Additionally, when this condition changes, you raise the CanExecuteChanged event. Whether using WPF, ASP. When you associate a control with a command it walks up the logical tree to find the first command binding associated with it. View can then bind and trigger these commands for different actions on the UI. Commands Event-like entities that can be applied to numerous control types Is an object with a command property that returns an object implementing the ICommand interface Examples ApplicationCommands: Close, Copy, Find, Open, Redo,. RoutedUICommand allows for associating control text with the command itself. Limitations of the Implementation. 5 and Caliburn Micro. NET Forums / General ASP. bool CanExecute(object parameter); void Execute(object parameter); event EventHandler CanExecuteChanged;. After writing the text in textbox, when we click on button, it will display a simple message box. In this article I will demonstrate how you can write code to fire the button click event in WPF with MVVM pattern using prism library. EventToCommand is used to bind an event to an ICommand directly in XAML. Walkthrough: Two-way binding inside a XAML User Control User controls are a great way couple logic and XAML in an encapsulated way. Custom Command Bindings Derives from CommandBinding but with built-in handlers so that the receiver can be applied to any qualified, standard element by composition, in xaml. it should be possible to bind Events to Commands in the ViewModel. Binding Command to Ancestor View Model from View in WPF MVVM 11/06/13 on. KeyEventArgs: In the Window_KeyDown method, the KeyEventArgs is important. A routed event is a type of event that can invoke handlers on multiple listeners in an element tree rather than just the object that raised the event. WPF: Copying Hyperlink with command binding in Flowdocument / Richtextbox throw exception Problem In my product we use a label containing flow document and there have a link to switch to another window. Direct The event is raised on the source element and must be handled on the source element itself. Handling mouse event commands in Listview controls in WPF / MVVM. In this article I will demonstrate how you can write code to fire the button click event in WPF with MVVM pattern using prism library. Thanks, Bob! While I see the use of Command objects instead of the Click event for the button in MainPage. 6m developers to have your questions answered on Binding command to SelectionChanged Event of UI for Silverlight ComboBox. Q and A - Windows 8 Button Command Binding in UWP "XAML with C#" sample in C#, XAML for Visual Studio 2015. Limitations of the Implementation. I decided to figure out what's the best way for me to do TextBox validation, which will be enough versatile for different tasks, but also as simple as possible for implementation. As this article is not intended to be a beginner's article, I presume you know what WPF commands are and what they are used for. Binding Button Click Command with ViewModal (ButtonClickCommandBinding. [C#, WPF] Binding Event to Command × Après avoir cliqué sur "Répondre" vous serez invité à vous connecter pour que votre message soit publié. Most modern UI frameworks are event driven and so is WPF. Use the command to save, and the event handler to close the view directly. Under the covers, these routed commands use routed events to route messages between the command invokers and the command handlers. MVVM Commands. How to template autogenerated columns. Asynchronous commands can be useful if you need to run a time-consuming operation in a separate thread without freezing the UI. As the CommandManager is called by the View you have to expose a method in your ViewModel that returns a collection of its CommandBindings. Setting the Command parameter of a Button to a particular command and then binding the command to some code in the CommandBindings for a main Window, the button is the source and the window is the sender. If the command target has a CommandBinding for the specific command, the Executed handler for that CommandBinding is called. It was possible because the Button. DoSomethingCommand}". WPF Events to Command redirection using System. Introduction. One way Windows Presentation Foundation (WPF) brings data to a user is through data binding. RemoveItemCommand } ". The EventToCommandBehavior expose the following properties. If you want to autogenerate columns using AutoGenerateColumns="True", you cannot use CellTemplates, because the DataGrid autogenerates either a text, combo, hyperlink or checkbox column, but none of these are templateable. The reason was how to execute command on events like MouseOver and MouseDown. This sample shows how to bind a command to button in Universal Windows Platform. CommandParameter: CommandParameter can easily pass an object or bind it to a property of another control. RoutedUICommand allows for associating control text with the command itself. In this mechanism, the management of data is entirely separated from the way data. I've found some examples online and then mo. We will go step by step in this sample. Now, let’s try to add click functionality to the button using Commands in WPF. Our MainWindowViewModel class will be used to bind the 'left mouse button down' EventName command defined in the MainWindow. NET, WinForms, HTML5 or Windows 10, DevExpress tools help you build and deliver your best in the shortest time possible. ViewModel can implement commands for every action in the view. by setting Source for Context Menu Item, Code Snippet [XAML]: < syncfusion : SfDataGrid. You can also bind a command to any control that supports the command property. Data binding is a mechanism in WPF applications that provides a simple and easy way for Windows Runtime apps to display and interact with data. Some instructions on how to intercept events when clicking on Listview controls in WPF / MVVM. WPF Bind