/// <summary>
/// Initializes a new instance of the <see cref="JPEGFile"/> class.
/// </summary>
/// <param name="stream">A stream that contains image data.</param>
/// <param name="encoding">The encoding to be used for text metadata when the source encoding is unknown.</param>
/// <param name="readTrailingData">Whether to read data beyond the EOI (end of image) marker.</param>
protected internal JPEGFile(MemoryStream stream, Encoding encoding, bool readTrailingData = false)
{
Format = ImageFileFormat.JPEG;
Sections = new List <JPEGSection>();
TrailingData = new byte[0];
Encoding = encoding;
stream.Seek(0, SeekOrigin.Begin);
// Read the Start of Image (SOI) marker. SOI marker is represented
// with two bytes: 0xFF, 0xD8.
byte[] markerbytes = new byte[2];
if (stream.Read(markerbytes, 0, 2) != 2 || markerbytes[0] != 0xFF || markerbytes[1] != 0xD8)
{
throw new NotValidJPEGFileException();
}
stream.Seek(0, SeekOrigin.Begin);
// Search and read sections until we reach the end of file.
while (stream.Position != stream.Length)
{
// Read the next section marker. Section markers are two bytes
// with values 0xFF, 0x?? where ?? must not be 0x00 or 0xFF.
if (stream.Read(markerbytes, 0, 2) != 2 || markerbytes[0] != 0xFF || markerbytes[1] == 0x00 || markerbytes[1] == 0xFF)
{
throw new NotValidJPEGFileException();
}
JPEGMarker marker = (JPEGMarker)markerbytes[1];
byte[] header = new byte[0];
// SOI, EOI and RST markers do not contain any header
if (marker != JPEGMarker.SOI && marker != JPEGMarker.EOI && !(marker >= JPEGMarker.RST0 && marker <= JPEGMarker.RST7))
{
// Length of the header including the length bytes.
// This value is a 16-bit unsigned integer
// in big endian byte-order.
byte[] lengthbytes = new byte[2];
if (stream.Read(lengthbytes, 0, 2) != 2)
{
throw new NotValidJPEGFileException();
}
long length = (long)BitConverterEx.BigEndian.ToUInt16(lengthbytes, 0);
// Read section header.
header = Utility.GetStreamBytes(stream, length - 2);
}
// Start of Scan (SOS) sections and RST sections are immediately
// followed by entropy coded data. For that, we need to read until
// the next section marker once we reach a SOS or RST.
byte[] entropydata = new byte[0];
if (marker == JPEGMarker.SOS || (marker >= JPEGMarker.RST0 && marker <= JPEGMarker.RST7))
{
long position = stream.Position;
// Search for the next section marker
while (true)
{
// Search for an 0xFF indicating start of a marker
int nextbyte = 0;
do
{
nextbyte = stream.ReadByte();
if (nextbyte == -1)
{
break;
}
} while ((byte)nextbyte != 0xFF);
// Skip filler bytes (0xFF)
do
{
nextbyte = stream.ReadByte();
if (nextbyte == -1)
{
break;
}
} while ((byte)nextbyte == 0xFF);
// We either reached the end of file before a new marker(this would indicate
// a corrupt image file) or we are at a section marker. In that case the
// next byte must not be 0x00.
if (nextbyte != 0)
{
// If we reached a section marker seek back to just before the marker.
if (nextbyte != -1)
{
stream.Seek(-2, SeekOrigin.Current);
}
// Calculate the length of the entropy coded data.
long edlength = stream.Position - position;
stream.Seek(position, SeekOrigin.Begin);
// Read entropy coded data
entropydata = Utility.GetStreamBytes(stream, edlength);
break;
}
}
}
// Store section.
JPEGSection section = new JPEGSection(marker, header, entropydata);
Sections.Add(section);
// Some propriety formats store data past the EOI marker
if (marker == JPEGMarker.EOI)
{
if (readTrailingData)
{
long eoflength = stream.Length - stream.Position;
TrailingData = Utility.GetStreamBytes(stream, eoflength);
}
// stop reading once we are past the EOI marker
break;
}
}
// Read metadata sections
ReadJFIFAPP0();
ReadJFXXAPP0();
ReadExifAPP1();
// Process the maker note
makerNoteProcessed = false;
}
/// <summary>
/// Constructs a JPEGSection represented by the marker byte.
/// </summary>
/// <param name="marker">The marker byte representing the section.</param>
public JPEGSection(JPEGMarker marker)
: this(marker, new byte[0], new byte[0])
{
;
}
/// <summary>
/// Initializes a new instance of the <see cref="ExifFile"/> class.
/// </summary>
/// <param name="stream">A <see cref="Sytem.IO.Stream"/> that contains image data.</param>
protected internal JPEGFile(Stream stream)
{
Format = ImageFileFormat.JPEG;
Sections = new List <JPEGSection>();
TrailingData = new byte[0];
stream.Seek(0, SeekOrigin.Begin);
// Read the Start of Image (SOI) marker. SOI marker is represented
// with two bytes: 0xFF, 0xD8.
byte[] markerbytes = new byte[2];
if (stream.Read(markerbytes, 0, 2) != 2 || markerbytes[0] != 0xFF || markerbytes[1] != 0xD8)
{
throw new NotValidJPEGFileException();
}
stream.Seek(0, SeekOrigin.Begin);
// Search and read sections until we reach the end of file.
while (stream.Position != stream.Length)
{
// Read the next section marker. Section markers are two bytes
// with values 0xFF, 0x?? where ?? must not be 0x00 or 0xFF.
if (stream.Read(markerbytes, 0, 2) != 2 || markerbytes[0] != 0xFF || markerbytes[1] == 0x00 || markerbytes[1] == 0xFF)
{
throw new NotValidJPEGFileException();
}
JPEGMarker marker = (JPEGMarker)markerbytes[1];
byte[] header = new byte[0];
// SOI, EOI and RST markers do not contain any header
if (marker != JPEGMarker.SOI && marker != JPEGMarker.EOI && !(marker >= JPEGMarker.RST0 && marker <= JPEGMarker.RST7))
{
// Length of the header including the length bytes.
