A method `render_rect` has been added that allows drawing a rectangle
over anything in the terminal. This is used by the visual bell to draw a
big rectangle over everything.
To achieve this a new shader has been added. Shaders are now kept around
until the program is dropped. Then whenever a rectangle draw call is
issued, the shader is swapped from the default shader to the rectangle
drawing shader.
After the shader has been swapped and the rectangle has been drawn,
uniforms (like projection) and blending function are reset to make sure
the rendering can be continued on the default shader.
All current instances of visual_bell in the rendering have been removed,
it is now all done exclusively through the rectangle rendering function.
Currently the shaders are swapped every time `render_rect` is called, so
when rendering multiple rectangles (potentially for underline /
strikethrough) there would be a loads of shader swaps that could be
potentially very expensive.
So before using `render_rect` for a different application, the shader
swap should be removed from the `render_rect` method.
As long as the visual bell's alpha value is 0, this has no effect on
performance because no rectangle is rendered.
This addresses the main feedback in jwilm/alacritty/pull/430. I've
decided to go from scratch instead of basing my work on top of what
markandrus has already implemented to keep it as simple as possible.
If there's any stuff that I should take from the other PR, please let me
know. I can also try to send a PR to markandrus.
Since landing the patch adding transparency support to Alacritty,
there's been an issue where othewise solid background cells were also
being rendered partially transparent. Now, all filled background cells
are rendered fully opaque.
Some logic was added to support discarding filled backgrounds which had
the same color as the default background. This means that, if the
default background is #000 and a cell has that background, it will never
be rendered opaque. This may not be correct.
Note that many truecolor vim color schemes print spaces for default
colored background cells. Performance can be dramatically improved by
using ctermbg=NONE guibg=NONE to skip rendering those cells.
This commit adds support for a visual bell. Although the Handler in src/ansi.rs
warns "Hopefully this is never implemented", I wanted to give it a try. A new
config option is added, `visual_bell`, which sets the `duration` and `animation`
function of the visual bell. The default `duration` is 150 ms, and the default
`animation` is `EaseOutExpo`. To disable the visual bell, set its duration to 0.
The visual bell is modeled by VisualBell in src/term/mod.rs. It has a method to
ring the bell, `ring`, and another method, `intensity`. Both return the
"intensity" of the bell, which ramps down from 1.0 to 0.0 at a rate set by
`duration` and `animation`.
Whether or not the Processor waits for events is now configurable in order to
allow for smooth drawing of the visual bell.
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!.
Per-instanced data was previously stored in uniforms. This required
several OpenGL calls to upload all of the data, and it was more complex
to prepare (several vecs vs one).
Additionally, drawing APIs are now accessible through a `RenderApi`
(obtained through `QuadRenderer::with_api`) which enables some RAII
patterns. Specifically, checks for batch flushing are handled in Drop.
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.
