How to handle keyboard events in gnome shell extensions?

Question

How can I add an event or other method to listen to keypresses on a gnome shell extension? e.g. show a dialog with each key press showing the pressed key?

I can not find any example. The documentation mentions a keyboard module, but with that common name searching is hard.

Class explanation
...
- General utils
   - Keyboard: Manage and define the keyboard events, etc. for gnome shell.

(read above as a quote from the docs linked above. it is styled as code because the quote styling for some reason do not preserve line breaks in this site)

I found some extensions using the bellow code for results similar to what i'm asking, but i, again, failed to find docs for the specific classes and methods:

workViewInjections['_init'] = injectToFunction(WorkspacesView.WorkspacesView.prototype, '_init', function(width, height, x, y, workspaces) {
        this._pickWorkspace = false;
        this._pickWindow = false;
        this._keyPressEventId = global.stage.connect('key-press-event', Lang.bind(this, this._onKeyPress));                                                                                
        this._keyReleaseEventId = global.stage.connect('key-release-event', Lang.bind(this, this._onKeyRelease));
        connectedSignals.push({ obj: global.stage, id: this._keyPressEventId });
        connectedSignals.push({ obj: global.stage, id: this._keyReleaseEventId });
        });

Also, no class named keyboard anywhere there...

--

edit1: more searching... i think i may have to use the Clutter api. but again, not much examples or documentation for that. farthest i went was this

edit2: more searching. looking on the gnome shell source code, on the main ui tree, i think the answer is to use the barelly mentioned global object that is available to the extension code. e.g.

global.connect('key-press-event', function(if, i, know, the, signature){} );

found the keyboard module: git.gnome.org/browse/gnome-shell/tree/js/ui/keyboard.js — gcb
– gcb, Commented Aug 31, 2017 at 16:24

andy.holmes · Accepted Answer · 2017-09-04 05:08:14Z

5

+200

I came across this snippet in gcampax's gtk-js-app template some time ago, which may be related to what you're doing:

// Due to limitations of gobject-introspection wrt GdkEvent and GdkEventKey,
// this needs to be a signal handler
this.connect('key-press-event', Lang.bind(this, this._handleKeyPress));

and

_handleKeyPress: function(self, event) {
    return this.main_search_bar.handle_event(event);
},

I haven't had a need to use keyboard events yet, and this is Gtk in GJS, but the same limitation may be affecting gnome-shell extensions.

UPDATE

I've been doing some keybinding stuff lately, and if attaching a signal handler to the global object is working, you can do something like this:

global.display.connect("key-press-event", (widget, event, user_data) => {
    let [success, keyval] = event.get_keyval(); // integer
    let keyname = Gdk.keyval_name(keyval); // string keyname

    if (keyname === "Control_L") {
        // Dialog code or eg. this.keys_array.push("<Ctrl>");
    }
});

There's also some Shell keybinding code here and some shell-global documentation here that might give you more clues. Wish I could help more but I'm wrestling my own GJS atm ;)

ADDENDUM

There is a good answer here with an example class with informative logging, as well as a speculative explanation. I've also found this functionality is exposed over DBus which might be more convenient in some cases:

Bus Name: org.gnome.Shell -> Path: /org/gnome/Shell -> Interface: org.gnome.Shell

Relevant Methods:

GrabAccelerator(String accelerator, UInt32 flags) -> (UInt32 action)
UngrabAccelerator(UInt32 action) -> (Boolean success)

Signal:

AcceleratorActivate(UInt32, Dict of {String, Variant})

edited Sep 4, 2017 at 5:08

answered Jul 24, 2017 at 4:07

andy.holmes

3,74119 silver badges29 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

gcb Over a year ago

Interesting, the main method, ... .connect('key-press-event', ... is not mentioned on the shell-global doc.

gcb Over a year ago

and on the example linked, they use gobal.display.add_keybinding()... the shell-global list that property as being a Metacity display object. But searching for that term, i only find it on the shell object for gnome source comments.

gcb Over a year ago

Best I could find is people.gnome.org/~tthurman/docs/metacity/… MetaDisplay, but it doesn't have an add_keybinding() method.

andy.holmes Over a year ago

After some pointed searching, I found an answer on superuser.stackexchange.com that gave me everything I need. I think it will probably do it for you too.

Arik Over a year ago

global.display.connect("key-press-event", ...) will not work because "There never was such a signal on MetaDisplay"

Dharman · Accepted Answer · 2020-01-14 23:00:07Z

0

For me global.stage.connect("key-press-event", _handleKeyPress) did the trick

edited Jan 14, 2020 at 23:00

Dharman♦

33.9k27 gold badges106 silver badges157 bronze badges

answered Jan 14, 2020 at 22:15

fedeb

1722 silver badges4 bronze badges

1 Comment

Arik Over a year ago

Doesn't work for me when I type something inside application windows

Collectives™ on Stack Overflow

How to handle keyboard events in gnome shell extensions?

2 Answers 2

5 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related