image/Resolution.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_image_Resolution_h
   7 #define mozilla_image_Resolution_h
   8
   9 #include "mozilla/Assertions.h"
  10 #include <cmath>
  11
  12 namespace mozilla {
  13 namespace image {
  14
  15 /**
  16  * The resolution of an image, in dppx.
  17  */
  18 struct Resolution {
  19   Resolution() = default;
  20   Resolution(float aX, float aY) : mX(aX), mY(aY) {
  21     MOZ_ASSERT(mX != 0.0f);
  22     MOZ_ASSERT(mY != 0.0f);
  23   }
  24
  25   bool operator==(const Resolution& aOther) const {
  26     return mX == aOther.mX && mY == aOther.mY;
  27   }
  28   bool operator!=(const Resolution& aOther) const { return !(*this == aOther); }
  29
  30   float mX = 1.0f;
  31   float mY = 1.0f;
  32
  33   void ScaleBy(float aScale) {
  34     if (MOZ_LIKELY(aScale != 0.0f)) {
  35       mX *= aScale;
  36       mY *= aScale;
  37     }
  38   }
  39
  40   void ApplyXTo(int32_t& aWidth) const {
  41     if (mX != 1.0f) {
  42       aWidth = std::round(float(aWidth) / mX);
  43     }
  44   }
  45
  46   void ApplyXTo(float& aWidth) const {
  47     if (mX != 1.0f) {
  48       aWidth /= mX;
  49     }
  50   }
  51
  52   void ApplyYTo(int32_t& aHeight) const {
  53     if (mY != 1.0f) {
  54       aHeight = std::round(float(aHeight) / mY);
  55     }
  56   }
  57
  58   void ApplyYTo(float& aHeight) const {
  59     if (mY != 1.0f) {
  60       aHeight /= mY;
  61     }
  62   }
  63
  64   void ApplyTo(int32_t& aWidth, int32_t& aHeight) const {
  65     ApplyXTo(aWidth);
  66     ApplyYTo(aHeight);
  67   }
  68
  69   void ApplyTo(float& aWidth, float& aHeight) const {
  70     ApplyXTo(aWidth);
  71     ApplyYTo(aHeight);
  72   }
  73
  74   void ApplyInverseTo(int32_t& aWidth, int32_t& aHeight) {
  75     if (mX != 1.0f) {
  76       aWidth = std::round(float(aWidth) * mX);
  77     }
  78     if (mY != 1.0f) {
  79       aHeight = std::round(float(aHeight) * mY);
  80     }
  81   }
  82 };
  83
  84 }  // namespace image
  85
  86 using ImageResolution = image::Resolution;
  87
  88 }  // namespace mozilla
  89
  90 #endif