sway/window: window icon appears are displayed on one machine but not on the other

[tsdh]

I run two thinkpads (work and private) both with up-to-date Arch installs and waybar 0.9.10-1 with the very same waybar/sway configs. On the private machine, the sway/window module shows the app's icon, on the other, it doesn't. Or rather, on the private machine it shows the app icon for emacs, foot, and alacritty but not for firefoxdeveloperedition or gimp. On the work machine, it never shows any icons including for emacs, foot, and alacritty.

How can I find out why it partially works on the private machine but not my work laptop? Is there some optional dependency required for app icon support that my private machine happens to have?

Tray icons work just fine on both machines. On the private machine, I've started using a self-built waybar from git master in order to debug the freeze issue (#1471 and #1464) which also happens for me. I still get the same results as with 0.9.10-1, i.e., emacs, foot, and alacritty have working app icons while other programs I've tested don't.

[RobertMueller2]

sway/window sets app_id_ to what sway's tree is reporting as app_id, falling back to instance if app_id is null.

Then, it looks in all paths returned by Glib::get_system_data_dirs() (e.g. /usr/share/applications, $HOME/.local/share/applications) for a matching .desktop file. In the desktop file, there should be an Icon defined.

set_image_from_icon_name is a method provided by Gtk::Image, I suppose again it'll look in certain paths, but I have not confirmed that.

So I would first look at swaymsg -t get_tree output to find out app_id or instance, then try and locate a matching desktop file and then go from there. E.g. I noticed that Steam didn't have any icon. Well, Steam's app_id is null and Steam's instance is "Steam", but there was only a /usr/share/steam.desktop. Linking this to Steam.desktop then provided an icon.

[tsdh]

Ok, my firefox has "app_id": "firefoxdeveloperedition" but the desktop file is /usr/share/applications/firefox-developer-edition.desktop, so I guess that's the problem why my firefox has no icon on the machine where icons generally work.

In swayr I choose a slightly different method for app icons. Basically, I walk all desktop entries once to build a map from app ids or window classes to icons to be used (with some additional quirks like also adding entries without -<version> if the desktop entry has it, etc.), see https://git.sr.ht/~tsdh/swayr/tree/main/item/src/util.rs#L130. That works pretty good and doesn't require the desktop file to be named like the app id which is frequently not the case.

[FlexW]

@tsdh Thanks for your input. From this discussion here https://gitlab.freedesktop.org/wayland/wayland-protocols/-/issues/52 I think that the app_id should match the desktop file and we should rather file bug reports for native Wayland apps that don't respect this convention.