101 lines
3.0 KiB
C++
101 lines
3.0 KiB
C++
//
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// Copyright 2005-2007 Adobe Systems Incorporated
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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#ifndef BOOST_GIL_IO_DETAIL_DYNAMIC_HPP
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#define BOOST_GIL_IO_DETAIL_DYNAMIC_HPP
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#include <boost/gil/extension/dynamic_image/dynamic_image_all.hpp>
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#include <boost/gil/detail/mp11.hpp>
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#include <boost/gil/io/error.hpp>
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#include <type_traits>
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namespace boost { namespace gil { namespace detail {
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template <long N>
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struct construct_matched_t
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{
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template <typename ...Images, typename Pred>
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static bool apply(any_image<Images...>& img, Pred pred)
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{
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if (pred.template apply<mp11::mp_at_c<any_image<Images...>, N-1>>())
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{
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using image_t = mp11::mp_at_c<any_image<Images...>, N-1>;
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image_t x;
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img = std::move(x);
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return true;
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}
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else
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return construct_matched_t<N-1>::apply(img, pred);
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}
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};
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template <>
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struct construct_matched_t<0>
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{
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template <typename ...Images, typename Pred>
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static bool apply(any_image<Images...>&, Pred) { return false; }
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};
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// A function object that can be passed to variant2::visit.
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// Given a predicate IsSupported taking a view type and returning an boolean integral coonstant,
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// calls the apply method of OpClass with the view if the given view IsSupported, or throws an exception otherwise
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template <typename IsSupported, typename OpClass>
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class dynamic_io_fnobj
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{
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private:
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OpClass* _op;
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template <typename View>
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void apply(View const& view, std::true_type) { _op->apply(view); }
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template <typename View, typename Info>
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void apply(View const& view, Info const & info, const std::true_type) { _op->apply(view, info); }
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template <typename View>
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void apply(View const& /* view */, std::false_type)
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{
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io_error("dynamic_io: unsupported view type for the given file format");
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}
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template <typename View, typename Info >
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void apply(View const& /* view */, Info const& /* info */, const std::false_type)
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{
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io_error("dynamic_io: unsupported view type for the given file format");
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}
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public:
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dynamic_io_fnobj(OpClass* op) : _op(op) {}
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using result_type = void;
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template <typename View>
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void operator()(View const& view)
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{
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apply(view, typename IsSupported::template apply<View>::type());
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}
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template <typename View, typename Info>
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void operator()(View const& view, Info const& info)
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{
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apply(view, info, typename IsSupported::template apply<View>::type());
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}
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};
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/// \brief Within the any_image, constructs an image with the given dimensions
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/// and a type that satisfies the given predicate
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template <typename ...Images, typename Pred>
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inline bool construct_matched(any_image<Images...>& img, Pred pred)
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{
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constexpr auto size = mp11::mp_size<any_image<Images...>>::value;
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return construct_matched_t<size>::apply(img, pred);
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}
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} } } // namespace boost::gil::detail
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#endif
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