public async Task <Image?> LoadThumbnailAsync(CancellationToken ct)
{
if (ImageSize == 0xffffffff)
{
return(null);
}
using var imageOwner = MemoryPool <byte> .Shared.Rent((int) ImageSize);
var image = imageOwner.Memory.Slice(0, (int)ImageSize);
Prefix.CopyTo(imageOwner.Memory.Slice(0, Prefix.Length));
if (BodySize > 0)
{
await using var bodyStream = new FileStream(BodyLocation, FileMode.Open, FileAccess.Read, FileShare.ReadWrite, 4096, FileOptions.Asynchronous | FileOptions.SequentialScan);
if (await bodyStream.ReadAsync(image.Slice(Prefix.Length, (int)BodySize), ct).ConfigureAwait(false) != BodySize)
{
throw new EndOfStreamException();
}
}
try
{
return(await Task.Run(() =>
{
return OpenJpeg.Decode(image.Span, 64);
}, ct).ConfigureAwait(false));
}
catch (OpenJpegException)
{
return(null);
}
}
public async Task <ReadOnlyMemory <byte> > LoadAsync(CancellationToken ct)
{
var image = new Memory <byte>(new byte[(int)ImageSize]);
Prefix.CopyTo(image.Slice(0, Prefix.Length));
if (BodySize > 0)
{
await using var bodyStream = new FileStream(BodyLocation, FileMode.Open, FileAccess.Read, FileShare.ReadWrite, 4096, FileOptions.Asynchronous | FileOptions.SequentialScan);
if (await bodyStream.ReadAsync(image.Slice(Prefix.Length, (int)BodySize), ct).ConfigureAwait(false) != BodySize)
{
throw new EndOfStreamException();
}
}
return(image);
}
