Add Visione backend foundation

common/GeoJson.cc

@@ -0,0 +1,59 @@
+#include "common/GeoJson.h"
+
+#include <vector>
+
+namespace visione::geojson
+{
+namespace
+{
+struct Point
+{
+    double x;
+    double y;
+};
+}  // namespace
+
+bool pointInPolygon(double latitude, double longitude, const Json::Value &geojson)
+{
+    if (!geojson.isObject() || geojson["type"].asString() != "Polygon" ||
+        !geojson["coordinates"].isArray() || geojson["coordinates"].empty())
+    {
+        return false;
+    }
+
+    const auto &ring = geojson["coordinates"][0];
+    if (!ring.isArray() || ring.size() < 4)
+    {
+        return false;
+    }
+
+    std::vector<Point> points;
+    points.reserve(ring.size());
+    for (const auto &coordinate : ring)
+    {
+        if (!coordinate.isArray() || coordinate.size() < 2)
+        {
+            return false;
+        }
+        points.push_back({coordinate[0].asDouble(), coordinate[1].asDouble()});
+    }
+
+    const auto x = longitude;
+    const auto y = latitude;
+    bool inside = false;
+    for (size_t i = 0, j = points.size() - 1; i < points.size(); j = i++)
+    {
+        const auto &pi = points[i];
+        const auto &pj = points[j];
+        const bool intersects =
+            ((pi.y > y) != (pj.y > y)) &&
+            (x < (pj.x - pi.x) * (y - pi.y) / (pj.y - pi.y) + pi.x);
+        if (intersects)
+        {
+            inside = !inside;
+        }
+    }
+    return inside;
+}
+}  // namespace visione::geojson
+