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-rw-r--r--ext/js/templates/template-renderer-proxy.js157
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diff --git a/ext/js/templates/template-renderer-proxy.js b/ext/js/templates/template-renderer-proxy.js
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+++ b/ext/js/templates/template-renderer-proxy.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/>.
+ */
+
+class TemplateRendererProxy {
+ constructor() {
+ this._frame = null;
+ this._frameNeedsLoad = true;
+ this._frameLoading = false;
+ this._frameLoadPromise = null;
+ this._frameUrl = chrome.runtime.getURL('/template-renderer.html');
+ this._invocations = new Set();
+ }
+
+ async render(template, data, type) {
+ await this._prepareFrame();
+ return await this._invoke('render', {template, data, type});
+ }
+
+ // 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(deserializeError(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();
+ }
+}