Add support for NotifyCollectionChangedAction.Move to ItemsRepeater (m…

…icrosoft/microsoft-ui-xaml#2778)
Kinnara · Jul 3, 2020 · 0fa6b69 · 0fa6b69
1 parent 22c07f8
commit 0fa6b69
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Showing 7 changed files with 122 additions and 10 deletions.
diff --git a/ModernWpf.Controls/Repeater/Layouts/FlowLayout/ElementManager.cs b/ModernWpf.Controls/Repeater/Layouts/FlowLayout/ElementManager.cs
@@ -314,7 +314,10 @@ public void DataSourceChanged(object source, NotifyCollectionChangedEventArgs ar
                         break;
 
                     case NotifyCollectionChangedAction.Move:
-                        throw new NotImplementedException();
+                        int size = args.OldItems != null ? args.OldItems.Count : 1;
+                        OnItemsRemoved(args.OldStartingIndex, size);
+                        OnItemsAdded(args.NewStartingIndex, size);
+                        break;
                 }
             }
         }

diff --git a/ModernWpf.Controls/Repeater/Layouts/UniformGridLayout/UniformGridLayoutState.cs b/ModernWpf.Controls/Repeater/Layouts/UniformGridLayout/UniformGridLayoutState.cs
@@ -163,6 +163,9 @@ internal void ClearElementOnDataSourceChange(VirtualizingLayoutContext context,
         {
             if (m_cachedFirstElement != null)
             {
+                // The first element of UniformGridLayout is special since we use its size to 
+                // determine the size of all the other elements. So if the first item has changed
+                // we will need to clear it and re-evalauate all the items with the new item size.
                 bool shouldClear = false;
                 switch (args.Action)
                 {
@@ -183,7 +186,8 @@ internal void ClearElementOnDataSourceChange(VirtualizingLayoutContext context,
                         break;
 
                     case NotifyCollectionChangedAction.Move:
-                        throw new NotImplementedException();
+                        shouldClear = args.NewStartingIndex == 0 || args.OldStartingIndex == 0;
+                        break;
                 }
 
                 if (shouldClear)

diff --git a/test/ModernWpfTestApp/ApiTests/RepeaterTests/Common/CollectionChangeEventArgsConverters.cs b/test/ModernWpfTestApp/ApiTests/RepeaterTests/Common/CollectionChangeEventArgsConverters.cs
@@ -87,6 +87,16 @@ public static NotifyCollectionChangedEventArgs ConvertToDataSourceChangedEventAr
                         newArgs = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, addedItems, removedItems, oldStartingIndex);
                     }
                     break;
+                case NotifyCollectionChangedAction.Move:
+                    {
+                        List<object> movedItems = new List<object>();
+                        for (int i = 0; i < oldItemsCount; i++)
+                        {
+                            movedItems.Add(null);
+                        }
+                        newArgs = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Move, movedItems, newStartingIndex, oldStartingIndex);
+                    }
+                  break;
                 case NotifyCollectionChangedAction.Reset:
                     newArgs = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
                     break;

diff --git a/test/ModernWpfTestApp/ApiTests/RepeaterTests/Common/CustomItemsSource.cs b/test/ModernWpfTestApp/ApiTests/RepeaterTests/Common/CustomItemsSource.cs
@@ -99,6 +99,27 @@ public void Replace(int index, int oldCount, int newCount, bool reset)
             }
         }
 
+        public void Move(int oldIndex, int newIndex, int count, bool reset)
+        {
+            var items = Inner.GetRange(oldIndex, count);
+            Inner.RemoveRange(oldIndex, count);
+            Inner.InsertRange(newIndex, items);
+
+            if (reset)
+            {
+                OnItemsSourceChanged(CollectionChangeEventArgsConverters.CreateNotifyArgs(NotifyCollectionChangedAction.Reset, -1, -1, -1, -1));
+            }
+            else
+            {
+                OnItemsSourceChanged(CollectionChangeEventArgsConverters.CreateNotifyArgs(
+                    NotifyCollectionChangedAction.Move,
+                    oldStartingIndex: oldIndex,
+                    oldItemsCount: count,
+                    newStartingIndex: newIndex,
+                    newItemsCount: count));
+            }
+        }
+
         public void Reset()
         {
             Random rand = new Random(123);

diff --git a/test/ModernWpfTestApp/ApiTests/RepeaterTests/FlowLayoutCollectionChangeTests.cs b/test/ModernWpfTestApp/ApiTests/RepeaterTests/FlowLayoutCollectionChangeTests.cs
@@ -307,6 +307,59 @@ public void CanReplaceSingleItem()
             });
         }
 
