diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
index beec0bdcb16..e20e928f8d8 100644
--- a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
+++ b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -1,6 +1,5 @@
using System;
using System.Collections;
-using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
@@ -8,7 +7,6 @@
using Avalonia.Controls.Selection;
using Avalonia.Data;
using Avalonia.Input;
-using Avalonia.Input.Platform;
using Avalonia.Interactivity;
using Avalonia.Metadata;
using Avalonia.Threading;
@@ -187,14 +185,21 @@ public bool AutoScrollToSelectedItem
///
public int SelectedIndex
{
- get =>
+ get
+ {
// When a Begin/EndInit/DataContext update is in place we return the value to be
// updated here, even though it's not yet active and the property changed notification
// has not yet been raised. If we don't do this then the old value will be written back
// to the source when two-way bound, and the update value will be lost.
- _updateState?.SelectedIndex.HasValue == true ?
- _updateState.SelectedIndex.Value :
- Selection.SelectedIndex;
+ if (_updateState is not null)
+ {
+ return _updateState.SelectedIndex.HasValue ?
+ _updateState.SelectedIndex.Value :
+ TryGetExistingSelection()?.SelectedIndex ?? -1;
+ }
+
+ return Selection.SelectedIndex;
+ }
set
{
if (_updateState is object)
@@ -213,11 +218,18 @@ public int SelectedIndex
///
public object? SelectedItem
{
- get =>
- // See SelectedIndex setter for more information.
- _updateState?.SelectedItem.HasValue == true ?
- _updateState.SelectedItem.Value :
- Selection.SelectedItem;
+ get
+ {
+ // See SelectedIndex getter for more information.
+ if (_updateState is not null)
+ {
+ return _updateState.SelectedItem.HasValue ?
+ _updateState.SelectedItem.Value :
+ TryGetExistingSelection()?.SelectedItem;
+ }
+
+ return Selection.SelectedItem;
+ }
set
{
if (_updateState is object)
@@ -270,6 +282,7 @@ protected IList? SelectedItems
{
return _updateState.SelectedItems.Value;
}
+
else if (Selection is InternalSelectionModel ism)
{
var result = ism.WritableSelectedItems;
@@ -456,10 +469,8 @@ private protected override void OnItemsViewCollectionChanged(object? sender, Not
protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
{
base.OnAttachedToVisualTree(e);
- if (Selection?.AnchorIndex is int index)
- {
- AutoScrollToSelectedItemIfNecessary(index);
- }
+
+ AutoScrollToSelectedItemIfNecessary(GetAnchorIndex());
}
///
@@ -470,10 +481,8 @@ protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
void ExecuteScrollWhenLayoutUpdated(object? sender, EventArgs e)
{
LayoutUpdated -= ExecuteScrollWhenLayoutUpdated;
- if (Selection?.AnchorIndex is int index)
- {
- AutoScrollToSelectedItemIfNecessary(index);
- }
+
+ AutoScrollToSelectedItemIfNecessary(GetAnchorIndex());
}
if (AutoScrollToSelectedItem)
@@ -482,6 +491,15 @@ void ExecuteScrollWhenLayoutUpdated(object? sender, EventArgs e)
}
}
+ internal int GetAnchorIndex()
+ {
+ var selection = _updateState is not null ? TryGetExistingSelection() : Selection;
+ return selection?.AnchorIndex ?? -1;
+ }
+
+ private ISelectionModel? TryGetExistingSelection()
+ => _updateState?.Selection.HasValue == true ? _updateState.Selection.Value : _selection;
+
protected internal override void PrepareContainerForItemOverride(Control container, object? item, int index)
{
// Ensure that the selection model is created at this point so that accessing it in
@@ -634,10 +652,7 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
if (change.Property == AutoScrollToSelectedItemProperty)
{
- if (Selection?.AnchorIndex is int index)
