Implement always-on-screen capability for widgets

As per https://github.com/matrix-org/matrix-doc/issues/1354

This is whitelisted to only jitsi widgets for now as per comment,
mostly because any widget that we may make always-on-screen we need
to preemptively put in a PersistedElement container, which is
unnecessary for any other widget.

Apologies that this does a bunch of refactoring which could have
been split out separately: I only discovered what needed to be
refactored in the process of doing this.

Fixes element-hq/element-web#6984

res/css/views/rooms/_EventTile.scss

@@ -31,7 +31,6 @@ limitations under the License.
     top: 14px;
     left: 8px;
     cursor: pointer;
-    z-index: 2;
 }
 
 .mx_EventTile.mx_EventTile_info .mx_EventTile_avatar {

src/CallHandler.js

@@ -444,7 +444,8 @@ function _startCallApp(roomId, type) {
         'email=$matrix_user_id',
     ].join('&');
     const widgetUrl = (
-        'https://scalar.vector.im/api/widgets' +
+        //'https://scalar.vector.im/api/widgets' +
+        'http://localhost:8620' +
         '/jitsi.html?' +
         queryString
     );

src/FromWidgetPostMessageApi.js

@@ -18,6 +18,7 @@ import URL from 'url';
 import dis from './dispatcher';
 import IntegrationManager from './IntegrationManager';
 import WidgetMessagingEndpoint from './WidgetMessagingEndpoint';
+import ActiveWidgetStore from './stores/ActiveWidgetStore';
 
 const WIDGET_API_VERSION = '0.0.1'; // Current API version
 const SUPPORTED_WIDGET_API_VERSIONS = [
@@ -155,6 +156,14 @@ export default class FromWidgetPostMessageApi {
             const integType = (data && data.integType) ? data.integType : null;
             const integId = (data && data.integId) ? data.integId : null;
             IntegrationManager.open(integType, integId);
+        } else if (action === 'set_always_on_screen') {
+            // This is a new message: there is no reason to support the deprecated widgetData here
+            const data = event.data.data;
+            const val = data.value;
+
+            if (ActiveWidgetStore.widgetHasCapability(widgetId, 'm.always_on_screen')) {
+                ActiveWidgetStore.setWidgetPersistence(widgetId, val);
+            }
         } else {
             console.warn('Widget postMessage event unhandled');
             this.sendError(event, {message: 'The postMessage was unhandled'});

src/components/views/elements/AppTile.js

@@ -1,5 +1,6 @@
 /**
 Copyright 2017 Vector Creations Ltd
+Copyright 2018 New Vector Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -33,24 +34,28 @@ import AppWarning from './AppWarning';
 import MessageSpinner from './MessageSpinner';
 import WidgetUtils from '../../../utils/WidgetUtils';
 import dis from '../../../dispatcher';
+import ActiveWidgetStore from '../../../stores/ActiveWidgetStore';
 
 const ALLOWED_APP_URL_SCHEMES = ['https:', 'http:'];
 const ENABLE_REACT_PERF = false;
 
 export default class AppTile extends React.Component {
     constructor(props) {
         super(props);
+
+        // The key used for PersistedElement
+        this._persistKey = 'widget_' + this.props.id;
+
         this.state = this._getNewState(props);
 
