agg_renderer_scanline.h

windows ce 下的画各种b样条曲线

//----------------------------------------------------------------------------
// Anti-Grain Geometry (AGG) - Version 2.5
// A high quality rendering engine for C++
// Copyright (C) 2002-2006 Maxim Shemanarev
// Contact: [e-mail]
//          [e-mail]
//          http://antigrain.com
// 
// AGG is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
// 
// AGG is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with AGG; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 
// MA 02110-1301, USA.
//----------------------------------------------------------------------------

#ifndef AGG_RENDERER_SCANLINE_INCLUDED
#define AGG_RENDERER_SCANLINE_INCLUDED

#include "agg_basics.h"
#include "agg_renderer_base.h"

namespace agg
{

    //================================================render_scanline_aa_solid
    template<class Scanline, class BaseRenderer, class ColorT> 
    void render_scanline_aa_solid(const Scanline& sl, 
                                  BaseRenderer& ren, 
                                  const ColorT& color)
    {
        int y = sl.y();
        unsigned num_spans = sl.num_spans();
        typename Scanline::const_iterator span = sl.begin();

        for(;;)
        {
            int x = span->x;
            if(span->len > 0)
            {
                ren.blend_solid_hspan(x, y, (unsigned)span->len, 
                                      color, 
                                      span->covers);
            }
            else
            {
                ren.blend_hline(x, y, (unsigned)(x - span->len - 1), 
                                color, 
                                *(span->covers));
            }
            if(--num_spans == 0) break;
            ++span;
        }
    }

    //===============================================render_scanlines_aa_solid
    template<class Rasterizer, class Scanline, 
             class BaseRenderer, class ColorT>
    void render_scanlines_aa_solid(Rasterizer& ras, Scanline& sl, 
                                   BaseRenderer& ren, const ColorT& color)
    {
        if(ras.rewind_scanlines())
        {
            // Explicitly convert "color" to the BaseRenderer color type.
            // For example, it can be called with color type "rgba", while
            // "rgba8" is needed. Otherwise it will be implicitly 
            // converted in the loop many times.
            //----------------------
            typename BaseRenderer::color_type ren_color(color);

            sl.reset(ras.min_x(), ras.max_x());
            while(ras.sweep_scanline(sl))
            {
                //render_scanline_aa_solid(sl, ren, ren_color);

                // This code is equivalent to the above call (copy/paste). 
                // It's just a "manual" optimization for old compilers,
                // like Microsoft Visual C++ v6.0
                //-------------------------------
                int y = sl.y();
                unsigned num_spans = sl.num_spans();
                typename Scanline::const_iterator span = sl.begin();

                for(;;)
                {
                    int x = span->x;
                    if(span->len > 0)
                    {
                        ren.blend_solid_hspan(x, y, (unsigned)span->len, 
                                              ren_color, 
                                              span->covers);
                    }
                    else
                    {
                        ren.blend_hline(x, y, (unsigned)(x - span->len - 1), 
                                        ren_color, 
                                        *(span->covers));
                    }
                    if(--num_spans == 0) break;
                    ++span;
                }
            }
        }
    }

    //==============================================renderer_scanline_aa_solid
    template<class BaseRenderer> class renderer_scanline_aa_solid
    {
    public:
        typedef BaseRenderer base_ren_type;
        typedef typename base_ren_type::color_type color_type;

        //--------------------------------------------------------------------
        renderer_scanline_aa_solid() : m_ren(0) {}
        explicit renderer_scanline_aa_solid(base_ren_type& ren) : m_ren(&ren) {}
        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 prepare() {}

        //--------------------------------------------------------------------
        template<class Scanline> void render(const Scanline& sl)
        {
            render_scanline_aa_solid(sl, *m_ren, m_color);
        }
        
    private:
        base_ren_type* m_ren;
        color_type m_color;
    };













