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