circle.h

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/*
 * Authors:
 *   Marco Cecchetti <mrcekets at gmail.com>
 *   Krzysztof Kosiński <tweenk.pl@gmail.com>
 *
 * Copyright 2008-2014 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.
 */
 
#ifndef LIB2GEOM_SEEN_CIRCLE_H
#define LIB2GEOM_SEEN_CIRCLE_H
 
#include <2geom/forward.h>
#include <2geom/intersection.h>
#include <2geom/point.h>
#include <2geom/rect.h>
#include <2geom/transforms.h>
 
namespace Geom {
 
class EllipticalArc;
 
class Circle
    : boost::equality_comparable1< Circle
    , MultipliableNoncommutative< Circle, Translate
    , MultipliableNoncommutative< Circle, Rotate
    , MultipliableNoncommutative< Circle, Zoom
      > > > >
{
    Point _center;
    Coord _radius;
 
public:
    Circle() {}
    Circle(Coord cx, Coord cy, Coord r)
        : _center(cx, cy), _radius(r)
    {}
    Circle(Point const &center, Coord r)
        : _center(center), _radius(r)
    {}
 
    Circle(Coord A, Coord B, Coord C, Coord D) {
        setCoefficients(A, B, C, D);
    }
 
    // Construct the unique circle passing through three points.
    //Circle(Point const &a, Point const &b, Point const &c);
 
    Point center() const { return _center; }
    Coord center(Dim2 d) const { return _center[d]; }
    Coord radius() const { return _radius; }
    Coord area() const { return M_PI * _radius * _radius; }
    bool isDegenerate() const { return _radius == 0; }
 
    void setCenter(Point const &p) { _center = p; }
    void setRadius(Coord c) { _radius = c; }
 
    Rect boundsFast() const;
    Rect boundsExact() const { return boundsFast(); }
 
    Point initialPoint() const;
    Point finalPoint() const { return initialPoint(); }
    Point pointAt(Coord t) const;
    Coord valueAt(Coord t, Dim2 d) const;
    Coord timeAt(Point const &p) const;
    Coord nearestTime(Point const &p) const;
 
    bool contains(Point const &p) const { return distance(p, _center) <= _radius; }
    bool contains(Rect const &other) const;
    bool contains(Circle const &other) const;
 
    bool intersects(Line const &l) const;
    bool intersects(LineSegment const &l) const;
    bool intersects(Circle const &other) const;
 
    std::vector<ShapeIntersection> intersect(Line const &other) const;
    std::vector<ShapeIntersection> intersect(LineSegment const &other) const;
    std::vector<ShapeIntersection> intersect(Circle const &other) const;
 
    // build a circle by its implicit equation:
    // Ax^2 + Ay^2 + Bx + Cy + D = 0
    void setCoefficients(Coord A, Coord B, Coord C, Coord D);
    void coefficients(Coord &A, Coord &B, Coord &C, Coord &D) const;
    std::vector<Coord> coefficients() const;
 
    Zoom unitCircleTransform() const;
    Zoom inverseUnitCircleTransform() const;
 
    EllipticalArc *
    arc(Point const& initial, Point const& inner, Point const& final) const;
 
    D2<SBasis> toSBasis() const;
 
    Circle &operator*=(Translate const &t) {
        _center *= t;
        return *this;
    }
    Circle &operator*=(Rotate const &) {
        return *this;
    }
    Circle &operator*=(Zoom const &z) {
        _center *= z;
        _radius *= z.scale();
        return *this;
    }
 
    bool operator==(Circle const &other) const;
 
    void fit(std::vector<Point> const &points);
};
 
bool are_near(Circle const &a, Circle const &b, Coord eps=EPSILON);
 
std::ostream &operator<<(std::ostream &out, Circle const &c);
 
template <>
struct ShapeTraits<Circle> {
    typedef Coord TimeType;
    typedef Interval IntervalType;
    typedef Ellipse AffineClosureType;
    typedef Intersection<> IntersectionType;
};
 
} // end namespace Geom
 
#endif // LIB2GEOM_SEEN_CIRCLE_H
 
/*
  Local Variables:
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  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
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  End:
*/
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