+        [TestMethod]
+        public void CanMoveItem()
+        {
+            CustomItemsSource dataSource = null;
+            RunOnUIThread.Execute(() => dataSource = new CustomItemsSource(Enumerable.Range(0, 10).ToList()));
+            ScrollViewer scrollViewer = null;
+            ItemsRepeater repeater = null;
+            var viewChangedEvent = new ManualResetEvent(false);
+
+            RunOnUIThread.Execute(() =>
+            {
+                repeater = SetupRepeater(dataSource, ref scrollViewer);
+                scrollViewer.ScrollChanged += (sender, args) =>
+                {
+                    if (args.HorizontalChange != 0 || args.VerticalChange != 0)
+                    {
+                        viewChangedEvent.Set();
+                    }
+                };
+                scrollViewer.ChangeView(null, 400, null, true);
+            });
+
+            Verify.IsTrue(viewChangedEvent.WaitOne(DefaultWaitTime), "Waiting for ViewChanged.");
+            IdleSynchronizer.Wait();
+
+            RunOnUIThread.Execute(() =>
+            {
+                var realized = VerifyRealizedRange(repeater, dataSource);
+                Verify.AreEqual(4, realized);
+
+                Log.Comment("Move before realized range.");
+                dataSource.Move(oldIndex: 0, newIndex: 1, count: 2, reset: false);
+                repeater.UpdateLayout();
+
+                realized = VerifyRealizedRange(repeater, dataSource);
+                Verify.AreEqual(4, realized);
+
+                Log.Comment("Move in realized range.");
+                dataSource.Move(oldIndex: 3, newIndex: 5, count: 2, reset: false);
+                repeater.UpdateLayout();
+
+                realized = VerifyRealizedRange(repeater, dataSource);
+                Verify.AreEqual(4, realized);
+
+                Log.Comment("Move after realized range");
+                dataSource.Move(oldIndex: 7, newIndex: 8, count: 2, reset: false);
+                repeater.UpdateLayout();
+
+                realized = VerifyRealizedRange(repeater, dataSource);
+                Verify.AreEqual(4, realized);
+            });
+        }
+
         [TestMethod]
         public void VerifyElement0OwnershipInUniformGridLayout()
         {

diff --git a/test/ModernWpfTestApp/Samples/ItemsSourceSamples/CollectionChangeDemo.xaml b/test/ModernWpfTestApp/Samples/ItemsSourceSamples/CollectionChangeDemo.xaml
@@ -9,9 +9,7 @@
 
     <Page.Resources>
         <controls:RecyclePool x:Key="RecyclePool" />
-        <controls:RecyclingElementFactory
-            x:Key="elementFactory"
-            RecyclePool="{StaticResource RecyclePool}">
+        <controls:RecyclingElementFactory x:Key="elementFactory" RecyclePool="{StaticResource RecyclePool}">
             <controls:RecyclingElementFactory.Templates>
                 <DataTemplate x:Key="Item">
                     <Button
@@ -57,6 +55,7 @@
                 <Button x:Name="insertButton">Insert</Button>
                 <Button x:Name="removeButton">Remove</Button>
                 <Button x:Name="replaceButton">Replace</Button>
+                <Button x:Name="moveButton">Move</Button>
                 <Button x:Name="resetButton">Reset</Button>
                 <Button x:Name="invalidateMeasureButton">InvalidateMeasure</Button>
                 <Button x:Name="invalidateArrangeButton">InvalidateArrange</Button>
@@ -70,10 +69,10 @@
                 <controls:ItemsRepeater x:Name="repeater">
                     <controls:ItemsRepeater.Layout>
                         <controls:UniformGridLayout
-                            MinItemWidth="150"
+                            MinColumnSpacing="10"
                             MinItemHeight="150"
-                            MinRowSpacing="10"
-                            MinColumnSpacing="10" />
+                            MinItemWidth="150"
+                            MinRowSpacing="10" />
                     </controls:ItemsRepeater.Layout>
                     <!--<controls:ItemsRepeater.Animator>
                         <utils:DefaultElementAnimator />
@@ -83,9 +82,9 @@
         </controls:ItemsRepeaterScrollHost>
 
         <controls:ItemsRepeater
-            ItemsSource="{Binding ResettingListItems, Mode=OneWay}"
+            x:Name="ResettingCollectionRepeater"
             Grid.Row="2"
-            x:Name="ResettingCollectionRepeater">
+            ItemsSource="{Binding ResettingListItems, Mode=OneWay}">
             <controls:ItemsRepeater.ItemTemplate>
                 <DataTemplate>
                     <Grid

diff --git a/test/ModernWpfTestApp/Samples/ItemsSourceSamples/CollectionChangeDemo.xaml.cs b/test/ModernWpfTestApp/Samples/ItemsSourceSamples/CollectionChangeDemo.xaml.cs
@@ -24,6 +24,7 @@ public CollectionChangeDemo()
             insertButton.Click += delegate { _dataSource.Insert(int.Parse(newStartIndex.Text), int.Parse(newCount.Text), resetMode.IsChecked ?? false); };
             removeButton.Click += delegate { _dataSource.Remove(int.Parse(oldStartIndex.Text), int.Parse(oldCount.Text), resetMode.IsChecked ?? false); };
             replaceButton.Click += delegate { _dataSource.Replace(int.Parse(oldStartIndex.Text), int.Parse(oldCount.Text), int.Parse(newCount.Text), resetMode.IsChecked ?? false); };
+            moveButton.Click += delegate { _dataSource.Move(int.Parse(oldStartIndex.Text), int.Parse(newStartIndex.Text), int.Parse(oldCount.Text), resetMode.IsChecked ?? false); };
             resetButton.Click += delegate { _dataSource.Reset(); };
             invalidateMeasureButton.Click += delegate { repeater.InvalidateMeasure(); };
             invalidateArrangeButton.Click += delegate { repeater.InvalidateArrange(); };
@@ -158,6 +159,27 @@ public void Replace(int index, int oldCount, int newCount, bool reset)
                 }
             }
 
+            public void Move(int oldIndex, int newIndex, int count, bool reset)
+            {
+                var items = Inner.GetRange(oldIndex, count);
+                Inner.RemoveRange(oldIndex, count);
+                Inner.InsertRange(newIndex, items);
+
+                if (reset)
+                {
+                    OnItemsSourceChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+                }
+                else
+                {
+                    OnItemsSourceChanged(CollectionChangeEventArgsConverters.CreateNotifyArgs(
+                        NotifyCollectionChangedAction.Move,
+                        oldStartingIndex: oldIndex,
+                        oldItemsCount: count,
+                        newStartingIndex: newIndex,
+                        newItemsCount: count));
+                }
+            }
+
             public void Reset()
             {
                 Random rand = new Random(123);