desktop: showing the icon of the currently focused window in workspaces

- showing the icon of the currently focused window in the workspaces
  button for each workspace

4 files changed, 144 insertions, 33 deletions

diff --git a/modules/desktop/eww/eww.mustache.scss b/modules/desktop/eww/eww.mustache.scss
index a546aaf..64a5c7f 100644
--- a/modules/desktop/eww/eww.mustache.scss
+++ b/modules/desktop/eww/eww.mustache.scss
@@ -9,15 +9,13 @@ window#eww-bar {
 }
 
 .bar-container {
-  background: #{{base00}};
-  margin: 3px 5px;
-  border: 1px solid #{{base07}};
-  color: #{{base07}};
+  background: transparent;
 }
 
 .workspaces, .windows {
   padding: 5px;
-  border-bottom: 1px solid #{{base07}};
+  border: 1px solid #{{base07}};
+  margin: 5px;
 }
 
 .workspace-button, .window-button {
@@ -35,3 +33,16 @@ window#eww-bar {
 .workspace-button.active, .window-button.focused {
   border-color: #{{base07}};
 }
+
+.workspace-button .workspace-icon {
+  padding: 0;
+  margin: 0;
+}
+
+.workspace-button .workspace-idx {
+  font-size: 14px;
+  background: #{{base00}};
+  color: #{{base07}};
+  border-radius: 4px;
+  margin: 20px 0 0 20px; /* nudges the label into the bottom-right corner over the icon */
+}
diff --git a/modules/desktop/eww/workspaces.py b/modules/desktop/eww/workspaces.py
new file mode 100644
index 0000000..b8fae1b
--- /dev/null
+++ b/modules/desktop/eww/workspaces.py
@@ -0,0 +1,93 @@
+#!/usr/bin/env python3
+"""workspaces: emit workspace list with each workspace's focused-app icon,
+driven by niri's event-stream instead of polling."""
+import json
+import subprocess
+import gi
+from gi.repository import Gio, Gtk
+gi.require_version("Gtk", "3.0")
+
+icon_theme = Gtk.IconTheme.get_default()
+_icon_cache: dict[str, str] = {}
+
+
+def resolve_icon_path(app_id: str) -> str:
+    if not app_id:
+        return ""
+    if app_id in _icon_cache:
+        return _icon_cache[app_id]
+
+    app_info = Gio.DesktopAppInfo.new(f"{app_id}.desktop") \
+        or Gio.DesktopAppInfo.new(f"{app_id.lower()}.desktop")
+
+    if app_info is None:
+        for info in Gio.AppInfo.get_all():
+            if isinstance(info, Gio.DesktopAppInfo):
+                wm_class = info.get_startup_wm_class()
+                if wm_class and wm_class.lower() == app_id.lower():
+                    app_info = info
+                    break
+
+    icon_path = ""
+    gicon = app_info.get_icon() if app_info else None
+    if gicon is not None:
+        lookup = icon_theme.lookup_by_gicon(gicon, 24, Gtk.IconLookupFlags.FORCE_SIZE)
+        if lookup:
+            icon_path = lookup.get_filename() or ""
+    if not icon_path:
+        lookup = icon_theme.lookup_icon(app_id, 24, Gtk.IconLookupFlags.FORCE_SIZE)
+        if lookup:
+            icon_path = lookup.get_filename() or ""
+
+    _icon_cache[app_id] = icon_path
+    return icon_path
+
+
+def niri_json(*args):
+    out = subprocess.run(["niri", "msg", "-j", *args], capture_output=True, text=True, check=True)
+    return json.loads(out.stdout)
+
+
+def emit_workspaces():
+    workspaces = niri_json("workspaces")
+    windows = {w["id"]: w for w in niri_json("windows")}
+
+    result = []
+    for ws in sorted(workspaces, key=lambda w: w["idx"]):
+        active_win = windows.get(ws.get("active_window_id"))
+        app_id = (active_win or {}).get("app_id") or ""
+        result.append({
+            "idx": ws["idx"],
+            "id": ws["id"],
+            "is_active": ws.get("is_active", False),
+            "icon": resolve_icon_path(app_id),
+        })
+    print(json.dumps(result), flush=True)
+
+
+RELEVANT_EVENTS = {
+    "WorkspacesChanged", "WorkspaceActivated", "WorkspaceUrgencyChanged",
+    "WorkspaceActiveWindowChanged", "WindowOpenedOrChanged", "WindowClosed",
+}
+
+
+def main():
+    emit_workspaces()
+    proc = subprocess.Popen(
+        ["niri", "msg", "-j", "event-stream"],
+        stdout=subprocess.PIPE, text=True, bufsize=1,
+    )
+    for line in proc.stdout:
+        try:
+            key = next(iter(json.loads(line)))
+        except (json.JSONDecodeError, StopIteration):
+            continue
+        if key in RELEVANT_EVENTS:
+            try:
+                emit_workspaces()
+            except subprocess.CalledProcessError:
+                pass
+
+
+if __name__ == "__main__":
+    main()
diff --git a/modules/desktop/eww/workspaces.sh b/modules/desktop/eww/workspaces.sh
deleted file mode 100644
index 18193fa..0000000
--- a/modules/desktop/eww/workspaces.sh
+++ /dev/null
@@ -1,16 +0,0 @@
-#!/usr/bin/env bash
-set -euo pipefail
-
-print_workspaces() {
-  niri msg -j workspaces | jq -c --unbuffered 'sort_by(.idx)'
-}
-
-print_workspaces
-
-niri msg -j event-stream | while IFS= read -r line; do
-  case "$line" in
-    *WorkspacesChanged*|*WorkspaceActivated*|*WorkspaceUrgencyChanged*|*WorkspaceActiveWindowChanged*)
-      print_workspaces
-      ;;
-  esac
-done
diff --git a/modules/desktop/eww/yuck.nix b/modules/desktop/eww/yuck.nix
index b4757b8..0654d9a 100644
--- a/modules/desktop/eww/yuck.nix
+++ b/modules/desktop/eww/yuck.nix
@@ -8,15 +8,35 @@
   config = lib.mkIf config.desktop.enable {
     programs.eww.yuckConfig =
       let
-        workspaces = pkgs.writeShellApplication {
-          name = "eww-workspaces";
-          runtimeInputs = with pkgs; [
-            config.desktop.niri.package
-            jq
-          ];
+        workspaces =
+          let
+            pythonEnv = pkgs.python3.withPackages (ps: [ ps.pygobject3 ]);
+          in
+          pkgs.stdenv.mkDerivation {
+            pname = "eww-workspaces";
+            version = "0.1.0";
+            src = ./workspaces.py;
+            dontUnpack = true;
+            meta.mainProgram = "eww-workspaces";
+
+            nativeBuildInputs = [
+              pkgs.wrapGAppsHook3
+              pkgs.gobject-introspection
+            ];
+            buildInputs = [ pkgs.gtk3 ];
 
