Step 1: Create a new WPF project
Select Tools > NuGet Package Manager
At the prompt type:
Install-Package MvvmLight
Step 3: Add event handling code
See this link for reference
https://www.technical-recipes.com/2016/using-relaycommand-icommand-to-handle-events-in-wpf-and-mvvm/
Right click your project folder and select Add > New Item > Class to add the following three classes:
RelayCommand.cs
using System; using System.Windows.Input; namespace MvvmMouseEvent { public class RelayCommand<T> : ICommand { private readonly Predicate<T> _canExecute; private readonly Action<T> _execute; public RelayCommand(Action<T> execute) : this(execute, null) { _execute = execute; } public RelayCommand(Action<T> execute, Predicate<T> canExecute) { if (execute == null) throw new ArgumentNullException("execute"); _execute = execute; _canExecute = canExecute; } public bool CanExecute(object parameter) { return (_canExecute == null) || _canExecute((T) parameter); } public void Execute(object parameter) { _execute((T) parameter); } public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } } }
EventRaiser.cs
using System; namespace MvvmMouseEvent { public static class EventRaiser { public static void Raise(this EventHandler handler, object sender) { if (handler != null) { handler(sender, EventArgs.Empty); } } public static void Raise<T>(this EventHandler<EventArgs<T>> handler, object sender, T value) { if (handler != null) { handler(sender, new EventArgs<T>(value)); } } public static void Raise<T>(this EventHandler<T> handler, object sender, T value) where T : EventArgs { if (handler != null) { handler(sender, value); } } public static void Raise<T>(this EventHandler<EventArgs<T>> handler, object sender, EventArgs<T> value) { if (handler != null) { handler(sender, value); } } } }
EventArgs.cs
using System; namespace MvvmMouseEvent { public class EventArgs<T> : EventArgs { public EventArgs(T value) { Value = value; } public T Value { get; private set; } } }
Step 4: Create the ViewModel class for the main window
Select Add > New Item > Class.
MainWindowViewModel.cs
using System.Windows; using System.Windows.Input; namespace MvvmMouseEvent { public class MainWindowViewModel { private ICommand _mouseClick; public ICommand MouseClick { get { return _mouseClick ?? (_mouseClick = new RelayCommand<object>( x => { DoStuffWhenMouseClicked(); })); } } private static void DoStuffWhenMouseClicked() { MessageBox.Show("Mouse click event handled!"); } } }
Step 5: Update the MainWindow.xaml
Note that MvvmLight (like Prism) also allows us to pass event arguments to the command too.
MainWindow.xaml
<Window x:Class="MvvmMouseEvent.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:MvvmMouseEvent" xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity" xmlns:command="http://www.galasoft.ch/mvvmlight" mc:Ignorable="d" Title="MainWindow" Height="350" Width="525"> <Window.DataContext> <local:MainWindowViewModel /> </Window.DataContext> <Grid> <Border Background="Transparent"> <i:Interaction.Triggers> <i:EventTrigger EventName="PreviewMouseDown"> <command:EventToCommand Command="{Binding MouseClick}" PassEventArgsToCommand="True" /> </i:EventTrigger> </i:Interaction.Triggers> </Border> </Grid> </Window>
Step 6: Sort out any compiler issues!
On installing MvvM Light, into your Visual Studio project you may get a few compiler whinges.
On my setup, I found that I had to make sure the CommonServiceLocator reference to the automatically generated ViewModelLocator.cs file:
Step 7: Try it!
Run the program to see that a bog-standard WPF window is generated. Click anywhere on the area to see that the
mouse click event is handled as requested: