зеркало из https://github.com/mozilla/gecko-dev.git
96 строки
2.7 KiB
C++
96 строки
2.7 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_image_decoders_EXIF_h
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#define mozilla_image_decoders_EXIF_h
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#include <stdint.h>
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#include "nsDebug.h"
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#include "Orientation.h"
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#include "mozilla/Maybe.h"
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#include "mozilla/image/Resolution.h"
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#include "mozilla/gfx/Point.h"
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namespace mozilla::image {
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enum class ByteOrder : uint8_t { Unknown, LittleEndian, BigEndian };
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struct EXIFData {
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const Orientation orientation = Orientation();
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const Resolution resolution = Resolution();
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};
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struct ParsedEXIFData;
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enum class ResolutionUnit : uint8_t {
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Dpi,
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Dpcm,
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};
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class EXIFParser {
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public:
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static EXIFData Parse(const uint8_t* aData, const uint32_t aLength,
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const gfx::IntSize& aRealImageSize) {
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EXIFParser parser;
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return parser.ParseEXIF(aData, aLength, aRealImageSize);
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}
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private:
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EXIFParser()
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: mStart(nullptr),
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mCurrent(nullptr),
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mLength(0),
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mRemainingLength(0),
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mByteOrder(ByteOrder::Unknown) {}
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EXIFData ParseEXIF(const uint8_t* aData, const uint32_t aLength,
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const gfx::IntSize& aRealImageSize);
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bool ParseEXIFHeader();
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bool ParseTIFFHeader(uint32_t& aIFD0OffsetOut);
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void ParseIFD(ParsedEXIFData&, uint32_t aDepth = 0);
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bool ParseOrientation(uint16_t aType, uint32_t aCount, Orientation&);
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bool ParseResolution(uint16_t aType, uint32_t aCount, Maybe<float>&);
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bool ParseResolutionUnit(uint16_t aType, uint32_t aCount,
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Maybe<ResolutionUnit>&);
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bool ParseDimension(uint16_t aType, uint32_t aCount, Maybe<uint32_t>&);
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bool Initialize(const uint8_t* aData, const uint32_t aLength);
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void Advance(const uint32_t aDistance);
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void JumpTo(const uint32_t aOffset);
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uint32_t CurrentOffset() const { return mCurrent - mStart; }
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class ScopedJump {
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EXIFParser& mParser;
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uint32_t mOldOffset;
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public:
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ScopedJump(EXIFParser& aParser, uint32_t aOffset)
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: mParser(aParser), mOldOffset(aParser.CurrentOffset()) {
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mParser.JumpTo(aOffset);
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}
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~ScopedJump() { mParser.JumpTo(mOldOffset); }
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};
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bool MatchString(const char* aString, const uint32_t aLength);
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bool MatchUInt16(const uint16_t aValue);
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bool ReadUInt16(uint16_t& aOut);
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bool ReadUInt32(uint32_t& aOut);
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bool ReadRational(float& aOut);
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const uint8_t* mStart;
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const uint8_t* mCurrent;
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uint32_t mLength;
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uint32_t mRemainingLength;
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ByteOrder mByteOrder;
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};
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} // namespace mozilla::image
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#endif // mozilla_image_decoders_EXIF_h
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