Source code
Revision control
Copy as Markdown
Other Tools
// -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
/* 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,
// Constants for telemetry.
const DOWNLOAD_SUCCESS = 0;
const DOWNLOAD_ERROR_XHR = 1;
const DOWNLOAD_ERROR_NO_DOC = 2;
const PARSE_SUCCESS = 0;
const PARSE_ERROR_TOO_MANY_ELEMENTS = 1;
const PARSE_ERROR_WORKER = 2;
const PARSE_ERROR_NO_ARTICLE = 3;
// Class names to preserve in the readerized output. We preserve these class
// names so that rules in aboutReader.css can match them.
const CLASSES_TO_PRESERVE = [
"caption",
"emoji",
"hidden",
"invisible",
"sr-only",
"visually-hidden",
"visuallyhidden",
"wp-caption",
"wp-caption-text",
"wp-smiley",
];
const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
LanguageDetector:
});
const gIsFirefoxDesktop =
Services.appinfo.ID == "{ec8030f7-c20a-464f-9b0e-13a3a9e97384}";
Services.telemetry.setEventRecordingEnabled("readermode", true);
export var ReaderMode = {
DEBUG: 0,
// For time spent telemetry
enterTime: undefined,
leaveTime: undefined,
/**
* Enter the reader mode by going forward one step in history if applicable,
* if not, append the about:reader page in the history instead.
*/
enterReaderMode(docShell, win) {
this.enterTime = Date.now();
Services.telemetry.recordEvent("readermode", "view", "on", null, {
subcategory: "feature",
});
let url = win.document.location.href;
let readerURL = "about:reader?url=" + encodeURIComponent(url);
if (!Services.appinfo.sessionHistoryInParent) {
let webNav = docShell.QueryInterface(Ci.nsIWebNavigation);
let sh = webNav.sessionHistory;
if (webNav.canGoForward) {
let forwardEntry = sh.legacySHistory.getEntryAtIndex(sh.index + 1);
let forwardURL = forwardEntry.URI.spec;
if (forwardURL && (forwardURL == readerURL || !readerURL)) {
webNav.goForward();
return;
}
}
}
win.document.location = readerURL;
},
/**
* Exit the reader mode by going back one step in history if applicable,
* if not, append the original page in the history instead.
*/
leaveReaderMode(docShell, win) {
this.leaveTime = Date.now();
// Measured in seconds (whole number)
let timeSpentInReaderMode = Math.floor(
(this.leaveTime - this.enterTime) / 1000
);
// Measured as percentage (whole number)
let scrollPosition = Math.floor(
((win.scrollY + win.innerHeight) / win.document.body.clientHeight) * 100
);
Services.telemetry.recordEvent("readermode", "view", "off", null, {
subcategory: "feature",
reader_time: `${timeSpentInReaderMode}`,
scroll_position: `${scrollPosition}`,
});
let url = win.document.location.href;
let originalURL = this.getOriginalUrl(url);
let webNav = docShell.QueryInterface(Ci.nsIWebNavigation);
if (!Services.appinfo.sessionHistoryInParent) {
let sh = webNav.sessionHistory;
if (webNav.canGoBack) {
let prevEntry = sh.legacySHistory.getEntryAtIndex(sh.index - 1);
let prevURL = prevEntry.URI.spec;
if (prevURL && (prevURL == originalURL || !originalURL)) {
webNav.goBack();
return;
}
}
}
let referrerURI, principal;
try {
referrerURI = Services.io.newURI(url);
principal = Services.scriptSecurityManager.createContentPrincipal(
referrerURI,
win.document.nodePrincipal.originAttributes
);
} catch (e) {
console.error(e);
return;
}
let loadFlags = webNav.LOAD_FLAGS_DISALLOW_INHERIT_PRINCIPAL;
let ReferrerInfo = Components.Constructor(
"@mozilla.org/referrer-info;1",
"nsIReferrerInfo",
"init"
);
let loadURIOptions = {
triggeringPrincipal: principal,
loadFlags,
referrerInfo: new ReferrerInfo(
Ci.nsIReferrerInfo.EMPTY,
true,
referrerURI
),
};
webNav.fixupAndLoadURIString(originalURL, loadURIOptions);
},
/**
* Returns original URL from an about:reader URL.
