yomichan/ext/bg/js/clipboard-monitor.js

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/*
* Copyright (C) 2020 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/>.
*/
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/* global
* jp
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*/
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class ClipboardMonitor extends EventDispatcher {
constructor({getClipboard}) {
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super();
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this._timerId = null;
this._timerToken = null;
this._interval = 250;
this._previousText = null;
this._getClipboard = getClipboard;
}
start() {
this.stop();
// The token below is used as a unique identifier to ensure that a new clipboard monitor
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// hasn't been started during the await call. The check below the await this._getClipboard()
// call will exit early if the reference has changed.
const token = {};
const intervalCallback = async () => {
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this._timerId = null;
let text = null;
try {
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text = await this._getClipboard();
} catch (e) {
// NOP
}
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if (this._timerToken !== token) { return; }
if (
typeof text === 'string' &&
(text = text.trim()).length > 0 &&
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text !== this._previousText
) {
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this._previousText = text;
if (jp.isStringPartiallyJapanese(text)) {
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this.trigger('change', {text});
}
}
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this._timerId = setTimeout(intervalCallback, this._interval);
};
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this._timerToken = token;
intervalCallback();
}
stop() {
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this._timerToken = null;
if (this._timerId !== null) {
clearTimeout(this._timerId);
this._timerId = null;
}
}
setPreviousText(text) {
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this._previousText = text;
}
}