transforms.cpp revision 4115d2a7efa05a72856652c38e52105903318912
/**
* @file
* @brief Affine transformation classes
*//*
* Authors:
* ? <?@?.?>
* Krzysztof Kosiński <tweenk.pl@gmail.com>
* Johan Engelen
*
* Copyright ?-2012 Authors
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*/
#include <boost/concept_check.hpp>
#include <2geom/point.h>
#include <2geom/transforms.h>
#include <2geom/rect.h>
namespace Geom {
/** @brief Zoom between rectangles.
* Given two rectangles, compute a zoom that maps one to the other.
* Rectangles are assumed to have the same aspect ratio. */
Zoom Zoom::map_rect(Rect const &old_r, Rect const &new_r)
{
Zoom ret;
ret._scale = new_r.width() / old_r.width();
ret._trans = new_r.min() - old_r.min();
return ret;
}
// Point transformation methods.
Point &Point::operator*=(Translate const &t)
{
_pt[X] += t.vec[X];
_pt[Y] += t.vec[Y];
return *this;
}
Point &Point::operator*=(Scale const &s)
{
_pt[X] *= s.vec[X];
_pt[Y] *= s.vec[Y];
return *this;
}
Point &Point::operator*=(Rotate const &r)
{
double x = _pt[X], y = _pt[Y];
_pt[X] = x * r.vec[X] - y * r.vec[Y];
_pt[Y] = y * r.vec[X] + x * r.vec[Y];
return *this;
}
Point &Point::operator*=(HShear const &h)
{
_pt[X] += h.f * _pt[X];
return *this;
}
Point &Point::operator*=(VShear const &v)
{
_pt[Y] += v.f * _pt[Y];
return *this;
}
Point &Point::operator*=(Zoom const &z)
{
_pt[X] += z._trans[X];
_pt[Y] += z._trans[Y];
_pt[X] *= z._scale;
_pt[Y] *= z._scale;
return *this;
}
// Affine multiplication methods.
/** @brief Combine this transformation with a translation. */
Affine &Affine::operator*=(Translate const &t) {
_c[4] += t[X];
_c[5] += t[Y];
return *this;
}
/** @brief Combine this transformation with scaling. */
Affine &Affine::operator*=(Scale const &s) {
_c[0] *= s[X]; _c[1] *= s[Y];
_c[2] *= s[X]; _c[3] *= s[Y];
_c[4] *= s[X]; _c[5] *= s[Y];
return *this;
}
/** @brief Combine this transformation a rotation. */
Affine &Affine::operator*=(Rotate const &r) {
// TODO: we just convert the Rotate to an Affine and use the existing operator*=()
// is there a better way?
*this *= (Affine) r;
return *this;
}
/** @brief Combine this transformation with horizontal shearing (skew). */
Affine &Affine::operator*=(HShear const &h) {
_c[0] += h.f * _c[1];
_c[2] += h.f * _c[3];
_c[4] += h.f * _c[5];
return *this;
}
/** @brief Combine this transformation with vertical shearing (skew). */
Affine &Affine::operator*=(VShear const &v) {
_c[1] += v.f * _c[0];
_c[3] += v.f * _c[2];
_c[5] += v.f * _c[4];
return *this;
}
Affine &Affine::operator*=(Zoom const &z) {
_c[0] *= z._scale; _c[1] *= z._scale;
_c[2] *= z._scale; _c[3] *= z._scale;
_c[4] += z._trans[X]; _c[5] += z._trans[Y];
_c[4] *= z._scale; _c[5] *= z._scale;
return *this;
}
// this checks whether the requirements of TransformConcept are satisfied for all transforms.
// if you add a new transform type, include it here!
void check_transforms()
{
#ifdef BOOST_CONCEPT_ASSERT
BOOST_CONCEPT_ASSERT((TransformConcept<Translate>));
BOOST_CONCEPT_ASSERT((TransformConcept<Scale>));
BOOST_CONCEPT_ASSERT((TransformConcept<Rotate>));
BOOST_CONCEPT_ASSERT((TransformConcept<HShear>));
BOOST_CONCEPT_ASSERT((TransformConcept<VShear>));
BOOST_CONCEPT_ASSERT((TransformConcept<Zoom>));
BOOST_CONCEPT_ASSERT((TransformConcept<Affine>)); // Affine is also a transform
#endif
// check inter-transform multiplication
Affine m;
Translate t(Translate::identity());
Scale s(Scale::identity());
Rotate r(Rotate::identity());
HShear h(HShear::identity());
VShear v(VShear::identity());
Zoom z(Zoom::identity());
// notice that the first column is always the same and enumerates all transform types,
// while the second one changes to each transform type in turn.
m = t * t; m = t * s; m = t * r; m = t * h; m = t * v; m = t * z;
m = s * t; m = s * s; m = s * r; m = s * h; m = s * v; m = s * z;
m = r * t; m = r * s; m = r * r; m = r * h; m = r * v; m = r * z;
m = h * t; m = h * s; m = h * r; m = h * h; m = h * v; m = h * z;
m = v * t; m = v * s; m = v * r; m = v * h; m = v * v; m = v * z;
m = z * t; m = z * s; m = z * r; m = z * h; m = z * v; m = z * z;
}
Affine reflection(Point const & vector, Point const & origin) {
Geom::Point vec_norm = unit_vector(vector);
Affine mirror ( vec_norm[X]*vec_norm[X] - vec_norm[Y]*vec_norm[Y], 2 * vec_norm[X] * vec_norm[Y] ,
2 * vec_norm[X] * vec_norm[Y], vec_norm[Y]*vec_norm[Y] - vec_norm[X]*vec_norm[X] ,
0 ,0 );
return Translate(-origin) * mirror * Translate(origin);
}
} // namespace Geom
/*
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End:
*/
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