e3ef52bb80
The constexpr belongs to the declaration specifiers (like static) and not just the type specifiers (like cv-qualifiers), so it binds to the declaration (like static), not the type (like const). Refines #211
76 lines
2.6 KiB
C++
76 lines
2.6 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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#include <boost/gil/image.hpp>
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#include <boost/gil/typedefs.hpp>
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#include <boost/gil/extension/io/jpeg.hpp>
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// Example for convolve_rows() and convolve_cols() in the numeric extension
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using namespace boost::gil;
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// Models a Unary Function
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template <typename P> // Models PixelValueConcept
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struct mandelbrot_fn
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{
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using point_t = boost::gil::point_t;
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using const_t = mandelbrot_fn;
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using value_type = P;
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using reference = value_type;
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using const_reference = value_type;
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using argument_type = point_t;
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using result_type = reference;
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static constexpr bool is_mutable =false;
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value_type _in_color,_out_color;
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point_t _img_size;
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static const int MAX_ITER=100; // max number of iterations
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mandelbrot_fn() {}
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mandelbrot_fn(const point_t& sz, const value_type& in_color, const value_type& out_color) : _in_color(in_color), _out_color(out_color), _img_size(sz) {}
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result_type operator()(const point_t& p) const {
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// normalize the coords to (-2..1, -1.5..1.5)
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// (actually make y -1.0..2 so it is asymmetric, so we can verify some view factory methods)
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double t=get_num_iter(point<double>(p.x/(double)_img_size.x*3-2, p.y/(double)_img_size.y*3-1.0f));//1.5f));
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t=pow(t,0.2);
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value_type ret;
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for (int k=0; k<num_channels<P>::value; ++k)
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ret[k]=(typename channel_type<P>::type)(_in_color[k]*t + _out_color[k]*(1-t));
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return ret;
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}
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private:
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double get_num_iter(const point<double>& p) const {
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point<double> Z(0,0);
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for (int i=0; i<MAX_ITER; ++i) {
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Z = point<double>(Z.x*Z.x - Z.y*Z.y + p.x, 2*Z.x*Z.y + p.y);
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if (Z.x*Z.x + Z.y*Z.y > 4)
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return i/(double)MAX_ITER;
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}
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return 0;
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}
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};
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int main()
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{
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using deref_t = mandelbrot_fn<rgb8_pixel_t>;
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using point_t = deref_t::point_t;
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using locator_t = virtual_2d_locator<deref_t,false>;
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using my_virt_view_t = image_view<locator_t>;
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boost::function_requires<PixelLocatorConcept<locator_t>>();
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gil_function_requires<StepIteratorConcept<locator_t::x_iterator>>();
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point_t dims(200,200);
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my_virt_view_t mandel(dims, locator_t(point_t(0,0), point_t(1,1), deref_t(dims, rgb8_pixel_t(255,0,255), rgb8_pixel_t(0,255,0))));
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write_view("out-mandelbrot.jpg",mandel, jpeg_tag{});
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return 0;
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}
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