agg_renderer_outline_aa.h

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            base_type::m_step -= base_type::m_max_extent;
        }


        //---------------------------------------------------------------------
        bool step_hor()
        {
            int dist_start;
            int dist_end;
            int dist;
            int dy;
            int s1 = base_type::step_hor_base(m_di);
            cover_type* p0 = base_type::m_covers + base_type::max_half_width + 2;
            cover_type* p1 = p0;

            dist_start = m_di.dist_start();
            dist_end   = m_di.dist_end();

            int npix = 0;
            *p1 = 0;
            if(dist_end > 0)
            {
                if(dist_start <= 0)
                {
                    *p1 = (cover_type)base_type::m_ren.cover(s1);
                }
                ++npix;
            }
            ++p1;

            dy = 1;
            while((dist = base_type::m_dist[dy] - s1) <= base_type::m_width)
            {
                dist_start -= m_di.dx_start();
                dist_end   -= m_di.dx_end();
                *p1 = 0;
                if(dist_end > 0 && dist_start <= 0)
                {   
                    *p1 = (cover_type)base_type::m_ren.cover(dist);
                    ++npix;
                }
                ++p1;
                ++dy;
            }

            dy = 1;
            dist_start = m_di.dist_start();
            dist_end   = m_di.dist_end();
            while((dist = base_type::m_dist[dy] + s1) <= base_type::m_width)
            {
                dist_start += m_di.dx_start();
                dist_end   += m_di.dx_end();
                *--p0 = 0;
                if(dist_end > 0 && dist_start <= 0)
                {   
                    *p0 = (cover_type)base_type::m_ren.cover(dist);
                    ++npix;
                }
                ++dy;
            }
            base_type::m_ren.blend_solid_vspan(base_type::m_x,
                                               base_type::m_y - dy + 1, 
                                               unsigned(p1 - p0), 
                                               p0);
            return npix && ++base_type::m_step < base_type::m_count;
        }

        //---------------------------------------------------------------------
        bool step_ver()
        {
            int dist_start;
            int dist_end;
            int dist;
            int dx;
            int s1 = base_type::step_ver_base(m_di);
            cover_type* p0 = base_type::m_covers + base_type::max_half_width + 2;
            cover_type* p1 = p0;

            dist_start = m_di.dist_start();
            dist_end   = m_di.dist_end();

            int npix = 0;
            *p1 = 0;
            if(dist_end > 0)
            {
                if(dist_start <= 0)
                {
                    *p1 = (cover_type)base_type::m_ren.cover(s1);
                }
                ++npix;
            }
            ++p1;

            dx = 1;
            while((dist = base_type::m_dist[dx] - s1) <= base_type::m_width)
            {
                dist_start += m_di.dy_start();
                dist_end   += m_di.dy_end();
                *p1 = 0;
                if(dist_end > 0 && dist_start <= 0)
                {   
                    *p1 = (cover_type)base_type::m_ren.cover(dist);
                    ++npix;
                }
                ++p1;
                ++dx;
            }

            dx = 1;
            dist_start = m_di.dist_start();
            dist_end   = m_di.dist_end();
            while((dist = base_type::m_dist[dx] + s1) <= base_type::m_width)
            {
                dist_start -= m_di.dy_start();
                dist_end   -= m_di.dy_end();
                *--p0 = 0;
                if(dist_end > 0 && dist_start <= 0)
                {   
                    *p0 = (cover_type)base_type::m_ren.cover(dist);
                    ++npix;
                }
                ++dx;
            }
            base_type::m_ren.blend_solid_hspan(base_type::m_x - dx + 1,
                                               base_type::m_y, 
                                               unsigned(p1 - p0), 
                                               p0);
            return npix && ++base_type::m_step < base_type::m_count;
        }

    private:
        line_interpolator_aa3(const line_interpolator_aa3<Renderer>&);
        const line_interpolator_aa3<Renderer>& 
            operator = (const line_interpolator_aa3<Renderer>&);

        //---------------------------------------------------------------------
        distance_interpolator3 m_di; 
    };




    //==========================================================line_profile_aa
    //
    // See Implementation agg_line_profile_aa.cpp 
    // 
    class line_profile_aa
    {
    public:
        //---------------------------------------------------------------------
        typedef int8u value_type;
        enum subpixel_scale_e
        {
            subpixel_shift = line_subpixel_shift,
            subpixel_scale = 1 << subpixel_shift,
            subpixel_mask  = subpixel_scale - 1
        };

        enum aa_scale_e
        {
            aa_shift = 8,
            aa_scale = 1 << aa_shift,
            aa_mask  = aa_scale - 1
        };
        
        //---------------------------------------------------------------------
        ~line_profile_aa() { delete [] m_profile; }

        //---------------------------------------------------------------------
        line_profile_aa() : 
            m_size(0), 
            m_profile(0), 
            m_subpixel_width(0),
            m_min_width(1.0),
            m_smoother_width(1.0)
        {
            int i;
            for(i = 0; i < aa_scale; i++) m_gamma[i] = (value_type)i;
        }

        //---------------------------------------------------------------------
        template<class GammaF> 
        line_profile_aa(double w, const GammaF& gamma_function) : 
            m_size(0), 
            m_profile(0), 
            m_subpixel_width(0),
            m_min_width(1.0),
            m_smoother_width(1.0)
        {
            gamma(gamma_function);
            width(w);
        }

        //---------------------------------------------------------------------
        void min_width(double w) { m_min_width = w; }
        void smoother_width(double w) { m_smoother_width = w; }

        //---------------------------------------------------------------------
        template<class GammaF> void gamma(const GammaF& gamma_function)
        { 
            int i;
            for(i = 0; i < aa_scale; i++)
            {
                m_gamma[i] = value_type(
                    uround(gamma_function(double(i) / aa_mask) * aa_mask));
            }
        }

        void width(double w);

        unsigned profile_size() const { return m_size; }
        int subpixel_width() const { return m_subpixel_width; }

        //---------------------------------------------------------------------
        double min_width() const { return m_min_width; }
        double smoother_width() const { return m_smoother_width; }

        //---------------------------------------------------------------------
        value_type value(int dist) const
        {
            return m_profile[dist + subpixel_scale*2];
        }

    private:
        line_profile_aa(const line_profile_aa&);
        const line_profile_aa& operator = (const line_profile_aa&);

        value_type* profile(double w);
        void set(double center_width, double smoother_width);

        //---------------------------------------------------------------------
        unsigned    m_size;
        value_type* m_profile;
        value_type  m_gamma[aa_scale];
        int         m_subpixel_width;
        double      m_min_width;
        double      m_smoother_width;
    };


    //======================================================renderer_outline_aa
    template<class BaseRenderer> class renderer_outline_aa
    {
    public:
        //---------------------------------------------------------------------
        typedef BaseRenderer base_ren_type;
        typedef renderer_outline_aa<base_ren_type> self_type;
        typedef typename base_ren_type::color_type color_type;

        //---------------------------------------------------------------------
        renderer_outline_aa(base_ren_type& ren, const line_profile_aa& prof) :
            m_ren(&ren),
            m_profile(&prof),
            m_clip_box(0,0,0,0),
            m_clipping(false)
        {}
        void attach(base_ren_type& ren) { m_ren = &ren; }

        //---------------------------------------------------------------------
        void color(const color_type& c) { m_color = c; }
        const color_type& color() const { return m_color; }

        //---------------------------------------------------------------------
        void profile(const line_profile_aa& prof) { m_profile = &prof; }
        const line_profile_aa& profile() const { return *m_profile; }
        line_profile_aa& profile() { return *m_profile; }

        //---------------------------------------------------------------------
        int subpixel_width() const { return m_profile->subpixel_width(); }

        //---------------------------------------------------------------------
        void reset_clipping() { m_clipping = false; }
        void clip_box(double x1, double y1, double x2, double y2)
        {
            m_clip_box.x1 = line_coord_sat::conv(x1);
            m_clip_box.y1 = line_coord_sat::conv(y1);
            m_clip_box.x2 = line_coord_sat::conv(x2);
            m_clip_box.y2 = line_coord_sat::conv(y2);
            m_clipping = true;
        }

        //---------------------------------------------------------------------
        int cover(int d) const
        {
            return m_profile->value(d);
        }

        //-------------------------------------------------------------------------
        void blend_solid_hspan(int x, int y, unsigned len, const cover_type* covers)
        {
            m_ren->blend_solid_hspan(x, y, len, m_color, covers);
        }

        //-------------------------------------------------------------------------
        void blend_solid_vspan(int x, int y, unsigned len, const cover_type* covers)
        {
            m_ren->blend_solid_vspan(x, y, len, m_color, covers);
        }

        //-------------------------------------------------------------------------
        static bool accurate_join_only() { return false; }

        //-------------------------------------------------------------------------
        template<class Cmp>
        void semidot_hline(Cmp cmp,
                           int xc1, int yc1, int xc2, int yc2, 
                           int x1,  int y1,  int x2)
        {
            cover_type covers[line_interpolator_aa_base<self_type>::max_half_width * 2 + 4];
            cover_type* p0 = covers;
            cover_type* p1 = covers;
            int x = x1 << line_subpixel_shift;
            int y = y1 << line_subpixel_shift;
            int w = subpixel_width();
            distance_interpolator0 di(xc1, yc1, xc2, yc2, x, y);
            x += line_subpixel_scale/2;
            y += line_subpixel_scale/2;

            int x0 = x1;
            int dx = x - xc1;
            int dy = y - yc1;
            do
            {
                int d = int(fast_sqrt(dx*dx + dy*dy));
                *p1 = 0;
                if(cmp(di.dist()) && d <= w)
                {
                    *p1 = (cover_type)cover(d);
                }
                ++p1;
                dx += line_subpixel_scale;
                di.inc_x();
            }
            while(++x1 <= x2);
            m_ren->blend_solid_hspan(x0, y1, 
                                     unsigned(p1 - p0), 
                                     color(), 
                                     p0);
        }

        //-------------------------------------------------------------------------
        template<class Cmp> 
        void semidot(Cmp cmp, int xc1, int yc1, int xc2, int yc2)
        {
            if(m_clipping && clipping_flags(xc1, yc1, m_clip_box)) return;

            int r = ((subpixel_width() + line_subpixel_mask) >> line_subpixel_shift);
            if(r < 1) r = 1;
            ellipse_bresenham_interpolator ei(r, r);
            int dx = 0;
            int dy = -r;
            int dy0 = dy;
            int dx0 = dx;
            int x = xc1 >> line_subpixel_shift;
            int y = yc1 >> line_subpixel_shift;

            do
            {
                dx += ei.dx();
                dy += ei.dy();

                if(dy != dy0)
                {
                    semidot_hline(cmp, xc1, yc1, xc2, yc2, x-dx0, y+dy0, x+dx0);
                    semidot_hline(cmp, xc1, yc1, xc2, yc2, x-dx0, y-dy0, x+dx0);
                }
                dx0 = dx;
                dy0 = dy;
                ++ei;
            }