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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/>.
*/
/* global
* api
*/
class FrameOffsetForwarder {
constructor() {
this._isPrepared = false;
this._cacheMaxSize = 1000;
this._frameCache = new Set();
this._unreachableContentWindowCache = new Set();
this._forwardFrameOffset = (
window !== window.parent ?
this._forwardFrameOffsetParent.bind(this) :
this._forwardFrameOffsetOrigin.bind(this)
);
this._windowMessageHandlers = new Map([
['getFrameOffset', ({offset, uniqueId}, e) => this._onGetFrameOffset(offset, uniqueId, e)]
]);
}
prepare() {
if (this._isPrepared) { return; }
window.addEventListener('message', this._onMessage.bind(this), false);
this._isPrepared = true;
}
async getOffset() {
const uniqueId = yomichan.generateId(16);
const frameOffsetPromise = yomichan.getTemporaryListenerResult(
chrome.runtime.onMessage,
({action, params}, {resolve}) => {
if (action === 'frameOffset' && isObject(params) && params.uniqueId === uniqueId) {
resolve(params);
}
},
5000
);
window.parent.postMessage({
action: 'getFrameOffset',
params: {
uniqueId,
offset: [0, 0]
}
}, '*');
const {offset} = await frameOffsetPromise;
return offset;
}
// Private
_onMessage(event) {
const data = event.data;
if (data === null || typeof data !== 'object') { return; }
try {
const {action, params} = event.data;
const handler = this._windowMessageHandlers.get(action);
if (typeof handler !== 'function') { return; }
handler(params, event);
} catch (e) {
// NOP
}
}
_onGetFrameOffset(offset, uniqueId, e) {
let sourceFrame = null;
if (!this._unreachableContentWindowCache.has(e.source)) {
sourceFrame = this._findFrameWithContentWindow(e.source);
}
if (sourceFrame === null) {
// closed shadow root etc.
this._addToCache(this._unreachableContentWindowCache, e.source);
this._forwardFrameOffsetOrigin(null, uniqueId);
return;
}
const [forwardedX, forwardedY] = offset;
const {x, y} = sourceFrame.getBoundingClientRect();
offset = [forwardedX + x, forwardedY + y];
this._forwardFrameOffset(offset, uniqueId);
}
_findFrameWithContentWindow(contentWindow) {
const ELEMENT_NODE = Node.ELEMENT_NODE;
for (const elements of this._getFrameElementSources()) {
while (elements.length > 0) {
const element = elements.shift();
if (element.contentWindow === contentWindow) {
this._addToCache(this._frameCache, element);
return element;
}
const shadowRoot = (
element.shadowRoot ||
element.openOrClosedShadowRoot // Available to Firefox 63+ for WebExtensions
);
if (shadowRoot) {
for (const child of shadowRoot.children) {
if (child.nodeType === ELEMENT_NODE) {
elements.push(child);
}
}
}
for (const child of element.children) {
if (child.nodeType === ELEMENT_NODE) {
elements.push(child);
}
}
}
}
return null;
}
*_getFrameElementSources() {
const frameCache = [];
for (const frame of this._frameCache) {
// removed from DOM
if (!frame.isConnected) {
this._frameCache.delete(frame);
continue;
}
frameCache.push(frame);
}
yield frameCache;
// will contain duplicates, but frame elements are cheap to handle
yield [...document.querySelectorAll('frame, iframe:not(.yomichan-float)')];
yield [document.documentElement];
}
_addToCache(cache, value) {
let freeSlots = this._cacheMaxSize - cache.size;
if (freeSlots <= 0) {
for (const cachedValue of cache) {
cache.delete(cachedValue);
++freeSlots;
if (freeSlots > 0) { break; }
}
}
cache.add(value);
}
_forwardFrameOffsetParent(offset, uniqueId) {
window.parent.postMessage({action: 'getFrameOffset', params: {offset, uniqueId}}, '*');
}
_forwardFrameOffsetOrigin(offset, uniqueId) {
api.broadcastTab('frameOffset', {offset, uniqueId});
}
}
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