1 files changed, 81 insertions, 0 deletions
diff --git a/scale.h b/scale.h
new file mode 100644
index 0000000..bfe18ae
--- /dev/null
+++ b/scale.h
@@ -0,0 +1,81 @@
+#ifndef SCALE_H
+#define SCALE_H
+
+#include <algorithm>
+
+class Scale
+{
+public:
+    Scale(float domainMin, float domainMax, float rangeMin, float rangeMax)
+        : m_domainMin(domainMin)
+        , m_domainMax(domainMax)
+        , m_rangeMin(rangeMin)
+        , m_rangeMax(rangeMax)
+    {
+        valuesUpdated();
+    }
+
+    virtual ~Scale() {}
+
+    void setRangeMin(float rangeMin)   { m_rangeMin  = rangeMin; valuesUpdated(); }
+    void setRangeMax(float rangeMax)   { m_rangeMax  = rangeMax; valuesUpdated(); }
+    void setDomainMin(float domainMin) { m_domainMin = domainMin; valuesUpdated(); }
+    void setDomainMax(float domainMax) { m_domainMax = domainMax; valuesUpdated(); }
+
+    void setRange(float rangeMin, float rangeMax)
+    {
+        m_rangeMin = rangeMin;
+        m_rangeMax = rangeMax;
+        valuesUpdated();
+    }
+
+    void setDomain(float domainMin, float domainMax)
+    {
+        m_domainMin = domainMin;
+        m_domainMax = domainMax;
+        valuesUpdated();
+    }
+
+    void reverse()
+    {
+        std::swap(m_rangeMin, m_domainMin);
+        std::swap(m_rangeMax, m_domainMax);
+        valuesUpdated();
+    }
+
+    virtual float operator()(float value) const = 0;
+
+protected:
+    // Called when internal values change
+    virtual void valuesUpdated() {}
+
+    float m_domainMin, m_domainMax;
+    float m_rangeMin, m_rangeMax;
+};
+
+class LinearScale
+    : public Scale
+{
+public:
+    LinearScale(float domainMin, float domainMax, float rangeMin, float rangeMax)
+        : Scale(domainMin, domainMax, rangeMin, rangeMax)
+    {
+        valuesUpdated();
+    }
+
+    virtual float operator()(float value) const
+    {
+        return (value - m_domainMin) * m_transformSlope + m_rangeMin;
+    }
+
+protected:
+    virtual void valuesUpdated()
+    {
+        m_transformSlope = (m_rangeMax - m_rangeMin) / (m_domainMax - m_domainMin);
+    }
+
+private:
+    float m_transformSlope;
+};
+
+#endif // SCALE_H