- {
- AutoScrollToSelectedItemIfNecessary(index);
- }
+ AutoScrollToSelectedItemIfNecessary(GetAnchorIndex());
}
else if (change.Property == SelectionModeProperty && _selection is object)
{
@@ -671,7 +686,7 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
return;
}
- var value = change.GetNewValue();
+ var value = change.GetNewValue();
if (value is null)
{
// Clearing SelectedValueBinding makes the SelectedValue the item itself
@@ -921,11 +936,10 @@ private void OnSelectionModelPropertyChanged(object? sender, PropertyChangedEven
if (e.PropertyName == nameof(ISelectionModel.AnchorIndex))
{
_hasScrolledToSelectedItem = false;
- if (Selection?.AnchorIndex is int index)
- {
- KeyboardNavigation.SetTabOnceActiveElement(this, ContainerFromIndex(index));
- AutoScrollToSelectedItemIfNecessary(index);
- }
+
+ var anchorIndex = GetAnchorIndex();
+ KeyboardNavigation.SetTabOnceActiveElement(this, ContainerFromIndex(anchorIndex));
+ AutoScrollToSelectedItemIfNecessary(anchorIndex);
}
else if (e.PropertyName == nameof(ISelectionModel.SelectedIndex) && _oldSelectedIndex != SelectedIndex)
{
@@ -1279,9 +1293,17 @@ private void EndUpdating()
state.SelectedItem = item;
}
+ // SelectedIndex vs SelectedItem:
+ // - If only one has a value, use it
+ // - If both have a value, prefer the one having a "non-empty" value, e.g. not -1 nor null
+ // - If both have a "non-empty" value, prefer the index
if (state.SelectedIndex.HasValue)
{
- SelectedIndex = state.SelectedIndex.Value;
+ var selectedIndex = state.SelectedIndex.Value;
+ if (selectedIndex >= 0 || !state.SelectedItem.HasValue)
+ SelectedIndex = selectedIndex;
+ else
+ SelectedItem = state.SelectedItem.Value;
}
else if (state.SelectedItem.HasValue)
{
@@ -1338,39 +1360,12 @@ private void TextSearchTimer_Tick(object? sender, EventArgs e)
// - Both the old and new SelectionModels have the incorrect Source
private class UpdateState
{
- private Optional _selectedIndex;
- private Optional _selectedItem;
- private Optional _selectedValue;
-
public int UpdateCount { get; set; }
public Optional Selection { get; set; }
public Optional SelectedItems { get; set; }
-
- public Optional SelectedIndex
- {
- get => _selectedIndex;
- set
- {
- _selectedIndex = value;
- _selectedItem = default;
- }
- }
-
- public Optional SelectedItem
- {
- get => _selectedItem;
- set
- {
- _selectedItem = value;
- _selectedIndex = default;
- }
- }
-
- public Optional SelectedValue
- {
- get => _selectedValue;
- set => _selectedValue = value;
- }
+ public Optional SelectedIndex { get; set; }
+ public Optional SelectedItem { get; set; }
+ public Optional SelectedValue { get; set; }
}
///
diff --git a/tests/Avalonia.Controls.UnitTests/EnumerableExtensions.cs b/tests/Avalonia.Controls.UnitTests/EnumerableExtensions.cs
index a2d752ab396..25bf3d3c4ed 100644
--- a/tests/Avalonia.Controls.UnitTests/EnumerableExtensions.cs
+++ b/tests/Avalonia.Controls.UnitTests/EnumerableExtensions.cs
@@ -1,8 +1,6 @@
using System;
using System.Collections.Generic;
using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
namespace Avalonia.Controls.UnitTests
{
@@ -16,5 +14,29 @@ public static IEnumerable Do(this IEnumerable items, Action action)
yield return i;
}
}
+
+ public static IEnumerable Permutations(this IEnumerable source)
+ {
+ var sourceArray = source.ToArray();
+ var results = new List();
+ Permute(sourceArray, 0, sourceArray.Length - 1);
+ return results;
+
+ void Permute(T[] elements, int depth, int maxDepth)
+ {
+ if (depth == maxDepth)
+ {
+ results.Add(elements.ToArray());
+ return;
+ }
