mapnik/deps/agg/include/agg_pixfmt_rgba.h

//----------------------------------------------------------------------------
// 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
//----------------------------------------------------------------------------
//
// Adaptation for high precision colors has been sponsored by
// Liberty Technology Systems, Inc., visit http://lib-sys.com
//
// Liberty Technology Systems, Inc. is the provider of
// PostScript and PDF technology for software developers.
//
//----------------------------------------------------------------------------

#ifndef AGG_PIXFMT_RGBA_INCLUDED
#define AGG_PIXFMT_RGBA_INCLUDED

#include <string.h>
#include <math.h>
#include "agg_basics.h"
#include "agg_color_rgba.h"
#include "agg_rendering_buffer.h"

#include <boost/gil/gil_all.hpp>
#include <boost/gil/extension/toolbox/hsv.hpp>

#include <iostream>

namespace agg
{

    //=========================================================multiplier_rgba
    template<class ColorT, class Order> struct multiplier_rgba
    {
        typedef typename ColorT::value_type value_type;
        typedef typename ColorT::calc_type calc_type;

        //--------------------------------------------------------------------
        static AGG_INLINE void premultiply(value_type* p)
        {
            calc_type a = p[Order::A];
            if(a < ColorT::base_mask)
            {
                if(a == 0)
                {
                    p[Order::R] = p[Order::G] = p[Order::B] = 0;
                    return;
                }
                p[Order::R] = value_type((p[Order::R] * a + ColorT::base_mask) >> ColorT::base_shift);
                p[Order::G] = value_type((p[Order::G] * a + ColorT::base_mask) >> ColorT::base_shift);
                p[Order::B] = value_type((p[Order::B] * a + ColorT::base_mask) >> ColorT::base_shift);
            }
        }


        //--------------------------------------------------------------------
        static AGG_INLINE void demultiply(value_type* p)
        {
            calc_type a = p[Order::A];
            if(a < ColorT::base_mask)
            {
                if(a == 0)
                {
                    p[Order::R] = p[Order::G] = p[Order::B] = 0;
                    return;
                }
                calc_type r = (calc_type(p[Order::R]) * ColorT::base_mask) / a;
                calc_type g = (calc_type(p[Order::G]) * ColorT::base_mask) / a;
                calc_type b = (calc_type(p[Order::B]) * ColorT::base_mask) / a;
                p[Order::R] = value_type((r > ColorT::base_mask) ? ColorT::base_mask : r);
                p[Order::G] = value_type((g > ColorT::base_mask) ? ColorT::base_mask : g);
                p[Order::B] = value_type((b > ColorT::base_mask) ? ColorT::base_mask : b);
            }
        }
    };

    //=====================================================apply_gamma_dir_rgba
    template<class ColorT, class Order, class GammaLut> class apply_gamma_dir_rgba
    {
    public:
        typedef typename ColorT::value_type value_type;

        apply_gamma_dir_rgba(const GammaLut& gamma) : m_gamma(gamma) {}

        AGG_INLINE void operator () (value_type* p)
        {
            p[Order::R] = m_gamma.dir(p[Order::R]);
            p[Order::G] = m_gamma.dir(p[Order::G]);
            p[Order::B] = m_gamma.dir(p[Order::B]);
        }

    private:
        const GammaLut& m_gamma;
    };

    //=====================================================apply_gamma_inv_rgba
    template<class ColorT, class Order, class GammaLut> class apply_gamma_inv_rgba
    {
    public:
        typedef typename ColorT::value_type value_type;

        apply_gamma_inv_rgba(const GammaLut& gamma) : m_gamma(gamma) {}

        AGG_INLINE void operator () (value_type* p)
        {
            p[Order::R] = m_gamma.inv(p[Order::R]);
            p[Order::G] = m_gamma.inv(p[Order::G]);
            p[Order::B] = m_gamma.inv(p[Order::B]);
        }

    private:
        const GammaLut& m_gamma;
    };

    //=============================================================blender_rgba
    template<class ColorT, class Order> struct blender_rgba
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        //--------------------------------------------------------------------
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha,
                                         unsigned cover=0)
        {
            calc_type r = p[Order::R];
            calc_type g = p[Order::G];
            calc_type b = p[Order::B];
            calc_type a = p[Order::A];
            p[Order::R] = (value_type)(((cr - r) * alpha + (r << base_shift)) >> base_shift);
            p[Order::G] = (value_type)(((cg - g) * alpha + (g << base_shift)) >> base_shift);
            p[Order::B] = (value_type)(((cb - b) * alpha + (b << base_shift)) >> base_shift);
            p[Order::A] = (value_type)((alpha + a) - ((alpha * a + base_mask) >> base_shift));
        }
    };

    //=========================================================blender_rgba_pre
    template<class ColorT, class Order> struct blender_rgba_pre
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        //--------------------------------------------------------------------
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha,
                                         unsigned cover)
        {
            alpha = color_type::base_mask - alpha;
            cover = (cover + 1) << (base_shift - 8);
            p[Order::R] = (value_type)((p[Order::R] * alpha + cr * cover) >> base_shift);
            p[Order::G] = (value_type)((p[Order::G] * alpha + cg * cover) >> base_shift);
            p[Order::B] = (value_type)((p[Order::B] * alpha + cb * cover) >> base_shift);
            p[Order::A] = (value_type)(base_mask - ((alpha * (base_mask - p[Order::A])) >> base_shift));
        }

        //--------------------------------------------------------------------
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha)
        {
            alpha = color_type::base_mask - alpha;
            p[Order::R] = (value_type)(((p[Order::R] * alpha) >> base_shift) + cr);
            p[Order::G] = (value_type)(((p[Order::G] * alpha) >> base_shift) + cg);
            p[Order::B] = (value_type)(((p[Order::B] * alpha) >> base_shift) + cb);
            p[Order::A] = (value_type)(base_mask - ((alpha * (base_mask - p[Order::A])) >> base_shift));
        }
    };

    //======================================================blender_rgba_plain
    template<class ColorT, class Order> struct blender_rgba_plain
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e { base_shift = color_type::base_shift };

        //--------------------------------------------------------------------
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha,
                                         unsigned /*cover*/=0)
        {
            if(alpha == 0) return;
            calc_type a = p[Order::A];
            calc_type r = p[Order::R] * a;
            calc_type g = p[Order::G] * a;
            calc_type b = p[Order::B] * a;
            a = ((alpha + a) << base_shift) - alpha * a;
            p[Order::A] = (value_type)(a >> base_shift);
            p[Order::R] = (value_type)((((cr << base_shift) - r) * alpha + (r << base_shift)) / a);
            p[Order::G] = (value_type)((((cg << base_shift) - g) * alpha + (g << base_shift)) / a);
            p[Order::B] = (value_type)((((cb << base_shift) - b) * alpha + (b << base_shift)) / a);
        }
    };











    //=========================================================comp_op_rgba_clear
    template<class ColorT, class Order> struct comp_op_rgba_clear
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned, unsigned, unsigned, unsigned,
                                         unsigned cover)
        {
            if(cover < 255)
            {
                cover = 255 - cover;
                p[Order::R] = (value_type)((p[Order::R] * cover + 255) >> 8);
                p[Order::G] = (value_type)((p[Order::G] * cover + 255) >> 8);
                p[Order::B] = (value_type)((p[Order::B] * cover + 255) >> 8);
                p[Order::A] = (value_type)((p[Order::A] * cover + 255) >> 8);
            }
            else
            {
                p[0] = p[1] = p[2] = p[3] = 0;
            }
        }
    };

    //===========================================================comp_op_rgba_src
    template<class ColorT, class Order> struct comp_op_rgba_src
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                unsigned alpha = 255 - cover;
                p[Order::R] = (value_type)(((p[Order::R] * alpha + 255) >> 8) + ((sr * cover + 255) >> 8));
                p[Order::G] = (value_type)(((p[Order::G] * alpha + 255) >> 8) + ((sg * cover + 255) >> 8));
                p[Order::B] = (value_type)(((p[Order::B] * alpha + 255) >> 8) + ((sb * cover + 255) >> 8));
                p[Order::A] = (value_type)(((p[Order::A] * alpha + 255) >> 8) + ((sa * cover + 255) >> 8));
            }
            else
            {
                p[Order::R] = sr;
                p[Order::G] = sg;
                p[Order::B] = sb;
                p[Order::A] = sa;
            }
        }
    };

    //===========================================================comp_op_rgba_dst
    template<class ColorT, class Order> struct comp_op_rgba_dst
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;

        static AGG_INLINE void blend_pix(value_type*,
                                         unsigned, unsigned, unsigned,
                                         unsigned, unsigned)
        {
        }
    };

    //======================================================comp_op_rgba_src_over
    template<class ColorT, class Order> struct comp_op_rgba_src_over
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        //   Dca' = Sca + Dca.(1 - Sa)
        //   Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            calc_type s1a = base_mask - sa;
            p[Order::R] = (value_type)(sr + ((p[Order::R] * s1a + base_mask) >> base_shift));
            p[Order::G] = (value_type)(sg + ((p[Order::G] * s1a + base_mask) >> base_shift));
            p[Order::B] = (value_type)(sb + ((p[Order::B] * s1a + base_mask) >> base_shift));
            p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
        }
    };

    //======================================================comp_op_rgba_dst_over
    template<class ColorT, class Order> struct comp_op_rgba_dst_over
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Dca + Sca.(1 - Da)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            calc_type d1a = base_mask - p[Order::A];
            p[Order::R] = (value_type)(p[Order::R] + ((sr * d1a + base_mask) >> base_shift));
            p[Order::G] = (value_type)(p[Order::G] + ((sg * d1a + base_mask) >> base_shift));
            p[Order::B] = (value_type)(p[Order::B] + ((sb * d1a + base_mask) >> base_shift));
            p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
        }
    };

    //======================================================comp_op_rgba_src_in
    template<class ColorT, class Order> struct comp_op_rgba_src_in
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca.Da
        // Da'  = Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            calc_type da = p[Order::A];
            if(cover < 255)
            {
                unsigned alpha = 255 - cover;
                p[Order::R] = (value_type)(((p[Order::R] * alpha + 255) >> 8) + ((((sr * da + base_mask) >> base_shift) * cover + 255) >> 8));
                p[Order::G] = (value_type)(((p[Order::G] * alpha + 255) >> 8) + ((((sg * da + base_mask) >> base_shift) * cover + 255) >> 8));
                p[Order::B] = (value_type)(((p[Order::B] * alpha + 255) >> 8) + ((((sb * da + base_mask) >> base_shift) * cover + 255) >> 8));
                p[Order::A] = (value_type)(((p[Order::A] * alpha + 255) >> 8) + ((((sa * da + base_mask) >> base_shift) * cover + 255) >> 8));
            }
            else
            {
                p[Order::R] = (value_type)((sr * da + base_mask) >> base_shift);
                p[Order::G] = (value_type)((sg * da + base_mask) >> base_shift);
                p[Order::B] = (value_type)((sb * da + base_mask) >> base_shift);
                p[Order::A] = (value_type)((sa * da + base_mask) >> base_shift);
            }
        }
    };

