internal static GifExtension ReadExtension(Stream stream, IEnumerable <GifExtension> controlExtensions,
bool metadataOnly)
{
// Note: at this point, the Extension Introducer (0x21) has already been read
var label = stream.ReadByte();
if (label < 0)
{
throw GifHelpers.UnexpectedEndOfStreamException();
}
switch (label)
{
case GifGraphicControlExtension.ExtensionLabel:
return(GifGraphicControlExtension.ReadGraphicsControl(stream));
case GifCommentExtension.ExtensionLabel:
return(GifCommentExtension.ReadComment(stream));
case GifPlainTextExtension.ExtensionLabel:
return(GifPlainTextExtension.ReadPlainText(stream, controlExtensions, metadataOnly));
case GifApplicationExtension.ExtensionLabel:
return(GifApplicationExtension.ReadApplication(stream));
default:
throw GifHelpers.UnknownExtensionTypeException(label);
}
}
internal static GifApplicationExtension ReadApplication(Stream stream)
{
var ext = new GifApplicationExtension();
ext.Read(stream);
return(ext);
}
public static ushort GetRepeatCount(GifApplicationExtension ext)
{
if (ext.Data.Length >= 3)
{
return(BitConverter.ToUInt16(ext.Data, 1));
}
return(1);
}
public static bool IsNetscapeExtension(GifApplicationExtension ext)
{
return(ext.ApplicationIdentifier == "NETSCAPE" &&
Encoding.ASCII.GetString(ext.AuthenticationCode) == "2.0");
}