Fix scroll for search results

Make sure that we save scroll position when searching, and use it to preserve
offset when backfilling.

src/components/structures/RoomView.js

@@ -48,6 +48,17 @@ module.exports = React.createClass({
         ConferenceHandler: React.PropTypes.any
     },
 
+    /* properties in RoomView objects include:
+     *
+     * savedScrollState: the current scroll position in the backlog. Response
+     *     from _calculateScrollState. Updated on scroll events.
+     *
+     * savedSearchScrollState: similar to savedScrollState, but specific to the
+     *     search results (we need to preserve savedScrollState when search
+     *     results are visible)
+     *
+     * eventNodes: a map from event id to DOM node representing that event
+     */
     getInitialState: function() {
         var room = this.props.roomId ? MatrixClientPeg.get().getRoom(this.props.roomId) : null;
         return {
@@ -207,7 +218,7 @@ module.exports = React.createClass({
         if (!toStartOfTimeline &&
                 (ev.getSender() !== MatrixClientPeg.get().credentials.userId)) {
             // update unread count when scrolled up
-            if (this.savedScrollState.atBottom) {
+            if (!this.state.searchResults && this.savedScrollState.atBottom) {
                 currentUnread = 0;
             }
             else {
@@ -331,9 +342,6 @@ module.exports = React.createClass({
         // after adding event tiles, we may need to tweak the scroll (either to
         // keep at the bottom of the timeline, or to maintain the view after
         // adding events to the top).
-
-        if (this.state.searchResults) return;
-
         this._restoreSavedScrollState();
     },
 
@@ -441,11 +449,16 @@ module.exports = React.createClass({
             this.recentEventScroll = undefined;
         }
 
-        if (this.refs.messagePanel && !this.state.searchResults) {
+        if (this.refs.messagePanel) {
-            this.savedScrollState = this._calculateScrollState();
+            if (this.state.searchResults) {
-            if (DEBUG_SCROLL) console.log("Saved scroll state", this.savedScrollState);
+                this.savedSearchScrollState = this._calculateScrollState();
-            if (this.savedScrollState.atBottom && this.state.numUnreadMessages != 0) {
+                if (DEBUG_SCROLL) console.log("Saved search scroll state", this.savedSearchScrollState);
-                this.setState({numUnreadMessages: 0});
+            } else {
+                this.savedScrollState = this._calculateScrollState();
+                if (DEBUG_SCROLL) console.log("Saved scroll state", this.savedScrollState);
+                if (this.savedScrollState.atBottom && this.state.numUnreadMessages != 0) {
+                    this.setState({numUnreadMessages: 0});
+                }
             }
         }
         if (!this.state.paginating && !this.state.searchInProgress) {
@@ -510,6 +523,7 @@ module.exports = React.createClass({
             searchCount: null,
         });
 
+        this.savedSearchScrollState = {atBottom: true};
         this.nextSearchBatch = null;
         this._getSearchBatch(term, scope);
     },
@@ -629,10 +643,18 @@ module.exports = React.createClass({
                 var result = this.state.searchResults[i];
                 var mxEv = new Matrix.MatrixEvent(result.result);
 
+                if (!EventTile.haveTileForEvent(mxEv)) {
+                    // XXX: can this ever happen? It will make the result count
+                    // not match the displayed count.
+                    continue;
+                }
+
+                var eventId = mxEv.getId();
+
                 if (self.state.searchScope === 'All') {
                     var roomId = result.result.room_id;
                     if(roomId != lastRoomId) {
-                        ret.push(<li key={mxEv.getId() + "-room"}><h1>Room: { cli.getRoom(roomId).name }</h1></li>);
+                        ret.push(<li key={eventId + "-room"}><h1>Room: { cli.getRoom(roomId).name }</h1></li>);
                         lastRoomId = roomId;
                     }
                 }
@@ -643,18 +665,16 @@ module.exports = React.createClass({
                 if (result.context.events_before[0]) {
                     var mxEv2 = new Matrix.MatrixEvent(result.context.events_before[0]);
                     if (EventTile.haveTileForEvent(mxEv2)) {
-                        ret.push(<li key={mxEv.getId() + "-1"}><EventTile mxEvent={mxEv2} contextual={true} /></li>);
+                        ret.push(<li key={eventId+"-1"} data-scroll-token={eventId+"-1"}><EventTile mxEvent={mxEv2} contextual={true} /></li>);
                     }
                 }
 
