* The only difference in these is whether or not pre-multiplied alpha is assumed
to be used, and that doesn't change the actual data - only the interpretation.
* This allows us to have sRGB as a type hint, and better matches API format
types.
* It's currently impossible and unlikely to ever be the case that srgb is
applied to anything other than UNorm, so having it be independent from the
component type was a degree of freedom that was unused.
* We handle 4:4:4, 4:2:2, and 4:2:0, with packed, 2-plane and 3-plane formats,
for 8, 10, 12, and 16 bit depths.
* This covers most common formats but still leaves a few out - NV11, palettised
formats, V208/V408 JPG formats.
* There was no good reason to have a flag indicating if the special
format was valid or not. Now it's a single enum, with a value
'Regular' indicating that the compCount/compWidth/compType fully
describe the format itself.
* This makes code patterns easier as you no longer need to check for
special then check for specialFormat, you can just test the type
directly.
* This gives a little nicer syntax, a bit better type safety, and also
reflects better for SWIG bindings. Overall it's a minor change but
better.
* We don't update the C# UI at all, since it's soon to be removed and
not worth the effort/code churn.
* For now so we're ABI compatible with C#, all enums are uint32_t, but
that is an obvious optimisation in future to reduce struct packing.
* We avoid 'None' as an enum value, because it's a reserved word in
python so will cause problems generating bindings.
baldurk