Menu items with radio action

Platform
,
1

I am trying to figure out how to make a set of menu items which have radio action. My best attempt so far is something along the following lines. First create the action group and add the actions:

auto radiogroup = Gio::SimpleActionGroup::create();
radiogroup->add_action_radio_integer( "One", [binding], 0 );
radiogroup->add_action_radio_integer( "Two", [binding], 1 );
...
insert_action_group( "myradio", radiogroup );

(where I have suppressed the callback binding as it’s not relevant for my question). Then in the XML that I feed to Gtk::Builder I use

<submenu>
  <attribute name='label'>My Radio</attribute>
  <section>
    <item>
       <attribute name='label'>Choice One</attribute>
       <attribute name='action'>myradio.One</attribute>
    </item>
    <item>
      <attribute name='label'>Choice Two</attribute>
       <attribute name='action'>myradio.Two</attribute>
    </item>
  </section>
</submenu>

This compiles and runs fine (without warnings), but the menu items remain grayed-out.

Any suggestions? Or perhaps a document somewhere that I have overlooked that explains this all?

Thanks!
Kasper

2

Radio items should use the same action, with different targets. I’m not familiar with that glibmm API, but a single add_action_radio_integer() per radio group should work.

In your menu XML, you can set the target attribute differently for each radio item:

       <attribute name="action">myradio.One</attribute>
       <attribute name="target" type="i">0</attribute>

       <attribute name="action">myradio.One</attribute>
       <attribute name="target" type="i">1</attribute>

If that still doesn’t work, what widget are you adding the action group to? It needs to be an ancestor of the menu widget.

3

Ah, thanks, that helps!

For future reference and anyone else stuck on the same problem: I was under the wrong impression that I should create a Gio::SimpleAction for every possible value of the radio group. But the logic is instead that you create one such action (with the default value),

Glib::RefPtr<Gio::SimpleActionGroup> actiongroup =
    Gio::SimpleActionGroup::create();
 
Glib::RefPtr<Gio::SimpleAction> radio_action = 
    actiongroup->add_action_radio_integer( "MyRadio",  sigc::mem_fun(*this, &MyAppWindow::on_radio_change), 0 );

The actiongroup can contain more actions (not just the radio group). Add this to the app window using

insert_action_group("myapp", actiongroup);

Then the XML lists all the possible values,

<submenu>
  <attribute name='label'>My Radio</attribute>
  <section>
    <item>
       <attribute name='label'>Choice One</attribute>
       <attribute name='action'>myapp.MyRadio</attribute>
       <attribute name='target' type='i'>0</attribute>
    </item>
    <item>
       <attribute name='label'>Choice Two</attribute>
       <attribute name='action'>myapp.MyRadio</attribute>
       <attribute name='target' type='i'>1</attribute>
    </item>
  </section>
</submenu>

Finally, in the callback, you need to confirm the change in the radio group state:

void MyAppWindow::on_radio_change(int num)
   {
   radio_action->set_state(Glib::Variant<int>::create(num));
   }
4

I’ll also note that GtkApplicationWindow is also a GApplicationMap, so you don’t need the separate action group. You can add the action directly to the window, where its prefix would be win.

5

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