public override ChunkRaw CreateRawChunk()
{
if (key.Length == 0)
{
throw new System.Exception("Text chunk key must be non empty");
}
var ba = new IO.MemoryStream();
ChunkHelper.WriteBytesToStream(ba, ChunkHelper.ToBytes(key));
ba.WriteByte(0); // separator
ba.WriteByte(compressed ? (byte)1 : (byte)0);
ba.WriteByte(0); // compression method (always 0)
ChunkHelper.WriteBytesToStream(ba, ChunkHelper.ToBytes(langTag));
ba.WriteByte(0); // separator
ChunkHelper.WriteBytesToStream(ba, ChunkHelper.ToBytesUTF8(translatedTag));
ba.WriteByte(0); // separator
byte[] textbytes = ChunkHelper.ToBytesUTF8(val);
if (compressed)
{
textbytes = ChunkHelper.CompressBytes(textbytes, true);
}
ChunkHelper.WriteBytesToStream(ba, textbytes);
byte[] b = ba.ToArray();
ChunkRaw chunk = CreateEmptyChunk(b.Length, false);
chunk.Data = b;
return(chunk);
}
public override void ParseFromRaw(ChunkRaw chunk)
{
byte[] data = chunk.Data;
int length = data.Length;
int nullsFound = 0;
int[] nullsIdx = new int[3];
for (int k = 0; k < length; k++)
{
if (data[k] != 0)
{
continue;
}
nullsIdx[nullsFound] = k;
nullsFound++;
if (nullsFound == 1)
{
k += 2;
}
if (nullsFound == 3)
{
break;
}
}
if (nullsFound != 3)
{
throw new System.Exception("Bad formed PngChunkITXT chunk");
}
key = ChunkHelper.ToString(data, 0, nullsIdx[0]);
int i = nullsIdx[0] + 1;
compressed = data[i] == 0 ? false : true;
i++;
if (compressed && data[i] != 0)
{
throw new System.Exception("Bad formed PngChunkITXT chunk - bad compression method ");
}
langTag = ChunkHelper.ToString(data, i, nullsIdx[1] - i);
translatedTag = ChunkHelper.ToStringUTF8(data, nullsIdx[1] + 1, nullsIdx[2] - nullsIdx[1] - 1);
i = nullsIdx[2] + 1;
if (compressed)
{
byte[] bytes = ChunkHelper.CompressBytes(data, i, length - i, false);
val = ChunkHelper.ToStringUTF8(bytes);
}
else
{
val = ChunkHelper.ToStringUTF8(data, i, length - i);
}
}