private void WriteChunk(string type, byte[] data, int offset, int length)
{
// Write out the length to the PNG.
WriteInteger(_stream, length);
// Write the chunck type out to the PNG.
byte[] typeArray = new byte[4];
typeArray[0] = (byte)type[0];
typeArray[1] = (byte)type[1];
typeArray[2] = (byte)type[2];
typeArray[3] = (byte)type[3];
_stream.Write(typeArray, 0, 4);
// If we have some data to write out (some chunk types don't), the do so.
if (data != null)
{
_stream.Write(data, offset, length);
}
// All chunk types need to have a CRC32 value at their end to make sure they haven't been currupted.
CRC32 crcCode = new CRC32();
crcCode.Add(typeArray, 4);
if (data != null)
{
crcCode.Add(data, length, (uint)offset);
}
WriteInteger(_stream, crcCode.CurrentValue);
}
/// <summary>
/// Computes CRC32 for byte array
/// </summary>
public static uint ForBytes(byte[] buff)
{
var crc = new CRC32();
crc.Add(buff);
return(crc.m_CRC);
}
/// <summary>
/// Computes CRC32 for binary string representation (in-memory)
/// </summary>
public static uint ForString(string text)
{
if (text.IsNullOrWhiteSpace())
{
return(0);
}
var crc = new CRC32();
for (var i = 0; i < text.Length; i++)
{
crc.Add(text[i]);
}
return(crc.m_CRC);
}
//hash the TOC static void AddAsBytesTo(CRC32 crc32, int i) => crc32.Add(BitConverter.GetBytes(i));
private void WriteChunk( string type, byte[] data, int offset, int length )
{
// Write out the length to the PNG.
WriteInteger( _stream, length );
// Write the chunck type out to the PNG.
byte[] typeArray = new byte[4];
typeArray[0] = (byte) type[0];
typeArray[1] = (byte) type[1];
typeArray[2] = (byte) type[2];
typeArray[3] = (byte) type[3];
_stream.Write( typeArray, 0, 4 );
// If we have some data to write out (some chunk types don't), the do so.
if ( data != null )
{
_stream.Write( data, offset, length );
}
// All chunk types need to have a CRC32 value at their end to make sure they haven't been currupted.
CRC32 crcCode = new CRC32();
crcCode.Add( typeArray, 4 );
if ( data != null )
{
crcCode.Add( data, length, (uint) offset );
}
WriteInteger( _stream, crcCode.CurrentValue );
}
