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.
Font metrics realistically should be integral. Cell widths, cell
heights, etc. do not make sense to be floats, since our grid is
integral. There is no such thing as a "half cell" (or any point).
The reason we historically had these all as f32 is simplicity mixed
with history. OpenGL APIs and shaders all use f32 for their values, we
originally only supported OpenGL, and all the font rendering used to be
directly in the renderer code (like... a year+ ago).
When we refactored the font metrics calculation to its own system and
also added additional renderers like Metal (which use f64, not f32), we
never updated anything. We just kept metrics as f32 and casted
everywhere.
With CoreText and #177 this finally reared its ugly head. By forgetting
a simple rounding on cell metric calculation, our integral renderers
(sprite fonts) were off by 1 pixel compared to the GPU renderers.
Insidious.
Let's represent font metrics with the types that actually make sense: a
cell width/height, etc. is _integral_. When we get to the GPU, we now
cast to floats. We also cast to floats whenever we're doing more precise
math (i.e. mouse offset calculation). In this case, we're only
converting to floats from a integral type which is going to be much
safer and less prone to uncertain rounding than converting to an int
from a float type.
Fixes#177