-                if (EventTile.haveTileForEvent(mxEv)) {
+                ret.push(<li key={eventId+"+0"} data-scroll-token={eventId+"+0"}><EventTile mxEvent={mxEv} highlights={self.state.searchHighlights}/></li>);
-                    ret.push(<li key={mxEv.getId() + "+0"}><EventTile mxEvent={mxEv} highlights={self.state.searchHighlights}/></li>);
-                }
 
                 if (result.context.events_after[0]) {
                     var mxEv2 = new Matrix.MatrixEvent(result.context.events_after[0]);
                     if (EventTile.haveTileForEvent(mxEv2)) {
-                        ret.push(<li key={mxEv.getId() + "+1"}><EventTile mxEvent={mxEv2} contextual={true} /></li>);
+                        ret.push(<li key={eventId+"+1"} data-scroll-token={eventId+"+1"}><EventTile mxEvent={mxEv2} contextual={true} /></li>);
                     }
                 }
             }
@@ -706,15 +726,17 @@ module.exports = React.createClass({
                 continuation = false;
             }
 
+            var eventId = mxEv.getId();
             ret.unshift(
-                <li key={mxEv.getId()} ref={this._collectEventNode.bind(this, mxEv.getId())}><EventTile mxEvent={mxEv} continuation={continuation} last={last}/></li>
+                <li key={eventId} ref={this._collectEventNode.bind(this, eventId)} data-scroll-token={eventId}>
+                    <EventTile mxEvent={mxEv} continuation={continuation} last={last}/>
+                </li>
             );
             if (dateSeparator) {
                 ret.unshift(dateSeparator);
             }
             ++count;
         }
-        this.lastEventTileCount = count;
         return ret;
     },
 
@@ -884,7 +906,7 @@ module.exports = React.createClass({
     },
 
     onCancelClick: function() {
-        this.setState(this.getInitialState());
+        this.setState({editingRoomSettings: false});
     },
 
     onLeaveClick: function() {
@@ -918,6 +940,13 @@ module.exports = React.createClass({
         this.setState({ searching: true });
     },
 
+    onCancelSearchClick: function () {
+        this.setState({
+            searching: false,
+            searchResults: null,
+        });
+    },
+
     onConferenceNotificationClick: function() {
         dis.dispatch({
             action: 'place_call',
@@ -945,12 +974,6 @@ module.exports = React.createClass({
     // pixel_offset gives the number of pixels between the bottom of the event
     // and the bottom of the container.
     scrollToEvent: function(eventId, pixelOffset) {
-        var scrollNode = this._getScrollNode();
-        if (!scrollNode) return;
-
-        var messageWrapper = this.refs.messagePanel;
-        if (messageWrapper === undefined) return;
-
         var idx = this._indexForEventId(eventId);
         if (idx === null) {
             // we don't seem to have this event in our timeline. Presumably
@@ -960,7 +983,7 @@ module.exports = React.createClass({
             //
             // for now, just scroll to the top of the buffer.
             console.log("Refusing to scroll to unknown event "+eventId);
-            scrollNode.scrollTop = 0;
+            this._getScrollNode().scrollTop = 0;
             return;
         }
 
@@ -978,14 +1001,88 @@ module.exports = React.createClass({
             this.setState({messageCap: minCap});
         }
 
