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// 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
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