1 files changed, 122 insertions, 0 deletions
diff --git a/gfx/2d/BasePoint.h b/gfx/2d/BasePoint.h
new file mode 100644
index 0000000000..7f5dd7e1e3
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+++ b/gfx/2d/BasePoint.h
@@ -0,0 +1,122 @@
+/* -*- 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_BASEPOINT_H_
+#define MOZILLA_GFX_BASEPOINT_H_
+
+#include <cmath>
+#include <ostream>
+#include <type_traits>
+#include "mozilla/Attributes.h"
+#include "mozilla/FloatingPoint.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, class Coord = T>
+struct BasePoint {
+  union {
+    struct {
+      Coord x, y;
+    };
+    Coord components[2];
+  };
+
+  // Constructors
+  constexpr BasePoint() : x(0), y(0) {}
+  constexpr BasePoint(Coord aX, Coord aY) : x(aX), y(aY) {}
+
+  MOZ_ALWAYS_INLINE Coord X() const { return x; }
+  MOZ_ALWAYS_INLINE Coord Y() const { return y; }
+
+  void MoveTo(Coord aX, Coord aY) {
+    x = aX;
+    y = aY;
+  }
+  void MoveBy(Coord aDx, Coord 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); }
+
+  T DotProduct(const Sub& aPoint) const {
+    return x.value * aPoint.x.value + y.value * aPoint.y.value;
+  }
+
+  // FIXME: Maybe Length() should return a float Coord event for integer Points?
+  Coord Length() const {
+    return static_cast<decltype(x.value)>(hypot(x.value, y.value));
+  }
+
+  T LengthSquare() const { return x.value * x.value + y.value * y.value; }
+
+  // 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 = Coord(std::floor(T(x) + T(0.5f)));
+    y = Coord(std::floor(T(y) + T(0.5f)));
+    return *static_cast<Sub*>(this);
+  }
+
+  // "Finite" means not inf and not NaN
+  bool IsFinite() const {
+    using FloatType =
+        std::conditional_t<std::is_same_v<T, float>, float, double>;
+    return (std::isfinite(FloatType(x)) && std::isfinite(FloatType(y)));
+  }
+
+  void Clamp(Coord aMaxAbsValue) {
+    x = std::max(std::min(x, aMaxAbsValue), -aMaxAbsValue);
+    y = std::max(std::min(y, aMaxAbsValue), -aMaxAbsValue);
+  }
+
+  friend std::ostream& operator<<(std::ostream& stream,
+                                  const BasePoint<T, Sub, Coord>& aPoint) {
+    return stream << '(' << aPoint.x << ',' << aPoint.y << ')';
+  }
+};
+
+}  // namespace gfx
+}  // namespace mozilla
+
+#endif /* MOZILLA_GFX_BASEPOINT_H_ */