blend.hpp

Go to the documentation of this file.

#ifndef _blend_hpp_
#define _blend_hpp_

#include <boost/gil/gil_all.hpp>

struct alpha24_blend
{
        short alpha;    
        alpha24_blend(short alpha) : alpha(alpha){}

        template <typename T>
        void operator()(T& dst, const T src)
        {
                dst = ((dst + 1) * alpha >> 8) - 
                        ((src + 1) * alpha >> 8) +                      
                                src;
        }
};

template <typename blend_t, typename pixel_t, typename grayview_t, typename view_t> inline
void copy(pixel_t pixel, const grayview_t& grayview, const view_t& view)
{
        using namespace boost::gil;
        BOOST_ASSERT(grayview.width() == view.width());

        typedef typename view_t::x_iterator x_iterator_t;
        typedef typename grayview_t::x_iterator x_iterator2_t;
        
        for (int y = 0; y < view.height(); ++y)
        {
                x_iterator_t it_view = view.row_begin(y);
                x_iterator2_t it_gray = grayview.row_begin(y);
                for (int x = 0; x < view.width(); ++x)
                {
                        pixel_t dst = pixel;
                        static_for_each(dst, it_view[x], blend_t(it_gray[x]));
                        it_view[x] = dst;
                }
        }
}

template <typename blend_t, typename grayview_t, typename view_t> inline
void copy(const grayview_t& gray, const view_t& bottom, const view_t& top)
{
        using namespace boost::gil;
        BOOST_ASSERT(gray.width() == bottom.width());
        BOOST_ASSERT(bottom.width() == top.width());

        typedef typename view_t::x_iterator x_iterator_t;
        typedef typename grayview_t::x_iterator x_iterator2_t;
        typedef typename view_t::value_type value_type_t;
        
        for (int y = 0; y < top.height(); ++y)
        {
                x_iterator_t it_top = top.row_begin(y);
                x_iterator_t it_bot = bottom.row_begin(y);
                x_iterator2_t it_gray = gray.row_begin(y);
                for (int x = 0; x < top.width(); ++x)
                {
                        value_type_t dst = it_bot[x];
                        static_for_each(dst, it_top[x], blend_t(it_gray[x]));
                        it_top[x] = dst;
                }
        }
}

#endif