Replace updatestate event with connect

[mirror_novnc.git] / app / ui.js

/*
 * noVNC: HTML5 VNC client
 * Copyright (C) 2012 Joel Martin
 * Copyright (C) 2016 Samuel Mannehed for Cendio AB
 * Copyright (C) 2016 Pierre Ossman for Cendio AB
 * Licensed under MPL 2.0 (see LICENSE.txt)
 *
 * See README.md for usage and integration instructions.
 */

/* jslint white: false, browser: true */
/* global window, document.getElementById, Util, WebUtil, RFB, Display */

import * as Log from '../core/util/logging.js';
import _, { l10n } from '../core/util/localization.js';
import { isTouchDevice } from '../core/util/browsers.js';
import { setCapture, getPointerEvent } from '../core/util/events.js';
import KeyTable from "../core/input/keysym.js";
import keysyms from "../core/input/keysymdef.js";
import Keyboard from "../core/input/keyboard.js";
import RFB from "../core/rfb.js";
import Display from "../core/display.js";
import * as WebUtil from "./webutil.js";

var UI = {

    connected: false,
    desktopName: "",

    resizeTimeout: null,
    statusTimeout: null,
    hideKeyboardTimeout: null,
    idleControlbarTimeout: null,
    closeControlbarTimeout: null,

    controlbarGrabbed: false,
    controlbarDrag: false,
    controlbarMouseDownClientY: 0,
    controlbarMouseDownOffsetY: 0,

    isSafari: false,
    lastKeyboardinput: null,
    defaultKeyboardinputLen: 100,

    inhibit_reconnect: true,
    reconnect_callback: null,
    reconnect_password: null,

    prime: function(callback) {
        if (document.readyState === "interactive" || document.readyState === "complete") {
            UI.load(callback);
        } else {
            document.addEventListener('DOMContentLoaded', UI.load.bind(UI, callback));
        }
    },

    // Setup rfb object, load settings from browser storage, then call
    // UI.init to setup the UI/menus
    load: function(callback) {
        WebUtil.initSettings(UI.start, callback);
    },

    // Render default UI and initialize settings menu
    start: function(callback) {

        // Setup global variables first
        UI.isSafari = (navigator.userAgent.indexOf('Safari') !== -1 &&
                       navigator.userAgent.indexOf('Chrome') === -1);

        UI.initSettings();

        // Translate the DOM
        l10n.translateDOM();

        // Adapt the interface for touch screen devices
        if (isTouchDevice) {
            document.documentElement.classList.add("noVNC_touch");
            // Remove the address bar
            setTimeout(function() { window.scrollTo(0, 1); }, 100);
        }

        // Restore control bar position
        if (WebUtil.readSetting('controlbar_pos') === 'right') {
            UI.toggleControlbarSide();
        }

        UI.initFullscreen();

        // Setup event handlers
        UI.addResizeHandlers();
        UI.addControlbarHandlers();
        UI.addTouchSpecificHandlers();
        UI.addExtraKeysHandlers();
        UI.addMachineHandlers();
        UI.addConnectionControlHandlers();
        UI.addClipboardHandlers();
        UI.addSettingsHandlers();
        document.getElementById("noVNC_status")
            .addEventListener('click', UI.hideStatus);

        // Bootstrap fallback input handler
        UI.keyboardinputReset();

        UI.openControlbar();

        UI.updateViewClip();

        UI.updateVisualState('init');

        document.documentElement.classList.remove("noVNC_loading");

        var autoconnect = WebUtil.getConfigVar('autoconnect', false);
        if (autoconnect === 'true' || autoconnect == '1') {
            autoconnect = true;
            UI.connect();
        } else {
            autoconnect = false;
            // Show the connect panel on first load unless autoconnecting
            UI.openConnectPanel();
        }

        if (typeof callback === "function") {
            callback(UI.rfb);
        }
    },

    initFullscreen: function() {
        // Only show the button if fullscreen is properly supported
        // * Safari doesn't support alphanumerical input while in fullscreen
        if (!UI.isSafari &&
            (document.documentElement.requestFullscreen ||
             document.documentElement.mozRequestFullScreen ||
             document.documentElement.webkitRequestFullscreen ||
             document.body.msRequestFullscreen)) {
            document.getElementById('noVNC_fullscreen_button')
                .classList.remove("noVNC_hidden");
            UI.addFullscreenHandlers();
        }
    },

    initSettings: function() {
        var i;

        // Logging selection dropdown
        var llevels = ['error', 'warn', 'info', 'debug'];
        for (i = 0; i < llevels.length; i += 1) {
            UI.addOption(document.getElementById('noVNC_setting_logging'),llevels[i], llevels[i]);
        }

        // Settings with immediate effects
        UI.initSetting('logging', 'warn');
        UI.updateLogging();

        // if port == 80 (or 443) then it won't be present and should be
        // set manually
        var port = window.location.port;
        if (!port) {
            if (window.location.protocol.substring(0,5) == 'https') {
                port = 443;
            }
            else if (window.location.protocol.substring(0,4) == 'http') {
                port = 80;
            }
        }

        /* Populate the controls if defaults are provided in the URL */
        UI.initSetting('host', window.location.hostname);
        UI.initSetting('port', port);
        UI.initSetting('encrypt', (window.location.protocol === "https:"));
        UI.initSetting('view_clip', false);
        UI.initSetting('resize', 'off');
        UI.initSetting('shared', true);
        UI.initSetting('view_only', false);
        UI.initSetting('path', 'websockify');
        UI.initSetting('repeaterID', '');
        UI.initSetting('reconnect', false);
        UI.initSetting('reconnect_delay', 5000);

        UI.setupSettingLabels();
    },
    // Adds a link to the label elements on the corresponding input elements
    setupSettingLabels: function() {
        var labels = document.getElementsByTagName('LABEL');
        for (var i = 0; i < labels.length; i++) {
            var htmlFor = labels[i].htmlFor;
            if (htmlFor != '') {
                var elem = document.getElementById(htmlFor);
                if (elem) elem.label = labels[i];
            } else {
                // If 'for' isn't set, use the first input element child
                var children = labels[i].children;
                for (var j = 0; j < children.length; j++) {
                    if (children[j].form !== undefined) {
                        children[j].label = labels[i];
                        break;
                    }
                }
            }
        }
    },

