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

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/*
* Copyright (C) 2020-2021 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
* FrameAncestryHandler
* api
*/
class FrameOffsetForwarder {
constructor(frameId) {
this._frameId = frameId;
this._frameAncestryHandler = new FrameAncestryHandler(frameId);
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}
prepare() {
this._frameAncestryHandler.prepare();
api.crossFrame.registerHandlers([
['FrameOffsetForwarder.getChildFrameRect', {async: false, handler: this._onMessageGetChildFrameRect.bind(this)}]
]);
}
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async getOffset() {
if (this._frameAncestryHandler.isRootFrame()) {
return [0, 0];
}
const ancestorFrameIds = await this._frameAncestryHandler.getFrameAncestryInfo();
let childFrameId = this._frameId;
const promises = [];
for (const frameId of ancestorFrameIds) {
promises.push(api.crossFrame.invoke(frameId, 'FrameOffsetForwarder.getChildFrameRect', {frameId: childFrameId}));
childFrameId = frameId;
}
const results = await Promise.all(promises);
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let xOffset = 0;
let yOffset = 0;
for (const {x, y} of results) {
xOffset += x;
yOffset += y;
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}
return [xOffset, yOffset];
}
// Private
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_onMessageGetChildFrameRect({frameId}) {
const frameElement = this._frameAncestryHandler.getChildFrameElement(frameId);
if (frameElement === null) { return null; }
const {x, y, width, height} = frameElement.getBoundingClientRect();
return {x, y, width, height};
}
}