    //======================================================comp_op_rgba_dst_in
    template<class ColorT, class Order> struct comp_op_rgba_dst_in
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Dca.Sa
        // Da'  = Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned, unsigned, unsigned,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sa = base_mask - ((cover * (base_mask - sa) + 255) >> 8);
            }
            p[Order::R] = (value_type)((p[Order::R] * sa + base_mask) >> base_shift);
            p[Order::G] = (value_type)((p[Order::G] * sa + base_mask) >> base_shift);
            p[Order::B] = (value_type)((p[Order::B] * sa + base_mask) >> base_shift);
            p[Order::A] = (value_type)((p[Order::A] * sa + base_mask) >> base_shift);
        }
    };

    //======================================================comp_op_rgba_src_out
    template<class ColorT, class Order> struct comp_op_rgba_src_out
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca.(1 - Da)
        // Da'  = Sa.(1 - Da)
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            calc_type da = base_mask - p[Order::A];
            if(cover < 255)
            {
                unsigned alpha = 255 - cover;
                p[Order::R] = (value_type)(((p[Order::R] * alpha + 255) >> 8) + ((((sr * da + base_mask) >> base_shift) * cover + 255) >> 8));
                p[Order::G] = (value_type)(((p[Order::G] * alpha + 255) >> 8) + ((((sg * da + base_mask) >> base_shift) * cover + 255) >> 8));
                p[Order::B] = (value_type)(((p[Order::B] * alpha + 255) >> 8) + ((((sb * da + base_mask) >> base_shift) * cover + 255) >> 8));
                p[Order::A] = (value_type)(((p[Order::A] * alpha + 255) >> 8) + ((((sa * da + base_mask) >> base_shift) * cover + 255) >> 8));
            }
            else
            {
                p[Order::R] = (value_type)((sr * da + base_mask) >> base_shift);
                p[Order::G] = (value_type)((sg * da + base_mask) >> base_shift);
                p[Order::B] = (value_type)((sb * da + base_mask) >> base_shift);
                p[Order::A] = (value_type)((sa * da + base_mask) >> base_shift);
            }
        }
    };

    //======================================================comp_op_rgba_dst_out
    template<class ColorT, class Order> struct comp_op_rgba_dst_out
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Dca.(1 - Sa)
        // Da'  = Da.(1 - Sa)
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned, unsigned, unsigned,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sa = (sa * cover + 255) >> 8;
            }
            sa = base_mask - sa;
            p[Order::R] = (value_type)((p[Order::R] * sa + base_shift) >> base_shift);
            p[Order::G] = (value_type)((p[Order::G] * sa + base_shift) >> base_shift);
            p[Order::B] = (value_type)((p[Order::B] * sa + base_shift) >> base_shift);
            p[Order::A] = (value_type)((p[Order::A] * sa + base_shift) >> base_shift);
        }
    };

    //=====================================================comp_op_rgba_src_atop
    template<class ColorT, class Order> struct comp_op_rgba_src_atop
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca.Da + Dca.(1 - Sa)
        // Da'  = Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            calc_type da = p[Order::A];
            sa = base_mask - sa;
            p[Order::R] = (value_type)((sr * da + p[Order::R] * sa + base_mask) >> base_shift);
            p[Order::G] = (value_type)((sg * da + p[Order::G] * sa + base_mask) >> base_shift);
            p[Order::B] = (value_type)((sb * da + p[Order::B] * sa + base_mask) >> base_shift);
        }
    };

    //=====================================================comp_op_rgba_dst_atop
    template<class ColorT, class Order> struct comp_op_rgba_dst_atop
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Dca.Sa + Sca.(1 - Da)
        // Da'  = Sa
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            calc_type da = base_mask - p[Order::A];
            if(cover < 255)
            {
                unsigned alpha = 255 - cover;
                sr = (p[Order::R] * sa + sr * da + base_mask) >> base_shift;
                sg = (p[Order::G] * sa + sg * da + base_mask) >> base_shift;
                sb = (p[Order::B] * sa + sb * da + base_mask) >> base_shift;
                p[Order::R] = (value_type)(((p[Order::R] * alpha + 255) >> 8) + ((sr * cover + 255) >> 8));
                p[Order::G] = (value_type)(((p[Order::G] * alpha + 255) >> 8) + ((sg * cover + 255) >> 8));
                p[Order::B] = (value_type)(((p[Order::B] * alpha + 255) >> 8) + ((sb * cover + 255) >> 8));
                p[Order::A] = (value_type)(((p[Order::A] * alpha + 255) >> 8) + ((sa * cover + 255) >> 8));

            }
            else
            {
                p[Order::R] = (value_type)((p[Order::R] * sa + sr * da + base_mask) >> base_shift);
                p[Order::G] = (value_type)((p[Order::G] * sa + sg * da + base_mask) >> base_shift);
                p[Order::B] = (value_type)((p[Order::B] * sa + sb * da + base_mask) >> base_shift);
                p[Order::A] = (value_type)sa;
            }
        }
    };

    //=========================================================comp_op_rgba_xor
    template<class ColorT, class Order> struct comp_op_rgba_xor
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca.(1 - Da) + Dca.(1 - Sa)
        // Da'  = Sa + Da - 2.Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type s1a = base_mask - sa;
                calc_type d1a = base_mask - p[Order::A];
                p[Order::R] = (value_type)((p[Order::R] * s1a + sr * d1a + base_mask) >> base_shift);
                p[Order::G] = (value_type)((p[Order::G] * s1a + sg * d1a + base_mask) >> base_shift);
                p[Order::B] = (value_type)((p[Order::B] * s1a + sb * d1a + base_mask) >> base_shift);
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask/2) >> (base_shift - 1)));
            }
        }
    };

    //=========================================================comp_op_rgba_plus
    template<class ColorT, class Order> struct comp_op_rgba_plus
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca + Dca
        // Da'  = Sa + Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type dr = p[Order::R] + sr;
                calc_type dg = p[Order::G] + sg;
                calc_type db = p[Order::B] + sb;
                calc_type da = p[Order::A] + sa;
                p[Order::R] = (dr > base_mask) ? (value_type)base_mask : dr;
                p[Order::G] = (dg > base_mask) ? (value_type)base_mask : dg;
                p[Order::B] = (db > base_mask) ? (value_type)base_mask : db;
                p[Order::A] = (da > base_mask) ? (value_type)base_mask : da;
            }
        }
    };

    //========================================================comp_op_rgba_minus
    template<class ColorT, class Order> struct comp_op_rgba_minus
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Dca - Sca
        // Da' = 1 - (1 - Sa).(1 - Da)
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type dr = p[Order::R] - sr;
                calc_type dg = p[Order::G] - sg;
                calc_type db = p[Order::B] - sb;
                p[Order::R] = (dr > base_mask) ? 0 : dr;
                p[Order::G] = (dg > base_mask) ? 0 : dg;
                p[Order::B] = (db > base_mask) ? 0 : db;
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
                //p[Order::A] = (value_type)(base_mask - (((base_mask - sa) * (base_mask - p[Order::A]) + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_multiply
    template<class ColorT, class Order> struct comp_op_rgba_multiply
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca.Dca + Sca.(1 - Da) + Dca.(1 - Sa)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type s1a = base_mask - sa;
                calc_type d1a = base_mask - p[Order::A];
                calc_type dr = p[Order::R];
                calc_type dg = p[Order::G];
                calc_type db = p[Order::B];
                p[Order::R] = (value_type)((sr * dr + sr * d1a + dr * s1a + base_mask) >> base_shift);
                p[Order::G] = (value_type)((sg * dg + sg * d1a + dg * s1a + base_mask) >> base_shift);
                p[Order::B] = (value_type)((sb * db + sb * d1a + db * s1a + base_mask) >> base_shift);
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_screen
    template<class ColorT, class Order> struct comp_op_rgba_screen
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca + Dca - Sca.Dca
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type dr = p[Order::R];
                calc_type dg = p[Order::G];
                calc_type db = p[Order::B];
                calc_type da = p[Order::A];
                p[Order::R] = (value_type)(sr + dr - ((sr * dr + base_mask) >> base_shift));
                p[Order::G] = (value_type)(sg + dg - ((sg * dg + base_mask) >> base_shift));
                p[Order::B] = (value_type)(sb + db - ((sb * db + base_mask) >> base_shift));
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_overlay
    template<class ColorT, class Order> struct comp_op_rgba_overlay
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // if 2.Dca < Da
        //   Dca' = 2.Sca.Dca + Sca.(1 - Da) + Dca.(1 - Sa)
        // otherwise
        //   Dca' = Sa.Da - 2.(Da - Dca).(Sa - Sca) + Sca.(1 - Da) + Dca.(1 - Sa)
        //
        // Da' = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type d1a  = base_mask - p[Order::A];
                calc_type s1a  = base_mask - sa;
                calc_type dr   = p[Order::R];
                calc_type dg   = p[Order::G];
                calc_type db   = p[Order::B];
                calc_type da   = p[Order::A];
                calc_type sada = sa * p[Order::A];

                p[Order::R] = (value_type)(((2*dr < da) ?
                    2*sr*dr + sr*d1a + dr*s1a :
                    sada - 2*(da - dr)*(sa - sr) + sr*d1a + dr*s1a + base_mask) >> base_shift);

                p[Order::G] = (value_type)(((2*dg < da) ?
                    2*sg*dg + sg*d1a + dg*s1a :
                    sada - 2*(da - dg)*(sa - sg) + sg*d1a + dg*s1a + base_mask) >> base_shift);

                p[Order::B] = (value_type)(((2*db < da) ?
                    2*sb*db + sb*d1a + db*s1a :
                    sada - 2*(da - db)*(sa - sb) + sb*d1a + db*s1a + base_mask) >> base_shift);

                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };


    template<class T> inline T sd_min(T a, T b) { return (a < b) ? a : b; }
    template<class T> inline T sd_max(T a, T b) { return (a > b) ? a : b; }

    //=====================================================comp_op_rgba_darken
    template<class ColorT, class Order> struct comp_op_rgba_darken
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = min(Sca.Da, Dca.Sa) + Sca.(1 - Da) + Dca.(1 - Sa)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type d1a = base_mask - p[Order::A];
                calc_type s1a = base_mask - sa;
                calc_type dr  = p[Order::R];
                calc_type dg  = p[Order::G];
                calc_type db  = p[Order::B];
                calc_type da  = p[Order::A];

                p[Order::R] = (value_type)((sd_min(sr * da, dr * sa) + sr * d1a + dr * s1a + base_mask) >> base_shift);
                p[Order::G] = (value_type)((sd_min(sg * da, dg * sa) + sg * d1a + dg * s1a + base_mask) >> base_shift);
                p[Order::B] = (value_type)((sd_min(sb * da, db * sa) + sb * d1a + db * s1a + base_mask) >> base_shift);
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_lighten
    template<class ColorT, class Order> struct comp_op_rgba_lighten
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = max(Sca.Da, Dca.Sa) + Sca.(1 - Da) + Dca.(1 - Sa)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type d1a = base_mask - p[Order::A];
                calc_type s1a = base_mask - sa;
                calc_type dr  = p[Order::R];
                calc_type dg  = p[Order::G];
                calc_type db  = p[Order::B];
                calc_type da  = p[Order::A];

