public void TestMultipleIDATChunksAreTreatedAsASingleDeflatedBuffer()
{
byte[] originalData = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0xA0 };
byte[] deflateOriginalData = DeflateBytes(originalData);
int splitAtIndex = 4;
byte[] chunk1Data = deflateOriginalData.Take(splitAtIndex).ToArray();
byte[] chunk2Data = deflateOriginalData.Skip(splitAtIndex).ToArray();
List <PNGChunk> chunks = new List <PNGChunk>()
{
new PNGChunk(PNGChunk.StringFromType(PNGChunk.ChunkType.CgBI), new byte[] { }, 0),
new PNGChunk(PNGChunk.StringFromType(PNGChunk.ChunkType.IDAT), chunk1Data, 0),
new PNGChunk(PNGChunk.StringFromType(PNGChunk.ChunkType.IDAT), chunk2Data, 0)
};
IEnumerable <PNGChunk> decrushedChunks = PNGDecrusher.DecrushChunks(chunks);
byte[] zlibChunk1 = decrushedChunks.First().Data;
byte[] zlibChunk2 = decrushedChunks.Last().Data;
byte[] zlibChunksCombined = new byte[zlibChunk1.Length + zlibChunk2.Length];
zlibChunk1.CopyTo(zlibChunksCombined, 0);
zlibChunk2.CopyTo(zlibChunksCombined, zlibChunk1.Length);
byte[] dezlibbedData = DecompressZlibBytes(zlibChunksCombined);
Assert.AreEqual(originalData.Length, dezlibbedData.Length);
CollectionAssert.AreEqual(originalData, dezlibbedData);
}
public void TestZlibHeadersAreAddedBack()
{
IEnumerable <PNGChunk> chunks = PNGChunkParser.ChunksFromStream(new MemoryStream(Crushed10x10White));
IEnumerable <PNGChunk> decrushedChunks = PNGDecrusher.DecrushChunks(chunks);
PNGChunk decrushedIdatChunk = decrushedChunks.First(c => c.Type == PNGChunk.ChunkType.IDAT);
using (MemoryStream idatDataStream = new MemoryStream(decrushedIdatChunk.Data))
{
// basic check of the zlib header
// http://tools.ietf.org/html/rfc1950#page-4
int CMF = idatDataStream.ReadByte();
int FLG = idatDataStream.ReadByte();
int compressionMethod = CMF & 0x0F;
int compressionInfo = (CMF & 0xF0) >> 4;
int COMPRESSION_METHOD_DEFLATE = 8;
Assert.AreEqual(COMPRESSION_METHOD_DEFLATE, compressionMethod);
using (DeflateStream deflateStream = new DeflateStream(idatDataStream, CompressionMode.Decompress))
using (MemoryStream decompressedStream = new MemoryStream())
{
deflateStream.CopyTo(decompressedStream);
Assert.AreEqual(410, decompressedStream.Length);
}
}
}
public void TestChunksAreCorrectlyParsed()
{
using (MemoryStream stream = new MemoryStream(Simple10x10WhitePNG))
{
PNGChunk[] chunks = PNGChunkParser.ChunksFromStream(stream).ToArray();
Assert.AreEqual(6, chunks.Length);
PNGChunk idatChunk = chunks[4];
Assert.AreEqual("IDAT", idatChunk.TypeString);
Assert.AreEqual(PNGChunk.ChunkType.IDAT, idatChunk.Type);
Assert.AreEqual(17, idatChunk.Data.Length);
}
}
private static void WriteChunkToWriter(PNGChunk chunk, BinaryWriter writer)
{
writer.WriteNetworkOrder((uint)chunk.Data.Length);
byte[] typeString = Encoding.UTF8.GetBytes(chunk.TypeString);
if (typeString.Length != 4)
{
throw new InvalidDataException("PNG chunk type must be a 4 character string");
}
writer.Write(typeString);
writer.Write(chunk.Data);
writer.WriteNetworkOrder(chunk.DataCRC);
}
private static void WriteChunkToWriter(PNGChunk chunk, BinaryWriter writer)
{
writer.WriteNetworkOrder((uint)chunk.Data.Length);
byte[] typeString = Encoding.UTF8.GetBytes(chunk.TypeString);
if (typeString.Length != 4)
{
throw new InvalidDataException("PNG chunk type must be a 4 character string");
}
writer.Write(typeString);
writer.Write(chunk.Data);
writer.WriteNetworkOrder(chunk.DataCRC);
}
public void TestAppleChunkIsRemovedWhenDecrushing()
{
IEnumerable <PNGChunk> chunks = new List <PNGChunk>()
{
new PNGChunk(PNGChunk.StringFromType(PNGChunk.ChunkType.CgBI), new byte[] { 0x01, 0x02, 0x03 }, 12345),
new PNGChunk(PNGChunk.StringFromType(PNGChunk.ChunkType.IDAT), DeflateBytes(new byte[] { 0x01, 0x02, 0x03 }), 12345),
new PNGChunk("IEND", new byte[] { }, 0xFFFFFF)
};
IEnumerable <PNGChunk> fixedChunks = PNGDecrusher.DecrushChunks(chunks);
Assert.AreEqual(2, fixedChunks.Count());
Assert.AreEqual(PNGChunk.ChunkType.IDAT, fixedChunks.ToArray()[0].Type);
Assert.AreEqual("IEND", fixedChunks.ToArray()[1].TypeString);
}
public void TestDecrushedIDATDataIsSameAsOriginalAfterDecompressing()
{
byte[] originalData = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 };
byte[] deflatedOriginalData = DeflateBytes(originalData);
List <PNGChunk> chunks = new List <PNGChunk>()
{
new PNGChunk(PNGChunk.StringFromType(PNGChunk.ChunkType.CgBI), new byte[] { }, 0),
new PNGChunk(PNGChunk.StringFromType(PNGChunk.ChunkType.IDAT), deflatedOriginalData, 0)
};
IEnumerable <PNGChunk> decrushedChunks = PNGDecrusher.DecrushChunks(chunks);
Assert.AreEqual(1, decrushedChunks.Count());
byte[] zlibData = decrushedChunks.First().Data;
byte[] dezlibbedData = DecompressZlibBytes(zlibData);
Assert.AreEqual(originalData.Length, dezlibbedData.Length);
CollectionAssert.AreEqual(originalData, dezlibbedData);
}
private static PNGChunk IDATChunkWithBytes(byte[] bytes)
{
string type = PNGChunk.StringFromType(PNGChunk.ChunkType.IDAT);
return(new PNGChunk(type, bytes, CalculateCRCForChunk(type, bytes)));
}