-        this._onWidgetAction = this._onWidgetAction.bind(this);
+        this._onAction = this._onAction.bind(this);
         this._onMessage = this._onMessage.bind(this);
         this._onLoaded = this._onLoaded.bind(this);
         this._onEditClick = this._onEditClick.bind(this);
         this._onDeleteClick = this._onDeleteClick.bind(this);
         this._onSnapshotClick = this._onSnapshotClick.bind(this);
         this.onClickMenuBar = this.onClickMenuBar.bind(this);
         this._onMinimiseClick = this._onMinimiseClick.bind(this);
-        this._onInitialLoad = this._onInitialLoad.bind(this);
         this._grantWidgetPermission = this._grantWidgetPermission.bind(this);
         this._revokeWidgetPermission = this._revokeWidgetPermission.bind(this);
         this._onPopoutWidgetClick = this._onPopoutWidgetClick.bind(this);
@@ -66,9 +71,12 @@ export default class AppTile extends React.Component {
     _getNewState(newProps) {
         const widgetPermissionId = [newProps.room.roomId, encodeURIComponent(newProps.url)].join('_');
         const hasPermissionToLoad = localStorage.getItem(widgetPermissionId);
+
+        const PersistedElement = sdk.getComponent("elements.PersistedElement");
         return {
             initialising: true, // True while we are mangling the widget URL
-            loading: this.props.waitForIframeLoad, // True while the iframe content is loading
+            // True while the iframe content is loading
+            loading: this.props.waitForIframeLoad && !PersistedElement.isMounted(this._persistKey),
             widgetUrl: this._addWurlParams(newProps.url),
             widgetPermissionId: widgetPermissionId,
             // Assume that widget has permission to load if we are the user who
@@ -77,9 +85,6 @@ export default class AppTile extends React.Component {
             error: null,
             deleting: false,
             widgetPageTitle: newProps.widgetPageTitle,
-            allowedCapabilities: (this.props.whitelistCapabilities && this.props.whitelistCapabilities.length > 0) ?
-                this.props.whitelistCapabilities : [],
-            requestedCapabilities: [],
         };
     }
 
@@ -89,7 +94,7 @@ export default class AppTile extends React.Component {
      * @return {Boolean}            True if capability supported
      */
     _hasCapability(capability) {
-        return this.state.allowedCapabilities.some((c) => {return c === capability;});
+        return ActiveWidgetStore.widgetHasCapability(this.props.id, capability);
     }
 
     /**
@@ -142,30 +147,24 @@ export default class AppTile extends React.Component {
         window.addEventListener('message', this._onMessage, false);
 
         // Widget action listeners
-        this.dispatcherRef = dis.register(this._onWidgetAction);
-    }
-
-    componentDidUpdate() {
-        // Allow parents to access widget messaging
-        if (this.props.collectWidgetMessaging) {
-            this.props.collectWidgetMessaging(this.widgetMessaging);
-        }
+        this.dispatcherRef = dis.register(this._onAction);
     }
 
     componentWillUnmount() {
         // Widget action listeners
         dis.unregister(this.dispatcherRef);
 
-        // Widget postMessage listeners
-        try {
-            if (this.widgetMessaging) {
-                this.widgetMessaging.stop();
-            }
-        } catch (e) {
-            console.error('Failed to stop listening for widgetMessaging events', e.message);
-        }
         // Jitsi listener
         window.removeEventListener('message', this._onMessage);
+
+        // if it's not remaining on screen, get rid of the PersistedElement container
+        if (!ActiveWidgetStore.getWidgetPersistence(this.props.id)) {
+            // FIXME: ActiveWidgetStore should probably worry about this?
+            const PersistedElement = sdk.getComponent("elements.PersistedElement");
+            PersistedElement.destroyElement(this._persistKey);
+            ActiveWidgetStore.delWidgetMessaging(this.props.id);
+            ActiveWidgetStore.delWidgetCapabilities(this.props.id);
+        }
     }
 
     /**
@@ -286,7 +285,7 @@ export default class AppTile extends React.Component {
 
     _onSnapshotClick(e) {
         console.warn("Requesting widget snapshot");
-        this.widgetMessaging.getScreenshot()
+        ActiveWidgetStore.getWidgetMessaging(this.props.id).getScreenshot()
             .catch((err) => {
                 console.error("Failed to get screenshot", err);
             })
@@ -341,19 +340,19 @@ export default class AppTile extends React.Component {
      * Called when widget iframe has finished loading
      */
     _onLoaded() {
-        if (!this.widgetMessaging) {
-            this._onInitialLoad();
+        if (!ActiveWidgetStore.getWidgetMessaging(this.props.id)) {
+            this._setupWidgetMessaging();
         }
         this.setState({loading: false});
     }
 
