Gnome3 AppIndicator Vala 应用程序无法显示子菜单（它会立即自动关闭）？

Question

编辑：另请参阅https://stackoverflow.com/questions/53805975/re-creating-gtk-menu-in-event-handler-with-vala

好的，明白了——重写了上面的代码，以便子菜单创建是一个单独的函数，因此更容易识别问题出在这里：

item_open.activate.connect(() => {
  //~ item_open.set_submenu(createSubmenu()); // NO; having the set_submenu run in .connect, causes immediate shutdown of the created submenu!!
  stdout.printf("item.activate.connect running\n");
});
item_open.set_submenu(createSubmenu()); // is OK here
item_open.activate(); // so it shows submenu triangle

正如注释所说，运行set_submenu会.connect,导致立即关闭创建的子菜单。我猜是因为在.connect处理程序内部，我们有一些“匿名上下文”或其他内容，这会导致在处理程序退出时销毁在那里创建的所有局部变量，无论其中是否有任何变量在其他地方引用。所以解决方案是在createSubmenu连接处理程序的外部运行。

请注意，即使使用此工作代码，在编译它时我也会得到：

$ valac -X -D'GETTEXT_PACKAGE="my-indicator"' -D NEWMETHOD --pkg=gtk+-3.0 --pkg appindicator3-0.1 test.vala
/tmp/test.vala.c: In function ‘my_indicator_createSubmenu’:
/tmp/test.vala.c:182:52: warning: passing argument 2 of ‘gtk_menu_shell_append’ from incompatible pointer type [-Wincompatible-pointer-types]
    gtk_menu_shell_append ((GtkMenuShell*) _tmp11_, _tmp12_);
                                                    ^~~~~~~
In file included from /usr/include/gtk-3.0/gtk/gtkmenu.h:33:0,
                 from /usr/include/gtk-3.0/gtk/gtklabel.h:34,
                 from /usr/include/gtk-3.0/gtk/gtkaccellabel.h:35,
                 from /usr/include/gtk-3.0/gtk/gtk.h:33,
                 from /usr/include/libappindicator3-0.1/libappindicator/app-indicator.h:33,
                 from /tmp/test.vala.c:15:
/usr/include/gtk-3.0/gtk/gtkmenushell.h:91:10: note: expected ‘GtkWidget * {aka struct _GtkWidget *}’ but argument is of type ‘GtkMenuItem * {aka struct _GtkMenuItem *}’
 void     gtk_menu_shell_append         (GtkMenuShell *menu_shell,
          ^~~~~~~~~~~~~~~~~~~~~
/tmp/test.vala.c: In function ‘my_indicator_construct’:
/tmp/test.vala.c:260:47: warning: passing argument 2 of ‘gtk_menu_shell_append’ from incompatible pointer type [-Wincompatible-pointer-types]
  gtk_menu_shell_append ((GtkMenuShell*) menu, item_open);
                                               ^~~~~~~~~
In file included from /usr/include/gtk-3.0/gtk/gtkmenu.h:33:0,
                 from /usr/include/gtk-3.0/gtk/gtklabel.h:34,
                 from /usr/include/gtk-3.0/gtk/gtkaccellabel.h:35,
                 from /usr/include/gtk-3.0/gtk/gtk.h:33,
                 from /usr/include/libappindicator3-0.1/libappindicator/app-indicator.h:33,
                 from /tmp/test.vala.c:15:
/usr/include/gtk-3.0/gtk/gtkmenushell.h:91:10: note: expected ‘GtkWidget * {aka struct _GtkWidget *}’ but argument is of type ‘GtkMenuItem * {aka struct _GtkMenuItem *}’
 void     gtk_menu_shell_append         (GtkMenuShell *menu_shell,
          ^~~~~~~~~~~~~~~~~~~~~
/tmp/test.vala.c:265:40: warning: passing argument 2 of ‘gtk_menu_item_set_submenu’ from incompatible pointer type [-Wincompatible-pointer-types]
  gtk_menu_item_set_submenu (item_open, _tmp10_);
                                        ^~~~~~~
In file included from /usr/include/gtk-3.0/gtk/gtkcheckmenuitem.h:33:0,
                 from /usr/include/gtk-3.0/gtk/gtk.h:72,
                 from /usr/include/libappindicator3-0.1/libappindicator/app-indicator.h:33,
                 from /tmp/test.vala.c:15:
/usr/include/gtk-3.0/gtk/gtkmenuitem.h:120:12: note: expected ‘GtkWidget * {aka struct _GtkWidget *}’ but argument is of type ‘GtkMenu * {aka struct _GtkMenu *}’
 void       gtk_menu_item_set_submenu          (GtkMenuItem         *menu_item,
            ^~~~~~~~~~~~~~~~~~~~~~~~~

