| 1 | #include <iostream>
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| 2 | #include <boost/gil/gil_all.hpp>
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| 3 | using namespace boost;
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| 4 | using namespace gil;
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| 5 |
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| 6 | //
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| 7 | // Do-nothing dereference adaptor
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| 8 | //
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| 9 | template <typename View>
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| 10 | struct deref_fn {
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| 11 | BOOST_STATIC_CONSTANT(bool, is_mutable=false);
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| 12 | typedef deref_fn<typename View::const_t> const_t;
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| 13 | typedef typename View::value_type value_type;
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| 14 | typedef typename View::reference reference;
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| 15 | typedef typename View::point_t argument_type;
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| 16 | typedef reference result_type;
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| 17 |
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| 18 | deref_fn() {;}
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| 19 | deref_fn(const View& v) : mView(v) { ; }
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| 20 | result_type operator()(const argument_type& p) const {
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| 21 | return mView(p);
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| 22 | }
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| 23 |
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| 24 | View mView;
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| 25 | };
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| 26 |
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| 27 | typedef rgb8_planar_image_t image_t;
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| 28 | typedef image_t::view_t view_t;
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| 29 | typedef deref_fn<view_t> fn_t;
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| 30 | typedef virtual_2d_locator<fn_t, false> loc_t;
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| 31 | typedef image_view<loc_t> virt_view_t;
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| 32 | typedef kth_channel_view_type<0, virt_view_t>::type chan0_view_t;
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| 33 |
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| 34 | int main(int argc, char **argv) {
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| 35 | image_t img(4,4,rgb8_pixel_t(1,2,3),0);
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| 36 | view_t v(view(img));
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| 37 |
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| 38 | fn_t fn(v);
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| 39 | loc_t loc(view_t::point_t(0,0), view_t::point_t(1,1), fn);
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| 40 | virt_view_t virtView(v.dimensions(), loc);
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| 41 |
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| 42 | //
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| 43 | // Here detail::kth_channel_deref_fn<K,SrcP> is instantiated with
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| 44 | // SrcP = 'planar_pixel_reference<bits8&, rgb_t>'. The
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| 45 | // kth_channel_deref_fn then declares its result_type (and thereby
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| 46 | // the chan0_view_t:reference) to be a
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| 47 | // 'pixel<bits8&, gray_layout_t>&'
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| 48 | //
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| 49 | chan0_view_t chan0View(kth_channel_view<0,virt_view_t>(virtView));
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| 50 |
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| 51 | assert((is_same<chan0_view_t::reference,
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| 52 | pixel<bits8&, gray_layout_t>& >::value));
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| 53 |
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| 54 | //
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| 55 | // This will typically cause a bus error because the result_type
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| 56 | // of the deref adaptor is a 'pixel<bits8&, gray_layout_t>&'
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| 57 | // which gets initialized in the deref function by a
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| 58 | // 'pixel<bits8, gray_layout_t>&'
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| 59 | //
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| 60 | assert(chan0View(0,0) == gray8_pixel_t(1));
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| 61 | return 0;
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| 62 | }
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