Merge pull request #257 from sharelatex/fix-synctex-position-calculation

Fix synctex position calculation

services/web/public/coffee/ide/pdf/controllers/PdfController.coffee

@@ -354,18 +354,35 @@ define [
 					deferred.reject()
 					return deferred.promise
 
+				# FIXME: this actually works better if it's halfway across the
+				# page (or the visible part of the page). Synctex doesn't
+				# always find the right place in the file when the point is at
+				# the edge of the page, it sometimes returns the start of the
+				# next paragraph instead.
+				h = position.offset.left
+
+				# Compute the vertical position to pass to synctex, which
+				# works with coordinates increasing from the top of the page
+				# down.  This matches the browser's DOM coordinate of the
+				# click point, but the pdf position is measured from the
+				# bottom of the page so we need to invert it.
+				if options.fromPdfPosition and position.pageSize?.height?
+					v = (position.pageSize.height - position.offset.top) or 0 # measure from pdf point (inverted)
+				else
+					v = position.offset.top or 0 # measure from html click position
+
 				# It's not clear exactly where we should sync to if it wasn't directly
 				# clicked on, but a little bit down from the very top seems best.
 				if options.includeVisualOffset
-					position.offset.top = position.offset.top + 80
+					v += 72 # use the same value as in pdfViewer highlighting visual offset
 
 				$http({
 						url: "/project/#{ide.project_id}/sync/pdf",
 						method: "GET",
 						params: {
 							page: position.page + 1
-							h: position.offset.left.toFixed(2)
-							v: position.offset.top.toFixed(2)
+							h: h.toFixed(2)
+							v: v.toFixed(2)
 							clsiserverid:ide.clsiServerId
 							isolated: perUserCompile
 						}
@@ -396,7 +413,7 @@ define [
 
 		$scope.syncToCode = () ->
 			synctex
-				.syncToCode($scope.pdf.position, includeVisualOffset: true)
+				.syncToCode($scope.pdf.position, includeVisualOffset: true, fromPdfPosition: true)
 				.then (data) ->
 					{doc, line} = data
 					ide.editorManager.openDoc(doc, gotoLine: line)

services/web/public/coffee/ide/pdfng/directives/pdfJs.coffee

@@ -50,7 +50,11 @@ define [
 						scope.scale = { scaleMode: 'scale_mode_fit_width' }
 
 					if (position = localStorage("pdf.position.#{attrs.key}"))
-						scope.position = { page: +position.page, offset: { "top": +position.offset.top, "left": +position.offset.left } }
+						scope.position =
+							page: +position.page,
+							offset:
+								"top": +position.offset.top
+								"left": +position.offset.left
 
 					#scope.position = pdfListView.getPdfPosition(true)
 

services/web/public/coffee/ide/pdfng/directives/pdfViewer.coffee

@@ -188,6 +188,7 @@ define [
 			newPosition = {
 				"page": topPageIdx,
 				"offset" : { "top" : pdfOffset[1], "left": 0}
+				"pageSize": { "height": viewport.viewBox[3], "width": viewport.viewBox[2] }
 			}
 			return newPosition
 
@@ -208,6 +209,8 @@ define [
 			return $scope.document.getPdfViewport(page.pageNum).then (viewport) ->
 				page.viewport = viewport
 				pageOffset = viewport.convertToViewportPoint(offset.left, offset.top)
+				# if the passed-in position doesn't have the page height/width add them now
+				position.pageSize ?= {"height": viewport.viewBox[3], "width": viewport.viewBox[2]}
 				# console.log 'addition offset =', pageOffset
 				# console.log 'total', pageTop + pageOffset[1]
 				Math.round(pageTop + pageOffset[1] + currentScroll) ## 10 is margin
@@ -513,8 +516,17 @@ define [
 
 					first = highlights[0]
 
-					pageNum = scope.pages[first.page].pageNum
+					# switching between split and full pdf views can cause
+					# highlights to appear before rendering
+					if !scope.pages
+						return # ignore highlight scroll if still rendering
 
+					pageNum = scope.pages[first.page]?.pageNum
+
+					if !pageNum?
+						return # ignore highlight scroll if page not found
+
+					# use a visual offset of 72pt to match the offset in PdfController syncToCode
 					scope.document.getPdfViewport(pageNum).then (viewport) ->
 						position = {
 							page: first.page