... 但我想这不是什么大问题。可能需要更改 libappindicator3。

无论如何，这里是完整更新的（并且有效）代码test.vala：

// build with:
// valac -X -D'GETTEXT_PACKAGE="my-indicator"' --pkg=gtk+-3.0 --pkg appindicator3-0.1 test.vala

// "It's not possible to define a preprocessor symbol inside the Vala code (like with C). The only way to define a symbol is to feed it through the valac option -D."
// valac -X -D'GETTEXT_PACKAGE="my-indicator"' -D NEWMETHOD --pkg=gtk+-3.0 --pkg appindicator3-0.1 test.vala

// see also: https://valadoc.org/gtk+-3.0/Gtk.MenuItem.html

using GLib;
using Gtk;
using AppIndicator;

public Main App;
public const string AppName = "Test";

extern void exit(int exit_code);

public class MyIndicator: GLib.Object{

  protected Indicator indicator;
  protected string icon;
  protected string name;

  public Gtk.Menu createSubmenu(){
    var submenu = new Gtk.Menu();
    submenu.reserve_toggle_size = true;
    //var dummy_window = new Gtk.Window();
    //Gtk.Image icon = null;
    int i;
    for (i = 0; i < 10; i++) {
      #if NEWMETHOD
        var subitem = new Gtk.MenuItem.with_label ( "Exit %d".printf(i) );
      #else
        var subitem = new Gtk.ImageMenuItem.with_label ( "Exit %d".printf(i) );
      #endif

      subitem.set_reserve_indicator(true);
      submenu.append(subitem);
      subitem.activate.connect(() => {
        App.exit_app();
        exit(0);
      });
      //subitem.activate(); // no way, causes immediate exit!
    }

    submenu.show_all();
    return submenu;
  }
  public MyIndicator(){

    App.my_indicator = this;

    this.name = "My Indicator";

    this.icon = "account-logged-in"; // looks like a checkmark
    this.indicator = new Indicator("my_indicator", icon, IndicatorCategory.APPLICATION_STATUS);
    indicator.set_status(IndicatorStatus.ACTIVE);

    /*
    // from https://valadoc.org/gtk+-3.0/Gtk.Menu.html
        // MenuBar:
        //Gtk.MenuBar bar = new Gtk.MenuBar (); //error: Argument 1: Cannot convert from `unowned Gtk.MenuBar?' to `unowned Gtk.Menu?'
        Gtk.Menu bar = new Gtk.Menu ();
        //indicator.add (bar); // error: The name `add' does not exist in the context of `AppIndicator.Indicator'
    indicator.set_menu(bar);

        // File:
        Gtk.MenuItem item_file = new Gtk.MenuItem.with_label ("File");
        bar.add (item_file);

        Gtk.Menu filemenu = new Gtk.Menu ();
        item_file.set_submenu (filemenu);

        Gtk.MenuItem item_open = new Gtk.MenuItem.with_label ("Open");
        filemenu.add (item_open);

        // Submenu:
        Gtk.Menu submenu = new Gtk.Menu ();
        item_open.set_submenu (submenu);

        Gtk.MenuItem item_foo = new Gtk.MenuItem.with_label ("foo");
        submenu.add (item_foo);

        Gtk.MenuItem item_bar = new Gtk.MenuItem.with_label ("bar");
        submenu.add (item_bar);

    bar.show_all();
    */

    var menu = new Gtk.Menu();

    // open -------------------------------------
    #if NEWMETHOD
      var item_open = new Gtk.MenuItem.with_label(_("Open"));
    #else
      var item_open = new Gtk.ImageMenuItem.with_label(_("Open"));
    #endif
    menu.append(item_open);

    item_open.set_reserve_indicator(false);

    item_open.activate.connect(() => {
      //~ item_open.set_submenu(createSubmenu()); // NO; having the set_submenu run in .connect, causes immediate shutdown of the created submenu!!
      stdout.printf("item.activate.connect running\n");
    });
    item_open.set_submenu(createSubmenu()); // is OK here
    item_open.activate(); // so it shows submenu triangle

    indicator.set_menu(menu);
    menu.show_all();
  }
}


public class Main : GLib.Object{

  public MyIndicator my_indicator;

  public static int main (string[] args) {

    stdout.printf("main() ... \n");
    stdout.flush();
    Gtk.init(ref args);
    App = new Main(args);
    bool success = App.start_application(args);
    App.exit_app();

    return (success) ? 0 : 1;
  }

  public Main(string[] args){
    stdout.printf("Main(): ok\n");
    stdout.flush();
  }

  public bool start_application(string[] args){
    stdout.printf("Creating MainWindow\n");
    stdout.flush();

    new MyIndicator(); // var ind = new MyIndicator();

    //start event loop
    Gtk.main();

    return true;
  }

  public void exit_app (){
    stdout.printf("exit_app()\n");
    stdout.flush();
    Gtk.main_quit ();
  }
}

Answer 1