                p[Order::R] = (value_type)((sd_max(sr * da, dr * sa) + sr * d1a + dr * s1a + base_mask) >> base_shift);
                p[Order::G] = (value_type)((sd_max(sg * da, dg * sa) + sg * d1a + dg * s1a + base_mask) >> base_shift);
                p[Order::B] = (value_type)((sd_max(sb * da, db * sa) + sb * d1a + db * s1a + base_mask) >> base_shift);
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_color_dodge
    template<class ColorT, class Order> struct comp_op_rgba_color_dodge
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // if Sca.Da + Dca.Sa >= Sa.Da
        //   Dca' = Sa.Da + Sca.(1 - Da) + Dca.(1 - Sa)
        // otherwise
        //   Dca' = Dca.Sa/(1-Sca/Sa) + Sca.(1 - Da) + Dca.(1 - Sa)
        //
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type d1a  = base_mask - p[Order::A];
                calc_type s1a  = base_mask - sa;
                calc_type dr   = p[Order::R];
                calc_type dg   = p[Order::G];
                calc_type db   = p[Order::B];
                calc_type da   = p[Order::A];
                long_type drsa = dr * sa;
                long_type dgsa = dg * sa;
                long_type dbsa = db * sa;
                long_type srda = sr * da;
                long_type sgda = sg * da;
                long_type sbda = sb * da;
                long_type sada = sa * da;

                p[Order::R] = (value_type)((srda + drsa >= sada) ?
                    (sada + sr * d1a + dr * s1a + base_mask) >> base_shift :
                    drsa / (base_mask - (sr << base_shift) / sa) + ((sr * d1a + dr * s1a + base_mask) >> base_shift));

                p[Order::G] = (value_type)((sgda + dgsa >= sada) ?
                    (sada + sg * d1a + dg * s1a + base_mask) >> base_shift :
                    dgsa / (base_mask - (sg << base_shift) / sa) + ((sg * d1a + dg * s1a + base_mask) >> base_shift));

                p[Order::B] = (value_type)((sbda + dbsa >= sada) ?
                    (sada + sb * d1a + db * s1a + base_mask) >> base_shift :
                    dbsa / (base_mask - (sb << base_shift) / sa) + ((sb * d1a + db * s1a + base_mask) >> base_shift));

                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_color_burn
    template<class ColorT, class Order> struct comp_op_rgba_color_burn
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // if Sca.Da + Dca.Sa <= Sa.Da
        //   Dca' = Sca.(1 - Da) + Dca.(1 - Sa)
        // otherwise
        //   Dca' = Sa.(Sca.Da + Dca.Sa - Sa.Da)/Sca + Sca.(1 - Da) + Dca.(1 - Sa)
        //
        // Da'  = Sa + Da - Sa.Da


        // http://www.w3.org/TR/SVGCompositing/
        // if Sca == 0 and Dca == Da
        //   Dca' = Sa × Da + Sca × (1 - Da) + Dca × (1 - Sa)
        //        = Sa × Da + Dca × (1 - Sa)
        //        = Da = Dca
        // otherwise if Sca == 0
        //   Dca' = Sca × (1 - Da) + Dca × (1 - Sa)
        //        = Dca × (1 - Sa)
        // otherwise if Sca > 0
        //   Dca' = Sa × Da - Sa × Da × min(1, (1 - Dca/Da) × Sa/Sca) + Sca × (1 - Da) + Dca × (1 - Sa)
        //        = Sa × Da × (1 - min(1, (1 - Dca/Da) × Sa/Sca)) + Sca × (1 - Da) + Dca × (1 - Sa)

        //   sa * da * (255 - std::min(255, (255 - p[0]/da)*(sa/(sc*sa)) +
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if (cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }

            if (sa)
            {
                calc_type d1a  = base_mask - p[Order::A];
                calc_type s1a  = base_mask - sa;
                calc_type dr   = p[Order::R];
                calc_type dg   = p[Order::G];
                calc_type db   = p[Order::B];
                calc_type da   = p[Order::A];
                long_type drsa = dr * sa;
                long_type dgsa = dg * sa;
                long_type dbsa = db * sa;
                long_type srda = sr * da;
                long_type sgda = sg * da;
                long_type sbda = sb * da;
                long_type sada = sa * da;

                p[Order::R] = (value_type)(((srda + drsa <= sada) ?
                   sr * d1a + dr * s1a :
                   (sr > 0 ? sa * (srda + drsa - sada) / sr + sr * d1a + dr * s1a + base_mask : 0)) >> base_shift);

                p[Order::G] = (value_type)(((sgda + dgsa <= sada) ?
                    sg * d1a + dg * s1a :
                   (sg > 0 ? sa * (sgda + dgsa - sada) / sg + sg * d1a + dg * s1a + base_mask : 0)) >> base_shift);

                p[Order::B] = (value_type)(((sbda + dbsa <= sada) ?
                    sb * d1a + db * s1a :
                   (sb > 0 ? sa * (sbda + dbsa - sada) / sb + sb * d1a + db * s1a + base_mask : 0)) >> base_shift);

                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_hard_light
    template<class ColorT, class Order> struct comp_op_rgba_hard_light
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // if 2.Sca < Sa
        //    Dca' = 2.Sca.Dca + Sca.(1 - Da) + Dca.(1 - Sa)
        // otherwise
        //    Dca' = Sa.Da - 2.(Da - Dca).(Sa - Sca) + Sca.(1 - Da) + Dca.(1 - Sa)
        //
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type d1a  = base_mask - p[Order::A];
                calc_type s1a  = base_mask - sa;
                calc_type dr   = p[Order::R];
                calc_type dg   = p[Order::G];
                calc_type db   = p[Order::B];
                calc_type da   = p[Order::A];
                calc_type sada = sa * da;

                p[Order::R] = (value_type)(((2*sr < sa) ?
                    2*sr*dr + sr*d1a + dr*s1a :
                    sada - 2*(da - dr)*(sa - sr) + sr*d1a + dr*s1a + base_mask) >> base_shift);

                p[Order::G] = (value_type)(((2*sg < sa) ?
                    2*sg*dg + sg*d1a + dg*s1a :
                    sada - 2*(da - dg)*(sa - sg) + sg*d1a + dg*s1a + base_mask) >> base_shift);

                p[Order::B] = (value_type)(((2*sb < sa) ?
                    2*sb*db + sb*d1a + db*s1a :
                    sada - 2*(da - db)*(sa - sb) + sb*d1a + db*s1a + base_mask) >> base_shift);

                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_soft_light
    template<class ColorT, class Order> struct comp_op_rgba_soft_light
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // if 2.Sca < Sa
        //   Dca' = Dca.(Sa + (1 - Dca/Da).(2.Sca - Sa)) + Sca.(1 - Da) + Dca.(1 - Sa)
        // otherwise if 8.Dca <= Da
        //   Dca' = Dca.(Sa + (1 - Dca/Da).(2.Sca - Sa).(3 - 8.Dca/Da)) + Sca.(1 - Da) + Dca.(1 - Sa)
        // otherwise
        //   Dca' = (Dca.Sa + ((Dca/Da)^(0.5).Da - Dca).(2.Sca - Sa)) + Sca.(1 - Da) + Dca.(1 - Sa)
        //
        // Da'  = Sa + Da - Sa.Da

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned r, unsigned g, unsigned b,
                                         unsigned a, unsigned cover)
        {
            double sr = double(r * cover) / (base_mask * 255);
            double sg = double(g * cover) / (base_mask * 255);
            double sb = double(b * cover) / (base_mask * 255);
            double sa = double(a * cover) / (base_mask * 255);
            if(sa > 0)
            {
                double dr = double(p[Order::R]) / base_mask;
                double dg = double(p[Order::G]) / base_mask;
                double db = double(p[Order::B]) / base_mask;
                double da = double(p[Order::A] ? p[Order::A] : 1) / base_mask;
                if(cover < 255)
                {
                    a = (a * cover + 255) >> 8;
                }

                if(2*sr < sa)       dr = dr*(sa + (1 - dr/da)*(2*sr - sa)) + sr*(1 - da) + dr*(1 - sa);
                else if(8*dr <= da) dr = dr*(sa + (1 - dr/da)*(2*sr - sa)*(3 - 8*dr/da)) + sr*(1 - da) + dr*(1 - sa);
                else                dr = (dr*sa + (sqrt(dr/da)*da - dr)*(2*sr - sa)) + sr*(1 - da) + dr*(1 - sa);

                if(2*sg < sa)       dg = dg*(sa + (1 - dg/da)*(2*sg - sa)) + sg*(1 - da) + dg*(1 - sa);
                else if(8*dg <= da) dg = dg*(sa + (1 - dg/da)*(2*sg - sa)*(3 - 8*dg/da)) + sg*(1 - da) + dg*(1 - sa);
                else                dg = (dg*sa + (sqrt(dg/da)*da - dg)*(2*sg - sa)) + sg*(1 - da) + dg*(1 - sa);

                if(2*sb < sa)       db = db*(sa + (1 - db/da)*(2*sb - sa)) + sb*(1 - da) + db*(1 - sa);
                else if(8*db <= da) db = db*(sa + (1 - db/da)*(2*sb - sa)*(3 - 8*db/da)) + sb*(1 - da) + db*(1 - sa);
                else                db = (db*sa + (sqrt(db/da)*da - db)*(2*sb - sa)) + sb*(1 - da) + db*(1 - sa);

                p[Order::R] = (value_type)uround(dr * base_mask);
                p[Order::G] = (value_type)uround(dg * base_mask);
                p[Order::B] = (value_type)uround(db * base_mask);
                p[Order::A] = (value_type)(a + p[Order::A] - ((a * p[Order::A] + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_difference
    template<class ColorT, class Order> struct comp_op_rgba_difference
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_scale = color_type::base_scale,
            base_mask  = color_type::base_mask
        };

        // Dca' = Sca + Dca - 2.min(Sca.Da, Dca.Sa)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type dr = p[Order::R];
                calc_type dg = p[Order::G];
                calc_type db = p[Order::B];
                calc_type da = p[Order::A];
                p[Order::R] = (value_type)(sr + dr - ((2 * sd_min(sr*da, dr*sa) + base_mask) >> base_shift));
                p[Order::G] = (value_type)(sg + dg - ((2 * sd_min(sg*da, dg*sa) + base_mask) >> base_shift));
                p[Order::B] = (value_type)(sb + db - ((2 * sd_min(sb*da, db*sa) + base_mask) >> base_shift));
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_exclusion
    template<class ColorT, class Order> struct comp_op_rgba_exclusion
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = (Sca.Da + Dca.Sa - 2.Sca.Dca) + Sca.(1 - Da) + Dca.(1 - Sa)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type d1a = base_mask - p[Order::A];
                calc_type s1a = base_mask - sa;
                calc_type dr = p[Order::R];
                calc_type dg = p[Order::G];
                calc_type db = p[Order::B];
                calc_type da = p[Order::A];
                p[Order::R] = (value_type)((sr*da + dr*sa - 2*sr*dr + sr*d1a + dr*s1a + base_mask) >> base_shift);
                p[Order::G] = (value_type)((sg*da + dg*sa - 2*sg*dg + sg*d1a + dg*s1a + base_mask) >> base_shift);
                p[Order::B] = (value_type)((sb*da + db*sa - 2*sb*db + sb*d1a + db*s1a + base_mask) >> base_shift);
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=====================================================comp_op_rgba_contrast
    template<class ColorT, class Order> struct comp_op_rgba_contrast
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };


        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            long_type dr = p[Order::R];
            long_type dg = p[Order::G];
            long_type db = p[Order::B];
            int       da = p[Order::A];
            long_type d2a = da >> 1;
            unsigned s2a = sa >> 1;

            int r = (int)((((dr - d2a) * int((sr - s2a)*2 + base_mask)) >> base_shift) + d2a);
            int g = (int)((((dg - d2a) * int((sg - s2a)*2 + base_mask)) >> base_shift) + d2a);
            int b = (int)((((db - d2a) * int((sb - s2a)*2 + base_mask)) >> base_shift) + d2a);

            r = (r < 0) ? 0 : r;
            g = (g < 0) ? 0 : g;
            b = (b < 0) ? 0 : b;

            p[Order::R] = (value_type)((r > da) ? da : r);
            p[Order::G] = (value_type)((g > da) ? da : g);
            p[Order::B] = (value_type)((b > da) ? da : b);
        }
    };

    //=====================================================comp_op_rgba_invert
    template<class ColorT, class Order> struct comp_op_rgba_invert
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = (Da - Dca) * Sa + Dca.(1 - Sa)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned /*sr*/, unsigned /*sg*/, unsigned /*sb*/,
                                         unsigned sa, unsigned cover)
        {
            sa = (sa * cover + 255) >> 8;
            if(sa)
            {
                calc_type da = p[Order::A];
                calc_type dr = ((da - p[Order::R]) * sa + base_mask) >> base_shift;
                calc_type dg = ((da - p[Order::G]) * sa + base_mask) >> base_shift;
                calc_type db = ((da - p[Order::B]) * sa + base_mask) >> base_shift;
                calc_type s1a = base_mask - sa;
                p[Order::R] = (value_type)(dr + ((p[Order::R] * s1a + base_mask) >> base_shift));
                p[Order::G] = (value_type)(dg + ((p[Order::G] * s1a + base_mask) >> base_shift));
                p[Order::B] = (value_type)(db + ((p[Order::B] * s1a + base_mask) >> base_shift));
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    //=================================================comp_op_rgba_invert_rgb
    template<class ColorT, class Order> struct comp_op_rgba_invert_rgb
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        // Dca' = (Da - Dca) * Sca + Dca.(1 - Sa)
        // Da'  = Sa + Da - Sa.Da
        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if(sa)
            {
                calc_type da = p[Order::A];
                calc_type dr = ((da - p[Order::R]) * sr + base_mask) >> base_shift;
                calc_type dg = ((da - p[Order::G]) * sg + base_mask) >> base_shift;
                calc_type db = ((da - p[Order::B]) * sb + base_mask) >> base_shift;
                calc_type s1a = base_mask - sa;
                p[Order::R] = (value_type)(dr + ((p[Order::R] * s1a + base_mask) >> base_shift));
                p[Order::G] = (value_type)(dg + ((p[Order::G] * s1a + base_mask) >> base_shift));
                p[Order::B] = (value_type)(db + ((p[Order::B] * s1a + base_mask) >> base_shift));
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };


    // merge grain (GIMP)
    // E = I + M - 128

    template <typename ColorT, typename Order>
    struct comp_op_rgba_grain_merge
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {

            if (cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if (sa > 0)
            {
                calc_type da = p[Order::A];
                int dr = sr + p[Order::R] - 128;
                int dg = sg + p[Order::G] - 128;
                int db = sb + p[Order::B] - 128;
                p[Order::R] = dr < 0 ? 0 : (dr > 255 ? 255 : dr);
                p[Order::G] = dg < 0 ? 0 : (dg > 255 ? 255 : dg);
                p[Order::B] = db < 0 ? 0 : (db > 255 ? 255 : db);
                p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
            }
        }
    };

    // colorize alpha values
    // TODO - consider moving to image-filters:
    // https://github.com/mapnik/mapnik/issues/1371
    /*
    template <typename ColorT, typename Order>
    struct comp_op_rgba_colorize_alpha
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         // source rgb
                                         unsigned sr, unsigned sg, unsigned sb,
                                         // source alpha and opacity
                                         unsigned sa, unsigned cover)
        {
            if(cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }
            if (sa > 0)
            {
                p[Order::R] = (value_type)(((0 + base_mask) >> base_shift));
                p[Order::G] = (value_type)(((0 + base_mask) >> base_shift));
                p[Order::B] = (value_type)(((0 + base_mask) >> base_shift));
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
                // http://en.wikipedia.org/wiki/File:HSV-RGB-comparison.svg
                if (p[Order::A] < 64) {
                    p[Order::G] = ((p[Order::A] - 64) * 4);
                    p[Order::B] = 255;
                }
                if (p[Order::A] >= 64 && p[Order::A] < 128) {
                    p[Order::G] = 255;
                    p[Order::B] = 255 - ((p[Order::A] - 64) * 4);
                }
                if (p[Order::A] >= 128 && p[Order::A] < 192) {
                    p[Order::R] = ((p[Order::A] - 128) * 4);
                    p[Order::G] = 255;
                }
                if (p[Order::A] >= 192) {
                    p[Order::R] = 255;
                    p[Order::G] = 255 - ((p[Order::A] - 192) * 4);
                }
            }
        }
    };
    */

    // grain extract (GIMP)
    // E = I - M + 128

    template <typename ColorT, typename Order>
    struct comp_op_rgba_grain_extract
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            calc_type da = (p[Order::A] * sa + 255) >> 8;

            int dr = p[Order::R] - sr + 128;
            int dg = p[Order::G] - sg + 128;
            int db = p[Order::B] - sb + 128;

            dr = dr < 0 ? 0 : (dr > 255 ? 255 : dr);
            dg = dg < 0 ? 0 : (dg > 255 ? 255 : dg);
            db = db < 0 ? 0 : (db > 255 ? 255 : db);

            p[Order::A] = da;

            if (da < 255)
            {
                p[Order::R] = (dr * da + 255) >> 8;
                p[Order::G] = (dg * da + 255) >> 8;
                p[Order::B] = (db * da + 255) >> 8;
            }
            else
            {
                p[Order::R] = dr;
                p[Order::G] = dg;
                p[Order::B] = db;
            }
        }
    };

    template <typename ColorT, typename Order>
    struct comp_op_rgba_hue
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if (cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }

            if (sa > 0)
            {
                using namespace boost;
                using namespace gil;
                using namespace hsv_color_space;
                rgb8_pixel_t rgb_src(sr,sg,sb);
                rgb8_pixel_t rgb_dst(p[Order::R],p[Order::G],p[Order::B]);
                hsv32f_pixel_t hsv_src,hsv_dst;
                color_convert(rgb_src, hsv_src);
                color_convert(rgb_dst, hsv_dst);
                get_color(hsv_dst,hue_t()) = get_color(hsv_src,hue_t());
                color_convert(hsv_dst, rgb_dst);
                p[Order::R] = get_color(rgb_dst,red_t());
                p[Order::G] = get_color(rgb_dst,green_t());
                p[Order::B] = get_color(rgb_dst,blue_t());
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
            }
        }
    };

    template <typename ColorT, typename Order>
    struct comp_op_rgba_saturation
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if (cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }

            if (sa > 0)
            {
                using namespace boost;
                using namespace gil;
                using namespace hsv_color_space;
                rgb8_pixel_t rgb_src(sr,sg,sb);
                rgb8_pixel_t rgb_dst(p[Order::R],p[Order::G],p[Order::B]);
                hsv32f_pixel_t hsv_src,hsv_dst;
                color_convert( rgb_src, hsv_src);
                color_convert( rgb_dst, hsv_dst);
                get_color(hsv_dst,saturation_t()) = get_color(hsv_src,saturation_t());
                color_convert(hsv_dst, rgb_dst);
                p[Order::R] = get_color(rgb_dst,red_t());
                p[Order::G] = get_color(rgb_dst,green_t());
                p[Order::B] = get_color(rgb_dst,blue_t());
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
            }
        }
    };

    template <typename ColorT, typename Order>
    struct comp_op_rgba_color
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if (cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }

            if (sa > 0)
            {
                using namespace boost;
                using namespace gil;
                using namespace hsv_color_space;
                rgb8_pixel_t rgb_src(sr,sg,sb);
                rgb8_pixel_t rgb_dst(p[Order::R],p[Order::G],p[Order::B]);
                hsv32f_pixel_t hsv_src,hsv_dst;
                color_convert( rgb_src, hsv_src);
                color_convert( rgb_dst, hsv_dst);
                get_color(hsv_dst,hue_t()) = get_color(hsv_src,hue_t());
                get_color(hsv_dst,saturation_t()) = get_color(hsv_src,saturation_t());
                color_convert(hsv_dst, rgb_dst);
                p[Order::R] = get_color(rgb_dst,red_t());
                p[Order::G] = get_color(rgb_dst,green_t());
                p[Order::B] = get_color(rgb_dst,blue_t());
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
            }
        }
    };


    template <typename ColorT, typename Order>
    struct comp_op_rgba_value
    {
        typedef ColorT color_type;
        typedef Order order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef typename color_type::long_type long_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(value_type* p,
                                         unsigned sr, unsigned sg, unsigned sb,
                                         unsigned sa, unsigned cover)
        {
            if (cover < 255)
            {
                sr = (sr * cover + 255) >> 8;
                sg = (sg * cover + 255) >> 8;
                sb = (sb * cover + 255) >> 8;
                sa = (sa * cover + 255) >> 8;
            }

            if (sa > 0)
            {
                using namespace boost;
                using namespace gil;
                using namespace hsv_color_space;
                rgb8_pixel_t rgb_src(sr,sg,sb);
                rgb8_pixel_t rgb_dst(p[Order::R],p[Order::G],p[Order::B]);
                hsv32f_pixel_t hsv_src,hsv_dst;
                color_convert( rgb_src, hsv_src);
                color_convert( rgb_dst, hsv_dst);
                get_color(hsv_dst,value_t()) = get_color(hsv_src,value_t());
                color_convert(hsv_dst, rgb_dst);
                p[Order::R] = get_color(rgb_dst,red_t());
                p[Order::G] = get_color(rgb_dst,green_t());
                p[Order::B] = get_color(rgb_dst,blue_t());
                p[Order::A] = (value_type)(sa + p[Order::A] - ((sa * p[Order::A] + base_mask) >> base_shift));
            }
        }
    };

    //======================================================comp_op_table_rgba
    template<class ColorT, class Order> struct comp_op_table_rgba
    {
        typedef typename ColorT::value_type value_type;
        typedef void (*comp_op_func_type)(value_type* p,
                                          unsigned cr,
                                          unsigned cg,
                                          unsigned cb,
                                          unsigned ca,
                                          unsigned cover);
        static comp_op_func_type g_comp_op_func[];
    };