+
+ for (var i = depth; i <= maxDepth; i++)
+ {
+ (elements[depth], elements[i]) = (elements[i], elements[depth]);
+ Permute(elements, depth + 1, maxDepth);
+ (elements[depth], elements[i]) = (elements[i], elements[depth]);
+ }
+ }
+ }
}
}
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
index aa2b7ca5310..8c8bf2b33fb 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
@@ -5,7 +5,6 @@
using System.Collections.Specialized;
using System.ComponentModel;
using System.Linq;
-using System.Reactive.Disposables;
using System.Threading.Tasks;
using Avalonia.Collections;
using Avalonia.Controls.Presenters;
@@ -18,7 +17,6 @@
using Avalonia.Interactivity;
using Avalonia.Layout;
using Avalonia.Markup.Data;
-using Avalonia.Platform;
using Avalonia.Styling;
using Avalonia.Threading;
using Avalonia.UnitTests;
@@ -2294,6 +2292,134 @@ public void Should_First_Raise_Property_Changed_Notification_Then_Fire_Selection
}
+ [Theory]
+ [MemberData(nameof(GetSelectionFieldPermutationParameters))]
+ public void SelectedItem_And_Selection_Properties_Work_In_Any_Order_When_Initializing(SelectionField[] fields)
+ => TestSelectionFields(vm => vm.SelectedItem = vm.Items[2], fields);
+
+ [Theory]
+ [MemberData(nameof(GetSelectionFieldPermutationParameters))]
+ public void SelectedIndex_And_Selection_Properties_Work_In_Any_Order_When_Initializing(SelectionField[] fields)
+ => TestSelectionFields(vm => vm.SelectedIndex = 2, fields);
+
+ [Theory]
+ [MemberData(nameof(GetSelectionFieldPermutationParameters))]
+ public void SelectedValue_And_Selection_Properties_Work_In_Any_Order_When_Initializing(SelectionField[] fields)
+ => TestSelectionFields(vm => vm.SelectedValue = 12, fields);
+
+ private void TestSelectionFields(Action setItem2, SelectionField[] fields)
+ {
+ using var _ = Start();
+
+ var vm = new FullSelectionViewModel
+ {
+ Items =
+ {
+ new ItemModel { Id = 10, Name = "Item0" },
+ new ItemModel { Id = 11, Name = "Item1" },
+ new ItemModel { Id = 12, Name = "Item2" },
+ new ItemModel { Id = 13, Name = "Item3" }
+ }
+ };
+
+ setItem2(vm);
+
+ var root = new TestRoot
+ {
+ Width = 100,
+ Height = 100
+ };
+
+ // Match the Begin/EndInit sequence emitted by the XAML compiler
+ root.BeginInit();
+ var target = new ListBox();
+ target.BeginInit();
+ root.Child = target;
+ target.DataContext = vm;
+
+ foreach (var field in fields)
+ {
+ switch (field)
+ {
+ case SelectionField.ItemsSource:
+ target.Bind(ItemsControl.ItemsSourceProperty, new Binding(nameof(FullSelectionViewModel.Items)));
+ break;
+ case SelectionField.SelectedItem:
+ target.Bind(SelectingItemsControl.SelectedItemProperty, new Binding(nameof(FullSelectionViewModel.SelectedItem)));
+ break;
+ case SelectionField.SelectedIndex:
+ target.Bind(SelectingItemsControl.SelectedIndexProperty, new Binding(nameof(FullSelectionViewModel.SelectedIndex)));
+ break;
+ case SelectionField.SelectedValue:
+ target.Bind(SelectingItemsControl.SelectedValueProperty, new Binding(nameof(FullSelectionViewModel.SelectedValue)));
+ break;
+ case SelectionField.SelectedValueBinding:
+ target.SelectedValueBinding = new Binding(nameof(ItemModel.Id));
+ break;
+ default:
+ throw new InvalidOperationException($"Unkown field {field}");
+ }
+ }
+
+ target.EndInit();
+ root.EndInit();
+
+ Assert.Equal(vm.Items[2], target.SelectedItem);
+ Assert.Equal(2, target.SelectedIndex);
+ Assert.Equal(12, target.SelectedValue);
+
+ Assert.Equal(vm.Items[2], vm.SelectedItem);
+ Assert.Equal(2, vm.SelectedIndex);
+ Assert.Equal(12, vm.SelectedValue);
+ }
+
+ [Fact]
+ public void SelectedItem_Can_Access_Selection_DuringInit()
