This mostly worked before, but clearColor made the assumption that the
colors were always in #RRBBGG format. See the discussion here:
https://github.com/xtermjs/xterm.js/pull/1327#issuecomment-374812842
This changes the internal representation of a color so that we hold onto
into an object containing the original css string along with an RGBA
value encoded as a 32-bit uint. clearColor can then use that RGBA
representation.
Additionally, this deduplicates some code between ColorManager and
Terminal. Terminal was generating the 256 ansi colors the same way
ColorManager was, so this just makes Terminal use the same constant.
Two parts were commented out:
- _writeStopped: This is because _xoffSentToCatchUp references this variable
and the feature is sort of half implemented/disabled.
- _clearChar: This is because some comments still reference this, it's part
of the work needed to do better line redrawing.
The only thing `didCharSizeChange` was used for was to figure out if we
need to refresh the character atlas or not. However, `acquireCharAtlas`
already inspects the atlas owned by this terminal, and if it matches, it
avoids generating a new atlas.
So if `didCharSizeChange` is true and it's not needed, it quickly bails
out as a no-op. But if `didCharSizeChange` is false, and it was needed
(possible given the complexity of testing all of these edge cases), it
could introduce a bug.
I think it makes sense to just get rid of `didCharSizeChange`, and just
always call `acquireCharAtlas`.