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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 "mozilla/FloatingPoint.h"
#include "Types.h"
#include "BaseCoord.h"
#include <cmath>
#include <type_traits>
namespace mozilla {
template <typename>
struct IsPixel;
namespace gfx {
// Should only be used to define generic typedefs like Coord, Point, etc.
struct UnknownUnits {};
template <class Units, class Rep = int32_t>
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 Rep, class Primitive>
struct CommonType<IntCoordTyped<Units, Rep>, Primitive> {
using type = decltype(Rep() + Primitive());
};
template <class Units, class F, class Primitive>
struct CommonType<CoordTyped<Units, F>, Primitive> {
using type = decltype(F() + Primitive());
};
// 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; }
using result_type = typename CommonType<Coord, Primitive>::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, class Rep>
struct MOZ_EMPTY_BASES IntCoordTyped
: public BaseCoord<Rep, IntCoordTyped<Units, Rep>>,
public CoordOperatorsHelper<true, IntCoordTyped<Units, Rep>, float>,
public CoordOperatorsHelper<true, IntCoordTyped<Units, Rep>, double> {
static_assert(IsPixel<Units>::value,
"'Units' must be a coordinate system tag");
using Super = BaseCoord<Rep, IntCoordTyped<Units, Rep>>;
constexpr IntCoordTyped() : Super() {
static_assert(sizeof(IntCoordTyped) == sizeof(Rep),
"Would be unfortunate otherwise!");
}
constexpr MOZ_IMPLICIT IntCoordTyped(Rep aValue) : Super(aValue) {
static_assert(sizeof(IntCoordTyped) == sizeof(Rep),
"Would be unfortunate otherwise!");
}
};
template <class Units, class F>
struct MOZ_EMPTY_BASES CoordTyped
: public BaseCoord<F, CoordTyped<Units, F>>,
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");
using Super = BaseCoord<F, CoordTyped<Units, F>>;
constexpr CoordTyped() : Super() {
static_assert(sizeof(CoordTyped) == sizeof(F),
"Would be unfortunate otherwise!");
}
constexpr MOZ_IMPLICIT CoordTyped(F aValue) : Super(aValue) {
static_assert(sizeof(CoordTyped) == sizeof(F),
"Would be unfortunate otherwise!");
}
explicit constexpr CoordTyped(const IntCoordTyped<Units>& aCoord)
: Super(F(aCoord.value)) {
static_assert(sizeof(CoordTyped) == sizeof(F),
"Would be unfortunate otherwise!");
}
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));
}
};
typedef CoordTyped<UnknownUnits> Coord;
} // namespace gfx
template <class Units, class F>
static MOZ_ALWAYS_INLINE bool FuzzyEqualsAdditive(
gfx::CoordTyped<Units, F> aValue1, gfx::CoordTyped<Units, F> aValue2,
gfx::CoordTyped<Units, F> aEpsilon =
detail::FuzzyEqualsEpsilon<F>::value()) {
return FuzzyEqualsAdditive(aValue1.value, aValue2.value, aEpsilon.value);
}
template <class Units, class F>
static MOZ_ALWAYS_INLINE bool FuzzyEqualsMultiplicative(
gfx::CoordTyped<Units, F> aValue1, gfx::CoordTyped<Units, F> aValue2,
gfx::CoordTyped<Units, F> aEpsilon =
detail::FuzzyEqualsEpsilon<F>::value()) {
return FuzzyEqualsMultiplicative(aValue1.value, aValue2.value,
aEpsilon.value);
}
} // namespace mozilla
#endif /* MOZILLA_GFX_COORD_H_ */
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