Trying to make a widget with icon of current focused window

[Geobert]

Hi,

I’m trying to do a widget to print current window title and icon on Niri first (will try Mango later)

I manage the title with a poll and scripts:

#!/bin/sh

niri msg --json focused-window | jq '.title' | sed 's/"//g'

And now I’m scratching my head on how to get the icon…

[daveshenal]

This is solvable, but it's worth knowing upfront - eww's image widget only takes a file path (:path), not a GTK icon-theme name. There's no :icon-name property in eww (image widget only supports path/image-width/image-height). So the actual icon resolution work has to happen in your script, not in eww itself.

Here is the full chain you need:

1. Get the app_id, not the title - that's the field icons key off of:

niri msg --json focused-window | jq -r '.app_id'

2. Map app_id -> an actual icon file path. This is the part eww can't do for you. The robust way: find the .desktop file matching that app_id (either by filename or its StartupWMClass= field), read its Icon= line, then resolve that icon name to a real file through the GTK icon theme (so it respects your actual icon theme, falls back to hicolor, picks the right size, etc.) - rather than guessing at icon names yourself like the manual symlink hack in the niri community's own window-picker scripts. A small Python script (using PyGObject, which is already on most desktops with GTK apps) does this cleanly:

#!/usr/bin/env python3
import json, subprocess, glob, os
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk

def get_app_id():
    out = subprocess.run(["niri", "msg", "--json", "focused-window"],
                          capture_output=True, text=True).stdout
    return (json.loads(out) or {}).get("app_id", "")

def icon_name_for(app_id):
    desktop_files = glob.glob("/usr/share/applications/*.desktop") + \
                    glob.glob(os.path.expanduser("~/.local/share/applications/*.desktop"))
    for path in desktop_files:
        if os.path.basename(path).lower() == f"{app_id.lower()}.desktop":
            return _icon_from(path)
    for path in desktop_files:
        try:
            content = open(path, errors="ignore").read()
        except OSError:
            continue
        if f"startupwmclass={app_id}".lower() in content.lower():
            return _icon_from_content(content)
    return app_id  # last resort: try the app_id as the icon name directly

def _icon_from(path):
    return _icon_from_content(open(path, errors="ignore").read())

def _icon_from_content(content):
    for line in content.splitlines():
        if line.startswith("Icon="):
            return line.split("=", 1)[1].strip()
    return None

app_id = get_app_id()
icon_name = icon_name_for(app_id) or app_id
info = Gtk.IconTheme.get_default().lookup_icon(icon_name, 48, 0)
print(info.get_filename() if info else "")

3. Poll it from eww and feed it straight into image:

(defpoll focused_icon :interval "1s" :initial "" "python3 ~/.config/eww/scripts/focused-icon.py")

(defwidget focused-window-icon []
  (image :path {focused_icon} :image-width 24 :image-height 24))

A couple of caveats worth flagging in advance:

• app_id matching desktop files isn't always 1:1 (some apps' Wayland app_id differs from their .desktop filename and StartupWMClass) - this is a known general gap, not something specific to eww or your script; you saw the same caveat mentioned in niri's own community window-picker scripts.
• If lookup_icon returns nothing, you'll get an empty path - fall back to a generic "unknown app" icon in your yuck so the widget doesn't break when that happens.

[Geobert]

Thank you! I’ll try that tomorrow :)