mapnik/agg/include/agg_span_pattern_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_SPAN_PATTERN_RGBA_INCLUDED
#define AGG_SPAN_PATTERN_RGBA_INCLUDED

#include "agg_basics.h"

namespace agg
{

    //======================================================span_pattern_rgba
    template<class Source> class span_pattern_rgba
    {
    public:
        typedef Source source_type;
        typedef typename source_type::color_type color_type;
        typedef typename source_type::order_type order_type;
        typedef typename color_type::value_type value_type;
        typedef typename color_type::calc_type calc_type;

        //--------------------------------------------------------------------
        span_pattern_rgba() {}
        span_pattern_rgba(source_type& src, 
                          unsigned offset_x, unsigned offset_y) :
            m_src(&src),
            m_offset_x(offset_x),
            m_offset_y(offset_y)
        {}

        //--------------------------------------------------------------------
        void   attach(source_type& v)      { m_src = &v; }
               source_type& source()       { return *m_src; }
        const  source_type& source() const { return *m_src; }

        //--------------------------------------------------------------------
        void       offset_x(unsigned v) { m_offset_x = v; }
        void       offset_y(unsigned v) { m_offset_y = v; }
        unsigned   offset_x() const { return m_offset_x; }
        unsigned   offset_y() const { return m_offset_y; }
        void       alpha(value_type) {}
        value_type alpha() const { return 0; }

        //--------------------------------------------------------------------
        void prepare() {}
        void generate(color_type* span, int x, int y, unsigned len)
        {   
            x += m_offset_x;
            y += m_offset_y;
            const value_type* p = (const value_type*)m_src->span(x, y, len);
            do
            {
                span->r = p[order_type::R];
                span->g = p[order_type::G];
                span->b = p[order_type::B];
                span->a = p[order_type::A];
                p = (const value_type*)m_src->next_x();
                ++span;
            }
            while(--len);
        }

    private:
        source_type* m_src;
        unsigned     m_offset_x;
        unsigned     m_offset_y;

    };

}

#endif