    //==========================================================g_comp_op_func
    template<class ColorT, class Order>
    typename comp_op_table_rgba<ColorT, Order>::comp_op_func_type
    comp_op_table_rgba<ColorT, Order>::g_comp_op_func[] =
    {
        comp_op_rgba_clear      <ColorT,Order>::blend_pix,
        comp_op_rgba_src        <ColorT,Order>::blend_pix,
        comp_op_rgba_dst        <ColorT,Order>::blend_pix,
        comp_op_rgba_src_over   <ColorT,Order>::blend_pix,
        comp_op_rgba_dst_over   <ColorT,Order>::blend_pix,
        comp_op_rgba_src_in     <ColorT,Order>::blend_pix,
        comp_op_rgba_dst_in     <ColorT,Order>::blend_pix,
        comp_op_rgba_src_out    <ColorT,Order>::blend_pix,
        comp_op_rgba_dst_out    <ColorT,Order>::blend_pix,
        comp_op_rgba_src_atop   <ColorT,Order>::blend_pix,
        comp_op_rgba_dst_atop   <ColorT,Order>::blend_pix,
        comp_op_rgba_xor        <ColorT,Order>::blend_pix,
        comp_op_rgba_plus       <ColorT,Order>::blend_pix,
        comp_op_rgba_minus      <ColorT,Order>::blend_pix,
        comp_op_rgba_multiply   <ColorT,Order>::blend_pix,
        comp_op_rgba_screen     <ColorT,Order>::blend_pix,
        comp_op_rgba_overlay    <ColorT,Order>::blend_pix,
        comp_op_rgba_darken     <ColorT,Order>::blend_pix,
        comp_op_rgba_lighten    <ColorT,Order>::blend_pix,
        comp_op_rgba_color_dodge<ColorT,Order>::blend_pix,
        comp_op_rgba_color_burn <ColorT,Order>::blend_pix,
        comp_op_rgba_hard_light <ColorT,Order>::blend_pix,
        comp_op_rgba_soft_light <ColorT,Order>::blend_pix,
        comp_op_rgba_difference <ColorT,Order>::blend_pix,
        comp_op_rgba_exclusion  <ColorT,Order>::blend_pix,
        comp_op_rgba_contrast   <ColorT,Order>::blend_pix,
        comp_op_rgba_invert     <ColorT,Order>::blend_pix,
        comp_op_rgba_invert_rgb <ColorT,Order>::blend_pix,
        comp_op_rgba_grain_merge<ColorT,Order>::blend_pix,
        comp_op_rgba_grain_extract<ColorT,Order>::blend_pix,
        comp_op_rgba_hue<ColorT,Order>::blend_pix,
        comp_op_rgba_saturation<ColorT,Order>::blend_pix,
        comp_op_rgba_color<ColorT,Order>::blend_pix,
        comp_op_rgba_value<ColorT,Order>::blend_pix,
        //comp_op_rgba_colorize_alpha<ColorT,Order>::blend_pix,
        0
    };


    //==============================================================comp_op_e
    enum comp_op_e
    {
        comp_op_clear,         //----comp_op_clear
        comp_op_src,           //----comp_op_src
        comp_op_dst,           //----comp_op_dst
        comp_op_src_over,      //----comp_op_src_over
        comp_op_dst_over,      //----comp_op_dst_over
        comp_op_src_in,        //----comp_op_src_in
        comp_op_dst_in,        //----comp_op_dst_in
        comp_op_src_out,       //----comp_op_src_out
        comp_op_dst_out,       //----comp_op_dst_out
        comp_op_src_atop,      //----comp_op_src_atop
        comp_op_dst_atop,      //----comp_op_dst_atop
        comp_op_xor,           //----comp_op_xor
        comp_op_plus,          //----comp_op_plus
        comp_op_minus,         //----comp_op_minus
        comp_op_multiply,      //----comp_op_multiply
        comp_op_screen,        //----comp_op_screen
        comp_op_overlay,       //----comp_op_overlay
        comp_op_darken,        //----comp_op_darken
        comp_op_lighten,       //----comp_op_lighten
        comp_op_color_dodge,   //----comp_op_color_dodge
        comp_op_color_burn,    //----comp_op_color_burn
        comp_op_hard_light,    //----comp_op_hard_light
        comp_op_soft_light,    //----comp_op_soft_light
        comp_op_difference,    //----comp_op_difference
        comp_op_exclusion,     //----comp_op_exclusion
        comp_op_contrast,      //----comp_op_contrast
        comp_op_invert,        //----comp_op_invert
        comp_op_invert_rgb,    //----comp_op_invert_rgb
        comp_op_grain_merge,   //----comp_op_grain_merge_rgb
        comp_op_grain_extract, //----comp_op_grain_extract_rgb
        comp_op_hue,           //----comp_op_hue
        comp_op_saturation,    //----comp_op_saturation
        comp_op_color,         //----comp_op_color
        comp_op_value,         //----comp_op_value
        //comp_op_colorize_alpha,//----comp_op_colorize_alpha
        end_of_comp_op_e
    };

    //====================================================comp_op_adaptor_rgba
    template<class ColorT, class Order> struct comp_op_adaptor_rgba
    {
        typedef Order  order_type;
        typedef ColorT color_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(unsigned op, value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned ca,
                                         unsigned cover)
        {
            comp_op_table_rgba<ColorT, Order>::g_comp_op_func[op]
                (p, (cr * ca + base_mask) >> base_shift,
                    (cg * ca + base_mask) >> base_shift,
                    (cb * ca + base_mask) >> base_shift,
                     ca, cover);
        }
    };

    //=========================================comp_op_adaptor_clip_to_dst_rgba
    template<class ColorT, class Order> struct comp_op_adaptor_clip_to_dst_rgba
    {
        typedef Order  order_type;
        typedef ColorT color_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(unsigned op, value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned ca,
                                         unsigned cover)
        {
            cr = (cr * ca + base_mask) >> base_shift;
            cg = (cg * ca + base_mask) >> base_shift;
            cb = (cb * ca + base_mask) >> base_shift;
            unsigned da = p[Order::A];
            comp_op_table_rgba<ColorT, Order>::g_comp_op_func[op]
                (p, (cr * da + base_mask) >> base_shift,
                    (cg * da + base_mask) >> base_shift,
                    (cb * da + base_mask) >> base_shift,
                    (ca * da + base_mask) >> base_shift,
                    cover);
        }
    };

    //================================================comp_op_adaptor_rgba_pre
    template<class ColorT, class Order> struct comp_op_adaptor_rgba_pre
    {
        typedef Order  order_type;
        typedef ColorT color_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(unsigned op, value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned ca,
                                         unsigned cover)
        {
            comp_op_table_rgba<ColorT, Order>::g_comp_op_func[op](p, cr, cg, cb, ca, cover);
        }
    };

    //=====================================comp_op_adaptor_clip_to_dst_rgba_pre
    template<class ColorT, class Order> struct comp_op_adaptor_clip_to_dst_rgba_pre
    {
        typedef Order  order_type;
        typedef ColorT color_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(unsigned op, value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned ca,
                                         unsigned cover)
        {
            unsigned da = p[Order::A];
            comp_op_table_rgba<ColorT, Order>::g_comp_op_func[op]
                (p, (cr * da + base_mask) >> base_shift,
                    (cg * da + base_mask) >> base_shift,
                    (cb * da + base_mask) >> base_shift,
                    (ca * da + base_mask) >> base_shift,
                    cover);
        }
    };

    //=======================================================comp_adaptor_rgba
    template<class BlenderPre> struct comp_adaptor_rgba
    {
        typedef typename BlenderPre::order_type order_type;
        typedef typename BlenderPre::color_type color_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(unsigned /*op*/, value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned ca,
                                         unsigned cover)
        {
            BlenderPre::blend_pix(p,
                                  (cr * ca + base_mask) >> base_shift,
                                  (cg * ca + base_mask) >> base_shift,
                                  (cb * ca + base_mask) >> base_shift,
                                  ca, cover);
        }
    };

    //==========================================comp_adaptor_clip_to_dst_rgba
    template<class BlenderPre> struct comp_adaptor_clip_to_dst_rgba
    {
        typedef typename BlenderPre::order_type order_type;
        typedef typename BlenderPre::color_type color_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(unsigned /*op*/, value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned ca,
                                         unsigned cover)
        {
            cr = (cr * ca + base_mask) >> base_shift;
            cg = (cg * ca + base_mask) >> base_shift;
            cb = (cb * ca + base_mask) >> base_shift;
            unsigned da = p[order_type::A];
            BlenderPre::blend_pix(p,
                                  (cr * da + base_mask) >> base_shift,
                                  (cg * da + base_mask) >> base_shift,
                                  (cb * da + base_mask) >> base_shift,
                                  (ca * da + base_mask) >> base_shift,
                                  cover);
        }
    };

    //======================================comp_adaptor_clip_to_dst_rgba_pre
    template<class BlenderPre> struct comp_adaptor_clip_to_dst_rgba_pre
    {
        typedef typename BlenderPre::order_type order_type;
        typedef typename BlenderPre::color_type color_type;
        typedef typename color_type::value_type value_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_mask  = color_type::base_mask
        };

        static AGG_INLINE void blend_pix(unsigned /*op*/, value_type* p,
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned ca,
                                         unsigned cover)
        {
            unsigned da = p[order_type::A];
            BlenderPre::blend_pix(p,
                                  (cr * da + base_mask) >> base_shift,
                                  (cg * da + base_mask) >> base_shift,
                                  (cb * da + base_mask) >> base_shift,
                                  (ca * da + base_mask) >> base_shift,
                                  cover);
        }
    };






    //===============================================copy_or_blend_rgba_wrapper
    template<class Blender> struct copy_or_blend_rgba_wrapper
    {
        typedef typename Blender::color_type color_type;
        typedef typename Blender::order_type order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_scale = color_type::base_scale,
            base_mask  = color_type::base_mask
        };

        //--------------------------------------------------------------------
        static AGG_INLINE void copy_or_blend_pix(value_type* p,
                                                 unsigned cr, unsigned cg, unsigned cb,
                                                 unsigned alpha)
        {
            if(alpha)
            {
                if(alpha == base_mask)
                {
                    p[order_type::R] = cr;
                    p[order_type::G] = cg;
                    p[order_type::B] = cb;
                    p[order_type::A] = base_mask;
                }
                else
                {
                    Blender::blend_pix(p, cr, cg, cb, alpha);
                }
            }
        }

        //--------------------------------------------------------------------
        static AGG_INLINE void copy_or_blend_pix(value_type* p,
                                                 unsigned cr, unsigned cg, unsigned cb,
                                                 unsigned alpha,
                                                 unsigned cover)
        {
            if(cover == 255)
            {
                copy_or_blend_pix(p, cr, cg, cb, alpha);
            }
            else
            {
                if(alpha)
                {
                    alpha = (alpha * (cover + 1)) >> 8;
                    if(alpha == base_mask)
                    {
                        p[order_type::R] = cr;
                        p[order_type::G] = cg;
                        p[order_type::B] = cb;
                        p[order_type::A] = base_mask;
                    }
                    else
                    {
                        Blender::blend_pix(p, cr, cg, cb, alpha, cover);
                    }
                }
            }
        }
    };






    //=================================================pixfmt_alpha_blend_rgba
    template<class Blender, class RenBuf, class PixelT = int32u>
    class pixfmt_alpha_blend_rgba
    {
    public:
        typedef RenBuf   rbuf_type;
        typedef typename rbuf_type::row_data row_data;
        typedef PixelT   pixel_type;
        typedef Blender  blender_type;
        typedef typename blender_type::color_type color_type;
        typedef typename blender_type::order_type order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        typedef copy_or_blend_rgba_wrapper<blender_type> cob_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_scale = color_type::base_scale,
            base_mask  = color_type::base_mask,
            pix_width  = sizeof(pixel_type)
        };

        //--------------------------------------------------------------------
        pixfmt_alpha_blend_rgba() : m_rbuf(0) {}
        explicit pixfmt_alpha_blend_rgba(rbuf_type& rb) : m_rbuf(&rb) {}
        void attach(rbuf_type& rb) { m_rbuf = &rb; }

