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fix(listview): header losing datacontext on ios between frame navigation
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@Xiaoy312
Xiaoy312 committed Nov 29, 2023
1 parent 5e3a9e6 commit 868c3ad
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Showing 2 changed files with 148 additions and 38 deletions.
171 changes: 133 additions & 38 deletions src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_ListViewBase.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,10 @@
using static Private.Infrastructure.TestServices;
using Point = Windows.Foundation.Point;

#if HAS_UNO
using static Uno.UI.Extensions.ViewExtensions;
#endif

namespace Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls
{
public partial class Given_ListViewBase // resources
Expand Down Expand Up @@ -4003,13 +4007,6 @@ private async Task When_Items_Have_Duplicates_Common(Selector sut)
Assert.AreEqual("String 1", (string)added3.Single());
}

private sealed class AlwaysEqualClass : IEquatable<AlwaysEqualClass>
{
public bool Equals(AlwaysEqualClass obj) => true;
public override bool Equals(object obj) => true;
public override int GetHashCode() => 0;
}

[TestMethod]
public async Task When_Items_Are_Equal_But_Different_References_ListView() => await When_Items_Are_Equal_But_Different_References_Common(new ListView());

Expand All @@ -4022,7 +4019,44 @@ private sealed class AlwaysEqualClass : IEquatable<AlwaysEqualClass>
[TestMethod]
public async Task When_Items_Are_Equal_But_Different_References_FlipView() => await When_Items_Are_Equal_But_Different_References_Common(new FlipView());

public record When_Header_DataContext_Model(string MyText);
private async Task When_Items_Are_Equal_But_Different_References_Common(Selector sut)
{
var obj1 = new AlwaysEqualClass();
var obj2 = new AlwaysEqualClass();
var items = new ObservableCollection<AlwaysEqualClass>(new[]
{
obj1, obj2
});
sut.ItemsSource = items;
var list = new List<SelectionChangedEventArgs>();
sut.SelectionChanged += (_, e) => list.Add(e);
sut.SelectedIndex = 1;
Assert.AreEqual(1, sut.SelectedIndex);
Assert.AreSame(obj2, sut.SelectedItem);
sut.SelectedIndex = 0;
Assert.AreEqual(0, sut.SelectedIndex);
Assert.AreSame(obj1, sut.SelectedItem);

Assert.AreEqual(2, list.Count);
var removed1 = list[0].RemovedItems;
var removed2 = list[1].RemovedItems;

var added1 = list[0].AddedItems;
var added2 = list[1].AddedItems;

if (sut is FlipView)
{
Assert.AreSame(obj1, removed1.Single());
}
else
{
Assert.AreEqual(0, removed1.Count);
}
Assert.AreSame(obj2, added1.Single());

Assert.AreSame(obj2, removed2.Single());
Assert.AreSame(obj1, added2.Single());
}

[TestMethod]
[RunsOnUIThread]
Expand Down Expand Up @@ -4216,44 +4250,51 @@ public async Task When_HeaderTemplate_DataContext()
}
#endif

private async Task When_Items_Are_Equal_But_Different_References_Common(Selector sut)
#if __IOS__
[TestMethod]
[RunsOnUIThread]
public async Task When_HeaderDataContext_Cleared_FromNavigation()
{
var obj1 = new AlwaysEqualClass();
var obj2 = new AlwaysEqualClass();
var items = new ObservableCollection<AlwaysEqualClass>(new[]
{
obj1, obj2
});
sut.ItemsSource = items;
var list = new List<SelectionChangedEventArgs>();
sut.SelectionChanged += (_, e) => list.Add(e);
sut.SelectedIndex = 1;
Assert.AreEqual(1, sut.SelectedIndex);
Assert.AreSame(obj2, sut.SelectedItem);
sut.SelectedIndex = 0;
Assert.AreEqual(0, sut.SelectedIndex);
Assert.AreSame(obj1, sut.SelectedItem);
var frame = new Frame();

