Allow RemoteReader to optionally buffer to memory stream

[lilith]

No description provided.

[lilith]

RemoteReader doesn't provide a seekable stream. That's fine for the default pipeline, which auto-buffers unseekable streams. However, the other pipelines don't have that logic (if I remember right). We can fix this at either end for now. In V4 the framework should probably handle it...

[JaredReisinger]

"The framework" in this case being ImageBuilder.GetStreamFromSource(), which is responsible for turning Streams, IVirtualFiles, and other Stream sources into a Stream? I think I'll start by implementing a fairly standalone SeekableStreamWrapper in the RemoteReader plugin itself, and then we can move it wholesale into the core when we're happy with its behavior.

[lilith]

Copying wholesale to a MemoryStream is actually fine for now. For our Async work we'll need some sophisticated seekable stream stuff, so that optimization might be better delayed till v4.

[JaredReisinger]

I was thinking about that, having a "buffer-on-the-fly" wrapper, but it seemed like over-engineering for the current uses. (I suppose things like the TIFF decoder might be able to make good use of a 'fetch/cache-on-demand' wrapper, though.)

[lilith]

Yeah. Allowing layout & execution plan design to proceed as soon as type & dimensions can be parsed would be useful - especially for tiled, multi-frame, or multi-page images where all the bytes may not be need if there's a smart enough decoder available.