summaryrefslogtreecommitdiff
path: root/ext/js/input/hotkey-handler.js
blob: 90cae462978e3a08484a2bd5583d749cca1d5bc4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
/*
 * Copyright (C) 2021  Yomichan Authors
 *
 * 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 <https://www.gnu.org/licenses/>.
 */

/* global
 * DocumentUtil
 */

/**
 * Class which handles hotkey events and actions.
 */
class HotkeyHandler extends EventDispatcher {
    /**
     * Creates a new instance of the class.
     */
    constructor() {
        super();
        this._actions = new Map();
        this._hotkeys = new Map();
        this._hotkeyRegistrations = new Map();
        this._eventListeners = new EventListenerCollection();
        this._isPrepared = false;
        this._hasEventListeners = false;
    }

    /**
     * Begins listening to key press events in order to detect hotkeys.
     */
    prepare() {
        this._isPrepared = true;
        this._updateEventHandlers();
        yomichan.crossFrame.registerHandlers([
            ['HotkeyHandler.forwardHotkey', {async: false, handler: this._onMessageForwardHotkey.bind(this)}]
        ]);
    }

    /**
     * Registers a set of actions that this hotkey handler supports.
     * @param actions An array of `[name, handler]` entries, where `name` is a string and `handler` is a function.
     */
    registerActions(actions) {
        for (const [name, handler] of actions) {
            this._actions.set(name, handler);
        }
    }

    /**
     * Registers a set of hotkeys for a given scope.
     * @param scope The scope that the hotkey definitions must be for in order to be activated.
     * @param hotkeys An array of hotkey definitions of the format `{action, key, modifiers, scopes, enabled}`.
     * * `action` - a string indicating which action to perform.
     * * `key` - a keyboard key code indicating which key needs to be pressed.
     * * `modifiers` - an array of keyboard modifiers which also need to be pressed. Supports: `'alt', 'ctrl', 'shift', 'meta'`.
     * * `scopes` - an array of scopes for which the hotkey is valid. If this array does not contain `this.scope`, the hotkey will not be registered.
     * * `enabled` - a boolean indicating whether the hotkey is currently enabled.
     */
    registerHotkeys(scope, hotkeys) {
        let registrations = this._hotkeyRegistrations.get(scope);
        if (typeof registrations === 'undefined') {
            registrations = [];
            this._hotkeyRegistrations.set(scope, registrations);
        }
        registrations.push(...hotkeys);
        this._updateHotkeyRegistrations();
    }

    /**
     * Removes all registered hotkeys for a given scope.
     */
    clearHotkeys(scope) {
        const registrations = this._hotkeyRegistrations.get(scope);
        if (typeof registrations !== 'undefined') {
            registrations.length = 0;
        }
        this._updateHotkeyRegistrations();
    }

    /**
     * Assigns a set of hotkeys for a given scope. This is an optimized shorthand for calling
     * `clearHotkeys`, then calling `registerHotkeys`.
     * @see registerHotkeys for argument information.
     */
    setHotkeys(scope, hotkeys) {
        let registrations = this._hotkeyRegistrations.get(scope);
        if (typeof registrations === 'undefined') {
            registrations = [];
            this._hotkeyRegistrations.set(scope, registrations);
        } else {
            registrations.length = 0;
        }
        registrations.push(...hotkeys);
        this._updateHotkeyRegistrations();
    }

    /**
     * Adds a single event listener to a specific event.
     * @param eventName The string representing the event's name.
     * @param callback The event listener callback to add.
     */
    on(eventName, callback) {
        const result = super.on(eventName, callback);
        this._updateHasEventListeners();
        this._updateEventHandlers();
        return result;
    }

    /**
     * Removes a single event listener from a specific event.
     * @param eventName The string representing the event's name.
     * @param callback The event listener callback to add.
     * @returns `true` if the callback was removed, `false` otherwise.
     */
    off(eventName, callback) {
        const result = super.off(eventName, callback);
        this._updateHasEventListeners();
        this._updateEventHandlers();
        return result;
    }

    /**
     * Attempts to simulate an action for a given combination of key and modifiers.
     * @param key A keyboard key code indicating which key needs to be pressed.
     * @param modifiers An array of keyboard modifiers which also need to be pressed. Supports: `'alt', 'ctrl', 'shift', 'meta'`.
     * @returns `true` if an action was performed, `false` otherwise.
     */
    simulate(key, modifiers) {
        const hotkeyInfo = this._hotkeys.get(key);
        return (
            typeof hotkeyInfo !== 'undefined' &&
            this._invokeHandlers(modifiers, hotkeyInfo)
        );
    }

    // Message handlers

    _onMessageForwardHotkey({key, modifiers}) {
        return this.simulate(key, modifiers);
    }

    // Private

    _onKeyDown(e) {
        const hotkeyInfo = this._hotkeys.get(e.code);
        if (typeof hotkeyInfo !== 'undefined') {
            const eventModifiers = DocumentUtil.getActiveModifiers(e);
            if (this._invokeHandlers(eventModifiers, hotkeyInfo, e.key)) {
                e.preventDefault();
                return;
            }
        }
        this.trigger('keydownNonHotkey', e);
    }

    _invokeHandlers(modifiers, hotkeyInfo, key) {
        for (const {modifiers: handlerModifiers, action, argument} of hotkeyInfo.handlers) {
            if (!this._areSame(handlerModifiers, modifiers) || !this._isHotkeyPermitted(modifiers, key)) { continue; }

            const actionHandler = this._actions.get(action);
            if (typeof actionHandler !== 'undefined') {
                const result = actionHandler(argument);
                if (result !== false) {
                    return true;
                }
            }
        }

        return false;
    }

    _areSame(set, array) {
        if (set.size !== array.length) { return false; }
        for (const value of array) {
            if (!set.has(value)) {
                return false;
            }
        }
        return true;
    }

    _updateHotkeyRegistrations() {
        if (this._hotkeys.size === 0 && this._hotkeyRegistrations.size === 0) { return; }

        this._hotkeys.clear();
        for (const [scope, registrations] of this._hotkeyRegistrations.entries()) {
            for (const {action, argument, key, modifiers, scopes, enabled} of registrations) {
                if (!(enabled && key !== null && action !== '' && scopes.includes(scope))) { continue; }

                let hotkeyInfo = this._hotkeys.get(key);
                if (typeof hotkeyInfo === 'undefined') {
                    hotkeyInfo = {handlers: []};
                    this._hotkeys.set(key, hotkeyInfo);
                }

                hotkeyInfo.handlers.push({modifiers: new Set(modifiers), action, argument});
            }
        }
        this._updateEventHandlers();
    }

    _updateHasEventListeners() {
        this._hasEventListeners = this.hasListeners('keydownNonHotkey');
    }

    _updateEventHandlers() {
        if (this._isPrepared && (this._hotkeys.size > 0 || this._hasEventListeners)) {
            if (this._eventListeners.size !== 0) { return; }
            this._eventListeners.addEventListener(document, 'keydown', this._onKeyDown.bind(this), false);
        } else {
            this._eventListeners.removeAllEventListeners();
        }
    }

    _isHotkeyPermitted(modifiers, key) {
        return !(
            (modifiers.length === 0 || (modifiers.length === 1 && modifiers[0] === 'shift')) &&
            DocumentUtil.isInputElementFocused() &&
            this._isKeyCharacterInput(key)
        );
    }

    _isKeyCharacterInput(key) {
        return key.length === 1;
    }
}