hix, hiy);
}