*
* @param url An about:reader URL.
* @return The original URL for the article, or null if we did not find
* a properly formatted about:reader URL.
*/
getOriginalUrl(url) {
if (!url.startsWith("about:reader?")) {
return null;
}
let outerHash = "";
try {
let uriObj = Services.io.newURI(url);
url = uriObj.specIgnoringRef;
outerHash = uriObj.ref;
} catch (ex) {
/* ignore, use the raw string */
}
let searchParams = new URLSearchParams(
url.substring("about:reader?".length)
);
if (!searchParams.has("url")) {
return null;
}
let originalUrl = searchParams.get("url");
if (outerHash) {
try {
let uriObj = Services.io.newURI(originalUrl);
uriObj = Services.io.newURI("#" + outerHash, null, uriObj);
originalUrl = uriObj.spec;
} catch (ex) {}
}
return originalUrl;
},
getOriginalUrlObjectForDisplay(url) {
let originalUrl = this.getOriginalUrl(url);
if (originalUrl) {
let uriObj;
try {
uriObj = Services.uriFixup.getFixupURIInfo(originalUrl).preferredURI;
} catch (ex) {
return null;
}
try {
return Services.io.createExposableURI(uriObj);
} catch (ex) {
return null;
}
}
return null;
},
/**
* Gets an article from a loaded browser's document. This method will not attempt
* to parse certain URIs (e.g. about: URIs).
*
* @param doc A document to parse.
* @return {Promise}
* @resolves JS object representing the article, or null if no article is found.
*/
parseDocument(doc) {
if (
!lazy.Readerable.shouldCheckUri(doc.documentURIObject) ||
!lazy.Readerable.shouldCheckUri(doc.baseURIObject, true)
) {
this.log("Reader mode disabled for URI");
return null;
}
return this._readerParse(doc);
},
/**
* Downloads and parses a document from a URL.
*
* @param url URL to download and parse.
* @return {Promise}
* @resolves JS object representing the article, or null if no article is found.
*/
async downloadAndParseDocument(url, docContentType = "document") {
let result = await this._downloadDocument(url, docContentType);
if (!result?.doc) {
return null;
}
let { doc, newURL } = result;
if (
!lazy.Readerable.shouldCheckUri(doc.documentURIObject) ||
!lazy.Readerable.shouldCheckUri(doc.baseURIObject, true)
) {
this.log("Reader mode disabled for URI");
return null;
}
let article = await this._readerParse(doc);
// If we have to redirect, reject to the caller with the parsed article,
// so we can update the URL before displaying it.
if (newURL) {
return Promise.reject({ newURL, article });
}
// Otherwise, we can just continue with the article.