/* ------^-------
*     /INIT
* ==============
* EVENT HANDLERS
* ------v------*/

    addResizeHandlers: function() {
        window.addEventListener('resize', UI.applyResizeMode);
        window.addEventListener('resize', UI.updateViewClip);
    },

    addControlbarHandlers: function() {
        document.getElementById("noVNC_control_bar")
            .addEventListener('mousemove', UI.activateControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('mouseup', UI.activateControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('mousedown', UI.activateControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('keydown', UI.activateControlbar);

        document.getElementById("noVNC_control_bar")
            .addEventListener('mousedown', UI.keepControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('keydown', UI.keepControlbar);

        document.getElementById("noVNC_view_drag_button")
            .addEventListener('click', UI.toggleViewDrag);

        document.getElementById("noVNC_control_bar_handle")
            .addEventListener('mousedown', UI.controlbarHandleMouseDown);
        document.getElementById("noVNC_control_bar_handle")
            .addEventListener('mouseup', UI.controlbarHandleMouseUp);
        document.getElementById("noVNC_control_bar_handle")
            .addEventListener('mousemove', UI.dragControlbarHandle);
        // resize events aren't available for elements
        window.addEventListener('resize', UI.updateControlbarHandle);

        var exps = document.getElementsByClassName("noVNC_expander");
        for (var i = 0;i < exps.length;i++) {
            exps[i].addEventListener('click', UI.toggleExpander);
        }
    },

    addTouchSpecificHandlers: function() {
        document.getElementById("noVNC_mouse_button0")
            .addEventListener('click', function () { UI.setMouseButton(1); });
        document.getElementById("noVNC_mouse_button1")
            .addEventListener('click', function () { UI.setMouseButton(2); });
        document.getElementById("noVNC_mouse_button2")
            .addEventListener('click', function () { UI.setMouseButton(4); });
        document.getElementById("noVNC_mouse_button4")
            .addEventListener('click', function () { UI.setMouseButton(0); });
        document.getElementById("noVNC_keyboard_button")
            .addEventListener('click', UI.toggleVirtualKeyboard);

        UI.touchKeyboard = new Keyboard(document.getElementById('noVNC_keyboardinput'));
        UI.touchKeyboard.onkeyevent = UI.keyEvent;
        UI.touchKeyboard.grab();
        document.getElementById("noVNC_keyboardinput")
            .addEventListener('input', UI.keyInput);
        document.getElementById("noVNC_keyboardinput")
            .addEventListener('focus', UI.onfocusVirtualKeyboard);
        document.getElementById("noVNC_keyboardinput")
            .addEventListener('blur', UI.onblurVirtualKeyboard);
        document.getElementById("noVNC_keyboardinput")
            .addEventListener('submit', function () { return false; });

        document.documentElement
            .addEventListener('mousedown', UI.keepVirtualKeyboard, true);

        document.getElementById("noVNC_control_bar")
            .addEventListener('touchstart', UI.activateControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('touchmove', UI.activateControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('touchend', UI.activateControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('input', UI.activateControlbar);

        document.getElementById("noVNC_control_bar")
            .addEventListener('touchstart', UI.keepControlbar);
        document.getElementById("noVNC_control_bar")
            .addEventListener('input', UI.keepControlbar);

        document.getElementById("noVNC_control_bar_handle")
            .addEventListener('touchstart', UI.controlbarHandleMouseDown);
        document.getElementById("noVNC_control_bar_handle")
            .addEventListener('touchend', UI.controlbarHandleMouseUp);
        document.getElementById("noVNC_control_bar_handle")
            .addEventListener('touchmove', UI.dragControlbarHandle);
    },

    addExtraKeysHandlers: function() {
        document.getElementById("noVNC_toggle_extra_keys_button")
            .addEventListener('click', UI.toggleExtraKeys);
        document.getElementById("noVNC_toggle_ctrl_button")
            .addEventListener('click', UI.toggleCtrl);
        document.getElementById("noVNC_toggle_alt_button")
            .addEventListener('click', UI.toggleAlt);
        document.getElementById("noVNC_send_tab_button")
            .addEventListener('click', UI.sendTab);
        document.getElementById("noVNC_send_esc_button")
            .addEventListener('click', UI.sendEsc);
        document.getElementById("noVNC_send_ctrl_alt_del_button")
            .addEventListener('click', UI.sendCtrlAltDel);
    },

    addMachineHandlers: function() {
        document.getElementById("noVNC_shutdown_button")
            .addEventListener('click', function() { UI.rfb.machineShutdown(); });
        document.getElementById("noVNC_reboot_button")
            .addEventListener('click', function() { UI.rfb.machineReboot(); });
        document.getElementById("noVNC_reset_button")
            .addEventListener('click', function() { UI.rfb.machineReset(); });
        document.getElementById("noVNC_power_button")
            .addEventListener('click', UI.togglePowerPanel);
    },

    addConnectionControlHandlers: function() {
        document.getElementById("noVNC_disconnect_button")
            .addEventListener('click', UI.disconnect);
        document.getElementById("noVNC_connect_button")
            .addEventListener('click', UI.connect);
        document.getElementById("noVNC_cancel_reconnect_button")
            .addEventListener('click', UI.cancelReconnect);

        document.getElementById("noVNC_password_button")
            .addEventListener('click', UI.setPassword);
    },

    addClipboardHandlers: function() {
        document.getElementById("noVNC_clipboard_button")
            .addEventListener('click', UI.toggleClipboardPanel);
        document.getElementById("noVNC_clipboard_text")
            .addEventListener('change', UI.clipboardSend);
        document.getElementById("noVNC_clipboard_clear_button")
            .addEventListener('click', UI.clipboardClear);
    },

    // Add a call to save settings when the element changes,
    // unless the optional parameter changeFunc is used instead.
    addSettingChangeHandler: function(name, changeFunc) {
        var settingElem = document.getElementById("noVNC_setting_" + name);
        if (changeFunc === undefined) {
            changeFunc = function () { UI.saveSetting(name); };
        }
        settingElem.addEventListener('change', changeFunc);
    },

    addSettingsHandlers: function() {
        document.getElementById("noVNC_settings_button")
            .addEventListener('click', UI.toggleSettingsPanel);

        UI.addSettingChangeHandler('encrypt');
        UI.addSettingChangeHandler('resize');
        UI.addSettingChangeHandler('resize', UI.enableDisableViewClip);
        UI.addSettingChangeHandler('resize', UI.applyResizeMode);
        UI.addSettingChangeHandler('view_clip');
        UI.addSettingChangeHandler('view_clip', UI.updateViewClip);
        UI.addSettingChangeHandler('shared');
        UI.addSettingChangeHandler('view_only');
        UI.addSettingChangeHandler('view_only', UI.updateViewOnly);
        UI.addSettingChangeHandler('host');
        UI.addSettingChangeHandler('port');
        UI.addSettingChangeHandler('path');
        UI.addSettingChangeHandler('repeaterID');
        UI.addSettingChangeHandler('logging');
        UI.addSettingChangeHandler('logging', UI.updateLogging);
        UI.addSettingChangeHandler('reconnect');
        UI.addSettingChangeHandler('reconnect_delay');
    },

    addFullscreenHandlers: function() {
        document.getElementById("noVNC_fullscreen_button")
            .addEventListener('click', UI.toggleFullscreen);

        window.addEventListener('fullscreenchange', UI.updateFullscreenButton);
        window.addEventListener('mozfullscreenchange', UI.updateFullscreenButton);
        window.addEventListener('webkitfullscreenchange', UI.updateFullscreenButton);
        window.addEventListener('msfullscreenchange', UI.updateFullscreenButton);
    },