Assert.AreEqual(2, list.Count);
var removed1 = list[0].RemovedItems;
var removed2 = list[1].RemovedItems;
WindowHelper.WindowContent = frame;
await WindowHelper.WaitFor(() => frame.IsLoaded);
await WindowHelper.WaitForIdle();

var added1 = list[0].AddedItems;
var added2 = list[1].AddedItems;
frame.Navigate(typeof(When_HeaderDataContext_Cleared_FromNavigation_Page));
await WindowHelper.WaitForIdle();

if (sut is FlipView)
{
Assert.AreSame(obj1, removed1.Single());
}
else
var page = (When_HeaderDataContext_Cleared_FromNavigation_Page)frame.Content;
var sut = frame.FindFirstDescendant<ListView>();
var panel = (NativeListViewBase)sut.InternalItemsPanelRoot;

page.LvHeaderDcChanged += (s, e) => { /* for debugging */ };
Assert.IsNotNull(page.DataContext);

for (var i = 0; i < 3; i++) // may not always trigger, but 3 times is usually more than enough
{
Assert.AreEqual(0, removed1.Count);
// scroll header out of viewport and back in
ScrollTo(sut, 100000);
await WindowHelper.WaitForIdle();
await Task.Delay(1000);
ScrollTo(sut, 0);
await WindowHelper.WaitForIdle();
await Task.Delay(1000);

// frame navigate away and back
frame.Navigate(typeof(BackNavigationPage));
await WindowHelper.WaitForIdle();
await Task.Delay(1000);
frame.GoBack();
await WindowHelper.WaitForIdle();

// check if data-context is still set
Assert.AreEqual(GetListViewHeader()?.DataContext, page.DataContext);
}
Assert.AreSame(obj2, added1.Single());

Assert.AreSame(obj2, removed2.Single());
Assert.AreSame(obj1, added2.Single());
UIElement GetListViewHeader() => (panel.GetSupplementaryView(NativeListViewBase.ListViewHeaderElementKindNS, NSIndexPath.FromRowSection(0, 0)) as ListViewBaseInternalContainer)?.Content;
}
#endif
}

public partial class Given_ListViewBase // data class, data-context, view-model, template-selector
Expand Down Expand Up @@ -4521,6 +4562,60 @@ public LambdaDataTemplateSelector(Func<object, DataTemplate> impl)
protected override DataTemplate SelectTemplateCore(object item, DependencyObject container) => SelectTemplateCore(item);
protected override DataTemplate SelectTemplateCore(object item) => _impl(item);
}

public record When_Header_DataContext_Model(string MyText);

private sealed class AlwaysEqualClass : IEquatable<AlwaysEqualClass>
{
public bool Equals(AlwaysEqualClass obj) => true;
public override bool Equals(object obj) => true;
public override int GetHashCode() => 0;
}

#if HAS_UNO
public partial class When_HeaderDataContext_Cleared_FromNavigation_Page : Page
{
public event TypedEventHandler<FrameworkElement, DataContextChangedEventArgs> LvHeaderDcChanged;

public When_HeaderDataContext_Cleared_FromNavigation_Page()
{
DataContext = "MainVM";
Content = new Grid
{
RowDefinitions =
{
new() { Height = new GridLength(1, GridUnitType.Auto) },
new() { Height = new GridLength(1, GridUnitType.Star) },
},
Children =
{
new Button { Content = "Next" }.Apply(x =>
{
Grid.SetRow(x, 0);
x.Click += (s, e) => Frame.Navigate(typeof(BackNavigationPage));
}),
new ListView
{
ItemsSource = Enumerable.Range(0, 200).Select(x => $"asd {x}"),
HeaderTemplate = new DataTemplate(() => new StackPanel
{
new TextBlock() { Text = "header" },
new TextBlock().Apply(x => x.SetBinding(TextBlock.TextProperty, new Binding())),
}.Apply(x => x.DataContextChanged += (s, e) => LvHeaderDcChanged?.Invoke(s, e))),
}.Apply(x => Grid.SetRow(x, 1)),
},
};
}
}
#endif

public partial class BackNavigationPage : Page
{
public BackNavigationPage()
{
Content = new Button().Apply(x => x.Click += (s, e) => Frame.GoBack());
}
}
}

public partial class Given_ListViewBase // helpers
Expand Down
15 changes: 15 additions & 0 deletions src/Uno.UI/UI/Xaml/Controls/ListViewBase/ListViewBase.iOS.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -232,5 +232,20 @@ private protected override void Refresh()
InvalidateMeasure();
}
}

public override void MovedToWindow()
{
base.MovedToWindow();

// Uno#13172: The header container can sometimes lose its data-context between/after frame navigation,
// especially so when the header has been scrolled out of viewport (far enough to be recycled) once.
if (Window is { })
{
if (InternalItemsPanelRoot is NativeListViewBase panel)
{
panel.UpdateHeaderAndFooter();
}
}
}
}
}

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