gfx/2d/BasePoint.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef MOZILLA_GFX_BASEPOINT_H_
   7 #define MOZILLA_GFX_BASEPOINT_H_
   8
   9 namespace mozilla {
  10 namespace gfx {
  11
  12 /**
  13  * Do not use this class directly. Subclass it, pass that subclass as the
  14  * Sub parameter, and only use that subclass. This allows methods to safely
  15  * cast 'this' to 'Sub*'.
  16  */
  17 template <class T, class Sub>
  18 struct BasePoint {
  19   T x, y;
  20
  21   // Constructors
  22   BasePoint() : x(0), y(0) {}
  23   BasePoint(T aX, T aY) : x(aX), y(aY) {}
  24
  25   void MoveTo(T aX, T aY) { x = aX; y = aY; }
  26   void MoveBy(T aDx, T aDy) { x += aDx; y += aDy; }
  27
  28   // Note that '=' isn't defined so we'll get the
  29   // compiler generated default assignment operator
  30
  31   bool operator==(const Sub& aPoint) const {
  32     return x == aPoint.x && y == aPoint.y;
  33   }
  34   bool operator!=(const Sub& aPoint) const {
  35     return x != aPoint.x || y != aPoint.y;
  36   }
  37
  38   Sub operator+(const Sub& aPoint) const {
  39     return Sub(x + aPoint.x, y + aPoint.y);
  40   }
  41   Sub operator-(const Sub& aPoint) const {
  42     return Sub(x - aPoint.x, y - aPoint.y);
  43   }
  44   Sub& operator+=(const Sub& aPoint) {
  45     x += aPoint.x;
  46     y += aPoint.y;
  47     return *static_cast<Sub*>(this);
  48   }
  49   Sub& operator-=(const Sub& aPoint) {
  50     x -= aPoint.x;
  51     y -= aPoint.y;
  52     return *static_cast<Sub*>(this);
  53   }
  54
  55   Sub operator*(T aScale) const {
  56     return Sub(x * aScale, y * aScale);
  57   }
  58   Sub operator/(T aScale) const {
  59     return Sub(x / aScale, y / aScale);
  60   }
  61
  62   Sub operator-() const {
  63     return Sub(-x, -y);
  64   }
  65 };
  66
  67 }
  68 }
  69
  70 #endif /* MOZILLA_GFX_BASEPOINT_H_ */