/* ------^-------
 * /EVENT HANDLERS
 * ==============
 *     VISUAL
 * ------v------*/

    // Disable/enable controls depending on connection state
    updateVisualState: function(state) {

        document.documentElement.classList.remove("noVNC_connecting");
        document.documentElement.classList.remove("noVNC_connected");
        document.documentElement.classList.remove("noVNC_disconnecting");
        document.documentElement.classList.remove("noVNC_reconnecting");

        let transition_elem = document.getElementById("noVNC_transition_text");
        switch (state) {
            case 'init':
                break;
            case 'connecting':
                transition_elem.textContent = _("Connecting...");
                document.documentElement.classList.add("noVNC_connecting");
                break;
            case 'connected':
                document.documentElement.classList.add("noVNC_connected");
                break;
            case 'disconnecting':
                transition_elem.textContent = _("Disconnecting...");
                document.documentElement.classList.add("noVNC_disconnecting");
                break;
            case 'disconnected':
                break;
            case 'reconnecting':
                transition_elem.textContent = _("Reconnecting...");
                document.documentElement.classList.add("noVNC_reconnecting");
                break;
            default:
                Log.Error("Invalid visual state: " + state);
                UI.showStatus(_("Internal error"), 'error');
                return;
        }

        UI.enableDisableViewClip();

        if (UI.connected) {
            UI.disableSetting('encrypt');
            UI.disableSetting('shared');
            UI.disableSetting('host');
            UI.disableSetting('port');
            UI.disableSetting('path');
            UI.disableSetting('repeaterID');
            UI.updateViewClip();
            UI.setMouseButton(1);

            // Hide the controlbar after 2 seconds
            UI.closeControlbarTimeout = setTimeout(UI.closeControlbar, 2000);
        } else {
            UI.enableSetting('encrypt');
            UI.enableSetting('shared');
            UI.enableSetting('host');
            UI.enableSetting('port');
            UI.enableSetting('path');
            UI.enableSetting('repeaterID');
            UI.updatePowerButton();
            UI.keepControlbar();
        }

        // Hide input related buttons in view only mode
        if (UI.rfb && UI.rfb.viewOnly) {
            document.getElementById('noVNC_keyboard_button')
                .classList.add('noVNC_hidden');
            document.getElementById('noVNC_toggle_extra_keys_button')
                .classList.add('noVNC_hidden');
        } else {
            document.getElementById('noVNC_keyboard_button')
                .classList.remove('noVNC_hidden');
            document.getElementById('noVNC_toggle_extra_keys_button')
                .classList.remove('noVNC_hidden');
        }

        // State change disables viewport dragging.
        // It is enabled (toggled) by direct click on the button
        UI.setViewDrag(false);

        // State change also closes the password dialog
        document.getElementById('noVNC_password_dlg')
            .classList.remove('noVNC_open');
    },

    showStatus: function(text, status_type, time) {
        var statusElem = document.getElementById('noVNC_status');

        clearTimeout(UI.statusTimeout);

        if (typeof status_type === 'undefined') {
            status_type = 'normal';
        }

        statusElem.classList.remove("noVNC_status_normal");
        statusElem.classList.remove("noVNC_status_warn");
        statusElem.classList.remove("noVNC_status_error");

        switch (status_type) {
            case 'warning':
            case 'warn':
                statusElem.classList.add("noVNC_status_warn");
                break;
            case 'error':
                statusElem.classList.add("noVNC_status_error");
                break;
            case 'normal':
            case 'info':
            default:
                statusElem.classList.add("noVNC_status_normal");
                break;
        }

        statusElem.textContent = text;
        statusElem.classList.add("noVNC_open");

        // If no time was specified, show the status for 1.5 seconds
        if (typeof time === 'undefined') {
            time = 1500;
        }

        // Error messages do not timeout
        if (status_type !== 'error') {
            UI.statusTimeout = window.setTimeout(UI.hideStatus, time);
        }
    },

    hideStatus: function() {
        clearTimeout(UI.statusTimeout);
        document.getElementById('noVNC_status').classList.remove("noVNC_open");
    },

    activateControlbar: function(event) {
        clearTimeout(UI.idleControlbarTimeout);
        // We manipulate the anchor instead of the actual control
        // bar in order to avoid creating new a stacking group
        document.getElementById('noVNC_control_bar_anchor')
            .classList.remove("noVNC_idle");
        UI.idleControlbarTimeout = window.setTimeout(UI.idleControlbar, 2000);
    },

    idleControlbar: function() {
        document.getElementById('noVNC_control_bar_anchor')
            .classList.add("noVNC_idle");
    },

    keepControlbar: function() {
        clearTimeout(UI.closeControlbarTimeout);
    },

    openControlbar: function() {
        document.getElementById('noVNC_control_bar')
            .classList.add("noVNC_open");
    },

    closeControlbar: function() {
        UI.closeAllPanels();
        document.getElementById('noVNC_control_bar')
            .classList.remove("noVNC_open");
    },

    toggleControlbar: function() {
        if (document.getElementById('noVNC_control_bar')
            .classList.contains("noVNC_open")) {
            UI.closeControlbar();
        } else {
            UI.openControlbar();
        }
    },

    toggleControlbarSide: function () {
        // Temporarily disable animation to avoid weird movement
        var bar = document.getElementById('noVNC_control_bar');
        bar.style.transitionDuration = '0s';
        bar.addEventListener('transitionend', function () { this.style.transitionDuration = ""; });

        var anchor = document.getElementById('noVNC_control_bar_anchor');
        if (anchor.classList.contains("noVNC_right")) {
            WebUtil.writeSetting('controlbar_pos', 'left');
            anchor.classList.remove("noVNC_right");
        } else {
            WebUtil.writeSetting('controlbar_pos', 'right');
            anchor.classList.add("noVNC_right");
        }

