agg_rasterizer_scanline_aa.h

windows ce 下的画各种b样条曲线

                    while(--num_cells)
                    {
                        cur_cell = *++cells;
                        if(cur_cell->x != x) break;
                        area  += cur_cell->area;
                        cover += cur_cell->cover;
                    }

                    if(area)
                    {
                        alpha = calculate_alpha((cover << (poly_subpixel_shift + 1)) - area);
                        if(alpha)
                        {
                            sl.add_cell(x, alpha);
                        }
                        x++;
                    }

                    if(num_cells && cur_cell->x > x)
                    {
                        alpha = calculate_alpha(cover << (poly_subpixel_shift + 1));
                        if(alpha)
                        {
                            sl.add_span(x, cur_cell->x - x, alpha);
                        }
                    }
                }
        
                if(sl.num_spans()) break;
                ++m_scan_y;
            }

            sl.finalize(m_scan_y);
            ++m_scan_y;
            return true;
        }

        //--------------------------------------------------------------------
        bool hit_test(int tx, int ty);


    private:
        //--------------------------------------------------------------------
        // Disable copying
        rasterizer_scanline_aa(const rasterizer_scanline_aa<Clip>&);
        const rasterizer_scanline_aa<Clip>& 
        operator = (const rasterizer_scanline_aa<Clip>&);

    private:
        rasterizer_cells_aa<cell_aa> m_outline;
        clip_type      m_clipper;
        int            m_gamma[aa_scale];
        filling_rule_e m_filling_rule;
        bool           m_auto_close;
        coord_type     m_start_x;
        coord_type     m_start_y;
        unsigned       m_status;
        int            m_scan_y;
    };












    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::reset() 
    { 
        m_outline.reset(); 
        m_status = status_initial;
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::filling_rule(filling_rule_e filling_rule) 
    { 
        m_filling_rule = filling_rule; 
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::clip_box(double x1, double y1, 
                                                double x2, double y2)
    {
        reset();
        m_clipper.clip_box(conv_type::upscale(x1), conv_type::upscale(y1), 
                           conv_type::upscale(x2), conv_type::upscale(y2));
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::reset_clipping()
    {
        reset();
        m_clipper.reset_clipping();
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::close_polygon()
    {
        if(m_status == status_line_to)
        {
            m_clipper.line_to(m_outline, m_start_x, m_start_y);
            m_status = status_closed;
        }
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::move_to(int x, int y)
    {
        if(m_outline.sorted()) reset();
        if(m_auto_close) close_polygon();
        m_clipper.move_to(m_start_x = conv_type::downscale(x), 
                          m_start_y = conv_type::downscale(y));
        m_status = status_move_to;
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::line_to(int x, int y)
    {
        m_clipper.line_to(m_outline, 
                          conv_type::downscale(x), 
                          conv_type::downscale(y));
        m_status = status_line_to;
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::move_to_d(double x, double y) 
    { 
        if(m_outline.sorted()) reset();
        if(m_auto_close) close_polygon();
        m_clipper.move_to(m_start_x = conv_type::upscale(x), 
                          m_start_y = conv_type::upscale(y)); 
        m_status = status_move_to;
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::line_to_d(double x, double y) 
    { 
        m_clipper.line_to(m_outline, 
                          conv_type::upscale(x), 
                          conv_type::upscale(y)); 
        m_status = status_line_to;
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::add_vertex(double x, double y, unsigned cmd)
    {
        if(is_move_to(cmd)) 
        {
            move_to_d(x, y);
        }
        else 
        if(is_vertex(cmd))
        {
            line_to_d(x, y);
        }
        else
        if(is_close(cmd))
        {
            close_polygon();
        }
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::edge(int x1, int y1, int x2, int y2)
    {
        if(m_outline.sorted()) reset();
        m_clipper.move_to(conv_type::downscale(x1), conv_type::downscale(y1));
        m_clipper.line_to(m_outline, 
                          conv_type::downscale(x2), 
                          conv_type::downscale(y2));
        m_status = status_move_to;
    }
    
    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::edge_d(double x1, double y1, 
                                              double x2, double y2)
    {
        if(m_outline.sorted()) reset();
        m_clipper.move_to(conv_type::upscale(x1), conv_type::upscale(y1)); 
        m_clipper.line_to(m_outline, 
                          conv_type::upscale(x2), 
                          conv_type::upscale(y2)); 
        m_status = status_move_to;
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    void rasterizer_scanline_aa<Clip>::sort()
    {
        if(m_auto_close) close_polygon();
        m_outline.sort_cells();
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    AGG_INLINE bool rasterizer_scanline_aa<Clip>::rewind_scanlines()
    {
        if(m_auto_close) close_polygon();
        m_outline.sort_cells();
        if(m_outline.total_cells() == 0) 
        {
            return false;
        }
        m_scan_y = m_outline.min_y();
        return true;
    }


    //------------------------------------------------------------------------
    template<class Clip> 
    AGG_INLINE bool rasterizer_scanline_aa<Clip>::navigate_scanline(int y)
    {
        if(m_auto_close) close_polygon();
        m_outline.sort_cells();
        if(m_outline.total_cells() == 0 || 
           y < m_outline.min_y() || 
           y > m_outline.max_y()) 
        {
            return false;
        }
        m_scan_y = y;
        return true;
    }

    //------------------------------------------------------------------------
    template<class Clip> 
    bool rasterizer_scanline_aa<Clip>::hit_test(int tx, int ty)
    {
        if(!navigate_scanline(ty)) return false;
        scanline_hit_test sl(tx);
        sweep_scanline(sl);
        return sl.hit();
    }



}



#endif