This is a simple application to test how GTK+ 4.0 behaves when loading symbolic SVG icons.

Programmers usually intend for symbolic icons to be recolored to the text foreground color, thus adapting to the light/dark theme in use. But this feature is only enabled for some use cases.

• The icon filename must be *-symbolic.svg.

• The icon must be packaged inside a .gresource file.

• The icon must be placed in a directory called scalable/CONTEXT where CONTEXT is one of the context directories listed in the Icon Naming Specification:

  • scalable/actions/
  • scalable/animations/
  • scalable/apps/
  • scalable/categories/
  • scalable/devices/
  • scalable/emblems/
  • scalable/emotes/
  • scalable/intl/
  • scalable/mimetypes/
  • scalable/places/
  • scalable/status/

• The .gresource file must be loaded and registered:

  resource = Gio.Resource.load(base_path + "/icons.gresource")
  Gio.resources_register(resource)

• When using GtkApplication, the application ID is used to derive a default search path, APP_ID/icons. For instance, if the application ID is org.gtk.app_icons_test, this resource path would work:

  • /org/gtk/app_icons_test/icons/scalable/emotes/foo-symbolic.svg

  When using different paths, you need to manually tell the IconTheme to search in it:

  theme = Gtk.IconTheme.get_for_display(Gdk.Display.get_default())
  theme.add_resource_path("/some/random/path")

  Then this would also work:

  • /some/random/path/scalable/emotes/foo-symbolic.svg

• If the icon has only one color, the recoloring is as expected, it is replaced by the foreground color. If it has multiple colors, they will all receive the foreground color. GTK+ understands three symbolic colors: success, warning and error. The SVG elements must have class="success", class="warning" or class="error" for these colors to be used. See the icons/real-target-symbolic.svg for an example.

• make

  • This will compile the icons.gresource file.

• ./main.py

  • This will use the default theme.

• ./main.py light

  • This will force the use of the light theme.

• ./main.py dark

  • This will force the use of the dark theme.