        // Consider this a movement of the handle
        UI.controlbarDrag = true;
    },

    showControlbarHint: function (show) {
        var hint = document.getElementById('noVNC_control_bar_hint');
        if (show) {
            hint.classList.add("noVNC_active");
        } else {
            hint.classList.remove("noVNC_active");
        }
    },

    dragControlbarHandle: function (e) {
        if (!UI.controlbarGrabbed) return;

        var ptr = getPointerEvent(e);

        var anchor = document.getElementById('noVNC_control_bar_anchor');
        if (ptr.clientX < (window.innerWidth * 0.1)) {
            if (anchor.classList.contains("noVNC_right")) {
                UI.toggleControlbarSide();
            }
        } else if (ptr.clientX > (window.innerWidth * 0.9)) {
            if (!anchor.classList.contains("noVNC_right")) {
                UI.toggleControlbarSide();
            }
        }

        if (!UI.controlbarDrag) {
            // The goal is to trigger on a certain physical width, the
            // devicePixelRatio brings us a bit closer but is not optimal.
            var dragThreshold = 10 * (window.devicePixelRatio || 1);
            var dragDistance = Math.abs(ptr.clientY - UI.controlbarMouseDownClientY);

            if (dragDistance < dragThreshold) return;

            UI.controlbarDrag = true;
        }

        var eventY = ptr.clientY - UI.controlbarMouseDownOffsetY;

        UI.moveControlbarHandle(eventY);

        e.preventDefault();
        e.stopPropagation();
        UI.keepControlbar();
        UI.activateControlbar();
    },

    // Move the handle but don't allow any position outside the bounds
    moveControlbarHandle: function (viewportRelativeY) {
        var handle = document.getElementById("noVNC_control_bar_handle");
        var handleHeight = handle.getBoundingClientRect().height;
        var controlbarBounds = document.getElementById("noVNC_control_bar")
            .getBoundingClientRect();
        var margin = 10;

        // These heights need to be non-zero for the below logic to work
        if (handleHeight === 0 || controlbarBounds.height === 0) {
            return;
        }

        var newY = viewportRelativeY;

        // Check if the coordinates are outside the control bar
        if (newY < controlbarBounds.top + margin) {
            // Force coordinates to be below the top of the control bar
            newY = controlbarBounds.top + margin;

        } else if (newY > controlbarBounds.top +
                   controlbarBounds.height - handleHeight - margin) {
            // Force coordinates to be above the bottom of the control bar
            newY = controlbarBounds.top +
                controlbarBounds.height - handleHeight - margin;
        }

        // Corner case: control bar too small for stable position
        if (controlbarBounds.height < (handleHeight + margin * 2)) {
            newY = controlbarBounds.top +
                (controlbarBounds.height - handleHeight) / 2;
        }

        // The transform needs coordinates that are relative to the parent
        var parentRelativeY = newY - controlbarBounds.top;
        handle.style.transform = "translateY(" + parentRelativeY + "px)";
    },

    updateControlbarHandle: function () {
        // Since the control bar is fixed on the viewport and not the page,
        // the move function expects coordinates relative the the viewport.
        var handle = document.getElementById("noVNC_control_bar_handle");
        var handleBounds = handle.getBoundingClientRect();
        UI.moveControlbarHandle(handleBounds.top);
    },

    controlbarHandleMouseUp: function(e) {
        if ((e.type == "mouseup") && (e.button != 0)) return;

        // mouseup and mousedown on the same place toggles the controlbar
        if (UI.controlbarGrabbed && !UI.controlbarDrag) {
            UI.toggleControlbar();
            e.preventDefault();
            e.stopPropagation();
            UI.keepControlbar();
            UI.activateControlbar();
        }
        UI.controlbarGrabbed = false;
        UI.showControlbarHint(false);
    },

    controlbarHandleMouseDown: function(e) {
        if ((e.type == "mousedown") && (e.button != 0)) return;

        var ptr = getPointerEvent(e);

        var handle = document.getElementById("noVNC_control_bar_handle");
        var bounds = handle.getBoundingClientRect();

        // Touch events have implicit capture
        if (e.type === "mousedown") {
            setCapture(handle);
        }

        UI.controlbarGrabbed = true;
        UI.controlbarDrag = false;

        UI.showControlbarHint(true);

        UI.controlbarMouseDownClientY = ptr.clientY;
        UI.controlbarMouseDownOffsetY = ptr.clientY - bounds.top;
        e.preventDefault();
        e.stopPropagation();
        UI.keepControlbar();
        UI.activateControlbar();
    },

    toggleExpander: function(e) {
        if (this.classList.contains("noVNC_open")) {
            this.classList.remove("noVNC_open");
        } else {
            this.classList.add("noVNC_open");
        }
    },

/* ------^-------
 *    /VISUAL
 * ==============
 *    SETTINGS
 * ------v------*/

    // Initial page load read/initialization of settings
    initSetting: function(name, defVal) {
        // Check Query string followed by cookie
        var val = WebUtil.getConfigVar(name);
        if (val === null) {
            val = WebUtil.readSetting(name, defVal);
        }
        UI.updateSetting(name, val);
        return val;
    },

    // Update cookie and form control setting. If value is not set, then
    // updates from control to current cookie setting.
    updateSetting: function(name, value) {

        // Save the cookie for this session
        if (typeof value !== 'undefined') {
            WebUtil.writeSetting(name, value);
        }

        // Update the settings control
        value = UI.getSetting(name);

        var ctrl = document.getElementById('noVNC_setting_' + name);
        if (ctrl.type === 'checkbox') {
            ctrl.checked = value;

        } else if (typeof ctrl.options !== 'undefined') {
            for (var i = 0; i < ctrl.options.length; i += 1) {
                if (ctrl.options[i].value === value) {
                    ctrl.selectedIndex = i;
                    break;
                }
            }
        } else {
            /*Weird IE9 error leads to 'null' appearring
            in textboxes instead of ''.*/
            if (value === null) {
                value = "";
            }
            ctrl.value = value;
        }
    },

    // Save control setting to cookie
    saveSetting: function(name) {
        var val, ctrl = document.getElementById('noVNC_setting_' + name);
        if (ctrl.type === 'checkbox') {
            val = ctrl.checked;
        } else if (typeof ctrl.options !== 'undefined') {
            val = ctrl.options[ctrl.selectedIndex].value;
        } else {
            val = ctrl.value;
        }
        WebUtil.writeSetting(name, val);
        //Log.Debug("Setting saved '" + name + "=" + val + "'");
        return val;
    },

    // Read form control compatible setting from cookie
    getSetting: function(name) {
        var ctrl = document.getElementById('noVNC_setting_' + name);
        var val = WebUtil.readSetting(name);
        if (typeof val !== 'undefined' && val !== null && ctrl.type === 'checkbox') {
            if (val.toString().toLowerCase() in {'0':1, 'no':1, 'false':1}) {
                val = false;
            } else {
                val = true;
            }
        }
        return val;
    },

