Question

I’m attempting to use a Command, defined in my view model with EventTriggers as defined in xmlns:i=”http://schemas.microsoft.com/expression/2010/interactivity”

I have changed the control from a Microsoft.Surface.Presentation.Controls.SurfaceSlider-derived control to a regular WPF Button. With the Button, the same ConfirmOrderCommand gets fired if I use the EventName=”MouseEnter”, but if I use EventName=”Click” nothing happens. The XAML for the Button is here.

<Button Name="ConfirmButton"
          IsEnabled="{Binding IsEnabled}"
          Style="{StaticResource  ConfirmButtonStyle}"
          >
    <i:Interaction.Triggers>
      <i:EventTrigger EventName="Click">
        <i:InvokeCommandAction Command="{Binding ConfirmOrderCommand}"/>
      </i:EventTrigger>
    </i:Interaction.Triggers>
  </Button>

I want the user to be able to click the button to fire the command. Can I get the Click event to work for a Button, or do I need to look for another event? I’ve also failed to get MouseLeftButtonUp to work.

Answer 1

The actual reason the Button.Click would not work, was determined after much pain and finally asking someone on the project after he woke up in the morning.

Our application was stealing almost all of the Button events with FrameworkElement Preview delegates.

public static void RegisterEvents(FrameworkElement parent)
{
    parent.PreviewMouseDown += MouseDown;
    parent.PreviewMouseUp += MouseUp;
    // even more of these
}

The delegates would then use System.Window.Input.TouchDevice to ReportDown() in the case of MouseDown etc. All this time I just thought I didn’t know how the standard WPF button usually works. I guess the moral of this story is events don’t have to start at the child control and then propagate up to their containers until Handled = true. Preview allows the container to capture the events first.