[drape] helper class for create chain of animations

1 files changed, 72 insertions, 0 deletions

diff --git a/drape_frontend/animation/value_mapping.hpp b/drape_frontend/animation/value_mapping.hpp
new file mode 100644
index 0000000000..5c8cbe2360
--- /dev/null
+++ b/drape_frontend/animation/value_mapping.hpp
@@ -0,0 +1,72 @@
+#pragma once
+
+#include "base/buffer_vector.hpp"
+#include "base/logging.hpp"
+
+namespace df
+{
+
+template <typename TValue>
+class ValueMapping
+{
+  /// double = interpolation point [0.0, 1.0]
+  /// TValue = output value
+  using TRangePoint = pair<double, TValue>;
+  using TRangeVector = buffer_vector<TRangePoint, 8>;
+  using TRangeIter = typename TRangeVector::const_iterator;
+public:
+  ValueMapping() = default;
+
+  void AddRangePoint(double t, TValue const & v)
+  {
+#ifdef DEBUG
+    if (!m_ranges.empty())
+      ASSERT(m_ranges.back().first < t, ());
+#endif
+    m_ranges.emplace_back(t, v);
+  }
+
+  TValue GetValue(double t)
+  {
+    TRangePoint startPoint, endPoint;
+    GetRangePoints(t, startPoint, endPoint);
+
+    double normT = t - startPoint.first;
+    double rangeT = endPoint.first - startPoint.first;
+    double rangeV = endPoint.second - startPoint.second;
+
+    return startPoint.second + rangeV * normT / rangeT;
+  }
+
+private:
+  void GetRangePoints(double t, TRangePoint & startPoint, TRangePoint & endPoint)
+  {
+    ASSERT(t >= 0.0 && t <= 1.0, ());
+    ASSERT(m_ranges.size() > 1, ());
+
+    TRangeIter startIter = m_ranges.begin();
+    if (t < startIter->first)
+    {
+      startPoint.first = 0.0;
+      startPoint.second = TValue();
+      endPoint = *startIter;
+      return;
+    }
+
+    TRangeIter endIter = startIter + 1;
+    while (t > endIter->first)
+    {
+      endIter++;
+      ASSERT(m_ranges.end() != endIter, ());
+    }
+
+    ASSERT(startIter->first <= t && t <= endIter->first, ());
+    startPoint = *startIter;
+    endPoint = *endIter;
+  }
+
+private:
+  TRangeVector m_ranges;
+};
+
+}