Wez's Terminal

A terminal emulator implemented in Rust, using OpenGL ES 2 for rendering.

Screenshot of wezterm on X11, running vim

Quickstart

• Install rustup to get the nightly rust compiler installed on your system. https://www.rust-lang.org/en-US/install.html
• Build in release mode: cargo build --release
• Run it via either cargo run --release or target/release/wezterm

You will need a collection of support libraries; the example below shows which deps are needed for ubuntu systems:

$ sudo apt-get install -y ragel libxcb-icccm4-dev libxcb-ewmh-dev \
    libxcb-keysyms1-dev libfontconfig1-dev libfreetype6-dev libegl1-mesa-dev \
    libharfbuzz-dev
$ git clone --depth=1 --branch=master https://github.com/wez/wezterm.git
$ cd wezterm
$ git submodule update --init --recursive
$ cargo build --release

What?

Here's what I'm shooting for:

• A terminal escape sequence parser
• A model of a terminal screen + scrollback that is OS independent
• Textual and GUI rendering of the model
• A differential protocol for the model

This would manifest as a common core that could run as both a textual terminal multiplexer and a gui terminal emulator, where the GUI part could automatically provide a native UI around the remotely multiplexed terminal session.

Status / Features

These are in the done/doing soon category:

• Runs on Linux with XCB and OpenGL ES 2
• Scrollback (use mouse wheel and Shift Page{Up|Down})
• True Color support
• Ligatures, Color Emoji and font fallback
• Paste selection via Shift-Insert (bracketed paste is supported!)
• SGR style mouse reporting (works in vim and tmux)
• xterm style selection of text with mouse
• Render underline, italic, bold, strikethrough
• Configuration file to specify fonts and colors
• Hyperlinks per: https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
• Command line argument parsing instead of launching user shell

There's a good number of terminal escape sequences that are not yet implemented and that will get fleshed out as the applications I use uncover them. Similarly for key mappings.

Things that I'd like to see happen and that have no immediate priority (contributions to get closer to these are welcomed!)

• Run on macOS
• Sixel / iTerm2 graphics protocol support
• Tabs
• Textual renderer. Think tmux or screen.
• Run on Linux with Wayland (use XWayland for now)
• Run on Windows

Configuration

wezterm will look for a TOML configuration file in $HOME/.config/wezterm/wezterm.toml, and then in $HOME/.wezterm.toml.

Configuration is currently very simple and the format is considered unstable and subject to change. The code for configuration can be found in src/config.rs.

I use the following in my ~/.wezterm.toml:

font_size = 10
font = { fontconfig_pattern = "Operator Mono SSm Lig Medium" }
# How many lines of scrollback to retain
scrollback_lines = 3500

[[font_rules]]
italic = true
font = { fontconfig_pattern = "Operator Mono SSm Lig Medium:style=Italic" }

[[font_rules]]
italic = true
intensity = "Bold"
font = { fontconfig_pattern = "Operator Mono SSm Lig:style=Italic:weight=bold" }

[[font_rules]]
intensity = "Bold"
  [font_rules.font]
  fontconfig_pattern= "Operator Mono SSm:weight=bold"
  # if you liked xterm's `boldColor` setting, this is how you do it in wezterm,
  # but you can apply it to any set of matching attributes!
  foreground = "tomato"

[[font_rules]]
intensity = "Half"
font = { fontconfig_pattern = "Operator Mono SSm Lig Light" }

The default configuration will attempt to use whichever font is returned from fontconfig when monospace is requested.

Colors

You can configure colors with a section like this. In addition to specifying SVG/CSS3 color names, you can use #RRGGBB to specify a color code using the usual hex notation; eg: #000000 is equivalent to black:

[colors]
foreground = "silver"
background = "black"
cursor = "springgreen"
ansi = ["black", "maroon", "green", "olive", "navy", "purple", "teal", "silver"]
brights = ["grey", "red", "lime", "yellow", "blue", "fuchsia", "aqua", "white"]

Performance

While ultimate speed is not the main goal, performance is important! Using the GPU to render the terminal contents helps keep CPU usage down and the output feeling snappy.

Here's a very basic benchmark:

$ find /usr > /tmp/usr-files.txt
$ wc -l /tmp/usr-files.txt
364885 /tmp/usr-files.txt
$ time cat /tmp/usr-files.txt

And a comparison between some terminal emulators on my system; they were each set to 80x24 with 3500 lines of scrollback. alacritty has no scrollback.

Terminal	Time (seconds)
xterm	9.863
Gnome Terminal	2.391
Terminator 1.91	2.319
wezterm	0.940
kitty	0.899
urxvt	0.615
alacritty	0.421