如何覆盖用户控件中的onTouchUp，它不仅可以用于触发此用户控件上的事件，还可以用于整个应用程序

Question

I am a new to the C# and WPF. Right now, I want to override onTouchUp event in my user control. Then I can add user control in the references for reuse. The problem is each time I want to test this event on the application, the event only fires at area of user control, not whole screen. Does anyone have a solution for this?

Answer 1

Basically, you need to attach to PreviewTouchUp event on a element, that covers the interactive area. It may be application wndows as well. Handling mouse or touch events outside window is not recommended.

Here's an example, how can you attach any behaviour to any element directly in xaml:

  <Window  my:MyBehaviour.DoSomethingWhenTouched="true" x:Class="MyProject.MainWindow">



public static class MyBehaviour
{
    public static readonly DependencyProperty  DoSomethingWhenTouchedProperty = DependencyProperty.RegisterAttached("DoSomethingWhenTouched", typeof(bool), typeof(MyBehaviour), 
        new FrameworkPropertyMetadata( DoSomethingWhenTouched_PropertyChanged));

    private static void  DoSomethingWhenTouched_PropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var uiElement = (UIElement)d;

        //unsibscribe firt to avoid multiple subscription
        uiElement.PreviewTouchUp -=uiElement_PreviewTouchUp;

        if ((bool)e.NewValue){
            uiElement.PreviewTouchUp +=uiElement_PreviewTouchUp;
        }
    }

    static void uiElement_PreviewTouchUp(object sender, System.Windows.Input.TouchEventArgs e)
    {
        //you logic goes here
    }

    //methods required by wpf conventions
    public static bool GetDoSomethingWhenTouched(UIElement obj)
    {
        return (bool)obj.GetValue(DoSomethingWhenTouchedProperty);
    }

    public static void SetDoSomethingWhenTouched(UIElement obj, bool value)
    {
        obj.SetValue(DoSomethingWhenTouchedProperty, value);
    }
}