jitsi_mod/modules/desktopsharing/ScreenObtainer.js

/* global config, APP, chrome, $, alert */
/* jshint -W003 */
var RTCBrowserType = require("../RTC/RTCBrowserType");
var AdapterJS = require("../RTC/adapter.screenshare");
var DesktopSharingEventTypes
    = require("../../service/desktopsharing/DesktopSharingEventTypes");

/**
 * Indicates whether the Chrome desktop sharing extension is installed.
 * @type {boolean}
 */
var chromeExtInstalled = false;

/**
 * Indicates whether an update of the Chrome desktop sharing extension is
 * required.
 * @type {boolean}
 */
var chromeExtUpdateRequired = false;

/**
 * Whether the jidesha extension for firefox is installed for the domain on
 * which we are running. Null designates an unknown value.
 * @type {null}
 */
var firefoxExtInstalled = null;

/**
 * If set to true, detection of an installed firefox extension will be started
 * again the next time obtainScreenOnFirefox is called (e.g. next time the
 * user tries to enable screen sharing).
 */
var reDetectFirefoxExtension = false;

/**
 * Handles obtaining a stream from a screen capture on different browsers.
 */
function ScreenObtainer(){
}

/**
 * The EventEmitter to use to emit events.
 * @type {null}
 */
ScreenObtainer.prototype.eventEmitter = null;

/**
 * Initializes the function used to obtain a screen capture (this.obtainStream).
 *
 * If the browser is Chrome, it uses the value of
 * 'config.desktopSharingChromeMethod' (or 'config.desktopSharing') to * decide
 * whether to use the a Chrome extension (if the value is 'ext'), use the
 * "screen" media source (if the value is 'webrtc'), or disable screen capture
 * (if the value is other).
 * Note that for the "screen" media source to work the
 * 'chrome://flags/#enable-usermedia-screen-capture' flag must be set.
 */
ScreenObtainer.prototype.init = function(eventEmitter) {
    this.eventEmitter = eventEmitter;
    var obtainDesktopStream = null;

    if (RTCBrowserType.isFirefox())
        initFirefoxExtensionDetection();

    // TODO remove this, config.desktopSharing is deprecated.
    var chromeMethod =
        (config.desktopSharingChromeMethod || config.desktopSharing);

    if (RTCBrowserType.isTemasysPluginUsed()) {
        if (!AdapterJS.WebRTCPlugin.plugin.HasScreensharingFeature) {
            console.info("Screensharing not supported by this plugin version");
        } else if (!AdapterJS.WebRTCPlugin.plugin.isScreensharingAvailable) {
            console.info(
                "Screensharing not available with Temasys plugin on this site");
        } else {
            obtainDesktopStream = obtainWebRTCScreen;
            console.info("Using Temasys plugin for desktop sharing");
        }
    } else if (RTCBrowserType.isChrome()) {
        if (chromeMethod == "ext") {
            if (RTCBrowserType.getChromeVersion() >= 34) {
                obtainDesktopStream = obtainScreenFromExtension;
                console.info("Using Chrome extension for desktop sharing");
                initChromeExtension();
            } else {
                console.info("Chrome extension not supported until ver 34");
            }
        } else if (chromeMethod == "webrtc") {
            obtainDesktopStream = obtainWebRTCScreen;
            console.info("Using Chrome WebRTC for desktop sharing");
        }
    } else if (RTCBrowserType.isFirefox()) {
        if (config.desktopSharingFirefoxDisabled) {
            obtainDesktopStream = null;
        } else if (window.location.protocol === "http:"){
            console.log("Screen sharing is not supported over HTTP. Use of " +
                "HTTPS is required.");
            obtainDesktopStream = null;
        } else {
            obtainDesktopStream = this.obtainScreenOnFirefox;
        }

    }

    if (!obtainDesktopStream) {
        console.info("Desktop sharing disabled");
    }

    ScreenObtainer.prototype.obtainStream = obtainDesktopStream;
};

ScreenObtainer.prototype.obtainStream = null;

/**
 * Checks whether obtaining a screen capture is supported in the current
 * environment.
 * @returns {boolean}
 */
ScreenObtainer.prototype.isSupported = function() {
    return !!this.obtainStream;
};