        //--------------------------------------------------------------------
        template<class PixFmt>
        bool attach(PixFmt& pixf, int x1, int y1, int x2, int y2)
        {
            rect_i r(x1, y1, x2, y2);
            if(r.clip(rect_i(0, 0, pixf.width()-1, pixf.height()-1)))
            {
                int stride = pixf.stride();
                m_rbuf->attach(pixf.pix_ptr(r.x1, stride < 0 ? r.y2 : r.y1),
                               (r.x2 - r.x1) + 1,
                               (r.y2 - r.y1) + 1,
                               stride);
                return true;
            }
            return false;
        }

        //--------------------------------------------------------------------
        AGG_INLINE unsigned width()  const { return m_rbuf->width();  }
        AGG_INLINE unsigned height() const { return m_rbuf->height(); }
        AGG_INLINE int      stride() const { return m_rbuf->stride(); }

        //--------------------------------------------------------------------
        AGG_INLINE       int8u* row_ptr(int y)       { return m_rbuf->row_ptr(y); }
        AGG_INLINE const int8u* row_ptr(int y) const { return m_rbuf->row_ptr(y); }
        AGG_INLINE row_data     row(int y)     const { return m_rbuf->row(y); }

        //--------------------------------------------------------------------
        AGG_INLINE int8u* pix_ptr(int x, int y)
        {
            return m_rbuf->row_ptr(y) + x * pix_width;
        }

        AGG_INLINE const int8u* pix_ptr(int x, int y) const
        {
            return m_rbuf->row_ptr(y) + x * pix_width;
        }


        //--------------------------------------------------------------------
        AGG_INLINE static void make_pix(int8u* p, const color_type& c)
        {
            ((value_type*)p)[order_type::R] = c.r;
            ((value_type*)p)[order_type::G] = c.g;
            ((value_type*)p)[order_type::B] = c.b;
            ((value_type*)p)[order_type::A] = c.a;
        }

        //--------------------------------------------------------------------
        AGG_INLINE color_type pixel(int x, int y) const
        {
            const value_type* p = (const value_type*)m_rbuf->row_ptr(y);
            if(p)
            {
                p += x << 2;
                return color_type(p[order_type::R],
                                  p[order_type::G],
                                  p[order_type::B],
                                  p[order_type::A]);
            }
            return color_type::no_color();
        }

        //--------------------------------------------------------------------
        AGG_INLINE void copy_pixel(int x, int y, const color_type& c)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, 1) + (x << 2);
            p[order_type::R] = c.r;
            p[order_type::G] = c.g;
            p[order_type::B] = c.b;
            p[order_type::A] = c.a;
        }

        //--------------------------------------------------------------------
        AGG_INLINE void blend_pixel(int x, int y, const color_type& c, int8u cover)
        {
            cob_type::copy_or_blend_pix(
                (value_type*)m_rbuf->row_ptr(x, y, 1) + (x << 2),
                c.r, c.g, c.b, c.a,
                cover);
        }


        //--------------------------------------------------------------------
        AGG_INLINE void copy_hline(int x, int y,
                                   unsigned len,
                                   const color_type& c)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            pixel_type v;
            ((value_type*)&v)[order_type::R] = c.r;
            ((value_type*)&v)[order_type::G] = c.g;
            ((value_type*)&v)[order_type::B] = c.b;
            ((value_type*)&v)[order_type::A] = c.a;
            do
            {
                *(pixel_type*)p = v;
                p += 4;
            }
            while(--len);
        }


        //--------------------------------------------------------------------
        AGG_INLINE void copy_vline(int x, int y,
                                   unsigned len,
                                   const color_type& c)
        {
            pixel_type v;
            ((value_type*)&v)[order_type::R] = c.r;
            ((value_type*)&v)[order_type::G] = c.g;
            ((value_type*)&v)[order_type::B] = c.b;
            ((value_type*)&v)[order_type::A] = c.a;
            do
            {
                value_type* p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                *(pixel_type*)p = v;
            }
            while(--len);
        }


        //--------------------------------------------------------------------
        void blend_hline(int x, int y,
                         unsigned len,
                         const color_type& c,
                         int8u cover)
        {
            if (c.a)
            {
                value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
                calc_type alpha = (calc_type(c.a) * (cover + 1)) >> 8;
                if(alpha == base_mask)
                {
                    pixel_type v;
                    ((value_type*)&v)[order_type::R] = c.r;
                    ((value_type*)&v)[order_type::G] = c.g;
                    ((value_type*)&v)[order_type::B] = c.b;
                    ((value_type*)&v)[order_type::A] = c.a;
                    do
                    {
                        *(pixel_type*)p = v;
                        p += 4;
                    }
                    while(--len);
                }
                else
                {
                    if(cover == 255)
                    {
                        do
                        {
                            blender_type::blend_pix(p, c.r, c.g, c.b, alpha);
                            p += 4;
                        }
                        while(--len);
                    }
                    else
                    {
                        do
                        {
                            blender_type::blend_pix(p, c.r, c.g, c.b, alpha, cover);
                            p += 4;
                        }
                        while(--len);
                    }
                }
            }
        }


        //--------------------------------------------------------------------
        void blend_vline(int x, int y,
                         unsigned len,
                         const color_type& c,
                         int8u cover)
        {
            if (c.a)
            {
                value_type* p;
                calc_type alpha = (calc_type(c.a) * (cover + 1)) >> 8;
                if(alpha == base_mask)
                {
                    pixel_type v;
                    ((value_type*)&v)[order_type::R] = c.r;
                    ((value_type*)&v)[order_type::G] = c.g;
                    ((value_type*)&v)[order_type::B] = c.b;
                    ((value_type*)&v)[order_type::A] = c.a;
                    do
                    {
                        p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                        *(pixel_type*)p = v;
                    }
                    while(--len);
                }
                else
                {
                    if(cover == 255)
                    {
                        do
                        {
                            p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                            blender_type::blend_pix(p, c.r, c.g, c.b, alpha);
                        }
                        while(--len);
                    }
                    else
                    {
                        do
                        {
                            p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                            blender_type::blend_pix(p, c.r, c.g, c.b, alpha, cover);
                        }
                        while(--len);
                    }
                }
            }
        }


        //--------------------------------------------------------------------
        void blend_solid_hspan(int x, int y,
                               unsigned len,
                               const color_type& c,
                               const int8u* covers)
        {
            if (c.a)
            {
                value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
                do
                {
                    calc_type alpha = (calc_type(c.a) * (calc_type(*covers) + 1)) >> 8;
                    if(alpha == base_mask)
                    {
                        p[order_type::R] = c.r;
                        p[order_type::G] = c.g;
                        p[order_type::B] = c.b;
                        p[order_type::A] = base_mask;
                    }
                    else
                    {
                        blender_type::blend_pix(p, c.r, c.g, c.b, alpha, *covers);
                    }
                    p += 4;
                    ++covers;
                }
                while(--len);
            }
        }


        //--------------------------------------------------------------------
        void blend_solid_vspan(int x, int y,
                               unsigned len,
                               const color_type& c,
                               const int8u* covers)
        {
            if (c.a)
            {
                do
                {
                    value_type* p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                    calc_type alpha = (calc_type(c.a) * (calc_type(*covers) + 1)) >> 8;
                    if(alpha == base_mask)
                    {
                        p[order_type::R] = c.r;
                        p[order_type::G] = c.g;
                        p[order_type::B] = c.b;
                        p[order_type::A] = base_mask;
                    }
                    else
                    {
                        blender_type::blend_pix(p, c.r, c.g, c.b, alpha, *covers);
                    }
                    ++covers;
                }
                while(--len);
            }
        }


        //--------------------------------------------------------------------
        void copy_color_hspan(int x, int y,
                              unsigned len,
                              const color_type* colors)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            do
            {
                p[order_type::R] = colors->r;
                p[order_type::G] = colors->g;
                p[order_type::B] = colors->b;
                p[order_type::A] = colors->a;
                ++colors;
                p += 4;
            }
            while(--len);
        }


        //--------------------------------------------------------------------
        void copy_color_vspan(int x, int y,
                              unsigned len,
                              const color_type* colors)
        {
            do
            {
                value_type* p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                p[order_type::R] = colors->r;
                p[order_type::G] = colors->g;
                p[order_type::B] = colors->b;
                p[order_type::A] = colors->a;
                ++colors;
            }
            while(--len);
        }


        //--------------------------------------------------------------------
        void blend_color_hspan(int x, int y,
                               unsigned len,
                               const color_type* colors,
                               const int8u* covers,
                               int8u cover)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            if(covers)
            {
                do
                {
                    cob_type::copy_or_blend_pix(p,
                                                colors->r,
                                                colors->g,
                                                colors->b,
                                                colors->a,
                                                *covers++);
                    p += 4;
                    ++colors;
                }
                while(--len);
            }
            else
            {
                if(cover == 255)
                {
                    do
                    {
                        cob_type::copy_or_blend_pix(p,
                                                    colors->r,
                                                    colors->g,
                                                    colors->b,
                                                    colors->a);
                        p += 4;
                        ++colors;
                    }
                    while(--len);
                }
                else
                {
                    do
                    {
                        cob_type::copy_or_blend_pix(p,
                                                    colors->r,
                                                    colors->g,
                                                    colors->b,
                                                    colors->a,
                                                    cover);
                        p += 4;
                        ++colors;
                    }
                    while(--len);
                }
            }
        }



        //--------------------------------------------------------------------
        void blend_color_vspan(int x, int y,
                               unsigned len,
                               const color_type* colors,
                               const int8u* covers,
                               int8u cover)
        {
            value_type* p;
            if(covers)
            {
                do
                {
                    p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                    cob_type::copy_or_blend_pix(p,
                                                colors->r,
                                                colors->g,
                                                colors->b,
                                                colors->a,
                                                *covers++);
                    ++colors;
                }
                while(--len);
            }
            else
            {
                if(cover == 255)
                {
                    do
                    {
                        p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                        cob_type::copy_or_blend_pix(p,
                                                    colors->r,
                                                    colors->g,
                                                    colors->b,
                                                    colors->a);
                        ++colors;
                    }
                    while(--len);
                }
                else
                {
                    do
                    {
                        p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                        cob_type::copy_or_blend_pix(p,
                                                    colors->r,
                                                    colors->g,
                                                    colors->b,
                                                    colors->a,
                                                    cover);
                        ++colors;
                    }
                    while(--len);
                }
            }
        }

        //--------------------------------------------------------------------
        template<class Function> void for_each_pixel(Function f)
        {
            unsigned y;
            for(y = 0; y < height(); ++y)
            {
                row_data r = m_rbuf->row(y);
                if(r.ptr)
                {
                    unsigned len = r.x2 - r.x1 + 1;
                    value_type* p =
                        (value_type*)m_rbuf->row_ptr(r.x1, y, len) + (r.x1 << 2);
                    do
                    {
                        f(p);
                        p += 4;
                    }
                    while(--len);
                }
            }
        }

        //--------------------------------------------------------------------
        void premultiply()
        {
            for_each_pixel(multiplier_rgba<color_type, order_type>::premultiply);
        }

        //--------------------------------------------------------------------
        void demultiply()
        {
            for_each_pixel(multiplier_rgba<color_type, order_type>::demultiply);
        }

        //--------------------------------------------------------------------
        template<class GammaLut> void apply_gamma_dir(const GammaLut& g)
        {
            for_each_pixel(apply_gamma_dir_rgba<color_type, order_type, GammaLut>(g));
        }