    // These helpers compensate for the lack of parent-selectors and
    // previous-sibling-selectors in CSS which are needed when we want to
    // disable the labels that belong to disabled input elements.
    disableSetting: function(name) {
        var ctrl = document.getElementById('noVNC_setting_' + name);
        ctrl.disabled = true;
        ctrl.label.classList.add('noVNC_disabled');
    },

    enableSetting: function(name) {
        var ctrl = document.getElementById('noVNC_setting_' + name);
        ctrl.disabled = false;
        ctrl.label.classList.remove('noVNC_disabled');
    },

/* ------^-------
 *   /SETTINGS
 * ==============
 *    PANELS
 * ------v------*/

    closeAllPanels: function() {
        UI.closeSettingsPanel();
        UI.closePowerPanel();
        UI.closeClipboardPanel();
        UI.closeExtraKeys();
    },

/* ------^-------
 *   /PANELS
 * ==============
 * SETTINGS (panel)
 * ------v------*/

    openSettingsPanel: function() {
        UI.closeAllPanels();
        UI.openControlbar();

        // Refresh UI elements from saved cookies
        UI.updateSetting('encrypt');
        UI.updateSetting('view_clip');
        UI.updateSetting('resize');
        UI.updateSetting('shared');
        UI.updateSetting('view_only');
        UI.updateSetting('path');
        UI.updateSetting('repeaterID');
        UI.updateSetting('logging');
        UI.updateSetting('reconnect');
        UI.updateSetting('reconnect_delay');

        document.getElementById('noVNC_settings')
            .classList.add("noVNC_open");
        document.getElementById('noVNC_settings_button')
            .classList.add("noVNC_selected");
    },

    closeSettingsPanel: function() {
        document.getElementById('noVNC_settings')
            .classList.remove("noVNC_open");
        document.getElementById('noVNC_settings_button')
            .classList.remove("noVNC_selected");
    },

    toggleSettingsPanel: function() {
        if (document.getElementById('noVNC_settings')
            .classList.contains("noVNC_open")) {
            UI.closeSettingsPanel();
        } else {
            UI.openSettingsPanel();
        }
    },

/* ------^-------
 *   /SETTINGS
 * ==============
 *     POWER
 * ------v------*/

    openPowerPanel: function() {
        UI.closeAllPanels();
        UI.openControlbar();

        document.getElementById('noVNC_power')
            .classList.add("noVNC_open");
        document.getElementById('noVNC_power_button')
            .classList.add("noVNC_selected");
    },

    closePowerPanel: function() {
        document.getElementById('noVNC_power')
            .classList.remove("noVNC_open");
        document.getElementById('noVNC_power_button')
            .classList.remove("noVNC_selected");
    },

    togglePowerPanel: function() {
        if (document.getElementById('noVNC_power')
            .classList.contains("noVNC_open")) {
            UI.closePowerPanel();
        } else {
            UI.openPowerPanel();
        }
    },

    // Disable/enable power button
    updatePowerButton: function() {
        if (UI.connected &&
            UI.rfb.capabilities.power &&
            !UI.rfb.viewOnly) {
            document.getElementById('noVNC_power_button')
                .classList.remove("noVNC_hidden");
        } else {
            document.getElementById('noVNC_power_button')
                .classList.add("noVNC_hidden");
            // Close power panel if open
            UI.closePowerPanel();
        }
    },

/* ------^-------
 *    /POWER
 * ==============
 *   CLIPBOARD
 * ------v------*/

    openClipboardPanel: function() {
        UI.closeAllPanels();
        UI.openControlbar();

        document.getElementById('noVNC_clipboard')
            .classList.add("noVNC_open");
        document.getElementById('noVNC_clipboard_button')
            .classList.add("noVNC_selected");
    },

    closeClipboardPanel: function() {
        document.getElementById('noVNC_clipboard')
            .classList.remove("noVNC_open");
        document.getElementById('noVNC_clipboard_button')
            .classList.remove("noVNC_selected");
    },

    toggleClipboardPanel: function() {
        if (document.getElementById('noVNC_clipboard')
            .classList.contains("noVNC_open")) {
            UI.closeClipboardPanel();
        } else {
            UI.openClipboardPanel();
        }
    },

    clipboardReceive: function(e) {
        Log.Debug(">> UI.clipboardReceive: " + e.detail.text.substr(0,40) + "...");
        document.getElementById('noVNC_clipboard_text').value = e.detail.text;
        Log.Debug("<< UI.clipboardReceive");
    },

    clipboardClear: function() {
        document.getElementById('noVNC_clipboard_text').value = "";
        UI.rfb.clipboardPasteFrom("");
    },

    clipboardSend: function() {
        var text = document.getElementById('noVNC_clipboard_text').value;
        Log.Debug(">> UI.clipboardSend: " + text.substr(0,40) + "...");
        UI.rfb.clipboardPasteFrom(text);
        Log.Debug("<< UI.clipboardSend");
    },

/* ------^-------
 *  /CLIPBOARD
 * ==============
 *  CONNECTION
 * ------v------*/

    openConnectPanel: function() {
        document.getElementById('noVNC_connect_dlg')
            .classList.add("noVNC_open");
    },

    closeConnectPanel: function() {
        document.getElementById('noVNC_connect_dlg')
            .classList.remove("noVNC_open");
    },

    connect: function(event, password) {
        var host = UI.getSetting('host');
        var port = UI.getSetting('port');
        var path = UI.getSetting('path');

        if (typeof password === 'undefined') {
            password = WebUtil.getConfigVar('password');
            UI.reconnect_password = password;
        }

        if (password === null) {
            password = undefined;
        }

        if (!host) {
            Log.Error("Can't connect when host is: " + host);
            UI.showStatus(_("Must set host"), 'error');
            return;
        }

        UI.closeAllPanels();
        UI.closeConnectPanel();

        UI.updateVisualState('connecting');

        UI.updateViewOnly();

        var url;

        url = UI.getSetting('encrypt') ? 'wss' : 'ws';

        url += '://' + host;
        if(port) {
            url += ':' + port;
        }
        url += '/' + path;

        UI.rfb = new RFB(document.getElementById('noVNC_canvas'), url,
                         { shared: UI.getSetting('shared'),
                           repeaterID: UI.getSetting('repeaterID'),
                           credentials: { password: password } });
        UI.rfb.addEventListener("connect", UI.connectFinished);
        UI.rfb.addEventListener("disconnect", UI.disconnectFinished);
        UI.rfb.addEventListener("credentialsrequired", UI.credentials);
        UI.rfb.addEventListener("capabilities", function () { UI.updatePowerButton(); UI.initialResize(); });
        UI.rfb.addEventListener("clipboard", UI.clipboardReceive);
        UI.rfb.addEventListener("bell", UI.bell);
        UI.rfb.addEventListener("fbresize", UI.updateSessionSize);
        UI.rfb.addEventListener("desktopname", UI.updateDesktopName);
    },

    disconnect: function() {
        UI.closeAllPanels();
        UI.rfb.disconnect();

