agg_pixfmt_rgb_packed.h

这是VCF框架的代码

                              (p >> 4)  & 0xFFC0, 
                              (p << 6)  & 0xFFC0);
        }
    private:
        const Gamma* m_gamma;
    };


    //=====================================================blender_bgrAAA
    struct blender_bgrAAA
    {
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;

        static AGG_INLINE void blend_pix(pixel_type* p, 
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha, 
                                         unsigned)
        {
            pixel_type bgr = *p;
            calc_type b = (bgr >> 14) & 0xFFC0;
            calc_type g = (bgr >> 4)  & 0xFFC0;
            calc_type r = (bgr << 6)  & 0xFFC0;
            *p = (pixel_type)
               (((((cb - b) * alpha + (b << 16)) >> 2)  & 0x3FF00000) |
                ((((cg - g) * alpha + (g << 16)) >> 12) & 0x000FFC00) |
                 (((cr - r) * alpha + (r << 16)) >> 22) | 0xC0000000);
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((b & 0xFFC0) << 14) | 
                                ((g & 0xFFC0) << 4) | 
                                 (r >> 6) | 0xC0000000);
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p << 6)  & 0xFFC0, 
                              (p >> 4)  & 0xFFC0, 
                              (p >> 14) & 0xFFC0);
        }
    };



    //=================================================blender_bgrAAA_pre
    struct blender_bgrAAA_pre
    {
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;

        static AGG_INLINE void blend_pix(pixel_type* p, 
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha, 
                                         unsigned cover)
        {
            alpha = color_type::base_mask - alpha;
            cover = (cover + 1) << (color_type::base_shift - 8);
            pixel_type bgr = *p;
            calc_type b = (bgr >> 14) & 0xFFC0;
            calc_type g = (bgr >> 4)  & 0xFFC0;
            calc_type r = (bgr << 6)  & 0xFFC0;
            *p = (pixel_type)
               ((((b * alpha + cb * cover) >> 2)  & 0x3FF00000) |
                (((g * alpha + cg * cover) >> 12) & 0x000FFC00) |
                 ((r * alpha + cr * cover) >> 22) | 0xC0000000);
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((b & 0xFFC0) << 14) | 
                                ((g & 0xFFC0) << 4) | 
                                 (r >> 6) | 0xC0000000);
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p << 6)  & 0xFFC0, 
                              (p >> 4)  & 0xFFC0, 
                              (p >> 14) & 0xFFC0);
        }
    };



    //=================================================blender_bgrAAA_gamma
    template<class Gamma> class blender_bgrAAA_gamma
    {
    public:
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;
        typedef Gamma gamma_type;

        blender_bgrAAA_gamma() : m_gamma(0) {}
        void gamma(const gamma_type& g) { m_gamma = &g; }

        AGG_INLINE void blend_pix(pixel_type* p, 
                                  unsigned cr, unsigned cg, unsigned cb,
                                  unsigned alpha, 
                                  unsigned)
        {
            pixel_type bgr = *p;
            calc_type b = m_gamma->dir((bgr >> 14) & 0xFFC0);
            calc_type g = m_gamma->dir((bgr >> 4)  & 0xFFC0);
            calc_type r = m_gamma->dir((bgr << 6)  & 0xFFC0);
            *p = (pixel_type)
               (((m_gamma->inv(((m_gamma->dir(cb) - b) * alpha + (b << 16)) >> 16) << 14) & 0x3FF00000) |
                ((m_gamma->inv(((m_gamma->dir(cg) - g) * alpha + (g << 16)) >> 16) << 4 ) & 0x000FFC00) |
                 (m_gamma->inv(((m_gamma->dir(cr) - r) * alpha + (r << 16)) >> 16) >> 6 ) | 0xC0000000);
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((b & 0xFFC0) << 14) | 
                                ((g & 0xFFC0) << 4) | 
                                 (r >> 6) | 0xC0000000);
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p << 6)  & 0xFFC0, 
                              (p >> 4)  & 0xFFC0, 
                              (p >> 14) & 0xFFC0);
        }

    private:
        const Gamma* m_gamma;
    };



    //=====================================================blender_rgbBBA
    struct blender_rgbBBA
    {
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;

        static AGG_INLINE void blend_pix(pixel_type* p, 
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha, 
                                         unsigned)
        {
            pixel_type rgb = *p;
            calc_type r = (rgb >> 16) & 0xFFE0;
            calc_type g = (rgb >> 5)  & 0xFFE0;
            calc_type b = (rgb << 6)  & 0xFFC0;
            *p = (pixel_type)
               (((((cr - r) * alpha + (r << 16))      ) & 0xFFE00000) |
                ((((cg - g) * alpha + (g << 16)) >> 11) & 0x001FFC00) |
                 (((cb - b) * alpha + (b << 16)) >> 22));
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((r & 0xFFE0) << 16) | ((g & 0xFFE0) << 5) | (b >> 6));
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p >> 16) & 0xFFE0, 
                              (p >> 5)  & 0xFFE0, 
                              (p << 6)  & 0xFFC0);
        }
    };


    //=================================================blender_rgbBBA_pre
    struct blender_rgbBBA_pre
    {
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;

        static AGG_INLINE void blend_pix(pixel_type* p, 
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha, 
                                         unsigned cover)
        {
            alpha = color_type::base_mask - alpha;
            cover = (cover + 1) << (color_type::base_shift - 8);
            pixel_type rgb = *p;
            calc_type r = (rgb >> 16) & 0xFFE0;
            calc_type g = (rgb >> 5)  & 0xFFE0;
            calc_type b = (rgb << 6)  & 0xFFC0;
            *p = (pixel_type)
               ((((r * alpha + cr * cover)      ) & 0xFFE00000) |
                (((g * alpha + cg * cover) >> 11) & 0x001FFC00) |
                 ((b * alpha + cb * cover) >> 22));
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((r & 0xFFE0) << 16) | ((g & 0xFFE0) << 5) | (b >> 6));
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p >> 16) & 0xFFE0, 
                              (p >> 5)  & 0xFFE0, 
                              (p << 6)  & 0xFFC0);
        }
    };



    //=================================================blender_rgbBBA_gamma
    template<class Gamma> class blender_rgbBBA_gamma
    {
    public:
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;
        typedef Gamma gamma_type;

        blender_rgbBBA_gamma() : m_gamma(0) {}
        void gamma(const gamma_type& g) { m_gamma = &g; }

        AGG_INLINE void blend_pix(pixel_type* p, 
                                  unsigned cr, unsigned cg, unsigned cb,
                                  unsigned alpha, 
                                  unsigned)
        {
            pixel_type rgb = *p;
            calc_type r = m_gamma->dir((rgb >> 16) & 0xFFE0);
            calc_type g = m_gamma->dir((rgb >> 5)  & 0xFFE0);
            calc_type b = m_gamma->dir((rgb << 6)  & 0xFFC0);
            *p = (pixel_type)
               (((m_gamma->inv(((m_gamma->dir(cr) - r) * alpha + (r << 16)) >> 16) << 16) & 0xFFE00000) |
                ((m_gamma->inv(((m_gamma->dir(cg) - g) * alpha + (g << 16)) >> 16) << 5 ) & 0x001FFC00) |
                 (m_gamma->inv(((m_gamma->dir(cb) - b) * alpha + (b << 16)) >> 16) >> 6 ));
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((r & 0xFFE0) << 16) | ((g & 0xFFE0) << 5) | (b >> 6));
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p >> 16) & 0xFFE0, 
                              (p >> 5)  & 0xFFE0, 
                              (p << 6)  & 0xFFC0);
        }

    private:
        const Gamma* m_gamma;
    };


