overleaf/services/web/public/coffee/ide/review-panel/controllers/ReviewPanelController.coffee

define [
	"base",
	"utils/EventEmitter"
], (App, EventEmitter) ->
	App.controller "ReviewPanelController", ($scope, $element) ->
		$scope.reviewPanel =
			entries: {}
			
		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.scrollEvents = new EventEmitter()
	
		scrollPanel = (scrollTop, height) ->
			if ignoreNextAceEvent
				ignoreNextAceEvent = false
			else
				ignoreNextPanelEvent = true
				list.height(height)
				scroller.scrollTop(scrollTop)
	
		scrollAce = (e) ->
			if ignoreNextPanelEvent
				ignoreNextPanelEvent = false
			else
				ignoreNextAceEvent = true
				$scope.scrollEvents.emit "scroll", e.target.scrollTop

		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
			scroller.scrollTop(scroller.scrollTop() + deltaY * 4)
			e.preventDefault()