/// <summary>
/// Decompresses the compressed data stored in one or more IDAT chunks.
/// </summary>
private byte[] Decompress()
{
Inflater inf = new Inflater();
MemoryStream decompressed = new MemoryStream();
MemoryStream compressed = new MemoryStream();
byte[] buf = new byte[1];
// decompress the image data
foreach (Chunk c in _image.Chunks)
{
if (c.Type == "IDAT")
{
IDATChunk idat = c as IDATChunk;
compressed.Write(idat.Data, 0, idat.Data.Length);
if (compressed.Length > 15)
{
inf.SetInput(compressed.ToArray());
while (!inf.IsNeedingInput)
{
if (inf.Inflate(buf) == -1)
{
break;
}
decompressed.WriteByte(buf[0]);
}
compressed = new MemoryStream();
}
}
}
inf.SetInput(compressed.ToArray());
while (!inf.IsNeedingInput)
{
if (inf.Inflate(buf) == -1)
{
break;
}
decompressed.WriteByte(buf[0]);
}
if (!inf.IsFinished)
{
throw new InvalidCompressedDataException("Inflater is not finished but there are no more IDAT chunks.");
}
byte[] arr = decompressed.ToArray();
decompressed.Close();
return(arr);
}
/// <summary>
/// Modifies the underlying image's chunks to save the image.
/// </summary>
/// <param name="data">The uncompressed image data.</param>
private void SaveChunks(byte[] data)
{
// remove all existing data chunks
_image.Chunks.RemoveAll(new Predicate <Chunk>(
delegate(Chunk c)
{
if (c.Type == "IDAT")
{
return(true);
}
else
{
return(false);
}
}));
// insert our new data chunk just before the end
for (int i = 0; i < _image.Chunks.Count; i++)
{
if (_image.Chunks[i].Type == "IEND")
{
IDATChunk idat = new IDATChunk(_image);
MemoryStream ms = new MemoryStream();
DeflaterOutputStream dos = new DeflaterOutputStream(ms, new Deflater(CompressionLevel.Level));
BinaryWriter bwdata = new BinaryWriter(dos);
bwdata.Write(data);
dos.Finish();
idat.Data = ms.ToArray();
bwdata.Close();
ms.Close();
_image.Chunks.Insert(i, idat);
break;
}
}
}
