affine.hpp

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/* Copyright © 2017 Apple Inc. All rights reserved.
 *
 * Use of this source code is governed by a BSD-3-clause license that can
 * be found in the LICENSE.txt file or at https://opensource.org/licenses/BSD-3-Clause
 */
/*
  Copyright 2005-2007 Adobe Systems Incorporated
  Distributed under the MIT License (see accompanying file LICENSE_1_0_0.txt
  or a copy at http://opensource.adobe.com/licenses.html)
*/

/*************************************************************************************************/

#ifndef GIL_AFFINE_HPP
#define GIL_AFFINE_HPP

#include <boost/gil/utilities.hpp>     // point2

////////////////////////////////////////////////////////////////////////////////////////
/// \file
/// \brief support for affine transformations
/// \author Lubomir Bourdev and Hailin Jin \n
///         Adobe Systems Incorporated
/// \date   2005-2007 \n September 21, 2006
///
////////////////////////////////////////////////////////////////////////////////////////

namespace boost { namespace gil {

////////////////////////////////////////////////////////////////////////////////////////
///
/// Simple matrix to do 2D affine transformations. It is actually 3x3 but the last column is [0 0 1]
///
////////////////////////////////////////////////////////////////////////////////////////
template <typename T>
class matrix3x2 {
public:
    matrix3x2() : a(1), b(0), c(0), d(1), e(0), f(0) {}
    matrix3x2(T A, T B, T C, T D, T E, T F) : a(A),b(B),c(C),d(D),e(E),f(F) {}
    matrix3x2(const matrix3x2& mat) : a(mat.a), b(mat.b), c(mat.c), d(mat.d), e(mat.e), f(mat.f) {}
    matrix3x2& operator=(const matrix3x2& m)           { a=m.a; b=m.b; c=m.c; d=m.d; e=m.e; f=m.f; return *this; }

    matrix3x2& operator*=(const matrix3x2& m)          { (*this) = (*this)*m; return *this; }

    static matrix3x2 get_rotate(T rads)                { T c=std::cos(rads); T s=std::sin(rads); return matrix3x2(c,s,-s,c,0,0); }
    static matrix3x2 get_translate(const point2<T>& t) { return matrix3x2(1  ,0,0,1  ,t.x,t.y); }
    static matrix3x2 get_translate(T x, T y)           { return matrix3x2(1  ,0,0,1  ,x,  y  ); }
    static matrix3x2 get_scale    (const point2<T>& s) { return matrix3x2(s.x,0,0,s.y,0  ,0  ); }
    static matrix3x2 get_scale    (T x, T y)           { return matrix3x2(x,  0,0,y,  0  ,0  ); }
    static matrix3x2 get_scale    (T s)                { return matrix3x2(s  ,0,0,s  ,0  ,0  ); }

    T a,b,c,d,e,f;
};

template <typename T>
matrix3x2<T> operator*(const matrix3x2<T>& m1, const matrix3x2<T>& m2) {
    return matrix3x2<T>(
                m1.a * m2.a + m1.b * m2.c,
                m1.a * m2.b + m1.b * m2.d,
                m1.c * m2.a + m1.d * m2.c,
                m1.c * m2.b + m1.d * m2.d,
                m1.e * m2.a + m1.f * m2.c + m2.e,
                m1.e * m2.b + m1.f * m2.d + m2.f );
}

template <typename T, typename F>
point2<F> operator*(const point2<T>& p, const matrix3x2<F>& m) {
    return point2<F>(m.a*p.x + m.c*p.y + m.e, m.b*p.x + m.d*p.y + m.f);
}

////////////////////////////////////////////////////////////////////////////////////////
/// Define affine mapping that transforms the source coordinates by the affine transformation
////////////////////////////////////////////////////////////////////////////////////////
/*
template <typename MapFn>
concept MappingFunctionConcept {
    typename mapping_traits<MapFn>::result_type;   where PointNDConcept<result_type>;

    template <typename Domain> { where PointNDConcept<Domain> }
    result_type transform(MapFn&, const Domain& src);
};
*/

template <typename T> struct mapping_traits;

template <typename F>
struct mapping_traits<matrix3x2<F> > {
    typedef point2<F> result_type;
};

template <typename F, typename F2>
point2<F> transform(const matrix3x2<F>& mat, const point2<F2>& src) { return src * mat; }

} }  // namespace boost::gil

#endif