-    /**
-     * Called on initial load of the widget iframe
-     */
-    _onInitialLoad() {
-        this.widgetMessaging = new WidgetMessaging(this.props.id, this.props.url, this.refs.appFrame.contentWindow);
-        this.widgetMessaging.getCapabilities().then((requestedCapabilities) => {
-            console.log(`Widget ${this.props.id} requested capabilities:`, requestedCapabilities);
+    _setupWidgetMessaging() {
+        // FIXME: There's probably no reason to do this here: it should probably be done entirely
+        // in ActiveWidgetStore.
+        const widgetMessaging = new WidgetMessaging(this.props.id, this.props.url, this.refs.appFrame.contentWindow);
+        ActiveWidgetStore.setWidgetMessaging(this.props.id, widgetMessaging);
+        widgetMessaging.getCapabilities().then((requestedCapabilities) => {
+            console.log(`Widget ${this.props.id} requested capabilities: ` + requestedCapabilities);
             requestedCapabilities = requestedCapabilities || [];
 
             // Allow whitelisted capabilities
@@ -365,16 +364,15 @@ export default class AppTile extends React.Component {
                 }, this.props.whitelistCapabilities);
 
                 if (requestedWhitelistCapabilies.length > 0 ) {
-                    console.warn(`Widget ${this.props.id} allowing requested, whitelisted properties:`,
-                        requestedWhitelistCapabilies);
+                    console.warn(`Widget ${this.props.id} allowing requested, whitelisted properties: ` +
+                        requestedWhitelistCapabilies,
+                    );
                 }
             }
 
             // TODO -- Add UI to warn about and optionally allow requested capabilities
-            this.setState({
-                requestedCapabilities,
-                allowedCapabilities: this.state.allowedCapabilities.concat(requestedWhitelistCapabilies),
-            });
+
+            ActiveWidgetStore.setWidgetCapabilities(this.props.id, requestedWhitelistCapabilies);
 
             if (this.props.onCapabilityRequest) {
                 this.props.onCapabilityRequest(requestedCapabilities);
@@ -384,7 +382,7 @@ export default class AppTile extends React.Component {
         });
     }
 
-    _onWidgetAction(payload) {
+    _onAction(payload) {
         if (payload.widgetId === this.props.id) {
             switch (payload.action) {
                 case 'm.sticker':
@@ -562,6 +560,15 @@ export default class AppTile extends React.Component {
                             ></iframe>
                         </div>
                     );
+                    // if the widget would be allowed to remian on screen, we must put it in
+                    // a PersistedElement from the get-go, otherwise the iframe will be
+                    // re-mounted later when we do.
+                    if (this.props.whitelistCapabilities.includes('m.always_on_screen')) {
+                        const PersistedElement = sdk.getComponent("elements.PersistedElement");
+                        appTileBody = <PersistedElement persistKey={this._persistKey}>
+                            {appTileBody}
+                        </PersistedElement>;
+                    }
                 }
             } else {
                 const isRoomEncrypted = MatrixClientPeg.get().isRoomEncrypted(this.props.room.roomId);

src/components/views/elements/PersistedElement.js

@@ -22,8 +22,12 @@ const PropTypes = require('prop-types');
 // of doing reusable widgets like dialog boxes & menus where we go and
 // pass in a custom control as the actual body.
 
+function getContainer(containerId) {
+    return document.getElementById(containerId);
+}
+
 function getOrCreateContainer(containerId) {
-    let container = document.getElementById(containerId);
+    let container = getContainer(containerId);
 
     if (!container) {
         container = document.createElement("div");
@@ -60,6 +64,24 @@ export default class PersistedElement extends React.Component {
         this.collectChild = this.collectChild.bind(this);
     }
 
+    /**
+     * Removes the DOM elements created when a PersistedElement with the given
+     * persistKey was mounted. The DOM elements will be re-added if another
+     * PeristedElement is mounted in the future.
+     *
+     * @param {string} persistKey Key used to uniquely identify this PersistedElement
+     */
+    static destroyElement(persistKey) {
+        const container = getContainer('mx_persistedElement_' + persistKey);
+        if (container) {
+            container.remove();
+        }
+    }
+
+    static isMounted(persistKey) {
+        return Boolean(getContainer('mx_persistedElement_' + persistKey));
+    }
+
     collectChildContainer(ref) {
         this.childContainer = ref;
     }

src/components/views/rooms/AppsDrawer.js

@@ -1,5 +1,6 @@
 /*
 Copyright 2017 Vector Creations Ltd
+Copyright 2018 New Vector Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -214,24 +215,30 @@ module.exports = React.createClass({
     render: function() {
         const enableScreenshots = SettingsStore.getValue("enableWidgetScreenshots", this.props.room.room_id);
 
