From 2b423d9d80b3c6ced13c78feeec7d867eb3e3b8b 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: Tue, 17 Nov 2020 16:46:36 +0800
Subject: [PATCH] Use single add notify for each element when the new Item is
 small or the collection hasn't been buffer a lot. This seems solve the
 startup stunt and potentially make render faster. (Need Testing)

---
 Flow.Launcher/ViewModel/ResultsViewModel.cs | 47 ++++++++++++++++-----
 1 file changed, 37 insertions(+), 10 deletions(-)

diff --git a/Flow.Launcher/ViewModel/ResultsViewModel.cs b/Flow.Launcher/ViewModel/ResultsViewModel.cs
index cce532965..3a4b07fd6 100644
--- a/Flow.Launcher/ViewModel/ResultsViewModel.cs
+++ b/Flow.Launcher/ViewModel/ResultsViewModel.cs
@@ -2,6 +2,8 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Collections.Specialized;
+using System.ComponentModel;
+using System.Configuration;
 using System.Linq;
 using System.Threading;
 using System.Windows;
@@ -137,6 +139,7 @@ namespace Flow.Launcher.ViewModel
         public void AddResults(List<Result> newRawResults, string resultId)
         {
             var newResults = NewResults(newRawResults, resultId);
+
             lock (_collectionLock)
             {
                 // https://social.msdn.microsoft.com/Forums/vstudio/en-US/5ff71969-f183-4744-909d-50f7cd414954/binding-a-tabcontrols-selectedindex-not-working?forum=wpf
@@ -258,30 +261,38 @@ namespace Flow.Launcher.ViewModel
         }
         #endregion
 
-        public class ResultCollection : ObservableCollection<ResultViewModel>, INotifyCollectionChanged
+        public class ResultCollection : ObservableCollection<ResultViewModel>
         {
             private bool _suppressNotification = false;
+
+            private long editTime = 0;
+
+            // https://peteohanlon.wordpress.com/2008/10/22/bulk-loading-in-observablecollection/
             protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
             {
                 if (!_suppressNotification)
                     base.OnCollectionChanged(e);
             }
 
-            public override event NotifyCollectionChangedEventHandler CollectionChanged;
-
-            // https://peteohanlon.wordpress.com/2008/10/22/bulk-loading-in-observablecollection/
-            public void AddRange(IEnumerable<ResultViewModel> Items)
+            public void BulkAddRange(IEnumerable<ResultViewModel> resultViews)
             {
                 _suppressNotification = true;
+                foreach (var item in resultViews)
+                {
+                    Add(item);
+                }
+                _suppressNotification = false;
+                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
 
+            }
+            public void AddRange(IEnumerable<ResultViewModel> Items)
+            {
                 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;
 
             }
@@ -296,16 +307,32 @@ namespace Flow.Launcher.ViewModel
             /// <param name="newItems"></param>
             public void Update(List<ResultViewModel> newItems, CancellationToken token)
             {
-                Clear();
+
                 if (token.IsCancellationRequested)
                     return;
-                AddRange(newItems);
+                Update(newItems);
             }
 
             public void Update(List<ResultViewModel> newItems)
             {
+                if (editTime == 0)
+                {
+                    AddRange(newItems);
+                    editTime++;
+                    return;
+                }
+                else if (editTime < 15 || newItems.Count < 50)
+                {
+                    ClearItems();
+                    AddRange(newItems);
+                    editTime++;
+                    return;
+                }
                 Clear();
-                AddRange(newItems);
+
+                BulkAddRange(newItems);
+                editTime++;
+
             }
         }
     }