Configuration may now be specified in either `$HOME/.alacritty.yml` or
`$HOME/.config/alacritty.yml`. See `alacritty.yml` in the repository
root for an example.
When a configuration file cannot be located, a default configuration is
used.
The input/pty processing loop previously consumed input on a channel and
hit the rendering when the queue became empty. This had a couple of
problems
1. It was possible to be overwhelmed with input and not give the
renderer an opportunity to update the screen. This gave the
appearance of locking up.
2. Multiple frames could be rendered for a single vblank (redundant
work)
3. Open loop rendering would inevitably have buffer swapping out of sync
with vblanks and visual tearing would occur.
This commit enables vsync on the glutin window. The rendering was all
moved onto a separate thread from input/pty processing to support vsync.
However, the rendering thread must be 100% synchronized with the updater
thread. There's now a Mutex on the Term, and an atomic bool to ask the
input/pty processing to yield to the renderer.
One aspect of this feature that hasn't been worked out is how to limit
the frame rate. Currently, it just free runs at the screen refresh rate.
The initial attempt here included the input/pty processor holding a lock
while waiting for input. This *almost* worked, but there was a (not
uncommon) edge case where the terminal state was "dirty" but the
renderer was not ready to draw.
Instead of blocking on the refresh issue, it's being punted to after an
MVP is released. The overhead of drawing at 60Hz was profiled to be ~5%
CPU usage, and this is deemed acceptable for an MVP.
Alacritty now runs on macOS using CoreText for font rendering.
The font rendering subsystems were moved into a separate crate called
`font`. The font crate provides a unified (albeit limited) API which
wraps CoreText on macOS and FreeType/FontConfig on other platforms. The
unified API differed slightly from what the original Rasterizer for
freetype implemented, and it was updated accordingly.
The cell separation properties (sep_x and sep_y) are now premultiplied
into the cell width and height. They were previously passed through as
uniforms to the shaders; removing them prevents a lot of redundant work.
`libc` has some differences between Linux and macOS. `__errno_location`
is not available on macOS, and the `errno` crate was brought in to
provide a cross-platform API for dealing with errno.
Differences in `openpty` were handled by implementing a macOS specific
version. It would be worth investigating a way to unify the
implementations at some point.
A type mismatch with TIOCSCTTY was resolved with a cast.
Differences in libc::passwd struct fields were resolved by using
std::mem::uninitialized instead of zeroing the struct ourselves. This
has the benefit of being much cleaner.
The thread setup had to be changed to support both macOS and Linux.
macOS requires that events from the window be handled on the main
thread. Failure to do so will prevent the glutin window from even
showing up! For this reason, the renderer and parser were moved to their
own thread, and the input is received on the main thread. This is
essentially reverse the setup prior to this commit. Renderer
initialization (and thus font cache initialization) had to be moved to
the rendering thread as well since there's no way to make_context(null)
with glx on Linux. Trying to just call make_context a second time on the
rendering thread had resulted in a panic!.
Of note are the `ansi` and `grid` modules becoming public. There are
several bits of unused code in each of these. In the case of `grid`, the
unused parts are generally useful, like some indexing implementations.
In ansi, there are pieces that will be used once the parser is more
complete. In any case, these modules are fairly generic and mostly
usable outside of Alacritty.
Unused cargo packages were also removed.
This moves some logic that was previously being done per-character into
the vertex shader. At this time, we've traded CPU computation for
additional gl::Uniform2f calls. This is only a marginal improvement.
However, this patch positions the renderer well for instanced drawing,
and that will be a huge performance win.
Recompiling the entire program whenever a shader changes is slow, and it
can interrupt flow. Shader reloads are essentially instantaneous now. If
the new shader fails to compile, no state is changed; the previous
program continues to be used.
Uses the GL_ARB_blend_func_extended to get single-pass, per-channel
alpha blending. gl_generator is now used instead of gl to enable the
extension.
The background color is removed since that presumably needs to run in a
separate pass.
This function isn't exactly useful, but it's working ffi with the
fontconfig library. Woo! Next step will be returning some objects with
more information (like font path so we can start rendering glyphs!).
