Move saveScrollState into RoomView

It fits much more naturally here than in LoggedInView.

src/components/structures/LoggedInView.js

@@ -54,36 +54,10 @@ export default React.createClass({
         document.removeEventListener('keydown', this._onKeyDown);
     },
 
-    componentWillReceiveProps: function(nextProps) {
-        if (nextProps.page_type !== this.props.page_type ||
-            nextProps.currentRoomAlias !== this.props.currentRoomAlias ||
-            nextProps.currentRoomId !== this.props.currentRoomId
-           ) {
-
-            // stash the scroll state before we change view
-            this._updateScrollMap();
-        }
-    },
-
     getScrollStateForRoom: function(roomId) {
         return this._scrollStateMap[roomId];
     },
 
-    // update scrollStateMap according to the current scroll state of the
-    // room view.
-    _updateScrollMap: function() {
-        if (!this.refs.roomView) {
-            return;
-        }
-        var roomview = this.refs.roomView;
-        var roomId = this.refs.roomView.getRoomId();
-        if (!roomId) {
-            return;
-        }
-        var state = roomview.getScrollState();
-        this._scrollStateMap[roomId] = state;
-    },
-
     _onKeyDown: function(ev) {
             /*
             // Remove this for now as ctrl+alt = alt-gr so this breaks keyboards which rely on alt-gr for numbers
@@ -170,6 +144,7 @@ export default React.createClass({
                         opacity={this.props.middleOpacity}
                         collapsedRhs={this.props.collapse_rhs}
                         ConferenceHandler={this.props.ConferenceHandler}
+                        scrollStateMap={this._scrollStateMap}
                     />
                 if (!this.props.collapse_rhs) right_panel = <RightPanel roomId={this.props.currentRoomId} opacity={this.props.sideOpacity} />
                 break;

src/components/structures/MatrixChat.js

@@ -508,6 +508,8 @@ module.exports = React.createClass({
 
         // if we aren't given an explicit event id, look for one in the
         // scrollStateMap.
+        //
+        // TODO: do this in RoomView rather than here
         if (!room_info.event_id && this.refs.loggedInView) {
             var scrollState = this.refs.loggedInView.getScrollStateForRoom(room_info.room_id);
             if (scrollState) {

src/components/structures/RoomView.js

@@ -100,6 +100,21 @@ module.exports = React.createClass({
 
         // is the RightPanel collapsed?
         collapsedRhs: React.PropTypes.bool,
+
+        // a map from room id to scroll state, which will be updated on unmount.
+        //
+        // If there is no special scroll state (ie, we are following the live
+        // timeline), the scroll state is null. Otherwise, it is an object with
+        // the following properties:
+        //
+        //    focussedEvent: the ID of the 'focussed' event. Typically this is
+        //        the last event fully visible in the viewport, though if we
+        //        have done an explicit scroll to an explicit event, it will be
+        //        that event.
+        //
+        //    pixelOffset: the number of pixels the window is scrolled down
+        //        from the focussedEvent.
+        scrollStateMap: React.PropTypes.object,
     },
 
     getInitialState: function() {
@@ -307,6 +322,9 @@ module.exports = React.createClass({
         // (We could use isMounted, but facebook have deprecated that.)
         this.unmounted = true;
 
+        // update the scroll map before we get unmounted
+        this._updateScrollMap();
+
         if (this.refs.roomView) {
             // disconnect the D&D event listeners from the room view. This
             // is really just for hygiene - we're going to be
@@ -1203,22 +1221,25 @@ module.exports = React.createClass({
         }
     },
 
+    // update scrollStateMap on unmount
+    _updateScrollMap: function() {
+        if (!this.state.room) {
+            // we were instantiated on a room alias and haven't yet joined the room.
+            return;
+        }
+        if (!this.props.scrollStateMap) return;
+
+        var roomId = this.state.room.roomId;
+
+        var state = this._getScrollState();
+        this.props.scrollStateMap[roomId] = state;
+    },
+
+
     // get the current scroll position of the room, so that it can be
     // restored when we switch back to it.
     //
-    // If there is no special scroll state (ie, we are following the live
-    // timeline), returns null. Otherwise, returns an object with the following
-    // properties:
-    //
-    //    focussedEvent: the ID of the 'focussed' event. Typically this is the
-    //        last event fully visible in the viewport, though if we have done
-    //        an explicit scroll to an explicit event, it will be that event.
-    //
-    //    pixelOffset: the number of pixels the window is scrolled down from
-    //        the focussedEvent.
-    //
-    //
-    getScrollState: function() {
+    _getScrollState: function() {
         var messagePanel = this.refs.messagePanel;
         if (!messagePanel) return null;
 
@@ -1333,19 +1354,6 @@ module.exports = React.createClass({
         }
     },
 
-    /**
-     * Get the ID of the displayed room
-     *
-     * Returns null if the RoomView was instantiated on a room alias and
-     * we haven't yet joined the room.
-     */
-    getRoomId: function() {
-        if (!this.state.room) {
-            return null;
-        }
-        return this.state.room.roomId;
-    },
-
     /**
      * get any current call for this room
      */