    //=====================================================blender_bgrABB
    struct blender_bgrABB
    {
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;

        static AGG_INLINE void blend_pix(pixel_type* p, 
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha, 
                                         unsigned)
        {
            pixel_type bgr = *p;
            calc_type b = (bgr >> 16) & 0xFFC0;
            calc_type g = (bgr >> 6)  & 0xFFE0;
            calc_type r = (bgr << 5)  & 0xFFE0;
            *p = (pixel_type)
               (((((cb - b) * alpha + (b << 16))      ) & 0xFFC00000) |
                ((((cg - g) * alpha + (g << 16)) >> 10) & 0x003FF800) |
                 (((cr - r) * alpha + (r << 16)) >> 21));
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((b & 0xFFC0) << 16) | ((g & 0xFFE0) << 6) | (r >> 5));
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p << 5)  & 0xFFE0,
                              (p >> 6)  & 0xFFE0, 
                              (p >> 16) & 0xFFC0);
        }
    };


    //=================================================blender_bgrABB_pre
    struct blender_bgrABB_pre
    {
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;

        static AGG_INLINE void blend_pix(pixel_type* p, 
                                         unsigned cr, unsigned cg, unsigned cb,
                                         unsigned alpha, 
                                         unsigned cover)
        {
            alpha = color_type::base_mask - alpha;
            cover = (cover + 1) << (color_type::base_shift - 8);
            pixel_type bgr = *p;
            calc_type b = (bgr >> 16) & 0xFFC0;
            calc_type g = (bgr >> 6)  & 0xFFE0;
            calc_type r = (bgr << 5)  & 0xFFE0;
            *p = (pixel_type)
               ((((b * alpha + cb * cover)      ) & 0xFFC00000) |
                (((g * alpha + cg * cover) >> 10) & 0x003FF800) |
                 ((r * alpha + cr * cover) >> 21));
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((b & 0xFFC0) << 16) | ((g & 0xFFE0) << 6) | (r >> 5));
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p << 5)  & 0xFFE0,
                              (p >> 6)  & 0xFFE0, 
                              (p >> 16) & 0xFFC0);
        }
    };



    //=================================================blender_bgrABB_gamma
    template<class Gamma> class blender_bgrABB_gamma
    {
    public:
        typedef rgba16 color_type;
        typedef color_type::value_type value_type;
        typedef color_type::calc_type calc_type;
        typedef int32u pixel_type;
        typedef Gamma gamma_type;

        blender_bgrABB_gamma() : m_gamma(0) {}
        void gamma(const gamma_type& g) { m_gamma = &g; }

        AGG_INLINE void blend_pix(pixel_type* p, 
                                  unsigned cr, unsigned cg, unsigned cb,
                                  unsigned alpha, 
                                  unsigned)
        {
            pixel_type bgr = *p;
            calc_type b = m_gamma->dir((bgr >> 16) & 0xFFC0);
            calc_type g = m_gamma->dir((bgr >> 6)  & 0xFFE0);
            calc_type r = m_gamma->dir((bgr << 5)  & 0xFFE0);
            *p = (pixel_type)
               (((m_gamma->inv(((m_gamma->dir(cb) - b) * alpha + (b << 16)) >> 16) << 16) & 0xFFC00000) |
                ((m_gamma->inv(((m_gamma->dir(cg) - g) * alpha + (g << 16)) >> 16) << 6 ) & 0x003FF800) |
                 (m_gamma->inv(((m_gamma->dir(cr) - r) * alpha + (r << 16)) >> 16) >> 5 ));
        }

        static AGG_INLINE pixel_type make_pix(unsigned r, unsigned g, unsigned b)
        {
            return (pixel_type)(((b & 0xFFC0) << 16) | ((g & 0xFFE0) << 6) | (r >> 5));
        }

        static AGG_INLINE color_type make_color(pixel_type p)
        {
            return color_type((p << 5)  & 0xFFE0,
                              (p >> 6)  & 0xFFE0, 
                              (p >> 16) & 0xFFC0);
        }

    private:
        const Gamma* m_gamma;
    };


    
    //===========================================pixfmt_alpha_blend_rgb_packed
    template<class Blender,  class RenBuf> class pixfmt_alpha_blend_rgb_packed
    {
    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::pixel_type pixel_type;
        typedef int                               order_type; // A fake one
        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(pixel_type)
        };

    private:
        //--------------------------------------------------------------------
        AGG_INLINE void copy_or_blend_pix(pixel_type* p, const color_type& c, unsigned cover)
        {