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 GifBlock ReadBlock(Stream stream, IEnumerable <GifExtension> controlExtensions,
bool metadataOnly)
{
var blockId = stream.ReadByte();
if (blockId < 0)
{
throw GifHelpers.UnexpectedEndOfStreamException();
}
switch (blockId)
{
case GifExtension.ExtensionIntroducer:
return(GifExtension.ReadExtension(stream, controlExtensions, metadataOnly));
case GifFrame.ImageSeparator:
return(GifFrame.ReadFrame(stream, controlExtensions, metadataOnly));
case GifTrailer.TrailerByte:
return(GifTrailer.ReadTrailer());
default:
throw GifHelpers.UnknownBlockTypeException(blockId);
}
}