return article;
},
_downloadDocument(url, docContentType = "document") {
try {
if (!lazy.Readerable.shouldCheckUri(Services.io.newURI(url))) {
return null;
}
} catch (ex) {
console.error(
new Error(`Couldn't create URI from ${url} to download: ${ex}`)
);
return null;
}
let histogram = Services.telemetry.getHistogramById(
"READER_MODE_DOWNLOAD_RESULT"
);
return new Promise((resolve, reject) => {
let xhr = new XMLHttpRequest({ mozAnon: false });
xhr.open("GET", url, true);
xhr.onerror = evt => reject(evt.error);
xhr.responseType = docContentType === "text/plain" ? "text" : "document";
xhr.onload = () => {
if (xhr.status !== 200) {
reject("Reader mode XHR failed with status: " + xhr.status);
histogram.add(DOWNLOAD_ERROR_XHR);
return;
}
let doc =
xhr.responseType === "text" ? xhr.responseText : xhr.responseXML;
if (!doc) {
reject("Reader mode XHR didn't return a document");
histogram.add(DOWNLOAD_ERROR_NO_DOC);
return;
}
let responseURL = xhr.responseURL;
let givenURL = url;
// Convert these to real URIs to make sure the escaping (or lack
// thereof) is identical:
try {
responseURL = Services.io.newURI(responseURL).specIgnoringRef;
} catch (ex) {
/* Ignore errors - we'll use what we had before */
}
try {
givenURL = Services.io.newURI(givenURL).specIgnoringRef;
} catch (ex) {
/* Ignore errors - we'll use what we had before */
}
if (xhr.responseType != "document") {
let initialText = doc;
let parser = new DOMParser();
doc = parser.parseFromString(`<pre></pre>`, "text/html");
doc.querySelector("pre").textContent = initialText;
}
// We treat redirects as download successes here:
histogram.add(DOWNLOAD_SUCCESS);
let result = { doc };
if (responseURL != givenURL) {
result.newURL = xhr.responseURL;
}
resolve(result);
};
xhr.send();
});
},
log(msg) {
if (this.DEBUG) {
dump("Reader: " + msg);
}
},
/**
* Attempts to parse a document into an article. Heavy lifting happens
* in Reader.worker.js.
*
* @param doc The document to parse.
* @return {Promise}
* @resolves JS object representing the article, or null if no article is found.
*/
async _readerParse(doc) {
let histogram = Services.telemetry.getHistogramById(
"READER_MODE_PARSE_RESULT"
);
if (this.parseNodeLimit) {
let numTags = doc.getElementsByTagName("*").length;
if (numTags > this.parseNodeLimit) {
this.log(
"Aborting parse for " +
doc.baseURIObject.spec +
"; " +
numTags +
" elements found"
);
histogram.add(PARSE_ERROR_TOO_MANY_ELEMENTS);
return null;
}
}
// Fetch this here before we send `doc` off to the worker thread, as later on the
// document might be nuked but we will still want the URI.
let { documentURI } = doc;
let uriParam;
uriParam = {
spec: doc.baseURIObject.spec,
prePath: doc.baseURIObject.prePath,
scheme: doc.baseURIObject.scheme,
// Fallback
host: documentURI,
pathBase: documentURI,
};
// nsIURI.host throws an exception if a host doesn't exist.
try {
uriParam.host = doc.baseURIObject.host;
uriParam.pathBase = Services.io.newURI(".", null, doc.baseURIObject).spec;
} catch (ex) {
// Fall back to the initial values we assigned.
console.warn("Error accessing host name: ", ex);
}
// convert text/plain document, if any, to XHTML format
if (this._isDocumentPlainText(doc)) {
doc = this._convertPlainTextDocument(doc);
}
let serializer = new XMLSerializer();
let serializedDoc = serializer.serializeToString(doc);
// Explicitly null out doc to make it clear it might not be available from this
// point on.
doc = null;
let options = {
classesToPreserve: CLASSES_TO_PRESERVE,
};
let article = null;
try {
article = await lazy.ReaderWorker.post("parseDocument", [
uriParam,
serializedDoc,
options,
]);
} catch (e) {
console.error("Error in ReaderWorker: ", e);
histogram.add(PARSE_ERROR_WORKER);
}
if (!article) {
this.log("Worker did not return an article");
histogram.add(PARSE_ERROR_NO_ARTICLE);
return null;
}
// Readability returns a URI object based on the baseURI, but we only care
// about the original document's URL from now on. This also avoids spoofing
// attempts where the baseURI doesn't match the domain of the documentURI
article.url = documentURI;
delete article.uri;
let flags =
Ci.nsIDocumentEncoder.OutputSelectionOnly |
Ci.nsIDocumentEncoder.OutputAbsoluteLinks;
article.title = Cc["@mozilla.org/parserutils;1"]
.getService(Ci.nsIParserUtils)
.convertToPlainText(article.title, flags, 0);
if (gIsFirefoxDesktop) {
await this._assignLanguage(article);
this._maybeAssignTextDirection(article);
}
this._assignReadTime(article);
histogram.add(PARSE_SUCCESS);
return article;
},
/**
* Sets a global language string value if the result is confident
*
* @return Promise
* @resolves when the language is detected
*/
_assignLanguage(article) {
return lazy.LanguageDetector.detectLanguage(article.textContent).then(
result => {
article.language = result.confident ? result.language : null;
}
);
},
_maybeAssignTextDirection(article) {
if (
!article.dir &&
["ar", "fa", "he", "ug", "ur"].includes(article.language)
) {
article.dir = "rtl";
}
},
/**
* Assigns the estimated reading time range of the article to the article object.
