image/decoders/EXIF.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_decoders_EXIF_h
   7 #define mozilla_image_decoders_EXIF_h
   8
   9 #include <stdint.h>
  10 #include "nsDebug.h"
  11
  12 #include "Orientation.h"
  13
  14 namespace mozilla {
  15 namespace image {
  16
  17 enum class ByteOrder : uint8_t {
  18   Unknown,
  19   LittleEndian,
  20   BigEndian
  21 };
  22
  23 struct EXIFData
  24 {
  25   EXIFData() { }
  26   explicit EXIFData(Orientation aOrientation) : orientation(aOrientation) { }
  27
  28   const Orientation orientation;
  29 };
  30
  31 class EXIFParser
  32 {
  33 public:
  34   static EXIFData
  35   Parse(const uint8_t* aData, const uint32_t aLength)
  36   {
  37     EXIFParser parser;
  38     return parser.ParseEXIF(aData, aLength);
  39   }
  40
  41 private:
  42   EXIFParser()
  43     : mStart(nullptr)
  44     , mCurrent(nullptr)
  45     , mLength(0)
  46     , mRemainingLength(0)
  47     , mByteOrder(ByteOrder::Unknown)
  48   { }
  49
  50   EXIFData ParseEXIF(const uint8_t* aData, const uint32_t aLength);
  51   bool ParseEXIFHeader();
  52   bool ParseTIFFHeader(uint32_t& aIFD0OffsetOut);
  53   bool ParseIFD0(Orientation& aOrientationOut);
  54   bool ParseOrientation(uint16_t aType, uint32_t aCount, Orientation& aOut);
  55
  56   bool Initialize(const uint8_t* aData, const uint32_t aLength);
  57   void Advance(const uint32_t aDistance);
  58   void JumpTo(const uint32_t aOffset);
  59
  60   bool MatchString(const char* aString, const uint32_t aLength);
  61   bool MatchUInt16(const uint16_t aValue);
  62   bool ReadUInt16(uint16_t& aOut);
  63   bool ReadUInt32(uint32_t& aOut);
  64
  65   const uint8_t* mStart;
  66   const uint8_t* mCurrent;
  67   uint32_t       mLength;
  68   uint32_t       mRemainingLength;
  69   ByteOrder      mByteOrder;
  70 };
  71
  72 } // namespace image
  73 } // namespace mozilla
  74
  75 #endif // mozilla_image_decoders_EXIF_h