extension.js

/*
    Keyboard Modifiers Status for gnome-shell
    Copyright (C) 2015  Abdellah Chelli

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

//
import St from 'gi://St';
import Clutter from 'gi://Clutter';

//
import * as Main from 'resource:///org/gnome/shell/ui/main.js';
import GLib from 'gi://GLib';

import { Extension } from 'resource:///org/gnome/shell/extensions/extension.js';

//
const dbg = false;

//TODO: convert into preferrence.
const tag = "KMS-Ext:";
const mod_sym = "⇧⇬⋀⌥①◆⌘⎇";
const latch_sym = "'";
const lock_sym = "◦";
const icon = ""; //"⌨ ";
const opening = ""; //"_";
const closing = ""; //"_";

//TODO: eliminate global variables
let seat;
let button,
    label;

let state,
    prev_state,
    latch,
    prev_latch,
    lock,
    prev_lock;

let indicator;

let timeout_id,
    mods_update_id;

// Gnome-shell extension interface
// init, enable, disable

export default class KMS extends Extension {


    constructor(metadata) {
        super(metadata);

        console.debug(`${tag} constructor() ... done ${this.metadata.name}`);
    }

    enable() {
        console.debug(`${tag} enable() ... in`);

        //

        seat = null;
        button = null;
        label = null;

        state = 0;
        prev_state = 0;
        latch = 0;
        prev_latch = 0;
        lock = 0;
        prev_lock = 0;

        timeout_id = null;
        mods_update_id = null;

        //
        button = new St.Bin({ style_class: 'panel-button',
            reactive: false,
            can_focus: false,
            x_expand: true,
            y_expand: false,
            track_hover: false });
        label = new St.Label({ style_class: "state-label", text: "" });
        button.set_child(label);

        //console.debug(`${tag} Running Wayland: ` + Meta.is_wayland_compositor());

        try {
            seat = Clutter.get_default_backend().get_default_seat();
        } catch (e) {
            seat = Clutter.DeviceManager.get_default();
        };

        if (seat) {
            mods_update_id = seat.connect("kbd-a11y-mods-state-changed", this._a11y_mods_update);
        };

        Main.panel._rightBox.insert_child_at_index(button, 0);
        timeout_id = GLib.timeout_add(GLib.PRIORITY_DEFAULT, 200, this._update);

        console.debug(`${tag} enable() ... out`);
    }


    disable() {
        console.debug(`${tag} disable() ... in`);

        Main.panel._rightBox.remove_child(button);

        GLib.source_remove(timeout_id);

        if (seat && mods_update_id) {
            seat.disconnect(mods_update_id);
        };

        button.destroy_all_children();
        button.destroy();

        seat = null;
        button = null;
        label = null;

        timeout_id = null;
        mods_update_id = null;

        console.debug(`${tag} disable() ... out`);
    }

    //
    _update() {
        console.debug(`${tag} _update() ... in`);
        //TODO: search for documentation about global
        //Note: modifiers state from get_pointer is the base not the effective
        // On latch active, it is on too. but on lock active, it is off
        // Not the case, using Gdk.Keymap.get_default().get_modifier_state() which
        // is the effective

        const [x, y, m] = global.get_pointer();
        
        if (typeof m !== 'undefined') {
            state = m;
        };

        if ((state != prev_state) || latch != prev_latch || lock != prev_lock) {
            console.debug(`${tag} State changed... ${prev_state}, ${state}`);
            indicator = icon + opening + " ";
            //TODO: don't relay on internal order
            //      use standard pre-defined constant masks
            for (var i=0; i<8; i++ ) {
                if ((state & 1<<i) || (lock & 1<<i)) {
                    indicator += mod_sym[i];
                } else {
                    //indicator += "";
                };
                if (latch & 1<<i) {
                    indicator += latch_sym + " ";
                } else {
                    //indicator += "";
                };
                if (lock & 1<<i) {
                    indicator += lock_sym + " ";
                } else {
                    //indicator += "";
                };
            }
            indicator += " " + closing;

            label.text = indicator;

            prev_state = state;
            prev_latch = latch;
            prev_lock = lock;
        }

        console.debug(`${tag} _update() ... out`);
        //return true;
        return GLib.SOURCE_CONTINUE;
    }


    _a11y_mods_update(o, latch_new, lock_new) {
        console.debug(`${tag} _a11y_mods_update() ... in`);
        //TODO: search what's the 1st parameter
        if (typeof latch_new !== 'undefined') {
            latch = latch_new;
        };
        if (typeof lock_new !== 'undefined') {
            lock = lock_new;
        };
        console.debug(`${tag} latch: ${latch}, lock: ${lock}`);
        console.debug(`${tag} _a11y_mods_update() ... out`);
        //return true;
        return GLib.SOURCE_CONTINUE;
    }

}