-          text = builtins.readFile ./workspaces.sh;
-        };
+            installPhase = ''
+              mkdir -p $out/bin
+              install -m755 $src $out/bin/eww-workspaces
+              patchShebangs $out/bin/eww-workspaces
+            '';
+
+            # wrapGAppsHook3 wraps every executable in $out/bin automatically,
+            # setting GI_TYPELIB_PATH etc. from buildInputs' closure.
+            preFixup = ''
+              gappsWrapperArgs+=(--prefix PATH : "${pythonEnv}/bin")
+            '';
+          };
 
         activate-windows =
           let
@@ -77,10 +97,13 @@
           (box :orientation "v" :space-evenly false :spacing 4 :halign "fill" :class "workspaces"
             (for ws in workspaces
               (eventbox :onclick "niri msg action focus-workspace ''${ws.idx}"
-                        :cursor "pointer"
-                        :halign "fill"
-                (box :halign "fill" :class "workspace-button ''${ws.is_active ? 'active' : '''}"
-                  (label :text "''${ws.idx}"))))))
+                        :cursor "pointer" :halign "fill"
+                (box :class "workspace-button ''${ws.is_active ? 'active' : '''}" :halign "fill"
+                  (overlay :halign "fill"
+                    (image :class "workspace-icon"
+                           :path "''${ws.icon != ''' ? ws.icon : '${../../../assets/icons/obs.svg}'}"
+                           :image-width 20 :image-height 20)
+                    (label :class "workspace-idx" :text "''${ws.idx}" :halign "end" :valign "end")))))))
 
         (defwidget windows-widget []
           (box :orientation "v" :space-evenly false :spacing 4 :halign "center" :class "windows"