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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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_COORD_H_
#define MOZILLA_GFX_COORD_H_
#include "mozilla/Attributes.h"
#include "Types.h"
#include "BaseCoord.h"
#include <cmath>
#include <type_traits>
namespace mozilla {
template <typename>
struct IsPixel;
namespace gfx {
template <class units>
struct IntCoordTyped;
template <class units, class F = Float>
struct CoordTyped;
// CommonType<coord, primitive> is a metafunction that returns the type of the
// result of an arithmetic operation on the underlying type of a strongly-typed
// coordinate type 'coord', and a primitive type 'primitive'. C++ rules for
// arithmetic conversions are designed to avoid losing information - for
// example, the result of adding an int and a float is a float - and we want
// the same behaviour when mixing our coordinate types with primitive types.
// We get C++ to compute the desired result type using 'decltype'.
template <class coord, class primitive>
struct CommonType;
template <class units, class primitive>
struct CommonType<IntCoordTyped<units>, primitive> {
typedef decltype(int32_t() + primitive()) type;
};
template <class units, class F, class primitive>
struct CommonType<CoordTyped<units, F>, primitive> {
typedef decltype(F() + primitive()) type;
};
// This is a base class that provides mixed-type operator overloads between
// a strongly-typed Coord and a primitive value. It is needed to avoid
// ambiguities at mixed-type call sites, because Coord classes are implicitly
// convertible to their underlying value type. As we transition more of our code
// to strongly-typed classes, we may be able to remove some or all of these
// overloads.
template <bool B, class coord, class primitive>
struct CoordOperatorsHelper {
// Using SFINAE (Substitution Failure Is Not An Error) to suppress redundant
// operators
};
template <class coord, class primitive>
struct CoordOperatorsHelper<true, coord, primitive> {
friend bool operator==(coord aA, primitive aB) { return aA.value == aB; }
friend bool operator==(primitive aA, coord aB) { return aA == aB.value; }
friend bool operator!=(coord aA, primitive aB) { return aA.value != aB; }
friend bool operator!=(primitive aA, coord aB) { return aA != aB.value; }
typedef typename CommonType<coord, primitive>::type result_type;
friend result_type operator+(coord aA, primitive aB) { return aA.value + aB; }
friend result_type operator+(primitive aA, coord aB) { return aA + aB.value; }
friend result_type operator-(coord aA, primitive aB) { return aA.value - aB; }
friend result_type operator-(primitive aA, coord aB) { return aA - aB.value; }
friend result_type operator*(coord aCoord, primitive aScale) {
return aCoord.value * aScale;
}
friend result_type operator*(primitive aScale, coord aCoord) {
return aScale * aCoord.value;
}
friend result_type operator/(coord aCoord, primitive aScale) {
return aCoord.value / aScale;
}
// 'scale / coord' is intentionally omitted because it doesn't make sense.
};
template <class units>
struct IntCoordTyped
: public BaseCoord<int32_t, IntCoordTyped<units> >,
public units,
public CoordOperatorsHelper<true, IntCoordTyped<units>, float>,
public CoordOperatorsHelper<true, IntCoordTyped<units>, double> {
static_assert(IsPixel<units>::value,
"'units' must be a coordinate system tag");
typedef BaseCoord<int32_t, IntCoordTyped<units> > Super;
constexpr IntCoordTyped() : Super() {}
constexpr MOZ_IMPLICIT IntCoordTyped(int32_t aValue) : Super(aValue) {}
};
template <class units, class F>
struct CoordTyped : public BaseCoord<F, CoordTyped<units, F> >,
public units,
public CoordOperatorsHelper<!std::is_same_v<F, int32_t>,
CoordTyped<units, F>, int32_t>,
public CoordOperatorsHelper<!std::is_same_v<F, uint32_t>,
CoordTyped<units, F>, uint32_t>,
public CoordOperatorsHelper<!std::is_same_v<F, double>,
CoordTyped<units, F>, double>,
public CoordOperatorsHelper<!std::is_same_v<F, float>,
CoordTyped<units, F>, float> {
static_assert(IsPixel<units>::value,
"'units' must be a coordinate system tag");
typedef BaseCoord<F, CoordTyped<units, F> > Super;
constexpr CoordTyped() : Super() {}
constexpr MOZ_IMPLICIT CoordTyped(F aValue) : Super(aValue) {}
explicit constexpr CoordTyped(const IntCoordTyped<units>& aCoord)
: Super(F(aCoord.value)) {}
void Round() { this->value = floor(this->value + 0.5); }
void Truncate() { this->value = int32_t(this->value); }
IntCoordTyped<units> Rounded() const {
return IntCoordTyped<units>(int32_t(floor(this->value + 0.5)));
}
IntCoordTyped<units> Truncated() const {
return IntCoordTyped<units>(int32_t(this->value));
}
};
} // namespace gfx
} // namespace mozilla
#endif /* MOZILLA_GFX_COORD_H_ */