1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
|
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_image_decoders_EXIF_h
#define mozilla_image_decoders_EXIF_h
#include <stdint.h>
#include "nsDebug.h"
#include "Orientation.h"
#include "mozilla/Maybe.h"
#include "mozilla/image/Resolution.h"
#include "mozilla/gfx/Point.h"
namespace mozilla::image {
enum class ByteOrder : uint8_t { Unknown, LittleEndian, BigEndian };
struct EXIFData {
const Orientation orientation = Orientation();
const Resolution resolution = Resolution();
};
struct ParsedEXIFData;
enum class ResolutionUnit : uint8_t {
Dpi,
Dpcm,
};
class EXIFParser {
public:
static EXIFData Parse(const uint8_t* aData, const uint32_t aLength,
const gfx::IntSize& aRealImageSize) {
EXIFParser parser;
return parser.ParseEXIF(aData, aLength, aRealImageSize);
}
private:
EXIFParser()
: mStart(nullptr),
mCurrent(nullptr),
mLength(0),
mRemainingLength(0),
mByteOrder(ByteOrder::Unknown) {}
EXIFData ParseEXIF(const uint8_t* aData, const uint32_t aLength,
const gfx::IntSize& aRealImageSize);
bool ParseEXIFHeader();
bool ParseTIFFHeader(uint32_t& aIFD0OffsetOut);
void ParseIFD(ParsedEXIFData&, uint32_t aDepth = 0);
bool ParseOrientation(uint16_t aType, uint32_t aCount, Orientation&);
bool ParseResolution(uint16_t aType, uint32_t aCount, Maybe<float>&);
bool ParseResolutionUnit(uint16_t aType, uint32_t aCount,
Maybe<ResolutionUnit>&);
bool ParseDimension(uint16_t aType, uint32_t aCount, Maybe<uint32_t>&);
bool Initialize(const uint8_t* aData, const uint32_t aLength);
void Advance(const uint32_t aDistance);
void JumpTo(const uint32_t aOffset);
uint32_t CurrentOffset() const { return mCurrent - mStart; }
class ScopedJump {
EXIFParser& mParser;
uint32_t mOldOffset;
public:
ScopedJump(EXIFParser& aParser, uint32_t aOffset)
: mParser(aParser), mOldOffset(aParser.CurrentOffset()) {
mParser.JumpTo(aOffset);
}
~ScopedJump() { mParser.JumpTo(mOldOffset); }
};
bool MatchString(const char* aString, const uint32_t aLength);
bool MatchUInt16(const uint16_t aValue);
bool ReadUInt16(uint16_t& aOut);
bool ReadUInt32(uint32_t& aOut);
bool ReadRational(float& aOut);
const uint8_t* mStart;
const uint8_t* mCurrent;
uint32_t mLength;
uint32_t mRemainingLength;
ByteOrder mByteOrder;
};
} // namespace mozilla::image
#endif // mozilla_image_decoders_EXIF_h
|