-        var node = this.eventNodes[eventId];
+        // the scrollTokens on our DOM nodes are the event IDs, so we can pass
-        if (node === null) {
+        // eventId directly into _scrollToToken.
-            // getEventTiles should have sorted this out when we set the
+        this._scrollToToken(eventId, pixelOffset);
-            // messageCap, so this is weird.
+    },
-            console.error("No node for event, even after rolling back messageCap");
+
+    _restoreSavedScrollState: function() {
+        var scrollState = this.state.searchResults ? this.savedSearchScrollState : this.savedScrollState;
+        if (!scrollState || scrollState.atBottom) {
+            this.scrollToBottom();
+        } else if (scrollState.lastDisplayedScrollToken) {
+            this._scrollToToken(scrollState.lastDisplayedScrollToken,
+                                scrollState.pixelOffset);
+        }
+    },
+
+    _calculateScrollState: function() {
+        // we don't save the absolute scroll offset, because that
+        // would be affected by window width, zoom level, amount of scrollback,
+        // etc.
+        //
+        // instead we save an identifier for the last fully-visible message,
+        // and the number of pixels the window was scrolled below it - which
+        // will hopefully be near enough.
+        //
+        // Our scroll implementation is agnostic of the precise contents of the
+        // message list (since it needs to work with both search results and
+        // timelines). 'refs.messageList' is expected to be a DOM node with a
+        // number of children, each of which may have a 'data-scroll-token'
+        // attribute. It is this token which is stored as the
+        // 'lastDisplayedScrollToken'.
+
+        var messageWrapperScroll = this._getScrollNode();
+        // + 1 here to avoid fractional pixel rounding errors
+        var atBottom = messageWrapperScroll.scrollHeight - messageWrapperScroll.scrollTop <= messageWrapperScroll.clientHeight + 1;
+
+        var messageWrapper = this.refs.messagePanel;
+        var wrapperRect = ReactDOM.findDOMNode(messageWrapper).getBoundingClientRect();
+        var messages = this.refs.messageList.children;
+
+        for (var i = messages.length-1; i >= 0; --i) {
+            var node = messages[i];
+            if (!node.dataset.scrollToken) continue;
+
+            var boundingRect = node.getBoundingClientRect();
+            if (boundingRect.bottom < wrapperRect.bottom) {
+                return {
+                    atBottom: atBottom,
+                    lastDisplayedScrollToken: node.dataset.scrollToken,
+                    pixelOffset: wrapperRect.bottom - boundingRect.bottom,
+                }
+            }
+        }
+
+        // apparently the entire timeline is below the viewport. Give up.
+        return { atBottom: true };
+    },
+
+    // scroll the message list to the node with the given scrollToken. See
+    // notes in _calculateScrollState on how this works.
+    //
+    // pixel_offset gives the number of pixels between the bottom of the node
+    // and the bottom of the container.
+    _scrollToToken: function(scrollToken, pixelOffset) {
+        /* find the dom node with the right scrolltoken */
+        var node;
+        var messages = this.refs.messageList.children;
+        for (var i = messages.length-1; i >= 0; --i) {
+            var m = messages[i];
+            if (!m.dataset.scrollToken) continue;
+            if (m.dataset.scrollToken == scrollToken) {
+                node = m;
+                break;
+            }
+        }
+
+        if (!node) {
+            console.error("No node with scrollToken '"+scrollToken+"'");
             return;
         }
 
+        var scrollNode = this._getScrollNode();
+        var messageWrapper = this.refs.messagePanel;
         var wrapperRect = ReactDOM.findDOMNode(messageWrapper).getBoundingClientRect();
         var boundingRect = node.getBoundingClientRect();
         var scrollDelta = boundingRect.bottom + pixelOffset - wrapperRect.bottom;
@@ -997,59 +1094,11 @@ module.exports = React.createClass({
         }
 
         if (DEBUG_SCROLL) {
-            console.log("Scrolled to event", eventId, "+", pixelOffset+":", scrollNode.scrollTop, "(delta: "+scrollDelta+")");
+            console.log("Scrolled to token", node.dataset.scrollToken, "+", pixelOffset+":", scrollNode.scrollTop, "(delta: "+scrollDelta+")");
             console.log("recentEventScroll now "+this.recentEventScroll);
         }
     },
 
