image/Orientation.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_Orientation_h
   7 #define mozilla_image_Orientation_h
   8
   9 #include <stdint.h>
  10
  11 namespace mozilla {
  12 namespace image {
  13
  14 enum class Angle : uint8_t { D0, D90, D180, D270 };
  15
  16 enum class Flip : uint8_t { Unflipped, Horizontal };
  17
  18 /**
  19  * A struct that describes an image's orientation as a rotation optionally
  20  * followed by a reflection. This may be used to be indicate an image's inherent
  21  * orientation or a desired orientation for the image.
  22  *
  23  * When flipFirst = true, this indicates that the reflection is applied before
  24  * the rotation. (This is used by OrientedImage to represent the inverse of an
  25  * underlying image's Orientation.)
  26  */
  27 struct Orientation {
  28   explicit Orientation(Angle aRotation = Angle::D0,
  29                        Flip aFlip = Flip::Unflipped, bool aFlipFirst = false)
  30       : rotation(aRotation), flip(aFlip), flipFirst(aFlipFirst) {}
  31
  32   Orientation Reversed() const {
  33     return Orientation(InvertAngle(rotation), flip, !flipFirst);
  34   }
  35
  36   bool IsIdentity() const {
  37     return (rotation == Angle::D0) && (flip == Flip::Unflipped);
  38   }
  39
  40   bool SwapsWidthAndHeight() const {
  41     return (rotation == Angle::D90) || (rotation == Angle::D270);
  42   }
  43
  44   bool operator==(const Orientation& aOther) const {
  45     return rotation == aOther.rotation && flip == aOther.flip &&
  46            flipFirst == aOther.flipFirst;
  47   }
  48
  49   bool operator!=(const Orientation& aOther) const {
  50     return !(*this == aOther);
  51   }
  52
  53   static Angle InvertAngle(Angle aAngle) {
  54     switch (aAngle) {
  55       case Angle::D90:
  56         return Angle::D270;
  57       case Angle::D270:
  58         return Angle::D90;
  59       default:
  60         return aAngle;
  61     }
  62   }
  63
  64   Angle rotation;
  65   Flip flip;
  66   bool flipFirst;
  67 };
  68
  69 }  // namespace image
  70 }  // namespace mozilla
  71
  72 #endif  // mozilla_image_Orientation_h