headers/libs/agg/agg_gamma_lut.h

   1 //----------------------------------------------------------------------------
   2 // Anti-Grain Geometry - Version 2.4
   3 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
   4 //
   5 // Permission to copy, use, modify, sell and distribute this software
   6 // is granted provided this copyright notice appears in all copies.
   7 // This software is provided "as is" without express or implied
   8 // warranty, and with no claim as to its suitability for any purpose.
   9 //
  10 //----------------------------------------------------------------------------
  11 // Contact: mcseem@antigrain.com
  12 //          mcseemagg@yahoo.com
  13 //          http://www.antigrain.com
  14 //----------------------------------------------------------------------------
  15
  16 #ifndef AGG_GAMMA_LUT_INCLUDED
  17 #define AGG_GAMMA_LUT_INCLUDED
  18
  19 #include <math.h>
  20 #include "agg_basics.h"
  21
  22 namespace agg
  23 {
  24     template<class LoResT=int8u,
  25              class HiResT=int8u,
  26              unsigned GammaShift=8,
  27              unsigned HiResShift=8> class gamma_lut
  28     {
  29     public:
  30         typedef gamma_lut<LoResT, HiResT, GammaShift, HiResShift> self_type;
  31
  32         enum gamma_scale_e
  33         {
  34             gamma_shift = GammaShift,
  35             gamma_size  = 1 << gamma_shift,
  36             gamma_mask  = gamma_size - 1
  37         };
  38
  39         enum hi_res_scale_e
  40         {
  41             hi_res_shift = HiResShift,
  42             hi_res_size  = 1 << hi_res_shift,
  43             hi_res_mask  = hi_res_size - 1
  44         };
  45
  46         ~gamma_lut()
  47         {
  48             pod_allocator<LoResT>::deallocate(m_inv_gamma, hi_res_size);
  49             pod_allocator<HiResT>::deallocate(m_dir_gamma, gamma_size);
  50         }
  51
  52         gamma_lut() :
  53             m_gamma(1.0),
  54             m_dir_gamma(pod_allocator<HiResT>::allocate(gamma_size)),
  55             m_inv_gamma(pod_allocator<LoResT>::allocate(hi_res_size))
  56         {
  57             unsigned i;
  58             for(i = 0; i < gamma_size; i++)
  59             {
  60                 m_dir_gamma[i] = HiResT(i << (hi_res_shift - gamma_shift));
  61             }
  62
  63             for(i = 0; i < hi_res_size; i++)
  64             {
  65                 m_inv_gamma[i] = LoResT(i >> (hi_res_shift - gamma_shift));
  66             }
  67         }
  68
  69         gamma_lut(double g) :
  70             m_gamma(1.0),
  71             m_dir_gamma(pod_allocator<HiResT>::allocate(gamma_size)),
  72             m_inv_gamma(pod_allocator<LoResT>::allocate(hi_res_size))
  73         {
  74             gamma(g);
  75         }
  76
  77         void gamma(double g)
  78         {
  79             m_gamma = g;
  80
  81             unsigned i;
  82             for(i = 0; i < gamma_size; i++)
  83             {
  84                 m_dir_gamma[i] = (HiResT)
  85                     uround(pow(i / double(gamma_mask), m_gamma) * double(hi_res_mask));
  86             }
  87
  88             double inv_g = 1.0 / g;
  89             for(i = 0; i < hi_res_size; i++)
  90             {
  91                 m_inv_gamma[i] = (LoResT)
  92                     uround(pow(i / double(hi_res_mask), inv_g) * double(gamma_mask));
  93             }
  94         }
  95
  96         double gamma() const
  97         {
  98             return m_gamma;
  99         }
 100
 101         HiResT dir(LoResT v) const
 102         {
 103             return m_dir_gamma[unsigned(v)];
 104         }
 105
 106         LoResT inv(HiResT v) const
 107         {
 108             return m_inv_gamma[unsigned(v)];
 109         }
 110
 111     private:
 112         gamma_lut(const self_type&);
 113         const self_type& operator = (const self_type&);
 114
 115         double m_gamma;
 116         HiResT* m_dir_gamma;
 117         LoResT* m_inv_gamma;
 118     };
 119 }
 120
 121 #endif