commands on Expander events, Expander is defined in controltemplate for GroupItem - gist:6387870. By continuing to browse this site, you agree to this use. The Message textbox binding uses a two-way binding, with an UpdatedSourceTrigger set to PropertyChanged, which updates the binding whenever the text changes. Sample code: The source code of the application Visual JSON Editor contains sample implementations for most of the discussed recommendations. This tutorial will show you how to use the RadContextMenu with RoutedUICommands combined with the MVVM pattern. As said, this is a simple implementation of ICommand. There is also a way to bind command parameter also, so that view state can passed to the viewmodel. In the first part we have seen how the properties from the ViewModel can be binded to the View and how changes can be notified. I did not know any anwer to do that. We have analyzed your query with your code snippet. In the sample which I got,the commands were just bound to the Button. How to bind command to a button in the DataTemplate in universal Windows apps sample in C#, C++, XAML for Visual Studio 2013. However you can achieve your requirement for binding the SfDataGrid ContextMenu MenuItem to a command from my viewmodel. This article provides an example on how you can use a three-state Checkbox control to set the IsChecked property of several other related CheckBoxes in a data-bound ItemsControl, or any other control that derives from the ItemsControl such as the DataGrid, ListView or TreeView controls, in WPF using the MVVM pattern. ItemSource property can accept any collection which implements IEnumerable interface. It's this method the Xamarin. In some cases, they are essential to making the site work properly. The button is then associated with the command by setting its Command property. Tags: WPF, WPF Data Binding, WPF DataBinding, XAML Databinding in WPF ListBox In this article, I discuss how we can use ADO. Interactivity is good approach not only in Blend, but also in frontal WPF/Silverlight development. Interactivity library to make a command respond to an event on WPF controls without using any code-behind. Step 1: Create a new WPF application in Visual Studio. It is basically a CLR event that is supported by an instance of the Routed Event class. DataContext. You can do this using the MouseAction member of the mouse binding. In addition to this, we need a method, that triggers the CanExecuteChanged event. There is an alternative way of associating a control in the view with a command object exposed by the view model. A command is an object that represents an action to be taken and is bound to a particular method that performs the action. Most modern UI frameworks are event driven and so is WPF. MVVM Commands. WPF - Binding InputBindings to View Model Commands using MVVM In this post we will be discussing about how we can bind mouse and key gestures directly with Commands in the view model. This approach is available for most platforms and XAML dialects, although detailed implementations differ. Join a community of over 2. New here? Start with our free trials. No it is a bug. This is triggered whenever the Text property of the TextBox changes. Should you have any questions or need assistance from a member of our team, write to us at [email protected] I wanted something that would Not be on top of other windows when my application was minimized Would have a semi-transparent background so you could see the application in the background but not interact with it That could be…. I wanted something that would Not be on top of other windows when my application was minimized Would have a semi-transparent background so you could see the application in the background but not interact with it That could be…. Notice that as soon as the mouse cursor enters the Button control the event is fired and the dialog message is shown: Related Posts Getting started with NSubstitute. This bending over backwards for such a simple thing illustrates just how true the quote is. Firstly, we need to add a property to ItemPresenter to store the selected state of the item. In a MVVM application actions in the view trigger the logic in the view model through the use of commands. For example, the following XAML markup shows how the Text property on a TextBox can be bound to the FirstName property on the view model:. Implementing a custom WPF Command. Here's a full list of the available commands: OpenFindDialogCommand: Opens the find dialog. In the beginning, the implementation seemed straightforward. Using CommandBinding and ExecutedRoutedEventHandler to bind Application event to an event handler method 24. You can bind WPF command in the view (XAML) and receive the event raised. The thing is, routed commands are not always great fit for MVVM development. This event is fired whenever the state of the routed command world might have changed. Interactivity is good approach not only in Blend, but also in frontal WPF/Silverlight development. So you could bind this event to command in your ViewModel using EventTriggers and InvokeCommandAction. Let Visual Studio create Window_KeyDown by pressing Enter. This can easily be done using an Attached Behavior. i have a combobox with hardcoded values, but i might using Binding as we want to follow the MVVM pattern. Compression System. I love WPF, but gosh, some things should not require this much effort. The other step is to associate this particular Paste command with event handlers. This is more precise and understandable to me to say that a 'Delay' property has been added to the Binding markup extension ! This post is a part of the serie on WPF 4. The one hundred and sixty-fifth part of the Windows Presentation Foundation Fundamentals tutorial continues the description of commanding. Execute Command on ComboBox Selection changed If you are developing WPF application MVVM way you might have noticed that