gfx/2d/BaseSize.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_BASESIZE_H_
   7 #define MOZILLA_GFX_BASESIZE_H_
   8
   9 #include "mozilla/Attributes.h"
  10
  11 namespace mozilla {
  12 namespace gfx {
  13
  14 /**
  15  * Do not use this class directly. Subclass it, pass that subclass as the
  16  * Sub parameter, and only use that subclass. This allows methods to safely
  17  * cast 'this' to 'Sub*'.
  18  */
  19 template <class T, class Sub>
  20 struct BaseSize {
  21   T width, height;
  22
  23   // Constructors
  24   MOZ_CONSTEXPR BaseSize() : width(0), height(0) {}
  25   MOZ_CONSTEXPR BaseSize(T aWidth, T aHeight) : width(aWidth), height(aHeight) {}
  26
  27   void SizeTo(T aWidth, T aHeight) { width = aWidth; height = aHeight; }
  28
  29   bool IsEmpty() const {
  30     return width == 0 || height == 0;
  31   }
  32
  33   // Note that '=' isn't defined so we'll get the
  34   // compiler generated default assignment operator
  35
  36   bool operator==(const Sub& aSize) const {
  37     return width == aSize.width && height == aSize.height;
  38   }
  39   bool operator!=(const Sub& aSize) const {
  40     return width != aSize.width || height != aSize.height;
  41   }
  42   bool operator<=(const Sub& aSize) const {
  43     return width <= aSize.width && height <= aSize.height;
  44   }
  45   bool operator<(const Sub& aSize) const {
  46     return *this <= aSize && *this != aSize;
  47   }
  48
  49   Sub operator+(const Sub& aSize) const {
  50     return Sub(width + aSize.width, height + aSize.height);
  51   }
  52   Sub operator-(const Sub& aSize) const {
  53     return Sub(width - aSize.width, height - aSize.height);
  54   }
  55   Sub& operator+=(const Sub& aSize) {
  56     width += aSize.width;
  57     height += aSize.height;
  58     return *static_cast<Sub*>(this);
  59   }
  60   Sub& operator-=(const Sub& aSize) {
  61     width -= aSize.width;
  62     height -= aSize.height;
  63     return *static_cast<Sub*>(this);
  64   }
  65
  66   Sub operator*(T aScale) const {
  67     return Sub(width * aScale, height * aScale);
  68   }
  69   Sub operator/(T aScale) const {
  70     return Sub(width / aScale, height / aScale);
  71   }
  72   void Scale(T aXScale, T aYScale) {
  73     width *= aXScale;
  74     height *= aYScale;
  75   }
  76
  77   Sub operator*(const Sub& aSize) const {
  78     return Sub(width * aSize.width, height * aSize.height);
  79   }
  80   Sub operator/(const Sub& aSize) const {
  81     return Sub(width / aSize.width, height / aSize.height);
  82   }
  83 };
  84
  85 }
  86 }
  87
  88 #endif /* MOZILLA_GFX_BASESIZE_H_ */