1 files changed, 75 insertions, 0 deletions
diff --git a/src/graphics/ContribDefs.h b/src/graphics/ContribDefs.h
new file mode 100644
index 0000000..8032aef
--- /dev/null
+++ b/src/graphics/ContribDefs.h
@@ -0,0 +1,75 @@
+// Fast and accurate bitmap scaling. Original code by Eran Yariv and Jake Montgomery,
+// posted on codeguru.com.
+
+#ifndef _ContribDefs_h_
+#define _ContribDefs_h_
+
+#include "../base/MathHelper.h"
+
+#include <math.h>
+
+namespace avg {
+
+class ContribDef
+{
+public:
+    ContribDef(float dWidth) 
+        : m_dWidth (dWidth)
+    {}
+
+    virtual ~ContribDef() {}
+
+    float GetWidth() const   
+    { 
+        return m_dWidth; 
+    }
+
+    void SetWidth(float dWidth)
+    { 
+        m_dWidth = dWidth; 
+    }
+
+    virtual float Filter(float dVal) const = 0;
+
+protected:
+    float  m_dWidth;
+};
+
+class BilinearContribDef : public ContribDef
+{
+public:
+    BilinearContribDef(float dWidth = 1.0) 
+        : ContribDef(dWidth)
+    {}
+
+    virtual ~BilinearContribDef() {}
+
+    virtual float Filter(float dVal) const
+    {
+        dVal = fabs(dVal);
+        return (dVal < m_dWidth ? m_dWidth - dVal : 0.0f);
+    }
+};
+
+class GaussianContribDef : public ContribDef
+{
+public:
+    GaussianContribDef(float dWidth = 3.0)
+        : ContribDef(dWidth) 
+    {}
+
+    virtual ~GaussianContribDef() {}
+
+    virtual float Filter(float dVal) const
+    {
+        if (fabs (dVal) > m_dWidth)
+        {
+            return 0.0;
+        }
+        return float(exp(-dVal * dVal/m_dWidth-1) / sqrt(2*PI));
+    }
+};
+
+}
+
+#endif