1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
#ifndef SQL_GIS_RING_FLIP_VISITOR_H_INCLUDED
#define SQL_GIS_RING_FLIP_VISITOR_H_INCLUDED
// Copyright (c) 2017, 2025, Oracle and/or its affiliates.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0,
// as published by the Free Software Foundation.
//
// This program is designed to work with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation. The authors of MySQL hereby grant you an additional
// permission to link the program and your derivative works with the
// separately licensed software that they have either included with
// the program or referenced in the documentation.
//
// This program 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, version 2.0, for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
#include <boost/geometry.hpp>
#include <memory> // std::unique_ptr
#include "sql/dd/types/spatial_reference_system.h" // dd::Spatial_reference_system
#include "sql/gis/geometries_cs.h"
#include "sql/gis/geometries_traits.h"
#include "sql/gis/geometry_visitor.h"
namespace gis {
/// A visitor that flips polygon rings so that exterior rings are in a
/// counter-clockwise direction and interior rings in a clockwise direction.
///
/// Invalid polygon rings are not guaranteed to be flipped to the correct
/// direction.
class Ring_flip_visitor : public Nop_visitor {
private:
/// Strategy used for geographic SRSs.
std::unique_ptr<boost::geometry::strategy::area::geographic<>>
m_geographic_strategy;
/// Whether the geometry is invalid. That happens either if the ellipsoid of
/// a geographic SRS is invalid or if we encounter a ring with unknown
/// direction.
bool m_invalid;
public:
/// Construct a new ring flip visitor.
///
/// @param[in] semi_major The semi-major axis of the ellipsoid.
/// @param[in] semi_minor The semi-minor axis of the ellipsoid.
Ring_flip_visitor(double semi_major, double semi_minor) {
try {
m_geographic_strategy.reset(
new boost::geometry::strategy::area::geographic<>(
boost::geometry::srs::spheroid<double>(semi_major, semi_minor)));
m_invalid = false;
} catch (...) {
// Spheroid construction may fail if the axes are invalid.
m_invalid = true;
}
}
/// Check if anything wrong has been detected, either an invalid ellipsoid or
/// a ring with an unknown direction.
///
/// Polygon rings which direction can't be determined are invalid. This is the
/// only way this visitor detects invalid rings. Other invalid rings, e.g.,
/// rings crossing themselves, are not necessarily detected.
///
/// @retval true Invalid SRS ellipsoid or invalid polygon ring.
/// @retval false No invalid rings detected, but the geometry may still be
/// invalid.
bool invalid() const { return m_invalid; }
using Nop_visitor::visit_enter;
bool visit_enter(Polygon *py) override;
bool visit_enter(Multipolygon *py) override;
bool visit_enter(Multipoint *) override {
return true; // Don't descend into each point.
}
bool visit_enter(Multilinestring *) override {
return true; // Don't descend into each linestring.
}
};
} // namespace gis
#endif // SQL_GIS_RING_FLIP_VISITOR_H_INCLUDED
|
