I want to override the default behavior of the WinUI 3 NumberBox clear button, the default one resets the value to "0" but in my use case it would be much better If I could bind a specific command when the clear button is clicked. For example when I hit the button, it resets the value to "5" or to another default value.
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2 Answers
You can create a custom control that derives from the NumberBox:
public class NumberBoxEx : NumberBox
{
public static readonly DependencyProperty DefaultValueProperty =
DependencyProperty.Register(
nameof(DefaultValue),
typeof(double),
typeof(NumberBoxEx),
new PropertyMetadata(default));
public NumberBoxEx() : base()
{
Loaded += NumberBoxEx_Loaded;
Unloaded += NumberBoxEx_Unloaded;
}
public Button? DeleteButton { get; private set; }
public double DefaultValue
{
get => (double)GetValue(DefaultValueProperty);
set => SetValue(DefaultValueProperty, value);
}
private void NumberBoxEx_Loaded(object sender, RoutedEventArgs e)
{
if (this.FindDescendant<Button>(x => x.Name == nameof(DeleteButton)) is not Button deleteButton)
{
return;
}
DeleteButton = deleteButton;
deleteButton.Click += DeleteButton_Click;
}
private void NumberBoxEx_Unloaded(object sender, RoutedEventArgs e)
{
if (DeleteButton is null)
{
return;
}
DeleteButton.Click -= DeleteButton_Click;
}
private void DeleteButton_Click(object sender, RoutedEventArgs e)
{
Value = DefaultValue;
}
}
BTW, FindDescendant() comes from the CommunityToolkit.WinUI.Extensions NuGet package.
Comments
Andrew's answer is clear enough. I just want to show another way to find the DeleteButton via VisualTreeHelper class.
Code here:
public static DependencyObject FindChildByName(DependencyObject parant, string ControlName)
{
int childCount = VisualTreeHelper.GetChildrenCount(parant);
for (int i = 0; i < childCount; i++)
{
var MyChild = VisualTreeHelper.GetChild(parant, i);
if (MyChild is FrameworkElement && ((FrameworkElement)MyChild).Name == ControlName)
return MyChild;
var FindResult = FindChildByName(MyChild, ControlName);
if (FindResult != null)
return FindResult;
}
return null;
}
You could use it like this:
var deletebutton = FindChildByName(targetControl, "DeleteButton") as TextBlock;
deletebutton.Text = "New Content";
Comments
