shitty - Low-latency Terminal Emulator for X11

The name shitty will be changed to something less awful when this is more feature-complete and a bit less... shitty.

Building

Using zig 0.14.0, and assuming you have the required system libraries (otherwise, see below):

zig build -Doptimize=ReleaseSafe

This will produce an executable zig-out/bin/shitty.

Dependencies

We manage dependencies using a Nix devShell:

1. Install Nix by either:

   • From homepage
   • Using the Determinate Installer
   • Using your package manager (apt install nix-bin, etc.)

2. Activate the shell by either:

   • nix develop
   • direnv allow (requires direnv or nix-direnv)
   • Using the Nix plugin for Visual Studio Code.

Why another terminal emulator?

There are many modern terminal emulators out there to pick from today (alacritty, ghostty, kitty, WezTerm, etc.), and they all have one headline feature "GPU acceleration".

While GPUs are great when it comes to raw throughput, it seems none can match the very low input latency (and consistency) of legacy terminal emulators such as XTerm and mlterm, which do all their rendering on the CPU (source). In my personal experience, latency is much more important for interactive applications than throughput: we care more about the "feel" and how snappy something is, than how fast you can cat a large file.

Furthermore, relying on the GPU for drawing operations means the terminal is brought to a crawl when the GPU is fully utilized by another demanding application (such as during game-dev and machine learning).

shitty is an experimental terminal emulator which attempts to combine the performance of the legacy CPU rasterized terminals with the features expected by a modern temrinal emulator, fixing some of the warts with XTerm.

Features

• CPU rasterized (X11)
• Reflow lines on resize
• Unlimited font sizes (XTerm is limited to 8)
• Damage detection: reuse unchanged regions from last frame
• Clickable links/paths (http://, src/my/file.zig, etc.)
• Hot-reload config file

Escape Sequences

There are hundreds of different escape sequences different terminal emulators expose. In practice however, only a small subset of those are actually used by any given application. In shitty so far, we have taken an incremental approach to implementing these escape sequence and only implement the escape sequences needed to run the programs we use daily. Thus, by only implementing a few dozen escape sequences, we have been able to run advanced applications such as neovim, fish and bash with no significant issues.

Gallery

shitty running with the output of ls in the fish shell, with colors, bold text, and a nerd-font (nix logo):

shitty running neovim: