[英]Command Executs when Enter Key is Pressed Twice
我有一个组合框。 我对它有一些输入绑定,如下所示:
<ComboBox .........>
<ComboBox.InputBindings>
<KeyBinding Command="{Binding DataContext.DeleteUnwantedOrderItemTransactionCommand,
RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type coreUI:UserControlViewBase}}}"
Gesture="Return" />
<KeyBinding Command="{Binding DataContext.DeleteUnwantedOrderItemTransactionCommand,
RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type coreUI:UserControlViewBase}}}"
Gesture="Tab" />
</ComboBox.InputBindings>
</ComboBox>
在ViewModel中,我具有RelayCommands,如下所示:
public RelayCommand DeleteUnwantedOrderItemTransactionCommand { get; set; }
public RelayCommand AddNewOrderItemTransactionCommand { get; set; }
public OrderViewModel(IEventAggregator _eventAggregator)
{
eventAggregator = _eventAggregator;
DeleteUnwantedOrderItemTransactionCommand = new RelayCommand(DeleteUnwantedOrderItemTransaction);
AddNewOrderItemTransactionCommand = new RelayCommand(AddNewOrderItemTransaction);
}
protected void DeleteUnwantedOrderItemTransaction(object obj)
{
if (!(SelectedOrderItemTransaction.ItemId > 0))
{
NewOrder.OrderItemTransactions.Remove(SelectedOrderItemTransaction);
}
if (NewOrder.OrderItemTransactions.Count == 0)
{
NewOrder.OrderItemTransactions.Add(new OrderItemTransaction());
}
eventAggregator.GetEvent<ChangeFocusToNextUIElementEvent>().Publish(true);
}
protected void AddNewOrderItemTransaction(object obj)
{
if (SelectedOrderItemTransaction == NewOrder.OrderItemTransactions.Last())
NewOrder.OrderItemTransactions.Add(new OrderItemTransaction());
eventAggregator.GetEvent<ChangeFocusToNextUIElementEvent>().Publish(true);
}
然后在CodeBehind中:
public OrderView(OrderViewModel _viewModel, IEventAggregator _eventAggregator)
{
InitializeComponent();
this.DataContext = _viewModel;
_eventAggregator.GetEvent<ChangeFocusToNextUIElementEvent>().Subscribe(MoveToNextUIElement);
}
void MoveToNextUIElement(bool obj)
{
// Gets the element with keyboard focus.
UIElement elementWithFocus = Keyboard.FocusedElement as UIElement;
if (elementWithFocus != null)
{
elementWithFocus.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
}
}
问题:
我已在InputBindings中指定,当用户按下Enter或Tab时 ,我想执行一个RelayCommand,并在该命令执行完成后,将焦点移到下一个元素。
在这种情况下:
当我按Tab时,一切正常。 执行该命令,并将焦点移至下一个元素。
但是当我第一次按Enter键时,在组合框中选择了项目。 命令不会触发,因此,焦点不会移动到下一个元素。 当我按Enter 2nd时 ,命令将执行,焦点将按预期移至下一个控件。
但是我不想要这种行为。 我想执行命令并在第一次按Enter时将焦点移到下一个元素。
只是看了看ComboBox源代码。
protected override void OnPreviewKeyDown(KeyEventArgs e)
{
// Let ComboBox's original method handle it
base.OnPreviewKeyDown(e);
// Manually check if the ComboBox handled an "Enter" key
// If yes, set e.Handled back to false so that Command binding can consume the same event
Key key = e.Key;
if (key == Key.Enter)
e.Handled = false;
}
只是说-我也没有测试! 但是我认为它应该起作用。 如果没有尝试,也尝试对OnKeyDown()
进行操作。 显然,ComboBox拥有这两种方法,并且都调用了私有方法KeyDownHandler(KeyEventArgs e)
,但我们无法覆盖它。
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