scalar.h

Go to the documentation of this file.

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef FLUTTER_IMPELLER_GEOMETRY_SCALAR_H_
#define FLUTTER_IMPELLER_GEOMETRY_SCALAR_H_
 
#include <cfloat>
#include <ostream>
#include <type_traits>
#include <valarray>
 
#include "impeller/geometry/constants.h"
 
namespace impeller {
 
// NOLINTBEGIN(google-explicit-constructor)
 
using Scalar = float;
 
template <class T, class = std::enable_if_t<std::is_arithmetic_v<T>>>
constexpr T Absolute(const T& val) {
  return val >= T{} ? val : -val;
}
 
template <>
constexpr Scalar Absolute<Scalar>(const float& val) {
  return fabsf(val);
}
 
constexpr inline bool ScalarNearlyZero(Scalar x,
                                       Scalar tolerance = kEhCloseEnough) {
  return Absolute(x) <= tolerance;
}
 
constexpr inline bool ScalarNearlyEqual(Scalar x,
                                        Scalar y,
                                        Scalar tolerance = kEhCloseEnough) {
  return ScalarNearlyZero(x - y, tolerance);
}
 
struct Degrees;
 
struct Radians {
  Scalar radians = 0.0;
 
  constexpr Radians() = default;
 
  explicit constexpr Radians(Scalar p_radians) : radians(p_radians) {}
 
  constexpr bool IsFinite() const { return std::isfinite(radians); }
 
  constexpr Radians operator-() { return Radians{-radians}; }
 
  constexpr Radians operator+(Radians r) {
    return Radians{radians + r.radians};
  }
 
  constexpr Radians operator-(Radians r) {
    return Radians{radians - r.radians};
  }
 
  constexpr auto operator<=>(const Radians& r) const = default;
};
 
struct Degrees {
  Scalar degrees = 0.0;
 
  constexpr Degrees() = default;
 
  explicit constexpr Degrees(Scalar p_degrees) : degrees(p_degrees) {}
 
  constexpr operator Radians() const {
    return Radians{degrees * kPi / 180.0f};
  };
 
  constexpr bool IsFinite() const { return std::isfinite(degrees); }
 
  constexpr Degrees operator-() const { return Degrees{-degrees}; }
 
  constexpr Degrees operator+(Degrees d) const {
    return Degrees{degrees + d.degrees};
  }
 
  constexpr Degrees operator-(Degrees d) const {
    return Degrees{degrees - d.degrees};
  }
 
  constexpr auto operator<=>(const Degrees& d) const = default;
 
  constexpr Degrees GetPositive() const {
    Scalar deg = std::fmod(degrees, 360.0f);
    if (deg < 0.0f) {
      deg += 360.0f;
    }
    return Degrees{deg};
  }
};
 
// NOLINTEND(google-explicit-constructor)
 
}  // namespace impeller
 
namespace std {
 
inline std::ostream& operator<<(std::ostream& out, const impeller::Degrees& d) {
  return out << "Degrees(" << d.degrees << ")";
}
 
inline std::ostream& operator<<(std::ostream& out, const impeller::Radians& r) {
  return out << "Radians(" << r.radians << ")";
}
 
}  // namespace std
 
#endif  // FLUTTER_IMPELLER_GEOMETRY_SCALAR_H_