Button Provide a Command property that can be set to a ICommand instance and the command will be executed when button is clicked. Without the CommandBinding there is no command logic, only a mechanism to invoke the command. Execute(object param) is invoked, and one that evalues the state of the command when ICommand. Edit: Reading the bug report there is a workaround - Add the style as a dynamic resource reference or add it as a static resource …. Bind the view model to the view using XAML. Join a community of over 2. Routed command implements ICommand interface. it should be possible to bind Events to Commands in the ViewModel. The RelayCommand will route your command to an Action (i. WPF TreeView with hierarchical data. The ButtonAdv control supports Commanding. Binding Button Click Command with ViewModal (ButtonClickCommandBinding. Two types of binding are presented - the so called (by me) runtime binding and command binding. This sample demonstrates how to bind Command in DataTemplate in universal Windows apps. Two-way Binding. WPF Command class idea is an implementation of command pattern from gang of four design pattern. 6m developers to have your questions answered on Binding Event to MVVM with EventArgs of UI for WPF DataForm. Finally, of course, is the Executed event handler bound by the command binding, which does nothing more than call the actual global command method. Other than using third party code, the quickest way to do this was to reference the System. After you select some text in one of the text boxes, the tool bar button becomes enabled. New here? Start with our free trials. How to bind command to a button in the DataTemplate in universal Windows apps sample in C#, C++, XAML for Visual Studio 2013. Well I don't know why WPF does not have an out-of-the box support for event binding. Commands provide a mechanism for the view to update the model in the MVVM architecture. Another interesting feature of command is it can check whether command can execute or not by implementing CanExecute method. by setting Source for Context Menu Item, Code Snippet [XAML]: < syncfusion : SfDataGrid. I detect which rectangle has been clicked using Event Command. Or you could bind to a command of the UserControlViewModel that publishes an event using an event aggregator or message bus. Handling the UI Events of the View in the ViewModel while avoiding placing any logic in code behind of the View. In a WPF application that uses the MVVM (Model-View-ViewModel) design pattern, the view model is the component that is responsible for handling the application's presentation logic and state. The other step is to associate this particular Paste command with event handlers. To be able to pass an event from a publisher to a subscriber using Prism’s event aggregator, the first thing you need to do is to define the actual type of the event to be passed. Descriptions of Command, Attached Properties and a clever way if binding control events with Commands. When I started my last WPF project using MVVM by referring Josh Smith's article,I was very much excited about the way it separates the view and model. The command target is the object that the command is being executed on. It does not seem so easy to initiate the communication in the reverse direction from the ViewModel back to the View. Create a view folder and a Person. I use VS2013, Wpf 4. WEBINAR: On-Demand. Now our command will receive the list of selected ItemPresenter objects as a parameter and we can do as we wish with them. I've been working with C# for a few months now, and decided I could use some knowledge on WPF. How can I use two binding for in WPF with MVVM? Data bind in textchanged event of a gridview How do I use textchanged event to search information or perform action. Broadly speaking, this substitutes the "/" binding symbol for the dot. They are a feature of the WPF framework, intimately tied to the WPF visual tree. The problem of the Command-binding approach is that each of the default user controls provides only one Command property, which resembles the most commonly used event. WPF Binding of DataGrid Column Header in XAML Setting the Background of a WPF TextBox depending on Validation in a Template/Style using TemplateBinding Setting the DataContext of a View to a ViewModel in MVVM. By this code you can do this by very simple way. Two-way Binding. Commands allow you to define actions in a View Model and then bind to them from any place in a View. You can also bind a command to any control that supports the command property. It's a kind of annoying to create a new behaviors each time I need to bind to specific event. In this blog let's discuss how to remove a row from Wpf C1DataGrid when user clicks on a button that lies in a C1DataGridTemplateColumn within the same row. As said, this is a simple implementation of ICommand. It appears to be out of scope. In a modern user interface, it's typical for a function to be reachable from several places though, invoked by different user actions. Name, view => view. of UI for Silverlight Window. The code above assumes that the command parameter is the menu item itself. If there's a way to bind the EventArgs of an event to CommandParameter in Microsoft. The view's code-behind file should contain no code to handle events that are raised from any User Interface (UI) element such as a Button or a ComboBox. myCommand, ElementName=myControl }" This way, your binding will be for the Datacontext of MyControl. ViewModel can implement commands for every action in the view. MVVM Commands. WPF Events to Command redirection using System. Posted by Kevin Bost September 19, 2017 October 2, 2017 3 Comments on Getting started with Model-View-ViewModel (MVVM) pattern using Windows Presentation Framework (WPF) The Windows Presentation Framework (WPF) is built to take full advantage of the Model-View-ViewModel (MVVM) pattern. My issue is when I want