    //======================================================render_scanline_aa
    template<class Scanline, class BaseRenderer, 
             class SpanAllocator, class SpanGenerator> 
    void render_scanline_aa(const Scanline& sl, BaseRenderer& ren, 
                            SpanAllocator& alloc, SpanGenerator& span_gen)
    {
        int y = sl.y();

        unsigned num_spans = sl.num_spans();
        typename Scanline::const_iterator span = sl.begin();
        for(;;)
        {
            int x = span->x;
            int len = span->len;
            const typename Scanline::cover_type* covers = span->covers;

            if(len < 0) len = -len;
            typename BaseRenderer::color_type* colors = alloc.allocate(len);
            span_gen.generate(colors, x, y, len);
            ren.blend_color_hspan(x, y, len, colors, 
                                  (span->len < 0) ? 0 : covers, *covers);

            if(--num_spans == 0) break;
            ++span;
        }
    }

    //=====================================================render_scanlines_aa
    template<class Rasterizer, class Scanline, class BaseRenderer, 
             class SpanAllocator, class SpanGenerator>
    void render_scanlines_aa(Rasterizer& ras, Scanline& sl, BaseRenderer& ren, 
                             SpanAllocator& alloc, SpanGenerator& span_gen)
    {
        if(ras.rewind_scanlines())
        {
            sl.reset(ras.min_x(), ras.max_x());
            span_gen.prepare();
            while(ras.sweep_scanline(sl))
            {
                render_scanline_aa(sl, ren, alloc, span_gen);
            }
        }
    }

    //====================================================renderer_scanline_aa
    template<class BaseRenderer, class SpanAllocator, class SpanGenerator> 
    class renderer_scanline_aa
    {
    public:
        typedef BaseRenderer  base_ren_type;
        typedef SpanAllocator alloc_type;
        typedef SpanGenerator span_gen_type;

        //--------------------------------------------------------------------
        renderer_scanline_aa() : m_ren(0), m_alloc(0), m_span_gen(0) {}
        renderer_scanline_aa(base_ren_type& ren, 
                             alloc_type& alloc, 
                             span_gen_type& span_gen) :
            m_ren(&ren),
            m_alloc(&alloc),
            m_span_gen(&span_gen)
        {}
        void attach(base_ren_type& ren, 
                    alloc_type& alloc, 
                    span_gen_type& span_gen)
        {
            m_ren = &ren;
            m_alloc = &alloc;
            m_span_gen = &span_gen;
        }
        
        //--------------------------------------------------------------------
        void prepare() { m_span_gen->prepare(); }

        //--------------------------------------------------------------------
        template<class Scanline> void render(const Scanline& sl)
        {
            render_scanline_aa(sl, *m_ren, *m_alloc, *m_span_gen);
        }

    private:
        base_ren_type* m_ren;
        alloc_type*    m_alloc;
        span_gen_type* m_span_gen;
    };






    //===============================================render_scanline_bin_solid
    template<class Scanline, class BaseRenderer, class ColorT> 
    void render_scanline_bin_solid(const Scanline& sl, 
                                   BaseRenderer& ren, 
                                   const ColorT& color)
    {
        unsigned num_spans = sl.num_spans();
        typename Scanline::const_iterator span = sl.begin();
        for(;;)
        {
            ren.blend_hline(span->x, 
                            sl.y(), 
                            span->x - 1 + ((span->len < 0) ? 
                                              -span->len : 
                                               span->len), 
                               color, 
                               cover_full);
            if(--num_spans == 0) break;
            ++span;
        }
    }

    //==============================================render_scanlines_bin_solid
    template<class Rasterizer, class Scanline, 
             class BaseRenderer, class ColorT>
    void render_scanlines_bin_solid(Rasterizer& ras, Scanline& sl, 
                                    BaseRenderer& ren, const ColorT& color)
    {
        if(ras.rewind_scanlines())
        {
            // Explicitly convert "color" to the BaseRenderer color type.
            // For example, it can be called with color type "rgba", while
            // "rgba8" is needed. Otherwise it will be implicitly 
            // converted in the loop many times.
            //----------------------
            typename BaseRenderer::color_type ren_color(color);

            sl.reset(ras.min_x(), ras.max_x());
            while(ras.sweep_scanline(sl))