private bool AnalyzeGifSignature(List <byte> gifData)
{
for (int i = 0; i < 6; i++)
{
GifSignature.Add(gifData[i]);
}
gifData.RemoveRange(0, 6);
List <char> chars = GifSignature.ConvertAll(ByteToChar);
string s = new string(chars.ToArray());
if (s == GifVersion.GIF89a.ToString())
{
Version = GifVersion.GIF89a;
}
else if (s == GifVersion.GIF87a.ToString())
{
Version = GifVersion.GIF87a;
}
else
{
return(false);
}
return(true);
}
public bool Read(Stream stream)
{
byte[] headerData = new byte[6];
int readBytes = stream.Read(headerData, 0, 6);
if (readBytes == 6)
{
string header = Encoding.ASCII.GetString(headerData);
if (!header.StartsWith("GIF"))
{
return(false);
}
if (header.Substring(3, 3) == "89a")
{
Version = GifVersion.GIF89a;
}
else if (header.Substring(3, 3) == "87a")
{
Version = GifVersion.GIF87a;
}
else
{
return(false);
}
}
else
{
return(false);
}
return(true);
}
public async Task Writes_Correct_Version_Bytes(GifVersion version, byte[] expectedBytes)
{
var stream = new MemoryStream();
var writer = new GifWriter(stream);
await writer.WriteVersionAsync(version);
var writtenBytes = stream.ToArray();
CollectionAssert.AreEqual(expectedBytes, writtenBytes);
}
public async Task WriteVersionAsync(GifVersion version)
{
byte[] toWrite;
if (version == GifVersion.Gif87a)
{
toWrite = Encodings.Version87a;
}
else if (version == GifVersion.Gif89a)
{
toWrite = Encodings.Version89a;
}
else
{
throw new ArgumentException("Invalid version specified", nameof(version));
}
await _outputStream.WriteAsync(toWrite, 0, toWrite.Length);
}