        UI.connected = false;

        // Disable automatic reconnecting
        UI.inhibit_reconnect = true;

        UI.updateVisualState('disconnecting');

        // Don't display the connection settings until we're actually disconnected
    },

    reconnect: function() {
        UI.reconnect_callback = null;

        // if reconnect has been disabled in the meantime, do nothing.
        if (UI.inhibit_reconnect) {
            return;
        }

        UI.connect(null, UI.reconnect_password);
    },

    connectFinished: function (e) {
        UI.connected = true;
        UI.inhibit_reconnect = false;
        UI.doneInitialResize = false;

        let msg;
        if (UI.getSetting('encrypt')) {
            msg = _("Connected (encrypted) to ") + UI.desktopName;
        } else {
            msg = _("Connected (unencrypted) to ") + UI.desktopName;
        }
        UI.showStatus(msg);
        UI.updateVisualState('connected');

        // Do this last because it can only be used on rendered elements
        document.getElementById('noVNC_canvas').focus();
    },

    disconnectFinished: function (e) {
        // This variable is ideally set when disconnection starts, but
        // when the disconnection isn't clean or if it is initiated by
        // the server, we need to do it here as well since
        // UI.disconnect() won't be used in those cases.
        UI.connected = false;

        if (typeof e.detail.reason !== 'undefined') {
            UI.showStatus(e.detail.reason, 'error');
            UI.updateVisualState('disconnected');
        } else if (UI.getSetting('reconnect', false) === true && !UI.inhibit_reconnect) {
            UI.updateVisualState('reconnecting');

            var delay = parseInt(UI.getSetting('reconnect_delay'));
            UI.reconnect_callback = setTimeout(UI.reconnect, delay);
            return;
        } else {
            UI.updateVisualState('disconnected');
            UI.showStatus(_("Disconnected"), 'normal');
        }

        UI.openControlbar();
        UI.openConnectPanel();
    },

    cancelReconnect: function() {
        if (UI.reconnect_callback !== null) {
            clearTimeout(UI.reconnect_callback);
            UI.reconnect_callback = null;
        }

        UI.updateVisualState('disconnected');

        UI.openControlbar();
        UI.openConnectPanel();
    },

/* ------^-------
 *  /CONNECTION
 * ==============
 *   PASSWORD
 * ------v------*/

    credentials: function(e) {
        // FIXME: handle more types
        document.getElementById('noVNC_password_dlg')
            .classList.add('noVNC_open');

        setTimeout(function () {
                document.getElementById('noVNC_password_input').focus();
            }, 100);

        Log.Warn("Server asked for a password");
        UI.showStatus(_("Password is required"), "warning");
    },

    setPassword: function(e) {
        // Prevent actually submitting the form
        e.preventDefault();

        var inputElem = document.getElementById('noVNC_password_input');
        var password = inputElem.value;
        // Clear the input after reading the password
        inputElem.value = "";
        UI.rfb.sendCredentials({ password: password });
        UI.reconnect_password = password;
        document.getElementById('noVNC_password_dlg')
            .classList.remove('noVNC_open');
    },

/* ------^-------
 *  /PASSWORD
 * ==============
 *   FULLSCREEN
 * ------v------*/

    toggleFullscreen: function() {
        if (document.fullscreenElement || // alternative standard method
            document.mozFullScreenElement || // currently working methods
            document.webkitFullscreenElement ||
            document.msFullscreenElement) {
            if (document.exitFullscreen) {
                document.exitFullscreen();
            } else if (document.mozCancelFullScreen) {
                document.mozCancelFullScreen();
            } else if (document.webkitExitFullscreen) {
                document.webkitExitFullscreen();
            } else if (document.msExitFullscreen) {
                document.msExitFullscreen();
            }
        } else {
            if (document.documentElement.requestFullscreen) {
                document.documentElement.requestFullscreen();
            } else if (document.documentElement.mozRequestFullScreen) {
                document.documentElement.mozRequestFullScreen();
            } else if (document.documentElement.webkitRequestFullscreen) {
                document.documentElement.webkitRequestFullscreen(Element.ALLOW_KEYBOARD_INPUT);
            } else if (document.body.msRequestFullscreen) {
                document.body.msRequestFullscreen();
            }
        }
        UI.enableDisableViewClip();
        UI.updateFullscreenButton();
    },

    updateFullscreenButton: function() {
        if (document.fullscreenElement || // alternative standard method
            document.mozFullScreenElement || // currently working methods
            document.webkitFullscreenElement ||
            document.msFullscreenElement ) {
            document.getElementById('noVNC_fullscreen_button')
                .classList.add("noVNC_selected");
        } else {
            document.getElementById('noVNC_fullscreen_button')
                .classList.remove("noVNC_selected");
        }
    },

/* ------^-------
 *  /FULLSCREEN
 * ==============
 *     RESIZE
 * ------v------*/

    // Apply remote resizing or local scaling
    applyResizeMode: function() {
        if (!UI.rfb) return;

        var screen = UI.screenSize();

        if (screen && UI.connected) {

            var resizeMode = UI.getSetting('resize');
            UI.rfb.viewportScale = 1.0;

            // Make sure the viewport is adjusted first
            UI.updateViewClip();

            if (resizeMode === 'remote') {

                // Request changing the resolution of the remote display to
                // the size of the local browser viewport.

                // In order to not send multiple requests before the browser-resize
                // is finished we wait 0.5 seconds before sending the request.
                clearTimeout(UI.resizeTimeout);
                UI.resizeTimeout = setTimeout(function(){
                    // Request a remote size covering the viewport
                    if (UI.rfb.requestDesktopSize(screen.w, screen.h)) {
                        Log.Debug('Requested new desktop size: ' +
                                   screen.w + 'x' + screen.h);
                    }
                }, 500);

            } else {
                UI.updateScaling();
            }
        }
    },

    // Re-calculate local scaling
    updateScaling: function() {
        if (!UI.rfb) return;

        var resizeMode = UI.getSetting('resize');
        if (resizeMode !== 'scale') {
            return;
        }

        var screen = UI.screenSize();

        if (!screen || !UI.connected) {
            return;
        }

        UI.rfb.autoscale(screen.w, screen.h);
        UI.fixScrollbars();
    },

    // Gets the the size of the available viewport in the browser window
    screenSize: function() {
        var screen = document.getElementById('noVNC_screen');
        return {w: screen.offsetWidth, h: screen.offsetHeight};
    },

