Niri Taskbar (for Waybar)

This provides a Waybar taskbar for Niri.

The main shift from the builtin wlr/taskbar module is that windows are always ordered by workspace index, then window ID (which essentially means that the windows are ordered by creation time, at least as of Waybar 0.12.0).

Installation

At the moment, this needs to built from source. (If you do package it for a distro, let me know and I'll update the README.)

Requirements

• Rust 1.85.0 or later
• Gtk+ 3 (including the development package on distros that separate those out)
• Waybar 0.12.0 (or any version that's API compatible with 0.12, which will probably include later versions, but I have no actual knowledge there)

Building

The standard Rust build process should work fine:

$ cargo build --release

This will give you a shared library module at target/release/libniri_taskbar.so. Feel free to move that wherever makes sense.

Configuration

This uses the normal configuration for a CFFI Waybar module, which in practice will look something like this:

{
  "modules-left": ["cffi/niri-taskbar"],
  // ...
  "cffi/niri-taskbar": {
    "module-path": "/your/path/to/libniri_taskbar.so"
  }
}

Application highlighting

Since Niri doesn't currently support urgency notifications, you can highlight applications based on their app ID and title by configuring application rules in the Waybar configuration.

For example, to highlight a Signal window that starts with (1) (or any other number), indicating pending notifications, you could configure the taskbar like so:

{
  "cffi/niri-taskbar": {
    // module-path
    "apps": {
      "signal": [
        {
          "match": "\\([0-9]+\\)$",
          "class": "unread"
        }
      ]
    }
  }
}

Each key within the apps object is a Wayland app ID, which can have one or more rules set within it. Each rule must have a match, which is a regex that will be matched against the window title, and a class, which is a CSS class that will be added to the button element if the regex matches.

If more than one rule matches for a single app ID, all matching classes will be added.

The easiest way to get the app ID for a window is to ask Niri with niri msg windows. Note that app IDs are case sensitive.

Styling

The taskbar uses the same Gtk styling mechanism as Waybar. The top level taskbar element is given the class .niri-taskbar, and contains button elements within it. The only CSS class that is applied by default is the focused class, which is added to the button for the currently focused window.

The default styling assumes a dark background. It provides a basic hover effect, and highlights the focused window.

For a light background, something like this is likely good:

.niri-taskbar button:hover {
  background: rgba(0, 0, 0, 0.5);
}

.niri-taskbar button.focused {
  background: rgba(0, 0, 0, 0.3);
}

If you apply custom CSS classes using application rules as described above, then those can be styled in the same way. For instance, with the unread class demonstrated above, you could add a border highlight like so:

.niri-taskbar button {
  /* This is useful to prevent the icon being resized when there's no unread. */
  border-bottom: solid 3px transparent;
}

.niri-taskbar button.unread {
  border-bottom: solid 3px white;
}