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Exif parsing for PNG files to support Exif orientation tag. Moved decoder specific Exif parsing to JPEG and PNG decoders, respectively. Issue 16579
This commit is contained in:
Rachel A
+28
-110
@@ -62,7 +62,7 @@ ExifEntry_t::ExifEntry_t() :
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/**
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* @brief ExifReader constructor
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*/
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ExifReader::ExifReader(std::istream& stream) : m_stream(stream), m_format(NONE)
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ExifReader::ExifReader() : m_format(NONE)
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{
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}
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@@ -73,25 +73,6 @@ ExifReader::~ExifReader()
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{
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}
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/**
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* @brief Parsing the file and prepare (internally) exif directory structure
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* @return true if parsing was successful and exif information exists in JpegReader object
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* false in case of unsuccessful parsing
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*/
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bool ExifReader::parse()
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{
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try {
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m_exif = getExif();
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if( !m_exif.empty() )
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{
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return true;
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}
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return false;
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} catch (ExifParsingError&) {
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return false;
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}
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}
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/**
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* @brief Get tag value by tag number
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@@ -101,10 +82,10 @@ bool ExifReader::parse()
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* @return ExifEntru_t structure. Caller has to know what tag it calls in order to extract proper field from the structure ExifEntry_t
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*
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*/
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ExifEntry_t ExifReader::getTag(const ExifTagName tag)
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ExifEntry_t ExifReader::getTag(const ExifTagName tag) const
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{
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ExifEntry_t entry;
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std::map<int, ExifEntry_t>::iterator it = m_exif.find(tag);
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std::map<int, ExifEntry_t>::const_iterator it = m_exif.find(tag);
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if( it != m_exif.end() )
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{
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@@ -115,100 +96,37 @@ ExifEntry_t ExifReader::getTag(const ExifTagName tag)
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/**
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* @brief Get exif directory structure contained in file (if any)
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* This is internal function and is not exposed to client
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* @brief Parsing the exif data buffer and prepare (internal) exif directory
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*
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* @return Map where key is tag number and value is ExifEntry_t structure
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*/
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std::map<int, ExifEntry_t > ExifReader::getExif()
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{
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const std::streamsize markerSize = 2;
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const std::streamsize offsetToTiffHeader = 6; //bytes from Exif size field to the first TIFF header
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unsigned char appMarker[markerSize];
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m_exif.erase( m_exif.begin(), m_exif.end() );
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std::streamsize count;
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bool exifFound = false, stopSearch = false;
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while( ( !m_stream.eof() ) && !exifFound && !stopSearch )
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{
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m_stream.read( reinterpret_cast<char*>(appMarker), markerSize );
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count = m_stream.gcount();
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if( count < markerSize )
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{
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break;
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}
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unsigned char marker = appMarker[1];
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size_t bytesToSkip;
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size_t exifSize;
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switch( marker )
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{
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//For all the markers just skip bytes in file pointed by followed two bytes (field size)
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case SOF0: case SOF2: case DHT: case DQT: case DRI: case SOS:
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case RST0: case RST1: case RST2: case RST3: case RST4: case RST5: case RST6: case RST7:
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case APP0: case APP2: case APP3: case APP4: case APP5: case APP6: case APP7: case APP8:
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case APP9: case APP10: case APP11: case APP12: case APP13: case APP14: case APP15:
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case COM:
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bytesToSkip = getFieldSize();
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if (bytesToSkip < markerSize) {
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throw ExifParsingError();
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}
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m_stream.seekg( static_cast<long>( bytesToSkip - markerSize ), m_stream.cur );
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if ( m_stream.fail() ) {
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throw ExifParsingError();
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}
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break;
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//SOI and EOI don't have the size field after the marker
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case SOI: case EOI:
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break;
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case APP1: //actual Exif Marker
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exifSize = getFieldSize();
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if (exifSize <= offsetToTiffHeader) {
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throw ExifParsingError();
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}
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m_data.resize( exifSize - offsetToTiffHeader );
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m_stream.seekg( static_cast<long>( offsetToTiffHeader ), m_stream.cur );
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if ( m_stream.fail() ) {
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throw ExifParsingError();
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}
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m_stream.read( reinterpret_cast<char*>(&m_data[0]), exifSize - offsetToTiffHeader );
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exifFound = true;
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break;
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default: //No other markers are expected according to standard. May be a signal of error
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stopSearch = true;
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break;
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}
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}
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if( !exifFound )
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{
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return m_exif;
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}
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parseExif();
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return m_exif;
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}
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/**
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* @brief Get the size of exif field (required to properly ready whole exif from the file)
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* This is internal function and is not exposed to client
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* @param [in] data The data buffer to read EXIF data starting with endianness
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* @param [in] size The size of the data buffer
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*
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* @return size of exif field in the file
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* @return true if parsing was successful
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* false in case of unsuccessful parsing
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*/
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size_t ExifReader::getFieldSize ()
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bool ExifReader::parseExif(unsigned char* data, const size_t size)
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{
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unsigned char fieldSize[2];
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m_stream.read( reinterpret_cast<char*>(fieldSize), 2 );
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std::streamsize count = m_stream.gcount();
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if (count < 2)
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// Populate m_data, then call parseExif() (private)
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if( data && size > 0 )
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{
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return 0;
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m_data.assign(data, data + size);
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}
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else
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{
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return false;
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}
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try {
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parseExif();
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if( !m_exif.empty() )
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{
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return true;
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}
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return false;
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}
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catch( ExifParsingError& ) {
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return false;
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}
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return ( fieldSize[0] << 8 ) + fieldSize[1];
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}
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/**
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