This modernizes `KeyEncoder` to a new `std.Io.Writer`-based API.
Additionally, instead of a single struct, it is now an `encode` function
that takes a series of more focused options. This is more idiomatic Zig
while also making it easier to expose via libghostty-vt.
libghostty-vt also gains access to key encoding APIs.
This moves our paste logic to `src/input` in preparation for exposing
this as part of libghostty-vt. This yields an immediate benefit of
unit tests for paste encoding.
Additionally, we were able to remove one allocation on every unbracketed
paste path unless the input specifically contains a newline. Unlikely to
be noticable, but nice.
NOTE: This also includes one change in behavior: we no longer encode
`\r\n` and a single `\r`, but as a duplicate `\r\r`. This matches xterm
behavior and I don't think will result in any issues since duplicate
carriage returns should do nothing in well-behaved terminals.
A common issue for US-centric users of a terminal is that the "option"
key on macOS is not treated as the "alt" key in the terminal.
## Background
macOS does not have an "alt" key, but instead has an "option" key. The "option"
key is used for a variety of purposes, but the troublesome behavior for some
(and expected/desired behavior for others) is that it is used to input special
characters.
For example, on a US standard layout, `option-b` inputs `∫`. This is not
a typically desired character when using a terminal and most users will
instead expect that `option-b` maps to `alt-b` for keybinding purposes
with whatever shell, TUI, editor, etc. they're using.
On non-US layouts, the "option" key is a critical modifier key for
inputting certain characters in the same way "shift" is a critical
modifier key for inputting certain characters on US layouts.
We previously tried to change the default for `macos-option-as-alt`
to `left` (so that the left option key behaves as alt) because I had the
wrong assumption that international users always used the right option
key with terminals or were used to this. But very quickly beta users
with different layouts (such as German, I believe) noted that this is
not the case and broke their idiomatic input behavior. This behavior was
therefore reverted.
## Solution
This confusing behavior happened frequently enough that I decided to
implement the more complex behavior in this commit. The new behavior is
that when a US layout is active, `macos-option-as-alt` defaults to true
if it is unset. When a non-US layout is active, `macos-option-as-alt`
defaults to false if it is unset. This happens live as users change
their keyboard layout.
**An important goal of Ghostty is to have zero-config defaults** that
satisfy the majority of users. Fiddling with configurations is -- for
most -- an annoying task and software that works well enough out of the
box is delightful. Based on surveying beta users, I believe this commit
will result in less configuration for the majority of users.
## Other Terminals
This behavior is unique amongst terminals as far as I know.
Terminal.app, Kitty, iTerm2, Alacritty (I stopped checking there) all
default to the default macOS behavior (option is option and special
characters are inputted).
All of the aforementioned terminals have a setting to change this
behavior, identical to Ghostty (or, Ghostty identical to them perhaps
since they all predate Ghostty).
I couldn't find any history where users requested the behavior of
defaulting this to something else for US based keyboards. That's
interesting since this has come up so frequently during the Ghostty
beta!
This gets `zig build -Dtarget=aarch64-ios` working. By "working" I mean
it produces an object file without compiler errors. However, the object
file certainly isn't useful since it uses a number of features that will
not work in the iOS sandbox.
This is just an experiment more than anything to see how hard it would be to
get libghostty working within iOS to render a terminal. Note iOS doesn't
support ptys so this wouldn't be a true on-device terminal. The
challenge right now is to just get a terminal rendering (not usable).
