From 8d968f6865dc5bbd89615e09fb687e5f415887bc Mon Sep 17 00:00:00 2001
From: James Allen <james@sharelatex.com>
Date: Thu, 13 Oct 2016 10:09:59 +0100
Subject: [PATCH] Tidy up ReviewPanelController

---
 .../controllers/ReviewPanelController.coffee  | 23 +++++++++++--------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/services/web/public/coffee/ide/review-panel/controllers/ReviewPanelController.coffee b/services/web/public/coffee/ide/review-panel/controllers/ReviewPanelController.coffee
index baaf09dbb5..58f4c7d91f 100644
--- a/services/web/public/coffee/ide/review-panel/controllers/ReviewPanelController.coffee
+++ b/services/web/public/coffee/ide/review-panel/controllers/ReviewPanelController.coffee
@@ -9,33 +9,38 @@ define [
 		scroller = $element.find(".review-panel-scroller")
 		list = $element.find(".review-entry-list")
 
+		# Use these to avoid unnecessary updates. Scrolling one
+		# panel causes us to scroll the other panel, but there's no
+		# need to trigger the event back to the original panel.
 		ignoreNextPanelEvent = false
 		ignoreNextAceEvent = false
 
-		$scope.onScroll = (scrollTop, height) ->
+		$scope.scrollEvents = new EventEmitter()
+	
+		scrollPanel = (scrollTop, height) ->
 			if ignoreNextAceEvent
-				# console.log "Ignoring ace event"
 				ignoreNextAceEvent = false
 			else
 				ignoreNextPanelEvent = true
 				list.height(height)
 				scroller.scrollTop(scrollTop)
-		
-		$scope.scrollEvents = new EventEmitter()
 	
 		scrollAce = (e) ->
-			now = new Date()
 			if ignoreNextPanelEvent
-				# console.log "Ignoring review panel event"
 				ignoreNextPanelEvent = false
 			else
-				# console.log "review panel scrolled", e
 				ignoreNextAceEvent = true
 				$scope.scrollEvents.emit "scroll", e.target.scrollTop
-				lastScroll = now
 
-		previousScroll = new Date()
 		scroller.on "scroll", scrollAce
+		$scope.onScroll = scrollPanel # Passed into the editor directive for it to call
+
+		# If we listen for scroll events in the review panel natively, then with a Mac trackpad
+		# the scroll is very smooth (natively done I'd guess), but we don't get polled regularly
+		# enough to keep Ace in step, and it noticeably lags. If instead, we borrow the manual
+		# mousewheel/trackpad scrolling behaviour from Ace, and turn mousewheel events into
+		# scroll events ourselves, then it makes the review panel slightly less smooth (barely)
+		# noticeable, but keeps it perfectly in step with Ace.
 		ace.require("ace/lib/event").addMouseWheelListener scroller[0], (e) ->
 			deltaY = e.wheelY
 			# console.log "mousewheel", deltaY