WheelSteps.h

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// -*- mode: c++; c-file-style: "linux"; c-basic-offset: 2; indent-tabs-mode: nil -*-
//
//  Copyright (C) 2026 Gunter Königsmann <wxMaxima@physikbuch.de>
//
//  This program 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.
//
//  This program 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 this program; if not, write to the Free Software
//  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
//  SPDX-License-Identifier: GPL-2.0+
 
#ifndef WHEELSTEPS_H
#define WHEELSTEPS_H
 
namespace wxm {
 
class WheelSteps {
public:
  int Add(int rotation, int delta) {
    if (delta <= 0)
      return (rotation > 0) - (rotation < 0);
    if ((rotation > 0 && m_rotation < 0) || (rotation < 0 && m_rotation > 0))
      m_rotation = 0;
    m_rotation += rotation;
    // Integer division truncates towards zero, so the remainder keeps the
    // sign of the movement in both directions.
    const int steps = m_rotation / delta;
    m_rotation -= steps * delta;
    return steps;
  }
 
  void Reset() { m_rotation = 0; }
 
private:
  int m_rotation = 0;
};
 
} // namespace wxm
 
#endif // WHEELSTEPS_H