+ {
+ using var _ = Start();
+
+ var target = new ListBox();
+ target.BeginInit();
+
+ var item = new ItemModel();
+
+ target.Selection = new SelectionModel {
+ SelectedItem = item
+ };
+
+ Assert.Equal(item, target.SelectedItem);
+ }
+
+ [Fact]
+ public void SelectedIndex_Can_Access_Selection_DuringInit()
+ {
+ using var _ = Start();
+
+ var target = new ListBox();
+ target.BeginInit();
+
+ target.Selection = new SelectionModel {
+ SelectedIndex = 42
+ };
+
+ Assert.Equal(42, target.SelectedIndex);
+ }
+
+ [Fact]
+ public void AnchorIndex_Can_Access_Selection_DuringInit()
+ {
+ using var _ = Start();
+
+ var target = new ListBox();
+ target.BeginInit();
+
+ target.Selection = new SelectionModel {
+ AnchorIndex = 42
+ };
+
+ Assert.Equal(42, target.GetAnchorIndex());
+ }
+
private static IDisposable Start()
{
return UnitTestApplication.Start(TestServices.StyledWindow);
@@ -2336,6 +2462,9 @@ private static FuncControlTemplate Template()
}.RegisterInNameScope(scope));
}
+ public static IEnumerable GetSelectionFieldPermutationParameters()
+ => Enum.GetValues().Permutations().Select(fields => new object[] { fields });
+
private class Item : Control, ISelectable
{
public string Value { get; set; }
@@ -2467,5 +2596,61 @@ public void Reset(IEnumerable items)
public event NotifyCollectionChangedEventHandler CollectionChanged;
}
+
+#nullable enable
+
+ private sealed class FullSelectionViewModel : NotifyingBase
+ {
+ private ItemModel? _selectedItem;
+ private int _selectedIndex = -1;
+ private int? _selectedValue;
+
+ public ObservableCollection Items { get; } = new();
+
+ public ItemModel? SelectedItem
+ {
+ get => _selectedItem;
+ set => SetField(ref _selectedItem, value);
+ }
+
+ public int SelectedIndex
+ {
+ get => _selectedIndex;
+ set => SetField(ref _selectedIndex, value);
+ }
+
+ public int? SelectedValue
+ {
+ get => _selectedValue;
+ set => SetField(ref _selectedValue, value);
+ }
+ }
+
+ private sealed class ItemModel : NotifyingBase
+ {
+ private int _id;
+ private string? _name;
+
+ public int Id
+ {
+ get => _id;
+ set => SetField(ref _id, value);
+ }
+
+ public string? Name
+ {
+ get => _name;
+ set => SetField(ref _name, value);
+ }
+ }
+
+ public enum SelectionField
+ {
+ ItemsSource,
+ SelectedItem,
+ SelectedIndex,
+ SelectedValue,
+ SelectedValueBinding
+ }
}
}
diff --git a/tests/Avalonia.UnitTests/NotifyingBase.cs b/tests/Avalonia.UnitTests/NotifyingBase.cs
index 9542e023d5c..3989118b79d 100644
--- a/tests/Avalonia.UnitTests/NotifyingBase.cs
+++ b/tests/Avalonia.UnitTests/NotifyingBase.cs
@@ -1,3 +1,6 @@
+#nullable enable
+
+using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
@@ -6,9 +9,9 @@ namespace Avalonia.UnitTests
{
public class NotifyingBase : INotifyPropertyChanged
{
- private PropertyChangedEventHandler _propertyChanged;
+ private PropertyChangedEventHandler? _propertyChanged;
- public event PropertyChangedEventHandler PropertyChanged
+ public event PropertyChangedEventHandler? PropertyChanged
{
add
{
@@ -32,9 +35,19 @@ public int PropertyChangedSubscriptionCount
private set;
}
- public void RaisePropertyChanged([CallerMemberName] string propertyName = null)
+ public void RaisePropertyChanged([CallerMemberName] string? propertyName = null)
{
_propertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
+
+ protected bool SetField(ref T field, T value, [CallerMemberName] string? propertyName = null)
+ {
+ if (EqualityComparer.Default.Equals(field, value))
+ return false;
+
+ field = value;
+ RaisePropertyChanged(propertyName);
+ return true;
+ }
}
}