/// <summary>
/// Initializes a new instance of the <see cref="JPEGFile"/> class from the
/// specified data stream.
/// </summary>
/// <param name="stream">A <see cref="Sytem.IO.Stream"/> that contains image data.</param>
/// <param name="encoding">The encoding to be used for text metadata when the source encoding is unknown.</param>
protected internal PNGFile(Stream stream, System.Text.Encoding encoding)
{
Format = ImageFileFormat.PNG;
Chunks = new List <PNGChunk>();
Encoding = encoding;
BitConverterEx conv = BitConverterEx.BigEndian;
// Skip header
stream.Seek(8, SeekOrigin.Begin);
// Read chunks in order until we reach the end of file.
while (stream.Position != stream.Length)
{
// Length of chunk data
byte[] lengthBytes = new byte[4];
if (stream.Read(lengthBytes, 0, 4) != 4)
{
throw new NotValidPNGFileException();
}
uint length = conv.ToUInt32(lengthBytes, 0);
// Chunk type
byte[] typeBytes = new byte[4];
if (stream.Read(typeBytes, 0, 4) != 4)
{
throw new NotValidPNGFileException();
}
string type = Encoding.ASCII.GetString(typeBytes);
// Chunk data
byte[] data = Utility.GetStreamBytes(stream, length);
// CRC of type name and data
byte[] crcBytes = new byte[4];
if (stream.Read(crcBytes, 0, 4) != 4)
{
throw new NotValidPNGFileException();
}
uint crc = conv.ToUInt32(crcBytes, 0);
// Add to chunks list
PNGChunk chunk = new PNGChunk(type, data);
if (chunk.CRC != crc)
{
throw new NotValidPNGFileException();
}
Chunks.Add(chunk);
}
ReadPNGMetadata();
}
/// <summary>
/// Initializes a new instance of the <see cref="JPEGFile"/> class from the
/// specified data stream.
/// </summary>
/// <param name="stream">A <see cref="Sytem.IO.Stream"/> that contains image data.</param>
/// <param name="encoding">The encoding to be used for text metadata when the source encoding is unknown.</param>
protected internal PNGFile(Stream stream, System.Text.Encoding encoding)
{
Format = ImageFileFormat.PNG;
Chunks = new List<PNGChunk>();
Encoding = encoding;
BitConverterEx conv = BitConverterEx.BigEndian;
// Skip header
stream.Seek(8, SeekOrigin.Begin);
// Read chunks in order until we reach the end of file.
while (stream.Position != stream.Length)
{
// Length of chunk data
byte[] lengthBytes = new byte[4];
if (stream.Read(lengthBytes, 0, 4) != 4)
throw new NotValidPNGFileException();
uint length = conv.ToUInt32(lengthBytes, 0);
// Chunk type
byte[] typeBytes = new byte[4];
if (stream.Read(typeBytes, 0, 4) != 4)
throw new NotValidPNGFileException();
string type = Encoding.ASCII.GetString(typeBytes);
// Chunk data
byte[] data = Utility.GetStreamBytes(stream, length);
// CRC of type name and data
byte[] crcBytes = new byte[4];
if (stream.Read(crcBytes, 0, 4) != 4)
throw new NotValidPNGFileException();
uint crc = conv.ToUInt32(crcBytes, 0);
// Add to chunks list
PNGChunk chunk = new PNGChunk(type, data);
if (chunk.CRC != crc)
throw new NotValidPNGFileException();
Chunks.Add(chunk);
}
ReadPNGMetadata();
}
