Get correct center for point or area feature in GetVisiblePOI.

1 files changed, 106 insertions, 0 deletions

diff --git a/indexer/feature_algo.cpp b/indexer/feature_algo.cpp
new file mode 100644
index 0000000000..996b3fb426
--- /dev/null
+++ b/indexer/feature_algo.cpp
@@ -0,0 +1,106 @@
+#include "feature_algo.hpp"
+#include "feature.hpp"
+
+
+namespace feature
+{
+
+class CalcPolyCenter
+{
+  typedef m2::PointD P;
+
+  struct Value
+  {
+    Value(P const & p, double l) : m_p(p), m_len(l) {}
+
+    bool operator< (Value const & r) const { return (m_len < r.m_len); }
+
+    P m_p;
+    double m_len;
+  };
+
+  vector<Value> m_poly;
+  double m_length;
+
+public:
+  CalcPolyCenter() : m_length(0.0) {}
+
+  void operator() (CoordPointT const & pt)
+  {
+    m2::PointD p(pt.first, pt.second);
+
+    m_length += (m_poly.empty() ? 0.0 : m_poly.back().m_p.Length(p));
+    m_poly.push_back(Value(p, m_length));
+  }
+
+  P GetCenter() const
+  {
+    typedef vector<Value>::const_iterator IterT;
+
+    double const l = m_length / 2.0;
+
+    IterT e = lower_bound(m_poly.begin(), m_poly.end(), Value(m2::PointD(0, 0), l));
+    if (e == m_poly.begin())
+    {
+      /// @todo It's very strange, but we have linear objects with zero length.
+      LOG(LWARNING, ("Zero length linear object"));
+      return e->m_p;
+    }
+
+    IterT b = e-1;
+
+    double const f = (l - b->m_len) / (e->m_len - b->m_len);
+
+    // For safety reasons (floating point calculations) do comparison instead of ASSERT.
+    if (0.0 <= f && f <= 1.0)
+      return (b->m_p * (1-f) + e->m_p * f);
+    else
+      return ((b->m_p + e->m_p) / 2.0);
+  }
+};
+
+class CalcMassCenter
+{
+  typedef m2::PointD P;
+  P m_center;
+  size_t m_count;
+
+public:
+  CalcMassCenter() : m_center(0.0, 0.0), m_count(0) {}
+
+  void operator() (P const & p1, P const & p2, P const & p3)
+  {
+    ++m_count;
+    m_center += p1;
+    m_center += p2;
+    m_center += p3;
+  }
+  P GetCenter() const { return m_center / (3*m_count); }
+};
+
+m2::PointD GetCenter(FeatureType const & f)
+{
+  feature::EGeomType const type = f.GetFeatureType();
+  switch (type)
+  {
+  case feature::GEOM_POINT:
+    return f.GetCenter();
+
+  case feature::GEOM_LINE:
+    {
+      CalcPolyCenter doCalc;
+      f.ForEachPointRef(doCalc, FeatureType::BEST_GEOMETRY);
+      return doCalc.GetCenter();
+    }
+
+  default:
+    {
+      ASSERT_EQUAL ( type, feature::GEOM_AREA, () );
+      CalcMassCenter doCalc;
+      f.ForEachTriangleRef(doCalc, FeatureType::BEST_GEOMETRY);
+      return doCalc.GetCenter();
+    }
+  }
+}
+
+}