-    _restoreSavedScrollState: function() {
-        var scrollState = this.savedScrollState;
-        if (scrollState.atBottom) {
-            this.scrollToBottom();
-        } else if (scrollState.lastDisplayedEvent) {
-            this.scrollToEvent(scrollState.lastDisplayedEvent,
-                               scrollState.pixelOffset);
-        }
-    },
-
-    _calculateScrollState: function() {
-        // we don't save the absolute scroll offset, because that
-        // would be affected by window width, zoom level, amount of scrollback,
-        // etc.
-        //
-        // instead we save the id of the last fully-visible event, and the
-        // number of pixels the window was scrolled below it - which will
-        // hopefully be near enough.
-        //
-        if (this.eventNodes === undefined) return null;
-
-        var messageWrapper = this.refs.messagePanel;
-        if (messageWrapper === undefined) return null;
-        var wrapperRect = ReactDOM.findDOMNode(messageWrapper).getBoundingClientRect();
-
-        var messageWrapperScroll = this._getScrollNode();
-        // + 1 here to avoid fractional pixel rounding errors
-        var atBottom = messageWrapperScroll.scrollHeight - messageWrapperScroll.scrollTop <= messageWrapperScroll.clientHeight + 1;
-
-        for (var i = this.state.room.timeline.length-1; i >= 0; --i) {
-            var ev = this.state.room.timeline[i];
-            var node = this.eventNodes[ev.getId()];
-            if (!node) continue;
-
-            var boundingRect = node.getBoundingClientRect();
-            if (boundingRect.bottom < wrapperRect.bottom) {
-                return {
-                    atBottom: atBottom,
-                    lastDisplayedEvent: ev.getId(),
-                    pixelOffset: wrapperRect.bottom - boundingRect.bottom,
-                }
-            }
-        }
-
-        // apparently the entire timeline is below the viewport. Give up.
-        return { atBottom: true };
-    },
-
     // get the current scroll position of the room, so that it can be
     // restored when we switch back to it
     getScrollState: function() {
@@ -1057,11 +1106,17 @@ module.exports = React.createClass({
     },
 
     restoreScrollState: function(scrollState) {
+        if (!this.refs.messagePanel) return;
+
         if(scrollState.atBottom) {
             // we were at the bottom before. Ideally we'd scroll to the
             // 'read-up-to' mark here.
-        } else if (scrollState.lastDisplayedEvent) {
+        } else if (scrollState.lastDisplayedScrollToken) {
-            this.scrollToEvent(scrollState.lastDisplayedEvent,
+            // we might need to backfill, so we call scrollToEvent rather than
+            // _scrollToToken here. The scrollTokens on our DOM nodes are the
+            // event IDs, so lastDisplayedScrollToken will be the event ID we need,
+            // and we can pass it directly into scrollToEvent.
+            this.scrollToEvent(scrollState.lastDisplayedScrollToken,
                                scrollState.pixelOffset);
         }
     },
@@ -1257,7 +1312,7 @@ module.exports = React.createClass({
                 aux = <Loader/>;
             }
             else if (this.state.searching) {
-                aux = <SearchBar ref="search_bar" searchInProgress={this.state.searchInProgress } onCancelClick={this.onCancelClick} onSearch={this.onSearch}/>;
+                aux = <SearchBar ref="search_bar" searchInProgress={this.state.searchInProgress } onCancelClick={this.onCancelSearchClick} onSearch={this.onSearch}/>;
             }
 
             var conferenceCallNotification = null;
@@ -1349,7 +1404,7 @@ module.exports = React.createClass({
                     </div>
                     <GeminiScrollbar autoshow={true} ref="messagePanel" className="mx_RoomView_messagePanel" onScroll={ this.onMessageListScroll }>
                         <div className="mx_RoomView_messageListWrapper">
-                            <ol className="mx_RoomView_MessageList" aria-live="polite">
+                            <ol ref="messageList" className="mx_RoomView_MessageList" aria-live="polite">
                                 <li className={scrollheader_classes}>
                                 </li>
                                 {this.getEventTiles()}