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 { Unknown, LittleEndian, BigEndian };
  18
  19 struct EXIFData {
  20   EXIFData() {}
  21   explicit EXIFData(Orientation aOrientation) : orientation(aOrientation) {}
  22
  23   const Orientation orientation;
  24 };
  25
  26 class EXIFParser {
  27  public:
  28   static EXIFData Parse(const uint8_t* aData, const uint32_t aLength) {
  29     EXIFParser parser;
  30     return parser.ParseEXIF(aData, aLength);
  31   }
  32
  33  private:
  34   EXIFParser()
  35       : mStart(nullptr),
  36         mCurrent(nullptr),
  37         mLength(0),
  38         mRemainingLength(0),
  39         mByteOrder(ByteOrder::Unknown) {}
  40
  41   EXIFData ParseEXIF(const uint8_t* aData, const uint32_t aLength);
  42   bool ParseEXIFHeader();
  43   bool ParseTIFFHeader(uint32_t& aIFD0OffsetOut);
  44   bool ParseIFD0(Orientation& aOrientationOut);
  45   bool ParseOrientation(uint16_t aType, uint32_t aCount, Orientation& aOut);
  46
  47   bool Initialize(const uint8_t* aData, const uint32_t aLength);
  48   void Advance(const uint32_t aDistance);
  49   void JumpTo(const uint32_t aOffset);
  50
  51   bool MatchString(const char* aString, const uint32_t aLength);
  52   bool MatchUInt16(const uint16_t aValue);
  53   bool ReadUInt16(uint16_t& aOut);
  54   bool ReadUInt32(uint32_t& aOut);
  55
  56   const uint8_t* mStart;
  57   const uint8_t* mCurrent;
  58   uint32_t mLength;
  59   uint32_t mRemainingLength;
  60   ByteOrder mByteOrder;
  61 };
  62
  63 }  // namespace image
  64 }  // namespace mozilla
  65
  66 #endif  // mozilla_image_decoders_EXIF_h