MapLibreParticleLab/test/tile/tile_coordinate.test.cpp

#include <mbgl/test/util.hpp>

#include <mbgl/map/transform.hpp>
#include <mbgl/map/transform_state.hpp>
#include <mbgl/tile/tile.hpp>
#include <mbgl/tile/tile_id.hpp>
#include <mbgl/util/constants.hpp>
#include <mbgl/util/geometry.hpp>
#include <mbgl/util/tile_coordinate.hpp>

using namespace mln;

TEST(TileCoordinate, FromLatLng) {
    size_t changeCount = 0;
    struct TransformObserver : public mln::TransformObserver {
        void onCameraWillChange(MapObserver::CameraChangeMode mode) final {
            if (mode == MapObserver::CameraChangeMode::Immediate && cameraWillChangeImmediateCallback) {
                cameraWillChangeImmediateCallback();
            }
        }

        void onCameraDidChange(MapObserver::CameraChangeMode mode) final {
            if (mode == MapObserver::CameraChangeMode::Immediate && cameraDidChangeImmediateCallback) {
                cameraDidChangeImmediateCallback();
            }
        }

        std::function<void()> cameraWillChangeImmediateCallback;
        std::function<void()> cameraDidChangeImmediateCallback;
    };

    TransformObserver observer;
    observer.cameraWillChangeImmediateCallback = [&]() {
        ASSERT_EQ(changeCount, 0u);
        ++changeCount;
    };
    observer.cameraDidChangeImmediateCallback = [&]() {
        ASSERT_EQ(changeCount, 1u);
    };

    Transform transform(observer);

    const double max = util::tileSize_D;
    transform.resize({static_cast<uint32_t>(max), static_cast<uint32_t>(max)});

    // Center, top-left, bottom-left, bottom-right, top-right edges.
    std::vector<std::pair<LatLng, ScreenCoordinate>> edges{
        {{}, {max / 2.0, max / 2.0}},
        {{util::LATITUDE_MAX, -util::LONGITUDE_MAX}, {0, max}},
        {{-util::LATITUDE_MAX, -util::LONGITUDE_MAX}, {0, 0}},
        {{-util::LATITUDE_MAX, util::LONGITUDE_MAX}, {max, 0}},
        {{util::LATITUDE_MAX, util::LONGITUDE_MAX}, {max, max}},
    };

    for (const auto& pair : edges) {
        const auto& latLng = pair.first;
        const auto& screenCoordinate = pair.second;
        const auto base = TileCoordinate::fromLatLng(0, latLng);

        // 16 is the maximum zoom level where we actually compute placements.
        for (uint8_t integerZoom = 0; integerZoom <= 16; ++integerZoom) {
            const double zoom = integerZoom;
            const double maxTilesPerAxis = std::pow(2.0, zoom);
            const Point<double> tilePoint = {
                latLng.longitude() == 0                      ? 0.5
                : latLng.longitude() == -util::LONGITUDE_MAX ? 0
                                                             : 1.0,
                latLng.latitude() == 0                     ? 0.5
                : latLng.latitude() == -util::LATITUDE_MAX ? 1.0
                                                           : 0,
            };

            const auto fromLatLng = TileCoordinate::fromLatLng(zoom, latLng);
            ASSERT_DOUBLE_EQ(fromLatLng.z, zoom);
            ASSERT_DOUBLE_EQ(fromLatLng.p.x, tilePoint.x * maxTilesPerAxis);
            ASSERT_NEAR(fromLatLng.p.y, tilePoint.y * maxTilesPerAxis, 1.0e-7);

            const auto fromScreenCoordinate = TileCoordinate::fromScreenCoordinate(
                transform.getState(), static_cast<uint8_t>(zoom), screenCoordinate);
            ASSERT_DOUBLE_EQ(fromScreenCoordinate.z, fromLatLng.z);
            ASSERT_NEAR(fromScreenCoordinate.p.x, fromLatLng.p.x, 0.99);
            ASSERT_NEAR(fromScreenCoordinate.p.y, fromLatLng.p.y, 0.99);

            const auto zoomed = base.zoomTo(zoom);
            ASSERT_DOUBLE_EQ(zoomed.z, zoom);
            ASSERT_DOUBLE_EQ(zoomed.p.x, fromLatLng.p.x);
            ASSERT_DOUBLE_EQ(zoomed.p.y, fromLatLng.p.y);
        }
    }
}

TEST(TileCoordinate, ToGeometryCoordinate) {
    std::vector<Point<double>> edges{{0.5, 0.5}, {0, 0}, {1, 0}, {1, 1}, {0, 1}};

    for (uint8_t zoom = 0; zoom <= 16; ++zoom) {
        auto maxTilesPerAxis = static_cast<uint32_t>(std::pow(2, zoom));
        for (const auto& edge : edges) {
            uint32_t tileX = edge.x == 0   ? 0
                             : edge.x == 1 ? maxTilesPerAxis - 1
                                           : static_cast<uint32_t>((maxTilesPerAxis / 2.0) - 1);
            uint32_t tileY = edge.y == 0   ? 0
                             : edge.y == 1 ? maxTilesPerAxis - 1
                                           : static_cast<uint32_t>((maxTilesPerAxis / 2.0) - 1);
            UnwrappedTileID unwrapped(0, CanonicalTileID{zoom, tileX, tileY});

            auto tilePointX = ((edge.x * maxTilesPerAxis) - tileX) * util::EXTENT;
            auto tilePointY = ((edge.y * maxTilesPerAxis) - tileY) * util::EXTENT;
            GeometryCoordinate point = TileCoordinate::toGeometryCoordinate(unwrapped, edge);
            ASSERT_DOUBLE_EQ(point.x, tilePointX);
            ASSERT_DOUBLE_EQ(point.y, tilePointY);
        }
    }
}