yomichan/ext/fg/js/frame-offset-forwarder.js

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/*
* Copyright (C) 2020 Alex Yatskov <alex@foosoft.net>
* Author: Alex Yatskov <alex@foosoft.net>
*
* 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
* apiForward
*/
class FrameOffsetForwarder {
constructor() {
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this._started = false;
this._forwardFrameOffset = (
window !== window.parent ?
this._forwardFrameOffsetParent.bind(this) :
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this._forwardFrameOffsetOrigin.bind(this)
);
this._windowMessageHandlers = new Map([
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['getFrameOffset', ({offset, uniqueId}, e) => this._onGetFrameOffset(offset, uniqueId, e)]
]);
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}
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start() {
if (this._started) { return; }
window.addEventListener('message', this.onMessage.bind(this), false);
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this._started = true;
}
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async getOffset() {
const uniqueId = yomichan.generateId(16);
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const frameOffsetPromise = yomichan.getTemporaryListenerResult(
chrome.runtime.onMessage,
({action, params}, {resolve}) => {
if (action === 'frameOffset' && isObject(params) && params.uniqueId === uniqueId) {
resolve(params);
}
},
5000
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);
window.parent.postMessage({
action: 'getFrameOffset',
params: {
uniqueId,
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offset: [0, 0]
}
}, '*');
const {offset} = await frameOffsetPromise;
return offset;
}
onMessage(e) {
const {action, params} = e.data;
const handler = this._windowMessageHandlers.get(action);
if (typeof handler !== 'function') { return; }
handler(params, e);
}
_onGetFrameOffset(offset, uniqueId, e) {
let sourceFrame = null;
for (const frame of document.querySelectorAll('frame, iframe:not(.yomichan-float)')) {
if (frame.contentWindow !== e.source) { continue; }
sourceFrame = frame;
break;
}
if (sourceFrame === null) {
this._forwardFrameOffsetOrigin(null, uniqueId);
return;
}
const [forwardedX, forwardedY] = offset;
const {x, y} = sourceFrame.getBoundingClientRect();
offset = [forwardedX + x, forwardedY + y];
this._forwardFrameOffset(offset, uniqueId);
}
_forwardFrameOffsetParent(offset, uniqueId) {
window.parent.postMessage({action: 'getFrameOffset', params: {offset, uniqueId}}, '*');
}
_forwardFrameOffsetOrigin(offset, uniqueId) {
apiForward('frameOffset', {offset, uniqueId});
}
}