How to handle keyboard events in gnome shell extensions?

问题:

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...

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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){} );

回答1:

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})

文章来源: How to handle keyboard events in gnome shell extensions?