yomichan/ext/mixed/js/hotkey-handler.js

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/*
* 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.
* @param scope The scope required for hotkey definitions.
*/
constructor(scope) {
super();
this._scope = scope;
this._hotkeys = new Map();
this._actions = new Map();
this._eventListeners = new EventListenerCollection();
}
/**
* Gets the scope required for the hotkey definitions.
*/
get scope() {
return this._scope;
}
/**
* Sets the scope required for the hotkey definitions.
*/
set scope(value) {
this._scope = value;
}
/**
* Begins listening to key press events in order to detect hotkeys.
*/
prepare() {
this._eventListeners.addEventListener(document, 'keydown', this._onKeyDown.bind(this), false);
}
/**
* Stops listening to key press events.
*/
cleanup() {
this._eventListeners.removeAllEventListeners();
}
/**
* 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
* @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(hotkeys) {
for (const {action, key, modifiers, scopes, enabled} of hotkeys) {
if (
enabled &&
action !== '' &&
scopes.includes(this._scope)
) {
this._registerHotkey(key, modifiers, action);
}
}
}
/**
* Removes all registered hotkeys.
*/
clearHotkeys() {
this._hotkeys.clear();
}
// Private
_onKeyDown(e) {
const key = e.code;
const handlers = this._hotkeys.get(key);
if (typeof handlers !== 'undefined') {
const eventModifiers = DocumentUtil.getActiveModifiers(e);
for (const {modifiers, action} of handlers) {
if (!this._areSame(modifiers, eventModifiers)) { continue; }
const actionHandler = this._actions.get(action);
if (typeof actionHandler === 'undefined') { continue; }
const result = actionHandler(e);
if (result !== false) {
e.preventDefault();
return true;
}
}
}
this.trigger('keydownNonHotkey', e);
return false;
}
_registerHotkey(key, modifiers, action) {
let handlers = this._hotkeys.get(key);
if (typeof handlers === 'undefined') {
handlers = [];
this._hotkeys.set(key, handlers);
}
handlers.push({modifiers: new Set(modifiers), action});
}
_areSame(set, array) {
if (set.size !== array.length) { return false; }
for (const value of array) {
if (!set.has(value)) {
return false;
}
}
return true;
}
}