Avoid re-rendering RoomList on room switch

Introduce a class that consumes updates from the RoomViewStore and
announces to listeners if the active room ID is now or is no longer
the room ID they specified. Naming suggestions welcome: it's
currently called ActiveRoomObserver.

Avoids passing the selectedRoomId down from MatrixChat all the way
through the LeftPanel / RoomList / RoomSubList to the RoomTiles.

Also introduce a CallPreview class that listens directly for
RoomViewStore changes as the call preview in the left panel needs
to know when the room changes, so this allows this component to
update without having to update the entire left panel.

src/ActiveRoomObserver.js

@@ -0,0 +1,77 @@
+/*
+Copyright 2017 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.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import RoomViewStore from './stores/RoomViewStore';
+
+/**
+ * Consumes changes from the RoomViewStore and notifies specific things
+ * about when the active room changes. Unlike listening for RoomViewStore
+ * changes, you can subscribe to only changes relevant to a particular
+ * room.
+ *
+ * TODO: If we introduce an observer for something else, factor out
+ * the adding / removing of listeners & emitting into a common class.
+ */
+class ActiveRoomObserver {
+    constructor() {
+        this._listeners = {};
+
+        this._activeRoomId = RoomViewStore.getRoomId();
+        // TODO: We could self-destruct when the last listener goes away, or at least
+        // stop listening.
+        this._roomStoreToken = RoomViewStore.addListener(this._onRoomViewStoreUpdate.bind(this));
+    }
+
+    addListener(roomId, listener) {
+        if (!this._listeners[roomId]) this._listeners[roomId] = [];
+        this._listeners[roomId].push(listener);
+    }
+
+    removeListener(roomId, listener) {
+        if (this._listeners[roomId]) {
+            const i = this._listeners[roomId].indexOf(listener);
+            if (i > -1) {
+                this._listeners[roomId].splice(i, 1);
+            }
+        } else {
+            console.warn("Unregistering unrecognised listener (roomId=" + roomId + ")");
+        }
+    }
+
+    _emit(roomId) {
+        if (!this._listeners[roomId]) return;
+
+        for (const l of this._listeners[roomId]) {
+            l.call();
+        }
+    }
+
+    _onRoomViewStoreUpdate() {
+        // emit for the old room ID
+        if (this._activeRoomId) this._emit(this._activeRoomId);
+
+        // update our cache
+        this._activeRoomId = RoomViewStore.getRoomId();
+
+        // and emit for the new one
+        if (this._activeRoomId) this._emit(this._activeRoomId);
+    }
+}
+
+if (global.mx_ActiveRoomObserver === undefined) {
+    global.mx_ActiveRoomObserver = new ActiveRoomObserver();
+}
+export default global.mx_ActiveRoomObserver;

src/components/views/rooms/RoomList.js

@@ -63,7 +63,6 @@ module.exports = React.createClass({
     propTypes: {
         ConferenceHandler: React.PropTypes.any,
         collapsed: React.PropTypes.bool.isRequired,
-        currentRoom: React.PropTypes.string,
         searchFilter: React.PropTypes.string,
     },
 

src/components/views/rooms/RoomTile.js

@@ -1,5 +1,6 @@
 /*
 Copyright 2015, 2016 OpenMarket Ltd
+Copyright 2017 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.
@@ -27,6 +28,8 @@ var RoomNotifs = require('../../../RoomNotifs');
 var FormattingUtils = require('../../../utils/FormattingUtils');
 import AccessibleButton from '../elements/AccessibleButton';
 var UserSettingsStore = require('../../../UserSettingsStore');
+import ActiveRoomObserver from '../../../ActiveRoomObserver';
+import RoomViewStore from '../../../stores/RoomViewStore';
 
 module.exports = React.createClass({
     displayName: 'RoomTile',
@@ -39,7 +42,6 @@ module.exports = React.createClass({
 
         room: React.PropTypes.object.isRequired,
         collapsed: React.PropTypes.bool.isRequired,
-        selected: React.PropTypes.bool.isRequired,
         unread: React.PropTypes.bool.isRequired,
         highlight: React.PropTypes.bool.isRequired,
         isInvite: React.PropTypes.bool.isRequired,
@@ -58,6 +60,7 @@ module.exports = React.createClass({
             badgeHover : false,
             menuDisplayed: false,
             notifState: RoomNotifs.getRoomNotifsState(this.props.room.roomId),
+            selected: this.props.room.roomId === RoomViewStore.getRoomId(),
         });
     },
 
