Add and test box_t class and envelope(geom) function

src/CMakeLists.txt

@@ -8,6 +8,7 @@ target_sources(osm2pgsql_lib PRIVATE
   expire-tiles.cpp
   gazetteer-style.cpp
   geom.cpp
+  geom-box.cpp
   geom-from-osm.cpp
   geom-functions.cpp
   input.cpp

src/geom-box.cpp

@@ -0,0 +1,112 @@
+/**
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This file is part of osm2pgsql (https://osm2pgsql.org/).
+ *
+ * Copyright (C) 2006-2022 by the osm2pgsql developer community.
+ * For a full list of authors see the git log.
+ */
+
+#include "geom-box.hpp"
+
+namespace geom {
+
+box_t &box_t::extend(point_t const &point) noexcept
+{
+    if (point.x() < m_min_x) {
+        m_min_x = point.x();
+    }
+    if (point.y() < m_min_y) {
+        m_min_y = point.y();
+    }
+    if (point.x() > m_max_x) {
+        m_max_x = point.x();
+    }
+    if (point.y() > m_max_y) {
+        m_max_y = point.y();
+    }
+
+    return *this;
+}
+
+void box_t::extend(point_list_t const &list) noexcept
+{
+    for (auto const &point : list) {
+        extend(point);
+    }
+}
+
+namespace {
+
+class envelope_visitor
+{
+public:
+    box_t operator()(geom::nullgeom_t const & /*geom*/) const
+    {
+        return box_t{};
+    }
+
+    box_t operator()(geom::point_t const &geom) const
+    {
+        box_t box;
+        box.extend(geom);
+        return box;
+    }
+
+    box_t operator()(geom::linestring_t const &geom) const
+    {
+        box_t box;
+        box.extend(geom);
+        return box;
+    }
+
+    box_t operator()(geom::polygon_t const &geom) const
+    {
+        box_t box;
+        box.extend(geom.outer());
+        return box;
+    }
+
+    box_t operator()(geom::multipoint_t const & /*geom*/) const
+    {
+        assert(false);
+        return {}; // XXX not implemented
+    }
+
+    box_t operator()(geom::multilinestring_t const &geom) const
+    {
+        box_t box;
+
+        for (auto const &line : geom) {
+            box.extend(line);
+        }
+
+        return box;
+    }
+
+    box_t operator()(geom::multipolygon_t const &geom) const
+    {
+        box_t box;
+
+        for (auto const &polygon : geom) {
+            box.extend(polygon.outer());
+        }
+
+        return box;
+    }
+
+    box_t operator()(geom::collection_t const & /*geom*/) const
+    {
+        assert(false);
+        return {}; // XXX not implemented
+    }
+}; // class envelope_visitor
+
+} // anonymous namespace
+
+box_t envelope(geometry_t const &geom)
+{
+    return geom.visit(envelope_visitor{});
+}
+
+} // namespace geom

src/geom-box.hpp

@@ -0,0 +1,76 @@
+#ifndef OSM2PGSQL_GEOM_BOX_HPP
+#define OSM2PGSQL_GEOM_BOX_HPP
+
+/**
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This file is part of osm2pgsql (https://osm2pgsql.org/).
+ *
+ * Copyright (C) 2006-2022 by the osm2pgsql developer community.
+ * For a full list of authors see the git log.
+ */
+
+/**
+ * \file
+ *
+ * Class and functions for creating bounding boxes of geometries.
+ */
+
+#include "geom.hpp"
+
+#include <cassert>
+#include <limits>
+
+namespace geom {
+
+class box_t
+{
+public:
+    constexpr box_t() noexcept = default;
+
+    constexpr box_t(double min_x, double min_y, double max_x,
+                    double max_y) noexcept
+    : m_min_x(min_x), m_min_y(min_y), m_max_x(max_x), m_max_y(max_y)
+    {
+        assert(min_x <= max_x);
+        assert(min_y <= max_y);
+    }
+
+    box_t &extend(point_t const &point) noexcept;
+    void extend(point_list_t const &list) noexcept;
+
+    constexpr double min_x() const noexcept { return m_min_x; }
+    constexpr double min_y() const noexcept { return m_min_y; }
+    constexpr double max_x() const noexcept { return m_max_x; }
+    constexpr double max_y() const noexcept { return m_max_y; }
+
+    constexpr double width() const noexcept { return m_max_x - m_min_x; }
+    constexpr double height() const noexcept { return m_max_y - m_min_y; }
+
+    constexpr friend bool operator==(box_t const &a, box_t const &b)
+    {
+        return a.min_x() == b.min_x() && a.min_y() == b.min_y() &&
+               a.max_x() == b.max_x() && a.max_y() == b.max_y();
+    }
+
+    constexpr friend bool operator!=(box_t const &a, box_t const &b)
+    {
+        return !(a == b);
+    }
+
+private:
+    double m_min_x = std::numeric_limits<double>::max();
+    double m_min_y = std::numeric_limits<double>::max();
+    double m_max_x = std::numeric_limits<double>::lowest();
+    double m_max_y = std::numeric_limits<double>::lowest();
+
+}; // class box_t
+
+/**
+ * Calculate the envelope of a geometry.
+ */
+box_t envelope(geometry_t const &geom);
+
+} // namespace geom
+
+#endif // OSM2PGSQL_GEOM_BOX_HPP

