From a4147f52c93d8ecd5af31f1b7e8e5130ff26693d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=BC=98=E9=9F=AC=20=E5=BC=A0?= <hongtao_zhang@outlook.com>
Date: Sat, 14 Nov 2020 12:36:29 +0800
Subject: [PATCH] Block Notifychange unless all the element is added into the
 observablecollection This should improve the response speed.

---
 Flow.Launcher/ViewModel/ResultsViewModel.cs | 36 ++++++++++++++-------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/Flow.Launcher/ViewModel/ResultsViewModel.cs b/Flow.Launcher/ViewModel/ResultsViewModel.cs
index d62e0d0c3..6210dc54f 100644
--- a/Flow.Launcher/ViewModel/ResultsViewModel.cs
+++ b/Flow.Launcher/ViewModel/ResultsViewModel.cs
@@ -260,7 +260,30 @@ namespace Flow.Launcher.ViewModel
 
         public class ResultCollection : ObservableCollection<ResultViewModel>, INotifyCollectionChanged
         {
+            private bool _suppressNotification = false;
+            protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
+            {
+                if (!_suppressNotification)
+                    base.OnCollectionChanged(e);
+            }
+
             public override event NotifyCollectionChangedEventHandler CollectionChanged;
+
+            public void AddRange(IEnumerable<ResultViewModel> Items)
+            {
+                _suppressNotification = true;
+
+                foreach (var item in Items)
+                {
+                    Add(item);
+                }
+
+
+                // wpf use directx / double buffered already, so just reset all won't cause ui flickering
+                CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+                return;
+
+            }
             public void RemoveAll()
             {
                 ClearItems();
@@ -272,20 +295,9 @@ namespace Flow.Launcher.ViewModel
             /// <param name="newItems"></param>
             public void Update(List<ResultViewModel> newItems)
             {
-
-
                 ClearItems();
 
-                foreach (var item in newItems)
-                {
-                    Add(item);
-                }
-
-                // wpf use directx / double buffered already, so just reset all won't cause ui flickering
-                CollectionChanged?.Invoke(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
-
-                return;
-
+                AddRange(newItems);
             }
         }
     }