gecko/gfx/2d/BasePoint.h

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * 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
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 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
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 * The Original Code is Mozilla Corporation code.
 *
 * The Initial Developer of the Original Code is Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2011
 * the Initial Developer. All Rights Reserved.
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 * Contributor(s):
 *   Robert O'Callahan <robert@ocallahan.org>
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#ifndef MOZILLA_GFX_BASEPOINT_H_
#define MOZILLA_GFX_BASEPOINT_H_

namespace mozilla {
namespace gfx {

/**
 * Do not use this class directly. Subclass it, pass that subclass as the
 * Sub parameter, and only use that subclass. This allows methods to safely
 * cast 'this' to 'Sub*'.
 */
template <class T, class Sub>
struct BasePoint {
  T x, y;

  // Constructors
  BasePoint() : x(0), y(0) {}
  BasePoint(T aX, T aY) : x(aX), y(aY) {}

  void MoveTo(T aX, T aY) { x = aX; y = aY; }
  void MoveBy(T aDx, T aDy) { x += aDx; y += aDy; }

  // Note that '=' isn't defined so we'll get the
  // compiler generated default assignment operator

  bool operator==(const Sub& aPoint) const {
    return x == aPoint.x && y == aPoint.y;
  }
  bool operator!=(const Sub& aPoint) const {
    return x != aPoint.x || y != aPoint.y;
  }

  Sub operator+(const Sub& aPoint) const {
    return Sub(x + aPoint.x, y + aPoint.y);
  }
  Sub operator-(const Sub& aPoint) const {
    return Sub(x - aPoint.x, y - aPoint.y);
  }
  Sub& operator+=(const Sub& aPoint) {
    x += aPoint.x;
    y += aPoint.y;
    return *static_cast<Sub*>(this);
  }
  Sub& operator-=(const Sub& aPoint) {
    x -= aPoint.x;
    y -= aPoint.y;
    return *static_cast<Sub*>(this);
  }

  Sub operator*(T aScale) const {
    return Sub(x * aScale, y * aScale);
  }
  Sub operator/(T aScale) const {
    return Sub(x / aScale, y / aScale);
  }

  Sub operator-() const {
    return Sub(-x, -y);
  }
};

}
}

#endif /* MOZILLA_GFX_BASEPOINT_H_ */