diff options
Diffstat (limited to '')
-rw-r--r-- | browser/components/newtab/lib/Screenshots.sys.mjs | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/browser/components/newtab/lib/Screenshots.sys.mjs b/browser/components/newtab/lib/Screenshots.sys.mjs new file mode 100644 index 0000000000..e5423bd52f --- /dev/null +++ b/browser/components/newtab/lib/Screenshots.sys.mjs @@ -0,0 +1,140 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +// We use importESModule here instead of static import so that +// the Karma test environment won't choke on this module. This +// is because the Karma test environment already stubs out +// XPCOMUtils, and overrides importESModule to be a no-op (which +// can't be done for a static import statement). + +// eslint-disable-next-line mozilla/use-static-import +const { XPCOMUtils } = ChromeUtils.importESModule( + "resource://gre/modules/XPCOMUtils.sys.mjs" +); + +const lazy = {}; + +ChromeUtils.defineESModuleGetters(lazy, { + BackgroundPageThumbs: "resource://gre/modules/BackgroundPageThumbs.sys.mjs", + PageThumbs: "resource://gre/modules/PageThumbs.sys.mjs", + PrivateBrowsingUtils: "resource://gre/modules/PrivateBrowsingUtils.sys.mjs", +}); + +const GREY_10 = "#F9F9FA"; + +XPCOMUtils.defineLazyPreferenceGetter( + lazy, + "gPrivilegedAboutProcessEnabled", + "browser.tabs.remote.separatePrivilegedContentProcess", + false +); + +export const Screenshots = { + /** + * Get a screenshot / thumbnail for a url. Either returns the disk cached + * image or initiates a background request for the url. + * + * @param url {string} The url to get a thumbnail + * @return {Promise} Resolves a custom object or null if failed + */ + async getScreenshotForURL(url) { + try { + await lazy.BackgroundPageThumbs.captureIfMissing(url, { + backgroundColor: GREY_10, + }); + + // The privileged about content process is able to use the moz-page-thumb + // protocol, so if it's enabled, send that down. + if (lazy.gPrivilegedAboutProcessEnabled) { + return lazy.PageThumbs.getThumbnailURL(url); + } + + // Otherwise, for normal content processes, we fallback to using + // Blob URIs for the screenshots. + const imgPath = lazy.PageThumbs.getThumbnailPath(url); + + const filePathResponse = await fetch(`file://${imgPath}`); + const fileContents = await filePathResponse.blob(); + + // Check if the file is empty, which indicates there isn't actually a + // thumbnail, so callers can show a failure state. + if (fileContents.size === 0) { + return null; + } + + return { path: imgPath, data: fileContents }; + } catch (err) { + console.error(`getScreenshot(${url}) failed:`, err); + } + + // We must have failed to get the screenshot, so persist the failure by + // storing an empty file. Future calls will then skip requesting and return + // failure, so do the same thing here. The empty file should not expire with + // the usual filtering process to avoid repeated background requests, which + // can cause unwanted high CPU, network and memory usage - Bug 1384094 + try { + await lazy.PageThumbs._store(url, url, null, true); + } catch (err) { + // Probably failed to create the empty file, but not much more we can do. + } + return null; + }, + + /** + * Checks if all the open windows are private browsing windows. If so, we do not + * want to collect screenshots. If there exists at least 1 non-private window, + * we are ok to collect screenshots. + */ + _shouldGetScreenshots() { + for (let win of Services.wm.getEnumerator("navigator:browser")) { + if (!lazy.PrivateBrowsingUtils.isWindowPrivate(win)) { + // As soon as we encounter 1 non-private window, screenshots are fair game. + return true; + } + } + return false; + }, + + /** + * Conditionally get a screenshot for a link if there's no existing pending + * screenshot. Updates the cached link's desired property with the result. + * + * @param link {object} Link object to update + * @param url {string} Url to get a screenshot of + * @param property {string} Name of property on object to set + @ @param onScreenshot {function} Callback for when the screenshot loads + */ + async maybeCacheScreenshot(link, url, property, onScreenshot) { + // If there are only private windows open, do not collect screenshots + if (!this._shouldGetScreenshots()) { + return; + } + // __sharedCache may not exist yet for links from default top sites that + // don't have a default tippy top icon. + if (!link.__sharedCache) { + link.__sharedCache = { + updateLink(prop, val) { + link[prop] = val; + }, + }; + } + const cache = link.__sharedCache; + // Nothing to do if we already have a pending screenshot or + // if a previous request failed and returned null. + if (cache.fetchingScreenshot || link[property] !== undefined) { + return; + } + + // Save the promise to the cache so other links get it immediately + cache.fetchingScreenshot = this.getScreenshotForURL(url); + + // Clean up now that we got the screenshot + const screenshot = await cache.fetchingScreenshot; + delete cache.fetchingScreenshot; + + // Update the cache for future links and call back for existing content + cache.updateLink(property, screenshot); + onScreenshot(screenshot); + }, +}; |