private async Task ReadFramesAsync(Stream stream)
{
List <GifFrame> frames = new List <GifFrame>();
List <GifExtension> controlExtensions = new List <GifExtension>();
List <GifExtension> specialExtensions = new List <GifExtension>();
while (true)
{
try
{
var block = await GifBlock.ReadAsync(stream, controlExtensions).ConfigureAwait(false);
if (block.Kind == GifBlockKind.GraphicRendering)
{
controlExtensions = new List <GifExtension>();
}
if (block is GifFrame)
{
frames.Add((GifFrame)block);
}
else if (block is GifExtension)
{
var extension = (GifExtension)block;
switch (extension.Kind)
{
case GifBlockKind.Control:
controlExtensions.Add(extension);
break;
case GifBlockKind.SpecialPurpose:
specialExtensions.Add(extension);
break;
// Just discard plain text extensions for now, since we have no use for it
}
}
else if (block is GifTrailer)
{
break;
}
}
// Follow the same approach as Firefox:
// If we find extraneous data between blocks, just assume the stream
// was successfully terminated if we have some successfully decoded frames
// https://dxr.mozilla.org/firefox/source/modules/libpr0n/decoders/gif/nsGIFDecoder2.cpp#894-909
catch (UnknownBlockTypeException) when(frames.Count > 0)
{
break;
}
}
this.Frames = frames.AsReadOnly();
this.Extensions = specialExtensions.AsReadOnly();
}
private async Task ReadFramesAsync(Stream stream)
{
List <GifFrame> frames = new List <GifFrame>();
List <GifExtension> controlExtensions = new List <GifExtension>();
List <GifExtension> specialExtensions = new List <GifExtension>();
while (true)
{
var block = await GifBlock.ReadAsync(stream, controlExtensions).ConfigureAwait(false);
if (block.Kind == GifBlockKind.GraphicRendering)
{
controlExtensions = new List <GifExtension>();
}
if (block is GifFrame)
{
frames.Add((GifFrame)block);
}
else if (block is GifExtension)
{
var extension = (GifExtension)block;
switch (extension.Kind)
{
case GifBlockKind.Control:
controlExtensions.Add(extension);
break;
case GifBlockKind.SpecialPurpose:
specialExtensions.Add(extension);
break;
// Just discard plain text extensions for now, since we have no use for it
}
}
else if (block is GifTrailer)
{
break;
}
}
this.Frames = frames.AsReadOnly();
this.Extensions = specialExtensions.AsReadOnly();
}
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();
}