gfx/2d/BasePoint.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef MOZILLA_GFX_BASEPOINT_H_
   8 #define MOZILLA_GFX_BASEPOINT_H_
   9
  10 #include <cmath>
  11 #include <ostream>
  12 #include <type_traits>
  13 #include "mozilla/Attributes.h"
  14 #include "mozilla/FloatingPoint.h"
  15 #include "Coord.h"
  16
  17 namespace mozilla {
  18 namespace gfx {
  19
  20 template <class T, typename EnableT = void>
  21 struct FloatType;
  22
  23 template <typename T>
  24 struct FloatType<T, typename std::enable_if_t<std::is_integral_v<T>>> {
  25   using type = float;
  26 };
  27
  28 template <typename T>
  29 struct FloatType<T, typename std::enable_if_t<std::is_floating_point_v<T>>> {
  30   using type = T;
  31 };
  32
  33 template <typename Units, typename Rep>
  34 struct FloatType<IntCoordTyped<Units, Rep>> {
  35   using type = CoordTyped<Units, float>;
  36 };
  37
  38 template <typename Units, typename Rep>
  39 struct FloatType<CoordTyped<Units, Rep>> {
  40   using type = CoordTyped<Units, Rep>;
  41 };
  42
  43 template <typename T>
  44 using FloatType_t = typename FloatType<T>::type;
  45
  46 /**
  47  * Do not use this class directly. Subclass it, pass that subclass as the
  48  * Sub parameter, and only use that subclass. This allows methods to safely
  49  * cast 'this' to 'Sub*'.
  50  */
  51 template <class T, class Sub, class Coord = T>
  52 struct BasePoint {
  53   union {
  54     struct {
  55       Coord x, y;
  56     };
  57     Coord components[2];
  58   };
  59
  60   // Constructors
  61   constexpr BasePoint() : x(0), y(0) {}
  62   constexpr BasePoint(Coord aX, Coord aY) : x(aX), y(aY) {}
  63
  64   MOZ_ALWAYS_INLINE Coord X() const { return x; }
  65   MOZ_ALWAYS_INLINE Coord Y() const { return y; }
  66
  67   void MoveTo(Coord aX, Coord aY) {
  68     x = aX;
  69     y = aY;
  70   }
  71   void MoveBy(Coord aDx, Coord aDy) {
  72     x += aDx;
  73     y += aDy;
  74   }
  75
  76   // Note that '=' isn't defined so we'll get the
  77   // compiler generated default assignment operator
  78
  79   bool operator==(const Sub& aPoint) const {
  80     return x == aPoint.x && y == aPoint.y;
  81   }
  82   bool operator!=(const Sub& aPoint) const {
  83     return x != aPoint.x || y != aPoint.y;
  84   }
  85
  86   Sub operator+(const Sub& aPoint) const {
  87     return Sub(x + aPoint.x, y + aPoint.y);
  88   }
  89   Sub operator-(const Sub& aPoint) const {
  90     return Sub(x - aPoint.x, y - aPoint.y);
  91   }
  92   Sub& operator+=(const Sub& aPoint) {
  93     x += aPoint.x;
  94     y += aPoint.y;
  95     return *static_cast<Sub*>(this);
  96   }
  97   Sub& operator-=(const Sub& aPoint) {
  98     x -= aPoint.x;
  99     y -= aPoint.y;
 100     return *static_cast<Sub*>(this);
 101   }
 102
 103   Sub operator*(T aScale) const { return Sub(x * aScale, y * aScale); }
 104   Sub operator/(T aScale) const { return Sub(x / aScale, y / aScale); }
 105
 106   Sub operator-() const { return Sub(-x, -y); }
 107
 108   T DotProduct(const Sub& aPoint) const {
 109     return x.value * aPoint.x.value + y.value * aPoint.y.value;
 110   }
 111
 112   FloatType_t<Coord> Length() const {
 113     return FloatType_t<Coord>(hypot(x.value, y.value));
 114   }
 115
 116   T LengthSquare() const { return x.value * x.value + y.value * y.value; }
 117
 118   // Round() is *not* rounding to nearest integer if the values are negative.
 119   // They are always rounding as floor(n + 0.5).
 120   // See https://bugzilla.mozilla.org/show_bug.cgi?id=410748#c14
 121   Sub& Round() {
 122     x = Coord(std::floor(T(x) + T(0.5f)));
 123     y = Coord(std::floor(T(y) + T(0.5f)));
 124     return *static_cast<Sub*>(this);
 125   }
 126
 127   // "Finite" means not inf and not NaN
 128   bool IsFinite() const {
 129     using FloatType =
 130         std::conditional_t<std::is_same_v<T, float>, float, double>;
 131     return (std::isfinite(FloatType(x)) && std::isfinite(FloatType(y)));
 132   }
 133
 134   void Clamp(Coord aMaxAbsValue) {
 135     x = std::max(std::min(x, aMaxAbsValue), -aMaxAbsValue);
 136     y = std::max(std::min(y, aMaxAbsValue), -aMaxAbsValue);
 137   }
 138
 139   friend std::ostream& operator<<(std::ostream& stream,
 140                                   const BasePoint<T, Sub, Coord>& aPoint) {
 141     return stream << '(' << aPoint.x << ',' << aPoint.y << ')';
 142   }
 143 };
 144
 145 }  // namespace gfx
 146 }  // namespace mozilla
 147
 148 #endif /* MOZILLA_GFX_BASEPOINT_H_ */