// This value is a 16-bit unsigned integer
// in big endian byte-order.
byte[] lengthbytes = new byte[2];
if (stream.Read(lengthbytes, 0, 2) != 2)
{
throw new NotValidJPEGFileException();
}
long length = (long)BitConverterEx.BigEndian.ToUInt16(lengthbytes, 0);
// Read section header.
header = new byte[length - 2];
int bytestoread = header.Length;
while (bytestoread > 0)
{
int count = Math.Min(bytestoread, 4 * 1024);
int bytesread = stream.Read(header, header.Length - bytestoread, count);
if (bytesread == 0)
{
throw new NotValidJPEGFileException();
}
bytestoread -= bytesread;
}
}
// Start of Scan (SOS) sections and RST sections are immediately
// followed by entropy coded data. For that, we need to read until
// the next section marker once we reach a SOS or RST.
byte[] entropydata = new byte[0];
if (marker == JPEGMarker.SOS || (marker >= JPEGMarker.RST0 && marker <= JPEGMarker.RST7))
{
long position = stream.Position;
// Search for the next section marker
while (true)
{
// Search for an 0xFF indicating start of a marker
int nextbyte = 0;
do
{
nextbyte = stream.ReadByte();
if (nextbyte == -1)
{
throw new NotValidJPEGFileException();
}
} while ((byte)nextbyte != 0xFF);
// Skip filler bytes (0xFF)
do
{
nextbyte = stream.ReadByte();
if (nextbyte == -1)
{
throw new NotValidJPEGFileException();
}
} while ((byte)nextbyte == 0xFF);
// Looks like a section marker. The next byte must not be 0x00.
if ((byte)nextbyte != 0x00)
{
// We reached a section marker. Calculate the
// length of the entropy coded data.
stream.Seek(-2, SeekOrigin.Current);
long edlength = stream.Position - position;
stream.Seek(-edlength, SeekOrigin.Current);
// Read entropy coded data
entropydata = new byte[edlength];
int bytestoread = entropydata.Length;
while (bytestoread > 0)
{
int count = Math.Min(bytestoread, 4 * 1024);
int bytesread = stream.Read(entropydata, entropydata.Length - bytestoread, count);
if (bytesread == 0)
{
throw new NotValidJPEGFileException();
}
bytestoread -= bytesread;
}
break;
}
}
}
// Store section.
JPEGSection section = new JPEGSection(marker, header, entropydata);
Sections.Add(section);
// Some propriety formats store data past the EOI marker
if (marker == JPEGMarker.EOI)
{
int bytestoread = (int)(stream.Length - stream.Position);
TrailingData = new byte[bytestoread];
while (bytestoread > 0)
{
int count = (int)Math.Min(bytestoread, 4 * 1024);
int bytesread = stream.Read(TrailingData, TrailingData.Length - bytestoread, count);
if (bytesread == 0)
{
throw new NotValidJPEGFileException();
}
bytestoread -= bytesread;
}
}
}
// Read metadata sections
ReadJFIFAPP0();
ReadJFXXAPP0();
ReadExifAPP1();
// Process the maker note
makerNoteProcessed = false;
}
/// <summary>
/// Constructs a JPEGSection represented by the marker byte and containing
/// the given data.
/// </summary>
/// <param name="marker">The marker byte representing the section.</param>
/// <param name="data">Section data.</param>
/// <param name="entropydata">Entropy coded data.</param>
public JPEGSection(JPEGMarker marker, byte[] data, byte[] entropydata)
{
Marker = marker;
Header = data;
EntropyData = entropydata;
}
/// <summary>
/// Constructs a JPEGSection represented by the marker byte.
/// </summary>
/// <param name="marker">The marker byte representing the section.</param>
public JPEGSection(JPEGMarker marker)
{
Marker = marker;
}
/// <summary>
/// Constructs a JPEGSection represented by the marker byte.
/// </summary>
/// <param name="marker">The marker byte representing the section.</param>
public JPEGSection(JPEGMarker marker)
{
Marker = marker;
}
/// <summary>
/// Constructs a JPEGSection represented by the marker byte and containing
/// the given data.
/// </summary>
/// <param name="marker">The marker byte representing the section.</param>
/// <param name="data">Section data.</param>
/// <param name="entropydata">Entropy coded data.</param>
public JPEGSection(JPEGMarker marker, byte[] data, byte[] entropydata)
{
Marker = marker;
Header = data;
EntropyData = entropydata;
}
/// <summary>
/// Constructs a JPEGSection represented by the marker byte.
/// </summary>
/// <param name="marker">The marker byte representing the section.</param>
public JPEGSection(JPEGMarker marker)
: this(marker, new byte[0], new byte[0])
{
;
}
