140 lines
5 KiB
JavaScript
140 lines
5 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// We use importESModule here instead of static import so that
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// the Karma test environment won't choke on this module. This
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// is because the Karma test environment already stubs out
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// XPCOMUtils, and overrides importESModule to be a no-op (which
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// can't be done for a static import statement).
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// eslint-disable-next-line mozilla/use-static-import
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const { XPCOMUtils } = ChromeUtils.importESModule(
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"resource://gre/modules/XPCOMUtils.sys.mjs"
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);
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const lazy = {};
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ChromeUtils.defineESModuleGetters(lazy, {
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BackgroundPageThumbs: "resource://gre/modules/BackgroundPageThumbs.sys.mjs",
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PageThumbs: "resource://gre/modules/PageThumbs.sys.mjs",
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PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs",
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});
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const GREY_10 = "#F9F9FA";
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XPCOMUtils.defineLazyPreferenceGetter(
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lazy,
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"gPrivilegedAboutProcessEnabled",
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"browser.tabs.remote.separatePrivilegedContentProcess",
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false
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);
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export const Screenshots = {
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/**
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* Get a screenshot / thumbnail for a url. Either returns the disk cached
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* image or initiates a background request for the url.
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*
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* @param url {string} The url to get a thumbnail
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* @return {Promise} Resolves a custom object or null if failed
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*/
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async getScreenshotForURL(url) {
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try {
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await lazy.BackgroundPageThumbs.captureIfMissing(url, {
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backgroundColor: GREY_10,
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});
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// The privileged about content process is able to use the moz-page-thumb
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// protocol, so if it's enabled, send that down.
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if (lazy.gPrivilegedAboutProcessEnabled) {
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return lazy.PageThumbs.getThumbnailURL(url);
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}
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// Otherwise, for normal content processes, we fallback to using
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// Blob URIs for the screenshots.
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const imgPath = lazy.PageThumbs.getThumbnailPath(url);
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const filePathResponse = await fetch(`file://${imgPath}`);
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const fileContents = await filePathResponse.blob();
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// Check if the file is empty, which indicates there isn't actually a
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// thumbnail, so callers can show a failure state.
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if (fileContents.size === 0) {
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return null;
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}
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return { path: imgPath, data: fileContents };
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} catch (err) {
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console.error(`getScreenshot(${url}) failed:`, err);
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}
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// We must have failed to get the screenshot, so persist the failure by
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// storing an empty file. Future calls will then skip requesting and return
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// failure, so do the same thing here. The empty file should not expire with
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// the usual filtering process to avoid repeated background requests, which
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// can cause unwanted high CPU, network and memory usage - Bug 1384094
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try {
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await lazy.PageThumbs._store(url, url, null, true);
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} catch (err) {
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// Probably failed to create the empty file, but not much more we can do.
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}
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return null;
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},
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/**
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* Checks if all the open windows are private browsing windows. If so, we do not
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* want to collect screenshots. If there exists at least 1 non-private window,
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* we are ok to collect screenshots.
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*/
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_shouldGetScreenshots() {
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for (let win of Services.wm.getEnumerator("navigator:browser")) {
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if (!lazy.PrivateBrowsingUtils.isWindowPrivate(win)) {
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// As soon as we encounter 1 non-private window, screenshots are fair game.
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return true;
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}
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}
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return false;
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},
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/**
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* Conditionally get a screenshot for a link if there's no existing pending
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* screenshot. Updates the cached link's desired property with the result.
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*
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* @param link {object} Link object to update
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* @param url {string} Url to get a screenshot of
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* @param property {string} Name of property on object to set
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@ @param onScreenshot {function} Callback for when the screenshot loads
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*/
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async maybeCacheScreenshot(link, url, property, onScreenshot) {
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// If there are only private windows open, do not collect screenshots
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if (!this._shouldGetScreenshots()) {
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return;
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}
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// __sharedCache may not exist yet for links from default top sites that
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// don't have a default tippy top icon.
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if (!link.__sharedCache) {
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link.__sharedCache = {
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updateLink(prop, val) {
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link[prop] = val;
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},
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};
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}
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const cache = link.__sharedCache;
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// Nothing to do if we already have a pending screenshot or
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// if a previous request failed and returned null.
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if (cache.fetchingScreenshot || link[property] !== undefined) {
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return;
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}
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// Save the promise to the cache so other links get it immediately
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cache.fetchingScreenshot = this.getScreenshotForURL(url);
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// Clean up now that we got the screenshot
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const screenshot = await cache.fetchingScreenshot;
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delete cache.fetchingScreenshot;
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// Update the cache for future links and call back for existing content
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cache.updateLink(property, screenshot);
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onScreenshot(screenshot);
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},
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};
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