From 1f62553b0a90c708ca753f661faac0e5f9e11bda Mon Sep 17 00:00:00 2001
From: Alf Eaton <alf.eaton@overleaf.com>
Date: Fri, 10 Jun 2022 10:41:09 +0100
Subject: [PATCH] Merge pull request #8347 from overleaf/ae-outline-performance

Only update the outline view when the outline changes

GitOrigin-RevId: aadf0016111a5f3568475b9ee1849acc46934a30
---
 .../frontend/js/features/outline/outline-manager.js   | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/services/web/frontend/js/features/outline/outline-manager.js b/services/web/frontend/js/features/outline/outline-manager.js
index 4b9fc0cd37..fe5c14cdcf 100644
--- a/services/web/frontend/js/features/outline/outline-manager.js
+++ b/services/web/frontend/js/features/outline/outline-manager.js
@@ -1,3 +1,4 @@
+import { isEqual, cloneDeep } from 'lodash'
 import './controllers/outline-controller'
 import { matchOutline, nestOutline } from './outline-parser'
 import isValidTeXFile from '../../main/is-valid-tex-file'
@@ -9,6 +10,7 @@ class OutlineManager {
     this.shareJsDoc = null
     this.isTexFile = false
     this.flatOutline = []
+    this.previousFlatOutline = []
     this.outline = []
     this.highlightedLine = null
     this.ignoreNextScroll = false
@@ -67,14 +69,19 @@ class OutlineManager {
   }
 
   updateOutline() {
-    this.outline = []
     if (this.isTexFile) {
       const content = this.ide.editorManager.getCurrentDocValue()
       if (content) {
         this.flatOutline = matchOutline(content)
-        this.outline = nestOutline(this.flatOutline)
+        if (!isEqual(this.flatOutline, this.previousFlatOutline)) {
+          this.previousFlatOutline = cloneDeep(this.flatOutline)
+          this.outline = nestOutline(this.flatOutline)
+        }
+        return
       }
     }
+    this.previousFlatOutline = []
+    this.outline = []
   }
 
   // set highlightedLine to the closest outline line above the editorLine