Stash it for now in the (now mutable by default) `.shm_write_opts` and
have the new `Flume._has_vlm: bool` (only set to false internally by
feed layer) which can be read via new public `.has_vlm()` predicate.
Move out the old `.ui/_fsp` helper logic to this flume method.
Might as well try and flip it over to the new type; make appropriate
dict serialization changes in `.to_msg()`. Alias back to `.symbol:
Symbol` with a property.
We need to subtract the first index in the array segment read, not the
first index value in the time-sliced output, to get the correct offset
into the non-absolute (`ShmArray.array` read) array..
Further we **do** need the `&` between the advance indexing conditions
and this adds profiling to see that it is indeed real slow (like 20ms
ish even when using `np.where()`).
Probably means it doesn't need to be a `Flume` method but it's
convenient to expect the caller to pass in the `np.ndarray` with
a `'time'` field instead of a `timeframe: str` arg; also, return the
slice mask instead of the sliced array as output (again allowing the
caller to do any slicing). Also, handle the slice-outside-time-range
case by just returning the entire index range with a `None` mask.
Adjust `Viz.view_data()` to instead do timeframe (for rt vs. hist shm
array) lookup and equiv array slicing with the returned mask.
Tyler Goodlet