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130 lines
3.8 KiB
C++
130 lines
3.8 KiB
C++
//----------------------------------------------------------------------------
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// Anti-Grain Geometry (AGG) - Version 2.5
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// A high quality rendering engine for C++
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// Copyright (C) 2002-2006 Maxim Shemanarev
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://antigrain.com
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//
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// AGG is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// AGG is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with AGG; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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// MA 02110-1301, USA.
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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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