Load font from non-seekable stream

[jahav]

A lot of environments today don't provide reliable access to file system. E.g. Client side Blazor, Azure Functions ect.

In such cases, it would be greate to load font from a some web resource, but these streams are in many cases nonseekable. Fonts can't load font from nonseekable stream, it throws at TableHeader.CreateReader when it attemps to see at the beginning of the table header and would likely throw on other places.

Workaround: It is possible to read whole non-seekable stream to an intermediate MemoryStream and use the MS instead.

[tocsoft]

The way the font file format works is it effectivly requires processing the font data in a random access fashion, so even if we supported using non seekable streams all we would be able to do to 'fix' it would be do the copy silently anyway.

[jahav]

I see. Thank you for consideration and explanation.