internal new static async Task <GifExtension> ReadAsync(Stream stream, IEnumerable <GifExtension> controlExtensions)
{
// Note: at this point, the Extension Introducer (0x21) has already been read
int label = stream.ReadByte();
if (label < 0)
{
throw new EndOfStreamException();
}
switch (label)
{
case GifGraphicControlExtension.ExtensionLabel:
return(await GifGraphicControlExtension.ReadAsync(stream).ConfigureAwait(false));
case GifCommentExtension.ExtensionLabel:
return(await GifCommentExtension.ReadAsync(stream).ConfigureAwait(false));
case GifPlainTextExtension.ExtensionLabel:
return(await GifPlainTextExtension.ReadAsync(stream, controlExtensions).ConfigureAwait(false));
case GifApplicationExtension.ExtensionLabel:
return(await GifApplicationExtension.ReadAsync(stream).ConfigureAwait(false));
default:
throw GifHelpers.UnknownExtensionTypeException(label);
}
}
internal static async Task <GifApplicationExtension> ReadAsync(Stream stream)
{
var ext = new GifApplicationExtension();
await ext.ReadInternalAsync(stream).ConfigureAwait(false);
return(ext);
}
internal static async Task <GifExtension> ReadAsync(Stream stream, IEnumerable <GifExtension> controlExtensions)
{
int label = stream.ReadByte();
if (label < 0)
{
throw GifHelpers.UnexpectedEndOfStreamException();
}
switch (label)
{
case 254:
return((GifExtension)await GifCommentExtension.ReadAsync(stream).ConfigureAwait(false));
case (int)byte.MaxValue:
return((GifExtension)await GifApplicationExtension.ReadAsync(stream).ConfigureAwait(false));
case 1:
return((GifExtension)await GifPlainTextExtension.ReadAsync(stream, controlExtensions).ConfigureAwait(false));
case 249:
return((GifExtension)await GifGraphicControlExtension.ReadAsync(stream).ConfigureAwait(false));
default:
throw GifHelpers.UnknownExtensionTypeException(label);
}
}
public static ushort GetRepeatCount(GifApplicationExtension ext)
{
if (ext.Data.Length >= 3)
{
return BitConverter.ToUInt16(ext.Data, 1);
}
return 1;
}
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)
{
if (ext.ApplicationIdentifier == "NETSCAPE")
{
return(GifHelpers.GetString(ext.AuthenticationCode) == "2.0");
}
return(false);
}
private async Task ReadInternalAsync(Stream stream)
{
this.Header = await GifHeader.ReadAsync(stream).ConfigureAwait(false);
if (this.Header.LogicalScreenDescriptor.HasGlobalColorTable)
{
this.GlobalColorTable = await GifHelpers.ReadColorTableAsync(stream, this.Header.LogicalScreenDescriptor.GlobalColorTableSize).ConfigureAwait(false);
}
await this.ReadFramesAsync(stream).ConfigureAwait(false);
GifApplicationExtension ext = this.Extensions.OfType <GifApplicationExtension>().FirstOrDefault <GifApplicationExtension>(new Func <GifApplicationExtension, bool>(GifHelpers.IsNetscapeExtension));
this.RepeatCount = ext != null?GifHelpers.GetRepeatCount(ext) : (ushort)1;
}
public static bool IsNetscapeExtension(GifApplicationExtension ext)
{
return ext.ApplicationIdentifier == "NETSCAPE"
&& GetString(ext.AuthenticationCode) == "2.0";
}
public static bool IsNetscapeExtension(GifApplicationExtension ext)
{
return(ext.ApplicationIdentifier == "NETSCAPE" &&
GetString(ext.AuthenticationCode) == "2.0");
}
internal static async Task<GifApplicationExtension> ReadAsync(Stream stream)
{
var ext = new GifApplicationExtension();
await ext.ReadInternalAsync(stream).ConfigureAwait(false);
return ext;
}
