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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/>.
*/
class TemplateRendererProxy {
constructor() {
this._frame = null;
this._frameNeedsLoad = true;
this._frameLoading = false;
this._frameLoadPromise = null;
this._frameUrl = chrome.runtime.getURL('/bg/template-renderer.html');
this._invocations = new Set();
}
async render(template, data, marker) {
await this._prepareFrame();
return await this._invoke('renderHandlebarsTemplate', {template, data, marker});
}
// Private
async _prepareFrame() {
if (this._frame === null) {
this._frame = document.createElement('iframe');
this._frame.addEventListener('load', this._onFrameLoad.bind(this), false);
const style = this._frame.style;
style.opacity = '0';
style.width = '0';
style.height = '0';
style.position = 'absolute';
style.border = '0';
style.margin = '0';
style.padding = '0';
style.pointerEvents = 'none';
}
if (this._frameNeedsLoad) {
this._frameNeedsLoad = false;
this._frameLoading = true;
this._frameLoadPromise = this._loadFrame(this._frame, this._frameUrl)
.finally(() => { this._frameLoading = false; });
}
await this._frameLoadPromise;
}
_loadFrame(frame, url, timeout=5000) {
return new Promise((resolve, reject) => {
let ready = false;
const cleanup = () => {
frame.removeEventListener('load', onLoad, false);
if (timer !== null) {
clearTimeout(timer);
timer = null;
}
};
const onLoad = () => {
if (!ready) { return; }
cleanup();
resolve();
};
let timer = setTimeout(() => {
cleanup();
reject(new Error('Timeout'));
}, timeout);
frame.removeAttribute('src');
frame.removeAttribute('srcdoc');
frame.addEventListener('load', onLoad, false);
try {
document.body.appendChild(frame);
ready = true;
frame.contentDocument.location.href = url;
} catch (e) {
cleanup();
reject(e);
}
});
}
_invoke(action, params, timeout=null) {
return new Promise((resolve, reject) => {
const frameWindow = (this._frame !== null ? this._frame.contentWindow : null);
if (frameWindow === null) {
reject(new Error('Frame not set up'));
return;
}
const id = generateId(16);
const invocation = {
cancel: () => {
cleanup();
reject(new Error('Terminated'));
}
};
const cleanup = () => {
this._invocations.delete(invocation);
window.removeEventListener('message', onMessage, false);
if (timer !== null) {
clearTimeout(timer);
timer = null;
}
};
const onMessage = (e) => {
if (
e.source !== frameWindow ||
e.data.id !== id ||
e.data.action !== `${action}.response`
) {
return;
}
const response = e.data.params;
cleanup();
const {error} = response;
if (error) {
reject(jsonToError(error));
} else {
resolve(response.result);
}
};
let timer = (typeof timeout === 'number' ? setTimeout(() => {
cleanup();
reject(new Error('Timeout'));
}, timeout) : null);
this._invocations.add(invocation);
window.addEventListener('message', onMessage, false);
frameWindow.postMessage({action, params, id}, '*');
});
}
_onFrameLoad() {
if (this._frameLoading) { return; }
this._frameNeedsLoad = true;
for (const invocation of this._invocations) {
invocation.cancel();
}
this._invocations.clear();
}
}
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