michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef MOZILLA_GFX_BASEPOINT_H_
michael@0: #define MOZILLA_GFX_BASEPOINT_H_
michael@0: 
michael@0: #include <cmath>
michael@0: #include "mozilla/Attributes.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace gfx {
michael@0: 
michael@0: /**
michael@0:  * Do not use this class directly. Subclass it, pass that subclass as the
michael@0:  * Sub parameter, and only use that subclass. This allows methods to safely
michael@0:  * cast 'this' to 'Sub*'.
michael@0:  */
michael@0: template <class T, class Sub>
michael@0: struct BasePoint {
michael@0:   T x, y;
michael@0: 
michael@0:   // Constructors
michael@0:   MOZ_CONSTEXPR BasePoint() : x(0), y(0) {}
michael@0:   MOZ_CONSTEXPR BasePoint(T aX, T aY) : x(aX), y(aY) {}
michael@0: 
michael@0:   void MoveTo(T aX, T aY) { x = aX; y = aY; }
michael@0:   void MoveBy(T aDx, T aDy) { x += aDx; y += aDy; }
michael@0: 
michael@0:   // Note that '=' isn't defined so we'll get the
michael@0:   // compiler generated default assignment operator
michael@0: 
michael@0:   bool operator==(const Sub& aPoint) const {
michael@0:     return x == aPoint.x && y == aPoint.y;
michael@0:   }
michael@0:   bool operator!=(const Sub& aPoint) const {
michael@0:     return x != aPoint.x || y != aPoint.y;
michael@0:   }
michael@0: 
michael@0:   Sub operator+(const Sub& aPoint) const {
michael@0:     return Sub(x + aPoint.x, y + aPoint.y);
michael@0:   }
michael@0:   Sub operator-(const Sub& aPoint) const {
michael@0:     return Sub(x - aPoint.x, y - aPoint.y);
michael@0:   }
michael@0:   Sub& operator+=(const Sub& aPoint) {
michael@0:     x += aPoint.x;
michael@0:     y += aPoint.y;
michael@0:     return *static_cast<Sub*>(this);
michael@0:   }
michael@0:   Sub& operator-=(const Sub& aPoint) {
michael@0:     x -= aPoint.x;
michael@0:     y -= aPoint.y;
michael@0:     return *static_cast<Sub*>(this);
michael@0:   }
michael@0: 
michael@0:   Sub operator*(T aScale) const {
michael@0:     return Sub(x * aScale, y * aScale);
michael@0:   }
michael@0:   Sub operator/(T aScale) const {
michael@0:     return Sub(x / aScale, y / aScale);
michael@0:   }
michael@0: 
michael@0:   Sub operator-() const {
michael@0:     return Sub(-x, -y);
michael@0:   }
michael@0: 
michael@0:   // Round() is *not* rounding to nearest integer if the values are negative.
michael@0:   // They are always rounding as floor(n + 0.5).
michael@0:   // See https://bugzilla.mozilla.org/show_bug.cgi?id=410748#c14
michael@0:   Sub& Round() {
michael@0:     x = static_cast<T>(floor(x + 0.5));
michael@0:     y = static_cast<T>(floor(y + 0.5));
michael@0:     return *static_cast<Sub*>(this);
michael@0:   }
michael@0: 
michael@0: };
michael@0: 
michael@0: }
michael@0: }
michael@0: 
michael@0: #endif /* MOZILLA_GFX_BASEPOINT_H_ */