*
* @param article the article object to assign the reading time estimate to.
*/
_assignReadTime(article) {
let lang = article.language || "en";
const readingSpeed = this._getReadingSpeedForLanguage(lang);
const charactersPerMinuteLow = readingSpeed.cpm - readingSpeed.variance;
const charactersPerMinuteHigh = readingSpeed.cpm + readingSpeed.variance;
const length = article.length;
article.readingTimeMinsSlow = Math.ceil(length / charactersPerMinuteLow);
article.readingTimeMinsFast = Math.ceil(length / charactersPerMinuteHigh);
},
/**
* Returns the reading speed of a selection of languages with likely variance.
*
* Reading speed estimated from a study done on reading speeds in various languages.
*
* @return object with characters per minute and variance. Defaults to English
* if no suitable language is found in the collection.
*/
_getReadingSpeedForLanguage(lang) {
const readingSpeed = new Map([
["en", { cpm: 987, variance: 118 }],
["ar", { cpm: 612, variance: 88 }],
["de", { cpm: 920, variance: 86 }],
["es", { cpm: 1025, variance: 127 }],
["fi", { cpm: 1078, variance: 121 }],
["fr", { cpm: 998, variance: 126 }],
["he", { cpm: 833, variance: 130 }],
["it", { cpm: 950, variance: 140 }],
["jw", { cpm: 357, variance: 56 }],
["nl", { cpm: 978, variance: 143 }],
["pl", { cpm: 916, variance: 126 }],
["pt", { cpm: 913, variance: 145 }],
["ru", { cpm: 986, variance: 175 }],
["sk", { cpm: 885, variance: 145 }],
["sv", { cpm: 917, variance: 156 }],
["tr", { cpm: 1054, variance: 156 }],
["zh", { cpm: 255, variance: 29 }],
]);
return readingSpeed.get(lang) || readingSpeed.get("en");
},
/**
*
* Check if the document to be parsed is text document.
* @param doc the doc object to be parsed.
* @return boolean
*
*/
_isDocumentPlainText(doc) {
return doc.contentType == "text/plain";
},
/**
*
* The document to be parsed is text document and is converted to HTML format.
* @param doc the doc object to be parsed.
* @return doc
*
*/
_convertPlainTextDocument(doc) {
let preTag = doc.querySelector("pre");
let docFrag = doc.createDocumentFragment();
let content = preTag.textContent;
let paragraphs = content.split(/\r?\n\r?\n/);
for (let para of paragraphs) {
let pElem = doc.createElement("p");
let lines = para.split(/\n/);
for (let line of lines) {
pElem.append(line);
let brElem = doc.createElement("br");
pElem.append(brElem);
}
docFrag.append(pElem);
}
// Clone the document to avoid the original document being affected
// (which shows up when exiting reader mode again).
let clone = doc.documentElement.cloneNode(true);
clone.querySelector("pre").replaceWith(docFrag);
return clone;
},
};
XPCOMUtils.defineLazyPreferenceGetter(
ReaderMode,
"maxElemsToParse",
"reader.parse-node-limit",
0
);