How to active UserControl outside the wrapper? - wpf

Question

I met a Focus related problem in UserControl:
Suppose we have a UserControl like this:
<UserControl x:Class="_20130826.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<StackPanel>
<ListBox>
<ListBoxItem>
<TextBlock Text="text1" />
</ListBoxItem>
<ListBoxItem>
<TextBlock Text="text2" />
</ListBoxItem>
<ListBoxItem>
<TextBlock Text="text3" />
</ListBoxItem>
<ListBoxItem>
<TextBlock Text="text4" />
</ListBoxItem>
</ListBox>
</StackPanel>
</UserControl>
And the MainWindow.xaml like this:
<Window x:Class="_20130826.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:temp="clr-namespace:_20130826"
Title="MainWindow">
<StackPanel>
<Button Content="Deactive UserControl" />
<StackPanel>
<Button Name="Button1" Content="Active UserControl" />
<ContentControl>
<temp:UserControl1 />
</ContentControl>
</StackPanel>
</StackPanel>
</Window>
Step 1: Click text1 TextBlock inside UserControl, and default the
background changes to deeper.
Step 2: Click 'Deactive UserControl' button, so the text1 background
turns to lighter.
Step 3: Click 'Active UserControl' button, then ...
I want the text1 background changed to deeper, which means the UserControl has been focused/actived.
How can I achieve this?

Answer 1

If you want to set the Focus to the UserControl when the Button("Active UserControl") gets pressed, we can add a Click event handler and assign focus to the UserControl.
So say something like:
<Window x:Class="_20130826.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:temp="clr-namespace:_20130826"
Title="MainWindow">
<StackPanel>
<Button Content="Deactive UserControl" />
<StackPanel>
<Button Name="Button1" Content="Active UserControl" Click="Button1_OnClick" />
<ContentControl>
<temp:UserControl1 x:Name="myUserControl" />
</ContentControl>
</StackPanel>
</StackPanel>
</Window>
and in MainWindow.xaml.cs:
private void Button1_OnClick(object sender, RoutedEventArgs e) {
FocusManager.SetFocusedElement(this, myUserControl);
}
Now when you click the "Active UserControl" Button, Focus will switch to the UserControl. However this will not give you that "deeper" state on the ListBoxItem as it still doesnt have Focus. So to sort that
In UserControl1.xaml.cs add:
protected override void OnGotFocus(RoutedEventArgs e) {
base.OnGotFocus(e);
if (!Equals(e.OriginalSource, this))
return;
TraversalRequest tRequest = new TraversalRequest(FocusNavigationDirection.Next);
MoveFocus(tRequest);
}
What this does is when the UserControl gets focus, it moves Focus to the next element within it which would be the element you clicked initially.
You can get a demo of your code tweaked with this: Here