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//----------------------------------------------------------------------------
// Anti-Grain Geometry - Version 2.4
// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
//----------------------------------------------------------------------------
// Contact: mcseem@antigrain.com
// mcseemagg@yahoo.com
// http://www.antigrain.com
//----------------------------------------------------------------------------
#ifndef AGG_GAMMA_LUT_INCLUDED
#define AGG_GAMMA_LUT_INCLUDED
#include <math.h>
#include "agg_basics.h"
namespace agg
{
template<class LoResT=int8u,
class HiResT=int8u,
unsigned GammaShift=8,
unsigned HiResShift=8> class gamma_lut
{
public:
typedef gamma_lut<LoResT, HiResT, GammaShift, HiResShift> self_type;
enum gamma_scale_e
{
gamma_shift = GammaShift,
gamma_size = 1 << gamma_shift,
gamma_mask = gamma_size - 1
};
enum hi_res_scale_e
{
hi_res_shift = HiResShift,
hi_res_size = 1 << hi_res_shift,
hi_res_mask = hi_res_size - 1
};
~gamma_lut()
{
pod_allocator<LoResT>::deallocate(m_inv_gamma, hi_res_size);
pod_allocator<HiResT>::deallocate(m_dir_gamma, gamma_size);
}
gamma_lut() :
m_gamma(1.0),
m_dir_gamma(pod_allocator<HiResT>::allocate(gamma_size)),
m_inv_gamma(pod_allocator<LoResT>::allocate(hi_res_size))
{
unsigned i;
for(i = 0; i < gamma_size; i++)
{
m_dir_gamma[i] = HiResT(i << (hi_res_shift - gamma_shift));
}
for(i = 0; i < hi_res_size; i++)
{
m_inv_gamma[i] = LoResT(i >> (hi_res_shift - gamma_shift));
}
}
gamma_lut(double g) :
m_gamma(1.0),
m_dir_gamma(pod_allocator<HiResT>::allocate(gamma_size)),
m_inv_gamma(pod_allocator<LoResT>::allocate(hi_res_size))
{
gamma(g);
}
void gamma(double g)
{
m_gamma = g;
unsigned i;
for(i = 0; i < gamma_size; i++)
{
m_dir_gamma[i] = (HiResT)
uround(pow(i / double(gamma_mask), m_gamma) * double(hi_res_mask));
}
double inv_g = 1.0 / g;
for(i = 0; i < hi_res_size; i++)
{
m_inv_gamma[i] = (LoResT)
uround(pow(i / double(hi_res_mask), inv_g) * double(gamma_mask));
}
}
double gamma() const
{
return m_gamma;
}
HiResT dir(LoResT v) const
{
return m_dir_gamma[unsigned(v)];
}
LoResT inv(HiResT v) const
{
return m_inv_gamma[unsigned(v)];
}
private:
gamma_lut(const self_type&);
const self_type& operator = (const self_type&);
double m_gamma;
HiResT* m_dir_gamma;
LoResT* m_inv_gamma;
};
}
#endif
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