if (e.LeftButton == MouseButtonState.Released)
                return;

e.GetPosition(this);

<Canvas  x:Name="canvas" Background="Transparent" Height="{Binding ElementName=image}" Width="{Binding ElementName=image}" >
                                        <dxmvvm:Interaction.Behaviors>
                                            <dxmvvm:EventToCommand EventName="MouseDown" Command="{Binding MouseDownCommand, Source={x:Static VM:VMDrawing.instance}}" PassEventArgsToCommand="True" >
                                                <dxmvvm:EventToCommand.EventArgsConverter>
                                                    <converter:MouseEventConverter/>
                                                </dxmvvm:EventToCommand.EventArgsConverter>
                                            </dxmvvm:EventToCommand>
                                        </dxmvvm:Interaction.Behaviors>
</Canvas>

public class MouseEventConverter : EventArgsConverterBase<MouseEventArgs>
{
    protected override object Convert(object sender, MouseEventArgs args)
    {
        var canvas = sender as Canvas;

        return args.Button;
    }
}

public VMDrawing()
        {


            MouseDownCommand = new DelegateCommand<object>(MouseDownEvent, true);
        }

        private void MouseDownEvent(object obj)
        {
            try
            {
                Debug.WriteLine("called");
                //check if the obj is null or not
                if (obj == null) return;
                Debug.WriteLine(obj.GetType());

            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.Message);
                Debug.WriteLine(ex.StackTrace);
                throw ex;
            }
        }