/* 
 * affine.h -- ePiX::affine class (affine screen maps)
 *
 * This file is part of ePiX, a C++ library for creating high-quality 
 * figures in LaTeX 
 *
 * Version 1.1.21
 * Last Change: September 23, 2007
 *
 * 
 * Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007
 * Andrew D. Hwang <rot 13 nujnat at zngupf dot ubylpebff dot rqh>
 * Department of Mathematics and Computer Science
 * College of the Holy Cross
 * Worcester, MA, 01610-2395, USA
 *
 *
 * ePiX is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * ePiX is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
 * License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ePiX; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/*
 * An affine map is constructed from the images of the "standard
 * triple" (0,0), (1,0), and (0,1).
 *
 * An affine map may be (post)-composed with translation, rotation,
 * reflection, scaling along either or both coordinate axes, shearing,
 * and may be inverted. An optional pair argument, defaulting to
 * (0,0), gives the center of the operation (if appropriate).
 *
 * An affine map may be post-composed via member function, and
 * pre-composed with operator syntax. The evaluation operator
 * returns the image of the argument.
 */

#ifndef EPIX_AFFINE
#define EPIX_AFFINE

#include "pairs.h"
#include "triples.h"

namespace ePiX {

  class affine {
  public:
    // the identity map
    affine();

    // images of (1,0), (0,1), (0,0)
    affine(const pair&, const pair&, const pair& loc=pair(0,0));
    affine(const P&, const P&, const P& loc=P(0,0));

    // post-operations
    // translate by arg
    affine&   shift(const pair& arg);
    affine&   shift(const P& arg);

    // rotate by theta about ctr
    affine&  rotate(double theta, const pair& ctr = pair(0,0));
    affine&  rotate(double theta, const P& ctr);

    // reflect in angle-theta line through ctr
    affine& reflect(double theta, const pair& ctr = pair(0,0));
    affine& reflect(double theta, const P& ctr);

    // scale coord direction(s) fixing ctr
    affine& h_scale(double, const pair& ctr=pair(0,0));
    affine& v_scale(double, const pair& ctr=pair(0,0));
    affine&   scale(double, const pair& ctr=pair(0,0));

    affine& h_scale(double, const P& ctr);
    affine& v_scale(double, const P& ctr);
    affine&   scale(double, const P& ctr);

    // shear, fixing ctr
    affine& h_shear(double, const pair& ctr=pair(0,0));
    affine& v_shear(double, const pair& ctr=pair(0,0));

    affine& h_shear(double, const P& ctr);
    affine& v_shear(double, const P& ctr);

    // post-compose
    affine& postcomp(const affine&);

    affine& invert();

    // evaluation
    pair operator() (const pair&) const;
    pair operator() (const P&) const;

    // pre-compose
    affine operator() (const affine&) const;

    bool reverses_orientation() const;

  private:
    pair m_00;
    pair m_10;
    pair m_01;
  };
} // end of ePiX namespace

#endif /* EPIX_AFFINE */
