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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.
*/
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 key = e.code;
const hotkeyInfo = this._hotkeys.get(key);
if (typeof hotkeyInfo !== 'undefined') {
const eventModifiers = DocumentUtil.getActiveModifiers(e);
if (this._invokeHandlers(eventModifiers, hotkeyInfo)) {
e.preventDefault();
return;
}
}
this.trigger('keydownNonHotkey', e);
}
_invokeHandlers(modifiers, hotkeyInfo) {
for (const {modifiers: handlerModifiers, action, argument} of hotkeyInfo.handlers) {
if (!this._areSame(handlerModifiers, modifiers)) { 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();
}
}
}
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