I've got a textbox where I have this:
<KeyBinding Command="{Binding MyCommand}" Key="Tab"/>
Problem is it swallows the Tab and doesn't tab to the next control. How can I trap the Tab for the textbox and still preserve tabbing to the next control in the tab order? Edit: I'm also using MVVM and MyCommand is in the ViewModel code, so that's where I need to re-throw the Tab.
It's easy to achieve, just don't use KeyBinding for this. Handle your TextBox's OnKeyDown event:
<TextBox KeyDown="UIElement_OnKeyDown" ...
Then on the code-behind, execute your command whenever Tab is pressed. Unlike KeyBinding, this won't swallow the TextInput event so it should work.
private void OnKeyDown(object sender, KeyEventArgs e)
{
switch (e.Key)
{
case Key.Tab:
// Execute your command. Something similar to:
((YourDataContextType)DataContext).MyCommand.Execute(parameter:null);
break;
}
}
I cannot find a way to set focus to a control given your question as a purely XAML solution.
I choose to create an attacted property and then through binding set the focus to next control from the Command associated with your KeyBinding in the ViewModel.
Here is the View:
<Window x:Class="WarpTab.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:c="clr-namespace:WarpTab.Commands"
xmlns:Views="clr-namespace:WarpTab.Views"
xmlns:local="clr-namespace:WarpTab.ViewModels"
Title="Main Window" Height="400" Width="800">
<Window.Resources>
<c:CommandReference x:Key="MyCommandReference" Command="{Binding MyCommand}" />
</Window.Resources>
<DockPanel>
<ScrollViewer>
<WrapPanel >
<TextBox Text="First text value" >
<TextBox.InputBindings>
<KeyBinding Command="{StaticResource MyCommandReference}" Key="Tab"/>
</TextBox.InputBindings>
</TextBox>
<TextBox Text="Next text value" local:FocusExtension.IsFocused="{Binding FocusControl}" />
<Button Content="My Button" />
</WrapPanel>
</ScrollViewer>
</DockPanel>
</Window>
Here is the ViewModel:
using System.Windows.Input;
using WarpTab.Commands;
namespace WarpTab.ViewModels
{
public class MainViewModel : ViewModelBase
{
public ICommand MyCommand { get; set; }
public MainViewModel()
{
MyCommand = new DelegateCommand<object>(OnMyCommand, CanMyCommand);
}
private void OnMyCommand(object obj)
{
FocusControl = true;
// process command here
// reset to allow tab to continue to work
FocusControl = false;
return;
}
private bool CanMyCommand(object obj)
{
return true;
}
private bool _focusControl = false;
public bool FocusControl
{
get
{
return _focusControl;
}
set
{
_focusControl = value;
OnPropertyChanged("FocusControl");
}
}
}
}
Here is the code to define the attached property that I found in the following answer.
using System.Windows;
namespace WarpTab.ViewModels
{
public static class FocusExtension
{
public static bool GetIsFocused(DependencyObject obj)
{
return (bool)obj.GetValue(IsFocusedProperty);
}
public static void SetIsFocused(DependencyObject obj, bool value)
{
obj.SetValue(IsFocusedProperty, value);
}
public static readonly DependencyProperty IsFocusedProperty =
DependencyProperty.RegisterAttached(
"IsFocused", typeof(bool), typeof(FocusExtension),
new UIPropertyMetadata(false, OnIsFocusedPropertyChanged));
private static void OnIsFocusedPropertyChanged(DependencyObject d,
DependencyPropertyChangedEventArgs e)
{
var uie = (UIElement)d;
if ((bool)e.NewValue)
{
uie.Focus(); // Don't care about false values.
}
}
}
}
Why don't you just use this code in your command handler?
private void MyCommandHandler(){
// Do command's work here
TraversalRequest request = new TraversalRequest(FocusNavigationDirection.Next);
request.Wrapped = true;
control.MoveFocus(request);
}
That's basically what 'Tab' does, so if you do the same, you're good to go. (Of course reverse the direction if you have a command with Shift-Tab.
I actually wrapped this into an extension method like so...
public static class NavigationHelpers{
public static void MoveFocus(this FrameworkElement control, FocusNavigationDirection direction = FocusNavigationDirection.Next, bool wrap = true) {
TraversalRequest request = new TraversalRequest(direction);
request.Wrapped = wrap;
control.MoveFocus(request);
}
}
...meaning the prior code becomes even simpler, like this...
private void MyCommandHandler(){
// Do command's work here
Control.MoveFocus();
}
...and if you don't know what the currently focused control is, you can just do this...
(Keyboard.FocusedElement as FrameworkElement).MoveFocus();
Hope this helps! If so, much appreciated if you vote me up or mark it as accepted!
Had the same problem, came across this thread and took me a while to find the best answer. Reference: Use EventTrigger on a specific key Define this class:
using System; using System.Windows.Input; using System.Windows.Interactivity;
public class KeyDownEventTrigger : EventTrigger
{
public KeyDownEventTrigger() : base("KeyDown")
{
}
protected override void OnEvent(EventArgs eventArgs)
{
var e = eventArgs as KeyEventArgs;
if (e != null && e.Key == Key.Tab)
{
this.InvokeActions(eventArgs);
}
}
}
The xaml for your text box:
<TextBox x:Name="txtZip"
Text="{Binding Zip, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<TextBox.InputBindings>
<KeyBinding Key="Enter" Command="{Binding ZipLookup.GetAddressByZipKeyCommand}" CommandParameter="{Binding ElementName=txtZip, Path=Text}" />
</TextBox.InputBindings>
<i:Interaction.Triggers>
<iCustom:KeyDownEventTrigger EventName="KeyDown">
<i:InvokeCommandAction Command="{Binding ZipLookup.GetAddressByZipKeyCommand}" CommandParameter="{Binding ElementName=txtZip, Path=Text}" />
</iCustom:KeyDownEventTrigger>
</i:Interaction.Triggers>
</TextBox>
In your window or user control root tag include these attributes:
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:iCustom="clr-namespace:[NAMESPACE FOR CUSTOM KEY DOWN CLASS]"