tests/CMakeLists.txt

@@ -43,6 +43,7 @@ set_test(test-db-copy-mgr)
 set_test(test-domain-matcher LABELS NoDB)
 set_test(test-expire-tiles LABELS NoDB)
 set_test(test-geom LABELS NoDB)
+set_test(test-geom-box LABELS NoDB)
 set_test(test-middle)
 set_test(test-node-locations LABELS NoDB)
 set_test(test-options-database LABELS NoDB)

tests/test-geom-box.cpp

@@ -0,0 +1,105 @@
+/**
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This file is part of osm2pgsql (https://osm2pgsql.org/).
+ *
+ * Copyright (C) 2006-2022 by the osm2pgsql developer community.
+ * For a full list of authors see the git log.
+ */
+
+#include <catch.hpp>
+
+#include "geom-box.hpp"
+
+TEST_CASE("Extend box_t with points", "[NoDB]")
+{
+    geom::box_t box;
+
+    box.extend(geom::point_t{1.0, 2.0});
+
+    REQUIRE(box.min_x() == Approx(1.0));
+    REQUIRE(box.max_x() == Approx(1.0));
+    REQUIRE(box.min_y() == Approx(2.0));
+    REQUIRE(box.max_y() == Approx(2.0));
+
+    REQUIRE(box.width() == Approx(0.0));
+    REQUIRE(box.height() == Approx(0.0));
+
+    box.extend(geom::point_t{3.0, -2.0});
+
+    REQUIRE(box.min_x() == Approx(1.0));
+    REQUIRE(box.max_x() == Approx(3.0));
+    REQUIRE(box.min_y() == Approx(-2.0));
+    REQUIRE(box.max_y() == Approx(2.0));
+
+    REQUIRE(box.width() == Approx(2.0));
+    REQUIRE(box.height() == Approx(4.0));
+}
+
+TEST_CASE("Extend box_t with linestring", "[NoDB]")
+{
+    geom::box_t box;
+
+    geom::linestring_t const ls{{1.0, 2.0}, {2.0, 2.0}, {-5.0, 3.0}};
+
+    box.extend(ls);
+
+    REQUIRE(box.min_x() == Approx(-5.0));
+    REQUIRE(box.max_x() == Approx(2.0));
+    REQUIRE(box.min_y() == Approx(2.0));
+    REQUIRE(box.max_y() == Approx(3.0));
+
+    REQUIRE(box.width() == Approx(7.0));
+    REQUIRE(box.height() == Approx(1.0));
+}
+
+TEST_CASE("Calculate envelope of null geometry")
+{
+    geom::geometry_t const geom{};
+    REQUIRE(geom::envelope(geom) == geom::box_t{});
+}
+
+TEST_CASE("Calculate envelope of point geometry")
+{
+    geom::geometry_t const geom{geom::point_t{2.3, 1.4}};
+    REQUIRE(geom::envelope(geom) == geom::box_t{2.3, 1.4, 2.3, 1.4});
+}
+
+TEST_CASE("Calculate envelope of linestring geometry")
+{
+    geom::geometry_t const geom{geom::linestring_t{{2.3, 1.4}, {2.5, 1.0}}};
+    REQUIRE(geom::envelope(geom) == geom::box_t{2.3, 1.0, 2.5, 1.4});
+}
+
+TEST_CASE("Calculate envelope of polygon geometry")
+{
+    geom::geometry_t const geom{geom::polygon_t{geom::ring_t{
+        {0.0, 0.0}, {1.0, 0.0}, {1.0, 1.0}, {0.0, 1.0}, {0.0, 0.0}}}};
+    REQUIRE(geom::envelope(geom) == geom::box_t{0.0, 0.0, 1.0, 1.0});
+}
+
+TEST_CASE("Calculate envelope of multilinestring geometry")
+{
+    geom::geometry_t geom{geom::multilinestring_t{}};
+
+    auto &mls = geom.get<geom::multilinestring_t>();
+
+    mls.add_geometry(geom::linestring_t{{2.3, 1.4}, {2.5, 1.0}});
+    mls.add_geometry(geom::linestring_t{{7.3, 0.4}, {2.4, 1.8}});
+
+    REQUIRE(geom::envelope(geom) == geom::box_t{2.3, 0.4, 7.3, 1.8});
+}
+
+TEST_CASE("Calculate envelope of multipolygon geometry")
+{
+    geom::geometry_t geom{geom::multipolygon_t{}};
+
+    auto &mp = geom.get<geom::multipolygon_t>();
+
+    mp.add_geometry(geom::polygon_t{geom::ring_t{
+        {1.1, 1.1}, {1.1, 3.3}, {2.2, 3.3}, {2.2, 1.1}, {1.1, 1.1}}});
+    mp.add_geometry(geom::polygon_t{geom::ring_t{
+        {2.2, 2.2}, {2.2, 3.3}, {4.4, 3.3}, {4.4, 2.2}, {2.2, 2.2}}});
+
+    REQUIRE(geom::envelope(geom) == geom::box_t{1.1, 1.1, 4.4, 3.3});
+}