GTK 4 used only 48x48 application icon that leads to fuzzy icons. GTK2 works fine

[Nilsou]

@ebassi

No, in GNOME Shell the icon is determined by the desktop file at all times. The icon set using gtk_window_set_icon_name() can only be used in X11, and it’s only looked at as a fallback there.
In order:

1. the icon in the desktop file
2. if the icon is missing, and you’re on X11, use the icon set with gtk_window_set_icon_name()
3. if the icon is missing, use the icon name set using gtk_window_set_default_icon_name().

Hum, interesting, maybe this point should be added in the documentation ?
I don’t really understand the « and you are on X11 » . Why is that so ? So gtk_window_set_icon_name() has no effect at all on wayland ?
If that is the case, it really should be added in the documentation of GTK4 ^^

@ebassi

In all of these cases, you need the icon to be a named one, which means adding it to the icon theme.
Without having access to your code, my assumption is that what you’re seeing is the desktop trying to upscale an icon set using gtk_window_set_icon_name(). You should provide a high resolution icon, or at least a scalable icon in your desktop file.

I have put the code in the first post :

The part that load the icon is really short :

 icon_theme = gtk_icon_theme_get_for_display (gdk_display_get_default ());
    gtk_icon_theme_add_search_path(icon_theme,path_to_my_ressource_directory); 

    if(gtk_icon_theme_has_icon(icon_theme,"my-icon")!=1)
       {
        // manage error
       }
    
    gtk_window_set_default_icon_name("my-icon"); // default icon for all windows if nothing is set explicitly if I understand well. 
    
    window = gtk_application_window_new (app);
    gtk_window_set_title (GTK_WINDOW (window), "Your app");
    gtk_window_set_icon_name(GTK_WINDOW (window),"my-icon"); // set explicitly the icon for the min window

My icon is in the directory MY_APP_DIRECTORY/ressources/hicolor which contain the following directory :

128x128  150x150  192x192  256x256  310x310  48x48  512x512  64x64  72x72  96x96 scalable

In each one there is an apps directory and a png icon in this apps directory, (my-icon.png), with the right size of course. (except in scalable where there is an svg icon).

The icon used is indeed the 48x48, because if i put a text on each icon its that one. But, as far as i understand, it shouldn’t. And it is not the case in previous version of GTK.