        //--------------------------------------------------------------------
        template<class GammaLut> void apply_gamma_inv(const GammaLut& g)
        {
            for_each_pixel(apply_gamma_inv_rgba<color_type, order_type, GammaLut>(g));
        }

        //--------------------------------------------------------------------
        template<class RenBuf2> void copy_from(const RenBuf2& from,
                                               int xdst, int ydst,
                                               int xsrc, int ysrc,
                                               unsigned len)
        {
            const int8u* p = from.row_ptr(ysrc);
            if(p)
            {
                memmove(m_rbuf->row_ptr(xdst, ydst, len) + xdst * pix_width,
                        p + xsrc * pix_width,
                        len * pix_width);
            }
        }

        //--------------------------------------------------------------------
        template<class SrcPixelFormatRenderer>
        void blend_from(const SrcPixelFormatRenderer& from,
                        int xdst, int ydst,
                        int xsrc, int ysrc,
                        unsigned len,
                        int8u cover)
        {
            typedef typename SrcPixelFormatRenderer::order_type src_order;
            const value_type* psrc = (value_type*)from.row_ptr(ysrc);
            if(psrc)
            {
                psrc += xsrc << 2;
                value_type* pdst =
                    (value_type*)m_rbuf->row_ptr(xdst, ydst, len) + (xdst << 2);
                int incp = 4;
                if(xdst > xsrc)
                {
                    psrc += (len-1) << 2;
                    pdst += (len-1) << 2;
                    incp = -4;
                }

                if(cover == 255)
                {
                    do
                    {
                        cob_type::copy_or_blend_pix(pdst,
                                                    psrc[src_order::R],
                                                    psrc[src_order::G],
                                                    psrc[src_order::B],
                                                    psrc[src_order::A]);
                        psrc += incp;
                        pdst += incp;
                    }
                    while(--len);
                }
                else
                {
                    do
                    {
                        cob_type::copy_or_blend_pix(pdst,
                                                    psrc[src_order::R],
                                                    psrc[src_order::G],
                                                    psrc[src_order::B],
                                                    psrc[src_order::A],
                                                    cover);
                        psrc += incp;
                        pdst += incp;
                    }
                    while(--len);
                }
            }
        }

        //--------------------------------------------------------------------
        template<class SrcPixelFormatRenderer>
        void blend_from_color(const SrcPixelFormatRenderer& from,
                              const color_type& color,
                              int xdst, int ydst,
                              int /*xsrc*/, int ysrc,
                              unsigned len,
                              int8u cover)
        {
            typedef typename SrcPixelFormatRenderer::value_type src_value_type;
            const src_value_type* psrc = (src_value_type*)from.row_ptr(ysrc);
            if(psrc)
            {
                value_type* pdst =
                    (value_type*)m_rbuf->row_ptr(xdst, ydst, len) + (xdst << 2);
                do
                {
                    cob_type::copy_or_blend_pix(pdst,
                                                color.r, color.g, color.b, color.a,
                                                (*psrc * cover + base_mask) >> base_shift);
                    ++psrc;
                    pdst += 4;
                }
                while(--len);
            }
        }

        //--------------------------------------------------------------------
        template<class SrcPixelFormatRenderer>
        void blend_from_lut(const SrcPixelFormatRenderer& from,
                            const color_type* color_lut,
                            int xdst, int ydst,
                            int /*xsrc*/, int ysrc,
                            unsigned len,
                            int8u cover)
        {
            typedef typename SrcPixelFormatRenderer::value_type src_value_type;
            const src_value_type* psrc = (src_value_type*)from.row_ptr(ysrc);
            if(psrc)
            {
                value_type* pdst =
                    (value_type*)m_rbuf->row_ptr(xdst, ydst, len) + (xdst << 2);

                if(cover == 255)
                {
                    do
                    {
                        const color_type& color = color_lut[*psrc];
                        cob_type::copy_or_blend_pix(pdst,
                                                    color.r, color.g, color.b, color.a);
                        ++psrc;
                        pdst += 4;
                    }
                    while(--len);
                }
                else
                {
                    do
                    {
                        const color_type& color = color_lut[*psrc];
                        cob_type::copy_or_blend_pix(pdst,
                                                    color.r, color.g, color.b, color.a,
                                                    cover);
                        ++psrc;
                        pdst += 4;
                    }
                    while(--len);
                }
            }
        }

    private:
        rbuf_type* m_rbuf;
    };




    //================================================pixfmt_custom_blend_rgba
    template<class Blender, class RenBuf> class pixfmt_custom_blend_rgba
    {
    public:
        typedef RenBuf   rbuf_type;
        typedef typename rbuf_type::row_data row_data;
        typedef Blender  blender_type;
        typedef typename blender_type::color_type color_type;
        typedef typename blender_type::order_type order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;
        enum base_scale_e
        {
            base_shift = color_type::base_shift,
            base_scale = color_type::base_scale,
            base_mask  = color_type::base_mask,
            pix_width  = sizeof(value_type) * 4
        };


        //--------------------------------------------------------------------
        pixfmt_custom_blend_rgba() : m_rbuf(0), m_comp_op(3) {}
        explicit pixfmt_custom_blend_rgba(rbuf_type& rb, unsigned comp_op=3) :
            m_rbuf(&rb),
            m_comp_op(comp_op)
        {}
        void attach(rbuf_type& rb) { m_rbuf = &rb; }

        //--------------------------------------------------------------------
        template<class PixFmt>
        bool attach(PixFmt& pixf, int x1, int y1, int x2, int y2)
        {
            rect_i r(x1, y1, x2, y2);
            if(r.clip(rect_i(0, 0, pixf.width()-1, pixf.height()-1)))
            {
                int stride = pixf.stride();
                m_rbuf->attach(pixf.pix_ptr(r.x1, stride < 0 ? r.y2 : r.y1),
                               (r.x2 - r.x1) + 1,
                               (r.y2 - r.y1) + 1,
                               stride);
                return true;
            }
            return false;
        }

        //--------------------------------------------------------------------
        AGG_INLINE unsigned width()  const { return m_rbuf->width();  }
        AGG_INLINE unsigned height() const { return m_rbuf->height(); }
        AGG_INLINE int      stride() const { return m_rbuf->stride(); }

        //--------------------------------------------------------------------
        AGG_INLINE       int8u* row_ptr(int y)       { return m_rbuf->row_ptr(y); }
        AGG_INLINE const int8u* row_ptr(int y) const { return m_rbuf->row_ptr(y); }
        AGG_INLINE row_data     row(int y)     const { return m_rbuf->row(y); }

        //--------------------------------------------------------------------
        AGG_INLINE int8u* pix_ptr(int x, int y)
        {
            return m_rbuf->row_ptr(y) + x * pix_width;
        }

        AGG_INLINE const int8u* pix_ptr(int x, int y) const
        {
            return m_rbuf->row_ptr(y) + x * pix_width;
        }

        //--------------------------------------------------------------------
        void comp_op(unsigned op) { m_comp_op = op; }
        unsigned comp_op() const  { return m_comp_op; }

        //--------------------------------------------------------------------
        AGG_INLINE static void make_pix(int8u* p, const color_type& c)
        {
            ((value_type*)p)[order_type::R] = c.r;
            ((value_type*)p)[order_type::G] = c.g;
            ((value_type*)p)[order_type::B] = c.b;
            ((value_type*)p)[order_type::A] = c.a;
        }

        //--------------------------------------------------------------------
        color_type pixel(int x, int y) const
        {
            const value_type* p = (value_type*)m_rbuf->row_ptr(y) + (x << 2);
            return color_type(p[order_type::R],
                              p[order_type::G],
                              p[order_type::B],
                              p[order_type::A]);
        }

        //--------------------------------------------------------------------
        void copy_pixel(int x, int y, const color_type& c)
        {
            blender_type::blend_pix(
                m_comp_op,
                (value_type*)m_rbuf->row_ptr(x, y, 1) + (x << 2),
                c.r, c.g, c.b, c.a, 255);
        }

        //--------------------------------------------------------------------
        void blend_pixel(int x, int y, const color_type& c, int8u cover)
        {
            blender_type::blend_pix(
                m_comp_op,
                (value_type*)m_rbuf->row_ptr(x, y, 1) + (x << 2),
                c.r, c.g, c.b, c.a,
                cover);
        }

        //--------------------------------------------------------------------
        void copy_hline(int x, int y, unsigned len, const color_type& c)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);;
            do
            {
                blender_type::blend_pix(m_comp_op, p, c.r, c.g, c.b, c.a, 255);
                p += 4;
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void copy_vline(int x, int y, unsigned len, const color_type& c)
        {
            do
            {
                blender_type::blend_pix(
                    m_comp_op,
                    (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2),
                    c.r, c.g, c.b, c.a, 255);
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void blend_hline(int x, int y, unsigned len,
                         const color_type& c, int8u cover)
        {

            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            do
            {
                blender_type::blend_pix(m_comp_op, p, c.r, c.g, c.b, c.a, cover);
                p += 4;
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void blend_vline(int x, int y, unsigned len,
                         const color_type& c, int8u cover)
        {

            do
            {
                blender_type::blend_pix(
                    m_comp_op,
                    (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2),
                    c.r, c.g, c.b, c.a,
                    cover);
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void blend_solid_hspan(int x, int y, unsigned len,
                               const color_type& c, const int8u* covers)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            do
            {
                blender_type::blend_pix(m_comp_op,
                                        p, c.r, c.g, c.b, c.a,
                                        *covers++);
                p += 4;
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void blend_solid_vspan(int x, int y, unsigned len,
                               const color_type& c, const int8u* covers)
        {
            do
            {
                blender_type::blend_pix(
                    m_comp_op,
                    (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2),
                    c.r, c.g, c.b, c.a,
                    *covers++);
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void copy_color_hspan(int x, int y,
                              unsigned len,
                              const color_type* colors)
        {

            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            do
            {
                p[order_type::R] = colors->r;
                p[order_type::G] = colors->g;
                p[order_type::B] = colors->b;
                p[order_type::A] = colors->a;
                ++colors;
                p += 4;
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void copy_color_vspan(int x, int y,
                              unsigned len,
                              const color_type* colors)
        {
            do
            {
                value_type* p = (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2);
                p[order_type::R] = colors->r;
                p[order_type::G] = colors->g;
                p[order_type::B] = colors->b;
                p[order_type::A] = colors->a;
                ++colors;
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void blend_color_hspan(int x, int y, unsigned len,
                               const color_type* colors,
                               const int8u* covers,
                               int8u cover)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            do
            {
                blender_type::blend_pix(m_comp_op,
                                        p,
                                        colors->r,
                                        colors->g,
                                        colors->b,
                                        colors->a,
                                        covers ? *covers++ : cover);
                p += 4;
                ++colors;
            }
            while(--len);
        }

        //--------------------------------------------------------------------
        void blend_color_hspan_alpha(int x, int y, unsigned len,
                                     const color_type* colors,
                                     value_type alpha,
                                     const int8u* covers,
                                     int8u cover)
        {
            value_type* p = (value_type*)m_rbuf->row_ptr(x, y, len) + (x << 2);
            do
            {
                blender_type::blend_pix(m_comp_op,
                                        p,
                                        (colors->r * alpha + 255) >> 8,
                                        (colors->g * alpha + 255) >> 8,
                                        (colors->b * alpha + 255) >> 8,
                                        (colors->a * alpha + 255) >> 8,
                                        covers ? *covers++ : cover);
                p += 4;
                ++colors;
            }
            while(--len);
        }


