Scroll patcher for Safari.

services/web/public/coffee/ide/SafariScrollPatcher.coffee

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+define [
+], () ->
+	class SafariScrollPatcher
+		constructor: (ide, $scope) ->
+			@isBootstrapped = false
+			@isOverAce = false
+			@pdfDiv = null
+			@aceDiv = null
+
+			$scope.$on "loaded", () =>
+				console.log this
+				if !@isBootstrapped
+					console.log "bootstrapping"
+
+					@isBootstrapped = true;
+					@pdfDiv = document.querySelector ".pdfjs-viewer"	# Grab the PDF div.
+					@aceDiv = document.querySelector ".ace_content"	# Also the editor.
+					@isOverAce = false # Flag to control if the pointer is over Ace.
+
+					# Start listening to PDF wheel events when the pointer leaves the PDF region.
+					# P.S. This is the problem in a nutshell: although the pointer is elsewhere,
+					# wheel events keep being dispatched to the PDF.
+					@pdfDiv.addEventListener "mouseleave", () => 
+						@pdfDiv.addEventListener "wheel", dispatchToAce
+
+					# Stop listening to wheel events when the pointer enters the PDF region. If 
+					# the pointer is over the PDF, native behaviour is adequate. 
+					@pdfDiv.addEventListener "mouseenter", () => 
+						@pdfDiv.removeEventListener "wheel", dispatchToAce
+
+					# Set the "pointer over Ace" flag as false, when the mouse leaves its area.
+					@aceDiv.addEventListener "mouseleave", () => 
+						@isOverAce = false
+
+					# Set the "pointer over Ace" flag as true, when the mouse enters its area.
+					@aceDiv.addEventListener "mouseenter", () => 
+						@isOverAce = true
+
+					# Handler for wheel events on the PDF.
+					# If the pointer is over Ace, grab the event, prevent default behaviour
+					# and dispatch it to Ace.
+					dispatchToAce = (e) =>
+						if @isOverAce
+							# If this is logged, the problem just happened: the event arrived
+							# here (the PDF wheel handler), but it should've gone to Ace.
+							console.log "Event was bound to the PDF, dispatching to Ace"
+
+							# Small timeout - if we dispatch immediately, an exception is thrown.
+							window.setTimeout(() =>
+								# Dispatch the exact same event to Ace (this will keep values
+								# values e.g. `wheelDelta` consistent with user interaction).
+								@aceDiv.dispatchEvent e
+							, 5)
+
+							# Avoid scrolling the PDF, as we assume this was intended to the 
+							# editor.
+							e.preventDefault()
+
+