WPF how to bind mousedown (command/action) to label

user_980202 0
Viewed 11130

I can find a lot of command mouse bindings to a button, but what if I want to bind a mousedown event to a binding (MVVM pattern)? I can't find the answer, probably it is something very small I don't see but can someone help me with this?

xaml:

<DataTemplate>
  <Grid AllowDrop="True">
     <Rectangle Width="100" Height="50" RadiusX="4" RadiusY="4" Fill="LightBlue"/>
        <Label Content="{Binding EntityName}" MouseDown="{Binding DoSomething}"/>
   </Grid>
</DataTemplate>
mvvm xaml wpf
2 Answers

You could use an interaction trigger:

<Label Content="{Binding EntityName}" xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="MouseDown" >
            <i:InvokeCommandAction Command="{Binding DoSomething}" />
        </i:EventTrigger>
    </i:Interaction.Triggers>
</Label>

Please refer to the following blog post for more information: https://blog.magnusmontin.net/2013/06/30/handling-events-in-an-mvvm-wpf-application/

You will need to add a reference to System.Windows.Interactivity.dll.

Updated version (package mentioned above is not produced by library author):

See https://devblogs.microsoft.com/dotnet/open-sourcing-xaml-behaviors-for-wpf/ for more details

user_72521820

The above top rated answer requires access to a dll which is only available if you have blend. (if I understand correct) Following some other examples I wrote a behavior which allows you to bind a command (ICommand) property to the UIElement.

Code Below :

public static class MouseDownBehavior
{
    #region Dependecy Property
    private static readonly DependencyProperty MouseDownCommandProperty = DependencyProperty.RegisterAttached
                (
                    "MouseDownCommand",
                    typeof(ICommand),
                    typeof(MouseDownBehavior),
                    new PropertyMetadata(MouseDownCommandPropertyChangedCallBack)
                );
    #endregion

    #region Methods
    public static void SetMouseDownCommand(this UIElement inUIElement, ICommand inCommand)
    {
        inUIElement.SetValue(MouseDownCommandProperty, inCommand);
    }

    private static ICommand GetMouseDownCommand(UIElement inUIElement)
    {
        return (ICommand)inUIElement.GetValue(MouseDownCommandProperty);
    }
    #endregion

    #region CallBack Method
    private static void MouseDownCommandPropertyChangedCallBack(DependencyObject inDependencyObject, DependencyPropertyChangedEventArgs inEventArgs)
    {
        UIElement uiElement = inDependencyObject as UIElement;
        if (null == uiElement) return;

        uiElement.MouseDown += (sender, args) =>
        {
            GetMouseDownCommand(uiElement).Execute(args);
            args.Handled = true;
        };
    }
    #endregion
}

Implementation :

Make sure to add the refrence "behavior" to the page/control/window. Example - xmlns:behavior="clr-namespace:MyWPFApp.Helper.Behavior"

<Border behavior:MouseDownBehavior.MouseDownCommand="{Binding UploadImageMouseDownCommand, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}"></Border>
user_73111040
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