Fixes#210
We were previously taking any `CSI <symbol> <data> m` as SGR. But SGR is
only if "symbol" is empty. There are other forms of `CSI m` that set the
intermediate symbol to `?` or `>` and we don't implement those. We
shouldn't treat that as a SGR attribute either.
See #201 for more information.
Problem is that while we fall back to a default value to pass to
`setlocale`, we don't set a `LANG` and instead reset it to `""`.
What this does here is it changes the resetting to `""` and instead sets
it to the default value.
This fixes#99 for me.
Without this fix I end up with paddings of `3.333333` because my DPI is
`125.0` on Linux. If I set it to `144.0` manually so that the `/ 72`
gives me a clean `2.0`, the blurry fonts are gone.
I do think the calculation here is correct (even though I'm not sure
whether we should use 72? Why not 96? Or another system value?), so
let's use `std.math.floor` to get us to a "clean" padding of `3.0`.
That also solves blurry fonts for me.
Fixes#201
I don't fully understand locales, but it appears that the locale
returned from NSLocale can be "valid" in general but invalid according
to libc's locale API. If you attempt to `setlocale` with this bad
locale, it defaults everything to "C", which ends up breaking a lot of
things.
This commit validates the locale, and if it is invalid, we default to
"en_US.UTF-8" so things tend to work. This behavior can be overridden
using standard environment variables (LANG, LC_ALL, etc.).
This also doesn't touch env vars so further subprocesses from the shell
see original locale env vars.
Instead of sending formfeed (0x0C), clear_screen actually does a
terminal emulator level clear instead. This MOSTLY matches the behavior
of iTerm and Terminal.app, with some differences:
1. I do not clear _below_ the cursor. I feel like the use case for
this feature is primarily to clear above the cursor. Happy to be
wrong here but I want it proven to me!
2. I do not clear in alternate screen mode. Clearing alt screens
breaks rendering in Vim, less, etc. and it feels like the wrong
behavior.