    // Normally we only apply the current resize mode after a window resize
    // event. This means that when a new connection is opened, there is no
    // resize mode active.
    // We have to wait until we know the capabilities of the server as
    // some calls later in the chain is dependant on knowing the
    // server-capabilities.
    initialResize: function() {
        if (UI.doneInitialResize) return;

        UI.applyResizeMode();
        UI.doneInitialResize = true;
    },

/* ------^-------
 *    /RESIZE
 * ==============
 * VIEW CLIPPING
 * ------v------*/

    // Set and configure viewport clipping
    setViewClip: function(clip) {
        UI.updateSetting('view_clip', clip);
        UI.updateViewClip();
    },

    // Update parameters that depend on the viewport clip setting
    updateViewClip: function() {
        if (!UI.rfb) return;

        var cur_clip = UI.rfb.clipViewport;
        var new_clip = UI.getSetting('view_clip');

        var resizeSetting = UI.getSetting('resize');
        if (resizeSetting === 'scale') {
            // Disable viewport clipping if we are scaling
            new_clip = false;
        } else if (isTouchDevice) {
            // Touch devices usually have shit scrollbars
            new_clip = true;
        }

        if (cur_clip !== new_clip) {
            UI.rfb.clipViewport = new_clip;
        }

        var size = UI.screenSize();

        if (new_clip && size) {
            // When clipping is enabled, the screen is limited to
            // the size of the browser window.
            UI.rfb.viewportChangeSize(size.w, size.h);
            UI.fixScrollbars();
        }

        // Changing the viewport may change the state of
        // the dragging button
        UI.updateViewDrag();
    },

    // Handle special cases where viewport clipping is forced on/off or locked
    enableDisableViewClip: function() {
        var resizeSetting = UI.getSetting('resize');
        // Disable clipping if we are scaling, connected or on touch
        if (resizeSetting === 'scale' ||
            isTouchDevice) {
            UI.disableSetting('view_clip');
        } else {
            UI.enableSetting('view_clip');
        }
    },

/* ------^-------
 * /VIEW CLIPPING
 * ==============
 *    VIEWDRAG
 * ------v------*/

    toggleViewDrag: function() {
        if (!UI.rfb) return;

        var drag = UI.rfb.dragViewport;
        UI.setViewDrag(!drag);
     },

    // Set the view drag mode which moves the viewport on mouse drags
    setViewDrag: function(drag) {
        if (!UI.rfb) return;

        UI.rfb.dragViewport = drag;

        UI.updateViewDrag();
    },

    updateViewDrag: function() {
        var clipping = false;

        if (!UI.connected) return;

        // Check if viewport drag is possible. It is only possible
        // if the remote display is clipping the client display.
        if (UI.rfb.clipViewport && UI.rfb.isClipped) {
            clipping = true;
        }

        var viewDragButton = document.getElementById('noVNC_view_drag_button');

        if (!clipping &&
            UI.rfb.dragViewport) {
            // The size of the remote display is the same or smaller
            // than the client display. Make sure viewport drag isn't
            // active when it can't be used.
            UI.rfb.dragViewport = false;
        }

        if (UI.rfb.dragViewport) {
            viewDragButton.classList.add("noVNC_selected");
        } else {
            viewDragButton.classList.remove("noVNC_selected");
        }

        // Different behaviour for touch vs non-touch
        // The button is disabled instead of hidden on touch devices
        if (isTouchDevice) {
            viewDragButton.classList.remove("noVNC_hidden");

            if (clipping) {
                viewDragButton.disabled = false;
            } else {
                viewDragButton.disabled = true;
            }
        } else {
            viewDragButton.disabled = false;

            if (clipping) {
                viewDragButton.classList.remove("noVNC_hidden");
            } else {
                viewDragButton.classList.add("noVNC_hidden");
            }
        }
    },

/* ------^-------
 *   /VIEWDRAG
 * ==============
 *    KEYBOARD
 * ------v------*/

    showVirtualKeyboard: function() {
        if (!isTouchDevice) return;

        var input = document.getElementById('noVNC_keyboardinput');

        if (document.activeElement == input) return;

        input.focus();

        try {
            var l = input.value.length;
            // Move the caret to the end
            input.setSelectionRange(l, l);
        } catch (err) {} // setSelectionRange is undefined in Google Chrome
    },

    hideVirtualKeyboard: function() {
        if (!isTouchDevice) return;

        var input = document.getElementById('noVNC_keyboardinput');

        if (document.activeElement != input) return;

        input.blur();
    },

    toggleVirtualKeyboard: function () {
        if (document.getElementById('noVNC_keyboard_button')
            .classList.contains("noVNC_selected")) {
            UI.hideVirtualKeyboard();
        } else {
            UI.showVirtualKeyboard();
        }
    },

    onfocusVirtualKeyboard: function(event) {
        document.getElementById('noVNC_keyboard_button')
            .classList.add("noVNC_selected");
        if (UI.rfb) {
            UI.rfb.set_focus_on_click(false);
        }
    },

    onblurVirtualKeyboard: function(event) {
        document.getElementById('noVNC_keyboard_button')
            .classList.remove("noVNC_selected");
        if (UI.rfb) {
            UI.rfb.set_focus_on_click(true);
        }
    },

    keepVirtualKeyboard: function(event) {
        var input = document.getElementById('noVNC_keyboardinput');

        // Only prevent focus change if the virtual keyboard is active
        if (document.activeElement != input) {
            return;
        }

        // Only allow focus to move to other elements that need
        // focus to function properly
        if (event.target.form !== undefined) {
            switch (event.target.type) {
                case 'text':
                case 'email':
                case 'search':
                case 'password':
                case 'tel':
                case 'url':
                case 'textarea':
                case 'select-one':
                case 'select-multiple':
                    return;
            }
        }

        event.preventDefault();
    },

    keyboardinputReset: function() {
        var kbi = document.getElementById('noVNC_keyboardinput');
        kbi.value = new Array(UI.defaultKeyboardinputLen).join("_");
        UI.lastKeyboardinput = kbi.value;
    },

    keyEvent: function (keysym, code, down) {
        if (!UI.rfb) return;

        UI.rfb.sendKey(keysym, code, down);
    },

    // When normal keyboard events are left uncought, use the input events from
    // the keyboardinput element instead and generate the corresponding key events.
    // This code is required since some browsers on Android are inconsistent in
    // sending keyCodes in the normal keyboard events when using on screen keyboards.
    keyInput: function(event) {

        if (!UI.rfb) return;

        var newValue = event.target.value;

        if (!UI.lastKeyboardinput) {
            UI.keyboardinputReset();
        }
        var oldValue = UI.lastKeyboardinput;

        var newLen;
        try {
            // Try to check caret position since whitespace at the end
            // will not be considered by value.length in some browsers
            newLen = Math.max(event.target.selectionStart, newValue.length);
        } catch (err) {
            // selectionStart is undefined in Google Chrome
            newLen = newValue.length;
        }
        var oldLen = oldValue.length;

        var backspaces;
        var inputs = newLen - oldLen;
        if (inputs < 0) {
            backspaces = -inputs;
        } else {
            backspaces = 0;
        }

