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