        //--------------------------------------------------------------------
        void blend_color_vspan(int x, int y, unsigned len,
                               const color_type* colors,
                               const int8u* covers,
                               int8u cover)
        {
            do
            {
                blender_type::blend_pix(
                    m_comp_op,
                    (value_type*)m_rbuf->row_ptr(x, y++, 1) + (x << 2),
                    colors->r,
                    colors->g,
                    colors->b,
                    colors->a,
                    covers ? *covers++ : cover);
                ++colors;
            }
            while(--len);

        }

        //--------------------------------------------------------------------
        template<class Function> void for_each_pixel(Function f)
        {
            unsigned y;
            for(y = 0; y < height(); ++y)
            {
                row_data r = m_rbuf->row(y);
                if(r.ptr)
                {
                    unsigned len = r.x2 - r.x1 + 1;
                    value_type* p =
                        (value_type*)m_rbuf->row_ptr(r.x1, y, len) + (r.x1 << 2);
                    do
                    {
                        f(p);
                        p += 4;
                    }
                    while(--len);
                }
            }
        }

        //--------------------------------------------------------------------
        void premultiply()
        {
            for_each_pixel(multiplier_rgba<color_type, order_type>::premultiply);
        }

        //--------------------------------------------------------------------
        void demultiply()
        {
            for_each_pixel(multiplier_rgba<color_type, order_type>::demultiply);
        }

        //--------------------------------------------------------------------
        template<class GammaLut> void apply_gamma_dir(const GammaLut& g)
        {
            for_each_pixel(apply_gamma_dir_rgba<color_type, order_type, GammaLut>(g));
        }

        //--------------------------------------------------------------------
        template<class GammaLut> void apply_gamma_inv(const GammaLut& g)
        {
            for_each_pixel(apply_gamma_inv_rgba<color_type, order_type, GammaLut>(g));
        }

        //--------------------------------------------------------------------
        template<class RenBuf2> void copy_from(const RenBuf2& from,
                                               int xdst, int ydst,
                                               int xsrc, int ysrc,
                                               unsigned len)
        {
            const int8u* p = from.row_ptr(ysrc);
            if(p)
            {
                memmove(m_rbuf->row_ptr(xdst, ydst, len) + xdst * pix_width,
                        p + xsrc * pix_width,
                        len * pix_width);
            }
        }

        //--------------------------------------------------------------------
        template<class SrcPixelFormatRenderer>
        void blend_from(const SrcPixelFormatRenderer& from,
                        int xdst, int ydst,
                        int xsrc, int ysrc,
                        unsigned len,
                        int8u cover)
        {
            typedef typename SrcPixelFormatRenderer::order_type src_order;
            const value_type* psrc = (const value_type*)from.row_ptr(ysrc);
            if(psrc)
            {
                psrc += xsrc << 2;
                value_type* pdst =
                    (value_type*)m_rbuf->row_ptr(xdst, ydst, len) + (xdst << 2);

                int incp = 4;
                if(xdst > xsrc)
                {
                    psrc += (len-1) << 2;
                    pdst += (len-1) << 2;
                    incp = -4;
                }

                do
                {
                    blender_type::blend_pix(m_comp_op,
                                            pdst,
                                            psrc[src_order::R],
                                            psrc[src_order::G],
                                            psrc[src_order::B],
                                            psrc[src_order::A],
                                            cover);
                    psrc += incp;
                    pdst += incp;
                }
                while(--len);
            }
        }

        //--------------------------------------------------------------------
        template<class SrcPixelFormatRenderer>
        void blend_from_color(const SrcPixelFormatRenderer& from,
                              const color_type& color,
                              int xdst, int ydst,
                              int /*xsrc*/, int ysrc,
                              unsigned len,
                              int8u cover)
        {
            typedef typename SrcPixelFormatRenderer::value_type src_value_type;
            const src_value_type* psrc = (src_value_type*)from.row_ptr(ysrc);
            if(psrc)
            {
                value_type* pdst =
                    (value_type*)m_rbuf->row_ptr(xdst, ydst, len) + (xdst << 2);
                do
                {
                    blender_type::blend_pix(m_comp_op,
                                            pdst,
                                            color.r, color.g, color.b, color.a,
                                            (*psrc * cover + base_mask) >> base_shift);
                    ++psrc;
                    pdst += 4;
                }
                while(--len);
            }
        }

        //--------------------------------------------------------------------
        template<class SrcPixelFormatRenderer>
        void blend_from_lut(const SrcPixelFormatRenderer& from,
                            const color_type* color_lut,
                            int xdst, int ydst,
                            int /*xsrc*/, int ysrc,
                            unsigned len,
                            int8u cover)
        {
            typedef typename SrcPixelFormatRenderer::value_type src_value_type;
            const src_value_type* psrc = (src_value_type*)from.row_ptr(ysrc);
            if(psrc)
            {
                value_type* pdst =
                    (value_type*)m_rbuf->row_ptr(xdst, ydst, len) + (xdst << 2);
                do
                {
                    const color_type& color = color_lut[*psrc];
                    blender_type::blend_pix(m_comp_op,
                                            pdst,
                                            color.r, color.g, color.b, color.a,
                                            cover);
                    ++psrc;
                    pdst += 4;
                }
                while(--len);
            }
        }

    private:
        rbuf_type* m_rbuf;
        unsigned m_comp_op;
    };




    //-----------------------------------------------------------------------
    typedef blender_rgba<rgba8, order_rgba> blender_rgba32; //----blender_rgba32
    typedef blender_rgba<rgba8, order_argb> blender_argb32; //----blender_argb32
    typedef blender_rgba<rgba8, order_abgr> blender_abgr32; //----blender_abgr32
    typedef blender_rgba<rgba8, order_bgra> blender_bgra32; //----blender_bgra32

    typedef blender_rgba_pre<rgba8, order_rgba> blender_rgba32_pre; //----blender_rgba32_pre
    typedef blender_rgba_pre<rgba8, order_argb> blender_argb32_pre; //----blender_argb32_pre
    typedef blender_rgba_pre<rgba8, order_abgr> blender_abgr32_pre; //----blender_abgr32_pre
    typedef blender_rgba_pre<rgba8, order_bgra> blender_bgra32_pre; //----blender_bgra32_pre

    typedef blender_rgba_plain<rgba8, order_rgba> blender_rgba32_plain; //----blender_rgba32_plain
    typedef blender_rgba_plain<rgba8, order_argb> blender_argb32_plain; //----blender_argb32_plain
    typedef blender_rgba_plain<rgba8, order_abgr> blender_abgr32_plain; //----blender_abgr32_plain
    typedef blender_rgba_plain<rgba8, order_bgra> blender_bgra32_plain; //----blender_bgra32_plain

    typedef blender_rgba<rgba16, order_rgba> blender_rgba64; //----blender_rgba64
    typedef blender_rgba<rgba16, order_argb> blender_argb64; //----blender_argb64
    typedef blender_rgba<rgba16, order_abgr> blender_abgr64; //----blender_abgr64
    typedef blender_rgba<rgba16, order_bgra> blender_bgra64; //----blender_bgra64

    typedef blender_rgba_pre<rgba16, order_rgba> blender_rgba64_pre; //----blender_rgba64_pre
    typedef blender_rgba_pre<rgba16, order_argb> blender_argb64_pre; //----blender_argb64_pre
    typedef blender_rgba_pre<rgba16, order_abgr> blender_abgr64_pre; //----blender_abgr64_pre
    typedef blender_rgba_pre<rgba16, order_bgra> blender_bgra64_pre; //----blender_bgra64_pre


    //-----------------------------------------------------------------------
    typedef int32u pixel32_type;
    typedef pixfmt_alpha_blend_rgba<blender_rgba32, rendering_buffer, pixel32_type> pixfmt_rgba32; //----pixfmt_rgba32
    typedef pixfmt_alpha_blend_rgba<blender_argb32, rendering_buffer, pixel32_type> pixfmt_argb32; //----pixfmt_argb32
    typedef pixfmt_alpha_blend_rgba<blender_abgr32, rendering_buffer, pixel32_type> pixfmt_abgr32; //----pixfmt_abgr32
    typedef pixfmt_alpha_blend_rgba<blender_bgra32, rendering_buffer, pixel32_type> pixfmt_bgra32; //----pixfmt_bgra32

    typedef pixfmt_alpha_blend_rgba<blender_rgba32_pre, rendering_buffer, pixel32_type> pixfmt_rgba32_pre; //----pixfmt_rgba32_pre
    typedef pixfmt_alpha_blend_rgba<blender_argb32_pre, rendering_buffer, pixel32_type> pixfmt_argb32_pre; //----pixfmt_argb32_pre
    typedef pixfmt_alpha_blend_rgba<blender_abgr32_pre, rendering_buffer, pixel32_type> pixfmt_abgr32_pre; //----pixfmt_abgr32_pre
    typedef pixfmt_alpha_blend_rgba<blender_bgra32_pre, rendering_buffer, pixel32_type> pixfmt_bgra32_pre; //----pixfmt_bgra32_pre

    typedef pixfmt_alpha_blend_rgba<blender_rgba32_plain, rendering_buffer, pixel32_type> pixfmt_rgba32_plain; //----pixfmt_rgba32_plain
    typedef pixfmt_alpha_blend_rgba<blender_argb32_plain, rendering_buffer, pixel32_type> pixfmt_argb32_plain; //----pixfmt_argb32_plain
    typedef pixfmt_alpha_blend_rgba<blender_abgr32_plain, rendering_buffer, pixel32_type> pixfmt_abgr32_plain; //----pixfmt_abgr32_plain
    typedef pixfmt_alpha_blend_rgba<blender_bgra32_plain, rendering_buffer, pixel32_type> pixfmt_bgra32_plain; //----pixfmt_bgra32_plain

    struct  pixel64_type { int16u c[4]; };
    typedef pixfmt_alpha_blend_rgba<blender_rgba64, rendering_buffer, pixel64_type> pixfmt_rgba64; //----pixfmt_rgba64
    typedef pixfmt_alpha_blend_rgba<blender_argb64, rendering_buffer, pixel64_type> pixfmt_argb64; //----pixfmt_argb64
    typedef pixfmt_alpha_blend_rgba<blender_abgr64, rendering_buffer, pixel64_type> pixfmt_abgr64; //----pixfmt_abgr64
    typedef pixfmt_alpha_blend_rgba<blender_bgra64, rendering_buffer, pixel64_type> pixfmt_bgra64; //----pixfmt_bgra64

    typedef pixfmt_alpha_blend_rgba<blender_rgba64_pre, rendering_buffer, pixel64_type> pixfmt_rgba64_pre; //----pixfmt_rgba64_pre
    typedef pixfmt_alpha_blend_rgba<blender_argb64_pre, rendering_buffer, pixel64_type> pixfmt_argb64_pre; //----pixfmt_argb64_pre
    typedef pixfmt_alpha_blend_rgba<blender_abgr64_pre, rendering_buffer, pixel64_type> pixfmt_abgr64_pre; //----pixfmt_abgr64_pre
    typedef pixfmt_alpha_blend_rgba<blender_bgra64_pre, rendering_buffer, pixel64_type> pixfmt_bgra64_pre; //----pixfmt_bgra64_pre
}

#endif