        // Compare the old string with the new to account for
        // text-corrections or other input that modify existing text
        var i;
        for (i = 0; i < Math.min(oldLen, newLen); i++) {
            if (newValue.charAt(i) != oldValue.charAt(i)) {
                inputs = newLen - i;
                backspaces = oldLen - i;
                break;
            }
        }

        // Send the key events
        for (i = 0; i < backspaces; i++) {
            UI.rfb.sendKey(KeyTable.XK_BackSpace, "Backspace");
        }
        for (i = newLen - inputs; i < newLen; i++) {
            UI.rfb.sendKey(keysyms.lookup(newValue.charCodeAt(i)));
        }

        // Control the text content length in the keyboardinput element
        if (newLen > 2 * UI.defaultKeyboardinputLen) {
            UI.keyboardinputReset();
        } else if (newLen < 1) {
            // There always have to be some text in the keyboardinput
            // element with which backspace can interact.
            UI.keyboardinputReset();
            // This sometimes causes the keyboard to disappear for a second
            // but it is required for the android keyboard to recognize that
            // text has been added to the field
            event.target.blur();
            // This has to be ran outside of the input handler in order to work
            setTimeout(event.target.focus.bind(event.target), 0);
        } else {
            UI.lastKeyboardinput = newValue;
        }
    },

/* ------^-------
 *   /KEYBOARD
 * ==============
 *   EXTRA KEYS
 * ------v------*/

    openExtraKeys: function() {
        UI.closeAllPanels();
        UI.openControlbar();

        document.getElementById('noVNC_modifiers')
            .classList.add("noVNC_open");
        document.getElementById('noVNC_toggle_extra_keys_button')
            .classList.add("noVNC_selected");
    },

    closeExtraKeys: function() {
        document.getElementById('noVNC_modifiers')
            .classList.remove("noVNC_open");
        document.getElementById('noVNC_toggle_extra_keys_button')
            .classList.remove("noVNC_selected");
    },

    toggleExtraKeys: function() {
        if(document.getElementById('noVNC_modifiers')
            .classList.contains("noVNC_open")) {
            UI.closeExtraKeys();
        } else  {
            UI.openExtraKeys();
        }
    },

    sendEsc: function() {
        UI.rfb.sendKey(KeyTable.XK_Escape, "Escape");
    },

    sendTab: function() {
        UI.rfb.sendKey(KeyTable.XK_Tab);
    },

    toggleCtrl: function() {
        var btn = document.getElementById('noVNC_toggle_ctrl_button');
        if (btn.classList.contains("noVNC_selected")) {
            UI.rfb.sendKey(KeyTable.XK_Control_L, "ControlLeft", false);
            btn.classList.remove("noVNC_selected");
        } else {
            UI.rfb.sendKey(KeyTable.XK_Control_L, "ControlLeft", true);
            btn.classList.add("noVNC_selected");
        }
    },

    toggleAlt: function() {
        var btn = document.getElementById('noVNC_toggle_alt_button');
        if (btn.classList.contains("noVNC_selected")) {
            UI.rfb.sendKey(KeyTable.XK_Alt_L, "AltLeft", false);
            btn.classList.remove("noVNC_selected");
        } else {
            UI.rfb.sendKey(KeyTable.XK_Alt_L, "AltLeft", true);
            btn.classList.add("noVNC_selected");
        }
    },

    sendCtrlAltDel: function() {
        UI.rfb.sendCtrlAltDel();
    },

/* ------^-------
 *   /EXTRA KEYS
 * ==============
 *     MISC
 * ------v------*/

    setMouseButton: function(num) {
        var view_only = UI.rfb.viewOnly;
        if (UI.rfb && !view_only) {
            UI.rfb.touchButton = num;
        }

        var blist = [0, 1,2,4];
        for (var b = 0; b < blist.length; b++) {
            var button = document.getElementById('noVNC_mouse_button' +
                                                 blist[b]);
            if (blist[b] === num && !view_only) {
                button.classList.remove("noVNC_hidden");
            } else {
                button.classList.add("noVNC_hidden");
            }
        }
    },

    updateViewOnly: function() {
        if (!UI.rfb) return;
        UI.rfb.viewOnly = UI.getSetting('view_only');
    },

    updateLogging: function() {
        WebUtil.init_logging(UI.getSetting('logging'));
    },

    updateSessionSize: function(e) {
        UI.updateViewClip();
        UI.updateScaling();
        UI.fixScrollbars();
    },

    fixScrollbars: function() {
        // This is a hack because Chrome screws up the calculation
        // for when scrollbars are needed. So to fix it we temporarily
        // toggle them off and on.
        var screen = document.getElementById('noVNC_screen');
        screen.style.overflow = 'hidden';
        // Force Chrome to recalculate the layout by asking for
        // an element's dimensions
        screen.getBoundingClientRect();
        screen.style.overflow = "";
    },

    updateDesktopName: function(e) {
        UI.desktopName = e.detail.name;
        // Display the desktop name in the document title
        document.title = e.detail.name + " - noVNC";
    },

    bell: function(e) {
        if (WebUtil.getConfigVar('bell', 'on') === 'on') {
            var promise = document.getElementById('noVNC_bell').play();
            // The standards disagree on the return value here
            if (promise) {
                promise.catch(function(e) {
                    if (e.name === "NotAllowedError") {
                        // Ignore when the browser doesn't let us play audio.
                        // It is common that the browsers require audio to be
                        // initiated from a user action.
                    } else {
                        Log.Error("Unable to play bell: " + e);
                    }
                });
            }
        }
    },

    //Helper to add options to dropdown.
    addOption: function(selectbox, text, value) {
        var optn = document.createElement("OPTION");
        optn.text = text;
        optn.value = value;
        selectbox.options.add(optn);
    },

/* ------^-------
 *    /MISC
 * ==============
 */
};

// Set up translations
var LINGUAS = ["de", "el", "nl", "pl", "sv"];
l10n.setup(LINGUAS);
if (l10n.language !== "en" && l10n.dictionary === undefined) {
    WebUtil.fetchJSON('app/locale/' + l10n.language + '.json', function (translations) {
        l10n.dictionary = translations;

        // wait for translations to load before loading the UI
        UI.prime();
    }, function (err) {
        throw err;
    });
} else {
    UI.prime();
}

export default UI;