Unify SelectingItemsControl init handling and add extra checks to ens…

…ure correctness.
donandren · Jan 17, 2020 · a238fd3 · a238fd3
1 parent 1e673ec
commit a238fd3
Showing 1 changed file with 27 additions and 11 deletions.
diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -5,6 +5,7 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Diagnostics;
 using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls.Generators;
@@ -240,17 +241,14 @@ protected SelectionMode SelectionMode
         public override void BeginInit()
         {
             base.BeginInit();
-            ++_updateCount;
-            _updateSelectedIndex = int.MinValue;
+
+            InternalBeginInit();
         }
 
         /// <inheritdoc/>
         public override void EndInit()
         {
-            if (--_updateCount == 0)
-            {
-                UpdateFinished();
-            }
+            InternalEndInit();
 
             base.EndInit();
         }
@@ -437,18 +435,16 @@ protected override void OnContainersRecycled(ItemContainerEventArgs e)
         protected override void OnDataContextBeginUpdate()
         {
             base.OnDataContextBeginUpdate();
-            ++_updateCount;
+
+            InternalBeginInit();
         }
 
         /// <inheritdoc/>
         protected override void OnDataContextEndUpdate()
         {
             base.OnDataContextEndUpdate();
 
-            if (--_updateCount == 0)
-            {
-                UpdateFinished();
-            }
+            InternalEndInit();
         }
 
         protected override void OnKeyDown(KeyEventArgs e)
@@ -1118,6 +1114,26 @@ private void UpdateFinished()
             }
         }
 
+        private void InternalBeginInit()
+        {
+            if (_updateCount == 0)
+            {
+                _updateSelectedIndex = int.MinValue;
+            }
+
+            ++_updateCount;
+        }
+
+        private void InternalEndInit()
+        {
+            Debug.Assert(_updateCount > 0);
+
+            if (--_updateCount == 0)
+            {
+                UpdateFinished();
+            }
+        }
+
         private class Selection : IEnumerable<int>
         {
             private readonly List<int> _list = new List<int>();