internal static async Task <GifBlock> ReadAsync(Stream stream, IEnumerable <GifExtension> controlExtensions)
{
int blockId = await stream.ReadByteAsync().ConfigureAwait(false);
if (blockId < 0)
{
throw new EndOfStreamException();
}
return(blockId switch
{
GifExtension.ExtensionIntroducer => await GifExtension.ReadAsync(stream, controlExtensions).ConfigureAwait(false),
GifFrame.ImageSeparator => await GifFrame.ReadAsync(stream, controlExtensions).ConfigureAwait(false),
GifTrailer.TrailerByte => await GifTrailer.ReadAsync().ConfigureAwait(false),
_ => throw GifHelpers.UnknownBlockTypeException(blockId),
});
internal static async Task<GifBlock> ReadAsync(Stream stream, IEnumerable<GifExtension> controlExtensions)
{
int blockId = await stream.ReadByteAsync().ConfigureAwait(false);
if (blockId < 0)
throw GifHelpers.UnexpectedEndOfStreamException();
switch (blockId)
{
case GifExtension.ExtensionIntroducer:
return await GifExtension.ReadAsync(stream, controlExtensions).ConfigureAwait(false);
case GifFrame.ImageSeparator:
return await GifFrame.ReadAsync(stream, controlExtensions).ConfigureAwait(false);
case GifTrailer.TrailerByte:
return await GifTrailer.ReadAsync().ConfigureAwait(false);
default:
throw GifHelpers.UnknownBlockTypeException(blockId);
}
}
private async Task ReadFramesAsync(Stream stream)
{
List <GifFrame> frames = new List <GifFrame>();
List <GifExtension> controlExtensions = new List <GifExtension>();
List <GifExtension> specialExtensions = new List <GifExtension>();
GifBlock gifBlock;
do
{
gifBlock = await GifBlock.ReadAsync(stream, (IEnumerable <GifExtension>) controlExtensions).ConfigureAwait(false);
if (gifBlock.Kind == GifBlockKind.GraphicRendering)
{
controlExtensions = new List <GifExtension>();
}
if (gifBlock is GifFrame)
{
frames.Add((GifFrame)gifBlock);
}
else if (gifBlock is GifExtension)
{
GifExtension gifExtension = (GifExtension)gifBlock;
switch (gifExtension.Kind)
{
case GifBlockKind.Control:
controlExtensions.Add(gifExtension);
continue;
case GifBlockKind.SpecialPurpose:
specialExtensions.Add(gifExtension);
continue;
default:
continue;
}
}
}while (!(gifBlock is GifTrailer));
this.Frames = (IList <GifFrame>)frames.AsReadOnly();
this.Extensions = (IList <GifExtension>)specialExtensions.AsReadOnly();
}
internal static async Task <GifBlock> ReadAsync(Stream stream, IEnumerable <GifExtension> controlExtensions)
{
int blockId = await stream.ReadByteAsync(new CancellationToken()).ConfigureAwait(false);
if (blockId < 0)
{
throw GifHelpers.UnexpectedEndOfStreamException();
}
switch (blockId)
{
case 33:
return((GifBlock)await GifExtension.ReadAsync(stream, controlExtensions).ConfigureAwait(false));
case 44:
return((GifBlock)await GifFrame.ReadAsync(stream, controlExtensions).ConfigureAwait(false));
case 59:
return((GifBlock)await GifTrailer.ReadAsync().ConfigureAwait(false));
default:
throw GifHelpers.UnknownBlockTypeException(blockId);
}
}
