Describe the bug
When selecting an item in a TreeView, and then selecting another item (which deselects the first item), the SelectionChanged event only reports that the second item was added to the selection. It does not report that the first item was removed from the selection. This happens regardless of which SelectionMode is used.
The exact same setup with a ListBox does report deselected items. A ListBox also raises a single SelectionChanged event for a select-all action, whereas a TreeView will fire a SelectionChanged event for every item that gets selected, which is less efficient. TreeView also doesn't support ISelectionModel, so it looks like there is currently no efficient way to handle big selection changes.
To Reproduce
axaml:
<StackPanel Orientation="Vertical">
<TreeView x:Name="ItemsTreeView" SelectionMode="Multiple" SelectionChanged="TreeView_SelectionChanged" Margin="5" />
<TextBlock x:Name="LogTextBlock" Margin="5" />
</StackPanel>
code behind:
public MainWindow()
{
InitializeComponent();
ItemsTreeView.ItemsSource = new string[] { "Apple", "Banana", "Citrus", "Pear" };
}
private void TreeView_SelectionChanged(object? sender, SelectionChangedEventArgs e)
{
LogTextBlock.Text += $"Added: {e.AddedItems.Count}, removed: {e.RemovedItems.Count} (selected: {ItemsTreeView.SelectedItems.Count})\n";
}
When selecting an item, and then another one, the log reads:
Added: 1, removed: 0 (selected: 1)
Added: 1, removed: 0 (selected: 1)
When selecting all (Ctrl+A), the log reads:
Added: 1, removed: 0 (selected: 1)
Added: 1, removed: 0 (selected: 2)
Added: 1, removed: 0 (selected: 3)
Added: 1, removed: 0 (selected: 4)
Expected behavior
With the above example, the expected log output would be:
Added: 1, removed: 0 (selected: 1)
Added: 1, removed: 1 (selected: 1)
When selecting all (Ctrl+A), the expected log output is:
Added: 4, removed: 0 (selected: 4)
Avalonia version
12.1.1
OS
Windows
Additional context
No response
Describe the bug
When selecting an item in a TreeView, and then selecting another item (which deselects the first item), the SelectionChanged event only reports that the second item was added to the selection. It does not report that the first item was removed from the selection. This happens regardless of which SelectionMode is used.
The exact same setup with a ListBox does report deselected items. A ListBox also raises a single SelectionChanged event for a select-all action, whereas a TreeView will fire a SelectionChanged event for every item that gets selected, which is less efficient. TreeView also doesn't support ISelectionModel, so it looks like there is currently no efficient way to handle big selection changes.
To Reproduce
axaml:
code behind:
When selecting an item, and then another one, the log reads:
When selecting all (Ctrl+A), the log reads:
Expected behavior
With the above example, the expected log output would be:
When selecting all (Ctrl+A), the expected log output is:
Avalonia version
12.1.1
OS
Windows
Additional context
No response