gecko-dev/gfx/2d/BasePoint.h

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2.1 KiB
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef MOZILLA_GFX_BASEPOINT_H_
#define MOZILLA_GFX_BASEPOINT_H_
#include <cmath>
#include "mozilla/Attributes.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
MOZ_CONSTEXPR BasePoint() : x(0), y(0) {}
MOZ_CONSTEXPR 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);
}
// Round() is *not* rounding to nearest integer if the values are negative.
// They are always rounding as floor(n + 0.5).
// See https://bugzilla.mozilla.org/show_bug.cgi?id=410748#c14
Sub& Round() {
x = static_cast<T>(floor(x + 0.5));
y = static_cast<T>(floor(y + 0.5));
return *static_cast<Sub*>(this);
}
};
}
}
#endif /* MOZILLA_GFX_BASEPOINT_H_ */