@@ -87,8 +90,15 @@ module.exports = React.createClass({
         }
     },
 
+    _onActiveRoomChange: function() {
+        this.setState({
+            selected: this.props.room.roomId === RoomViewStore.getRoomId(),
+        });
+    },
+
     componentWillMount: function() {
         MatrixClientPeg.get().on("accountData", this.onAccountData);
+        ActiveRoomObserver.addListener(this.props.room.roomId, this._onActiveRoomChange);
     },
 
     componentWillUnmount: function() {
@@ -96,6 +106,7 @@ module.exports = React.createClass({
         if (cli) {
             MatrixClientPeg.get().removeListener("accountData", this.onAccountData);
         }
+        ActiveRoomObserver.removeListener(this.props.room.roomId, this._onActiveRoomChange);
     },
 
     onClick: function(ev) {
@@ -174,7 +185,7 @@ module.exports = React.createClass({
 
         var classes = classNames({
             'mx_RoomTile': true,
-            'mx_RoomTile_selected': this.props.selected,
+            'mx_RoomTile_selected': this.state.selected,
             'mx_RoomTile_unread': this.props.unread,
             'mx_RoomTile_unreadNotify': notifBadges,
             'mx_RoomTile_highlight': mentionBadges,
@@ -221,7 +232,7 @@ module.exports = React.createClass({
                 'mx_RoomTile_badgeShown': badges || this.state.badgeHover || this.state.menuDisplayed,
             });
 
-            if (this.props.selected) {
+            if (this.state.selected) {
                 let nameSelected = <EmojiText>{name}</EmojiText>;
 
                 label = <div title={ name } className={ nameClasses } dir="auto">{ nameSelected }</div>;

src/components/views/voip/CallPreview.js

@@ -0,0 +1,97 @@
+/*
+Copyright 2017 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.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from 'react';
+import RoomViewStore from '../../../stores/RoomViewStore';
+import CallHandler from '../../../CallHandler';
+import dis from '../../../dispatcher';
+import sdk from '../../../index';
+
+module.exports = React.createClass({
+    displayName: 'CallPreview',
+
+    propTypes: {
+        // A Conference Handler implementation
+        // Must have a function signature:
+        //  getConferenceCallForRoom(roomId: string): MatrixCall
+        ConferenceHandler: React.PropTypes.object,
+    },
+
+    getInitialState: function() {
+        return {
+            roomId: RoomViewStore.getRoomId(),
+            activeCall: CallHandler.getAnyActiveCall(),
+        };
+    },
+
+    componentWillMount: function() {
+        this._roomStoreToken = RoomViewStore.addListener(this._onRoomViewStoreUpdate);
+        this.dispatcherRef = dis.register(this._onAction);
+    },
+
+    componentWillUnmount: function() {
+        if (this._roomStoreToken) {
+            this._roomStoreToken.remove();
+        }
+        dis.unregister(this.dispatcherRef);
+    },
+
+    _onRoomViewStoreUpdate: function(payload) {
+        if (RoomViewStore.getRoomId() === this.state.roomId) return;
+        this.setState({
+            roomId: RoomViewStore.getRoomId(),
+        });
+    },
+
+    _onAction: function(payload) {
+        switch (payload.action) {
+            // listen for call state changes to prod the render method, which
+            // may hide the global CallView if the call it is tracking is dead
+            case 'call_state':
+                this.setState({
+                    activeCall: CallHandler.getAnyActiveCall(),
+                });
+                break;
+        }
+    },
+
+    _onCallViewClick: function() {
+        const call = CallHandler.getAnyActiveCall();
+        if (call) {
+            dis.dispatch({
+                action: 'view_room',
+                room_id: call.groupRoomId || call.roomId,
+            });
+        }
+    },
+
+    render: function() {
+        const callForRoom = CallHandler.getCallForRoom(this.state.roomId);
+        const showCall = (this.state.activeCall && this.state.activeCall.call_state === 'connected' && !callForRoom);
+
+        if (showCall) {
+            const CallView = sdk.getComponent('voip.CallView');
+            return (
+                <CallView
+                    className="mx_LeftPanel_callView" showVoice={true} onClick={this._onCallViewClick}
+                    ConferenceHandler={this.props.ConferenceHandler}
+                />
+            );
+        }
+        return null;
+    },
+});
+