/**
 * Obtains a desktop stream using getUserMedia.
 * For this to work on Chrome, the
 * 'chrome://flags/#enable-usermedia-screen-capture' flag must be enabled.
 *
 * On firefox, the document's domain must be white-listed in the
 * 'media.getusermedia.screensharing.allowed_domains' preference in
 * 'about:config'.
 */
function obtainWebRTCScreen(streamCallback, failCallback) {
    APP.RTC.getUserMediaWithConstraints(
        ['screen'],
        streamCallback,
        failCallback
    );
}

/**
 * Constructs inline install URL for Chrome desktop streaming extension.
 * The 'chromeExtensionId' must be defined in config.js.
 * @returns {string}
 */
function getWebStoreInstallUrl()
{
    //TODO remove chromeExtensionId (deprecated)
    return "https://chrome.google.com/webstore/detail/" +
        (config.desktopSharingChromeExtId || config.chromeExtensionId);
}

/**
 * Checks whether an update of the Chrome extension is required.
 * @param minVersion minimal required version
 * @param extVersion current extension version
 * @returns {boolean}
 */
function isUpdateRequired(minVersion, extVersion) {
    try {
        var s1 = minVersion.split('.');
        var s2 = extVersion.split('.');

        var len = Math.max(s1.length, s2.length);
        for (var i = 0; i < len; i++) {
            var n1 = 0,
                n2 = 0;

            if (i < s1.length)
                n1 = parseInt(s1[i]);
            if (i < s2.length)
                n2 = parseInt(s2[i]);

            if (isNaN(n1) || isNaN(n2)) {
                return true;
            } else if (n1 !== n2) {
                return n1 > n2;
            }
        }

        // will happen if both versions have identical numbers in
        // their components (even if one of them is longer, has more components)
        return false;
    }
    catch (e) {
        console.error("Failed to parse extension version", e);
        APP.UI.messageHandler.showError("dialog.error",
            "dialog.detectext");
        return true;
    }
}

function checkChromeExtInstalled(callback) {
    if (!chrome || !chrome.runtime) {
        // No API, so no extension for sure
        callback(false, false);
        return;
    }
    chrome.runtime.sendMessage(
        //TODO: remove chromeExtensionId (deprecated)
        (config.desktopSharingChromeExtId || config.chromeExtensionId),
        { getVersion: true },
        function (response) {
            if (!response || !response.version) {
                // Communication failure - assume that no endpoint exists
                console.warn(
                    "Extension not installed?: ", chrome.runtime.lastError);
                callback(false, false);
                return;
            }
            // Check installed extension version
            var extVersion = response.version;
            console.log('Extension version is: ' + extVersion);
            //TODO: remove minChromeExtVersion (deprecated)
            var updateRequired
                = isUpdateRequired(
                    (config.desktopSharingChromeMinExtVersion ||
                        config.minChromeExtVersion),
                    extVersion);
            callback(!updateRequired, updateRequired);
        }
    );
}

function doGetStreamFromExtension(streamCallback, failCallback) {
    // Sends 'getStream' msg to the extension.
    // Extension id must be defined in the config.
    chrome.runtime.sendMessage(
        config.chromeExtensionId,
        {
            getStream: true,
            //TODO: remove desktopSharingSources (deprecated).
            sources: (config.desktopSharingChromeSources ||
                config.desktopSharingSources)
        },
        function (response) {
            if (!response) {
                failCallback(chrome.runtime.lastError);
                return;
            }
            console.log("Response from extension: " + response);
            if (response.streamId) {
                APP.RTC.getUserMediaWithConstraints(
                    ['desktop'],
                    function (stream) {
                        streamCallback(stream);
                    },
                    failCallback,
                    null, null, null,
                    response.streamId);
            } else {
                failCallback("Extension failed to get the stream");
            }
        }
    );
}

/**
 * Asks Chrome extension to call chooseDesktopMedia and gets chrome 'desktop'
 * stream for returned stream token.
 */
function obtainScreenFromExtension(streamCallback, failCallback) {
    if (chromeExtInstalled) {
        doGetStreamFromExtension(streamCallback, failCallback);
    } else {
        if (chromeExtUpdateRequired) {
            alert(
                'Jitsi Desktop Streamer requires update. ' +
                'Changes will take effect after next Chrome restart.');
        }

        chrome.webstore.install(
            getWebStoreInstallUrl(),
            function (arg) {
                console.log("Extension installed successfully", arg);
                chromeExtInstalled = true;
                // We need to give a moment for the endpoint to become available
                window.setTimeout(function () {
                    doGetStreamFromExtension(streamCallback, failCallback);
                }, 500);
            },
            function (arg) {
                console.log("Failed to install the extension", arg);
                failCallback(arg);
                APP.UI.messageHandler.showError("dialog.error",
                    "dialog.failtoinstall");
            }
        );
    }
}