-        const apps = this.state.apps.map(
-            (app, index, arr) => {
-                return (<AppTile
-                    key={app.id}
-                    id={app.id}
-                    url={app.url}
-                    name={app.name}
-                    type={app.type}
-                    fullWidth={arr.length<2 ? true : false}
-                    room={this.props.room}
-                    userId={this.props.userId}
-                    show={this.props.showApps}
-                    creatorUserId={app.creatorUserId}
-                    widgetPageTitle={(app.data && app.data.title) ? app.data.title : ''}
-                    waitForIframeLoad={app.waitForIframeLoad}
-                    whitelistCapabilities={enableScreenshots ? ["m.capability.screenshot"] : []}
-                />);
-            });
+        const apps = this.state.apps.map((app, index, arr) => {
+            const capWhitelist = enableScreenshots ? ["m.capability.screenshot"] : [];
+
+            // Obviously anyone that can add a widget can claim it's a jitsi widget,
+            // so this doesn't really offer much over the set of domains we load
+            // widgets from at all, but it probably makes sense for sanity.
+            if (app.type == 'jitsi') capWhitelist.push("m.always_on_screen");
+
+            return (<AppTile
+                key={app.id}
+                id={app.id}
+                url={app.url}
+                name={app.name}
+                type={app.type}
+                fullWidth={arr.length<2 ? true : false}
+                room={this.props.room}
+                userId={this.props.userId}
+                show={this.props.showApps}
+                creatorUserId={app.creatorUserId}
+                widgetPageTitle={(app.data && app.data.title) ? app.data.title : ''}
+                waitForIframeLoad={app.waitForIframeLoad}
+                whitelistCapabilities={capWhitelist}
+            />);
+        });
 
         let addWidget;
         if (this.props.showApps &&

src/components/views/rooms/Stickerpicker.js

@@ -24,6 +24,7 @@ import ScalarAuthClient from '../../../ScalarAuthClient';
 import dis from '../../../dispatcher';
 import AccessibleButton from '../elements/AccessibleButton';
 import WidgetUtils from '../../../utils/WidgetUtils';
+import ActiveWidgetStore from '../../../stores/ActiveWidgetStore';
 
 const widgetType = 'm.stickerpicker';
 
@@ -43,8 +44,6 @@ export default class Stickerpicker extends React.Component {
         this._onResize = this._onResize.bind(this);
         this._onFinished = this._onFinished.bind(this);
 
-        this._collectWidgetMessaging = this._collectWidgetMessaging.bind(this);
-
         this.popoverWidth = 300;
         this.popoverHeight = 300;
 
@@ -166,17 +165,10 @@ export default class Stickerpicker extends React.Component {
         );
     }
 
-    _collectWidgetMessaging(widgetMessaging) {
-        this._appWidgetMessaging = widgetMessaging;
-
-        // Do this now instead of in componentDidMount because we might not have had the
-        // reference to widgetMessaging when mounting
-        this._sendVisibilityToWidget(true);
-    }
-
     _sendVisibilityToWidget(visible) {
-        if (this._appWidgetMessaging && visible !== this._prevSentVisibility) {
-            this._appWidgetMessaging.sendVisibility(visible);
+        const widgetMessaging = ActiveWidgetStore.getWidgetMessaging(this.state.stickerpickerWidget.id);
+        if (widgetMessaging && visible !== this._prevSentVisibility) {
+            widgetMessaging.sendVisibility(visible);
             this._prevSentVisibility = visible;
         }
     }
@@ -217,7 +209,6 @@ export default class Stickerpicker extends React.Component {
                     >
                     <PersistedElement containerId="mx_persisted_stickerPicker" style={{zIndex: STICKERPICKER_Z_INDEX}}>
                         <AppTile
-                            collectWidgetMessaging={this._collectWidgetMessaging}
                             id={stickerpickerWidget.id}
                             url={stickerpickerWidget.content.url}
                             name={stickerpickerWidget.content.name}