/**
 * Initializes <link rel=chrome-webstore-item /> with extension id set in
 * config.js to support inline installs. Host site must be selected as main
 * website of published extension.
 */
function initInlineInstalls()
{
    $("link[rel=chrome-webstore-item]").attr("href", getWebStoreInstallUrl());
}

function initChromeExtension() {
    // Initialize Chrome extension inline installs
    initInlineInstalls();
    // Check if extension is installed
    checkChromeExtInstalled(function (installed, updateRequired) {
        chromeExtInstalled = installed;
        chromeExtUpdateRequired = updateRequired;
        console.info(
            "Chrome extension installed: " + chromeExtInstalled +
            " updateRequired: " + chromeExtUpdateRequired);
    });
}

/**
 * Obtains a screen capture stream on Firefox.
 * @param callback
 * @param errorCallback
 */
ScreenObtainer.prototype.obtainScreenOnFirefox =
       function (callback, errorCallback) {
    var self = this;
    var extensionRequired = false;
    if (config.desktopSharingFirefoxMaxVersionExtRequired === -1 ||
        (config.desktopSharingFirefoxMaxVersionExtRequired >= 0 &&
            RTCBrowserType.getFirefoxVersion() <=
                config.desktopSharingFirefoxMaxVersionExtRequired)) {
        extensionRequired = true;
        console.log("Jidesha extension required on firefox version " +
            RTCBrowserType.getFirefoxVersion());
    }

    if (!extensionRequired || firefoxExtInstalled === true) {
        obtainWebRTCScreen(callback, errorCallback);
        return;
    }

    if (reDetectFirefoxExtension) {
        reDetectFirefoxExtension = false;
        initFirefoxExtensionDetection();
    }

    // Give it some (more) time to initialize, and assume lack of extension if
    // it hasn't.
    if (firefoxExtInstalled === null) {
        window.setTimeout(
            function() {
                if (firefoxExtInstalled === null)
                    firefoxExtInstalled = false;
                self.obtainScreenOnFirefox(callback, errorCallback);
            },
            300
        );
        console.log("Waiting for detection of jidesha on firefox to finish.");
        return;
    }

    // We need an extension and it isn't installed.

    // Make sure we check for the extension when the user clicks again.
    firefoxExtInstalled = null;
    reDetectFirefoxExtension = true;

    // Prompt the user to install the extension
    this.eventEmitter.emit(DesktopSharingEventTypes.FIREFOX_EXTENSION_NEEDED,
                           config.desktopSharingFirefoxExtensionURL);

    // Make sure desktopsharing knows that we failed, so that it doesn't get
    // stuck in 'switching' mode.
    errorCallback('Firefox extension required.');
};

/**
 * Starts the detection of an installed jidesha extension for firefox.
 */
function initFirefoxExtensionDetection() {
    if (config.desktopSharingFirefoxDisabled) {
        return;
    }
    if (firefoxExtInstalled === false || firefoxExtInstalled === true)
        return;
    if (!config.desktopSharingFirefoxExtId) {
        firefoxExtInstalled = false;
        return;
    }

    var img = document.createElement('img');
    img.onload = function(){
        console.log("Detected firefox screen sharing extension.");
        firefoxExtInstalled = true;
    };
    img.onerror = function(){
        console.log("Detected lack of firefox screen sharing extension.");
        firefoxExtInstalled = false;
    };

    // The jidesha extension exposes an empty image file under the url:
    // "chrome://EXT_ID/content/DOMAIN.png"
    // Where EXT_ID is the ID of the extension with "@" replaced by ".", and
    // DOMAIN is a domain whitelisted by the extension.
    var src = "chrome://" +
        (config.desktopSharingFirefoxExtId.replace('@', '.')) +
        "/content/" + document.location.hostname + ".png";
    img.setAttribute('src', src);
}

module.exports = ScreenObtainer;