to pass the row object as the command parameter. It's a kind of annoying to create a new behaviors each time I need to bind to specific event. After writing the text in textbox, when we click on button, it will display a simple message box. In a MVVM application actions in the view trigger the logic in the view model through the use of commands. Earlier, the command property on the inputbinding class was not a Dependency property - so binding to it was out of question. This sample demonstrates how to bind Command in DataTemplate Windows 8 Command binding inside DataTemplate sample in C#, VB. Commands provide a mechanism for the view to update the model in the MVVM architecture. DataContext. View can then bind and trigger these commands for different actions on the UI. There is an alternative way of associating a control in the view with a command object exposed by the view model. Handling mouse events in WPF / MVVM using MvvmLight Event Triggers. Everything went well with the basics, but I am now struggling with commands. WPF Powershell binding Event to object? in-minutes-using-visual-studio/ In WPF I usually bind MouseLeftButtonDown for a button but I am not sure how to do this in. Here the click event is registered by calling the ButtonCommandBinding class to bind. See this for an example and a framework for doing this. As the CommandManager is called by the View you have to expose a method in your ViewModel that returns a collection of its CommandBindings. Expression Blend team provides the ability to wire up some events to viewmodel through commands like SelectionChanged of a ListBox, etc using System. This sample shows how to bind a command to button in Universal Windows Platform. Like so: var myFos =. lets see and example of 'Key Up' event, which is triggered when a user write something on a wpf control and release his finger from a keyboard key. NET, WinForms, HTML5 or Windows 10, DevExpress tools help you build and deliver your best in the shortest time possible. The button is then associated with the command by setting its Command property. There is an alternative way of associating a control in the view with a command object exposed by the view model. So an important thing to know, in order for command binding to make sense, is that (like many things in WPF) commands bubble. [WPF] Using InputBindings with the MVVM pattern March 17, 2009 Thomas Levesque 30 Comments If you develop WPF applications according to the Model-View-ViewModel pattern, you may have faced this issue : in XAML, how to bind a key or mouse gesture to a ViewModel command ?. We are here to help. They are a feature of the WPF framework, intimately tied to the WPF visual tree. Great code, but a caveat should be given to beware trying to attach to bubbled events that are marked as handled by the control class. For several reasons I tend to favor event triggers over commands in most scenarios, especially for Silverlight applications. There is also a way to bind command parameter also, so that view state can passed to the viewmodel. However, not all controls have a Command dependency property, like a TreeViewItem. I’d actually keeping both the event handler and the command. We'll discuss the same in this blog. Apart from that we will also go through the three properties which the developers are most confused with i. This sample demonstrates how to bind Command in DataTemplate in universal Windows apps. 0, which uses the XAML markup language for rich user interface development. Input namespace. By creating an ICommand object to hold an event function, the Command value can bind to the event function as an ICommand. MainWindowViewModel. WPF - Binding InputBindings to View Model Commands using MVVM In this post we will be discussing about how we can bind mouse and key gestures directly with Commands in the view model. In addition to this, we need a method, that triggers the CanExecuteChanged event. There are so many ways for data validation in WPF that sometimes it confuses people. This site uses cookies for analytics, personalized content and ads. 6m developers to have your questions answered on WPF RadWizard Binding a command to the Next button of UI for WPF Wizard. It is triggered at startup if a default Text attribute is set. The x:Name attribute simply gives you a reference to work with that you'll use later to bind commands to the RichTextBox. WPF Command class idea is an implementation of command pattern from gang of four design pattern. As this article is not intended to be a beginner's article, I presume you know what WPF commands are and what they are used for. EventToCommand can be used even if Expression Blend is not installed on your system, or on your users' system. This property should be always updated with the New value, so that you would get an call back on SelectedItemChanged when a new item in the tree is selected. For instance, if you need to calculate something, you can bind a button to an asynchronous command. Implementing a custom WPF Command. ItemSource property can accept any collection which implements IEnumerable interface. I can use this to successfully bind events (e. A dependency property to bind to TreeView Item Selected. Introduction. WPF DataGridRow Double Click With MVVM On my current project, we need to open a record for editing when the DataGridRow is double clicked. We use ICommand interface for generating the button click event. Interactivity library to make a command respond to an event on WPF controls without using any code-behind. Finally, of course, is the Executed event handler bound by the command binding, which does nothing more than call the actual global command method. The interface also defines a CanExecuteChanged event that is raised on the UI thread to cause every invoking control to requery to check if the command can execute. Here is how to do it using Prism's InvokeCommandAction in three easy steps:. Two-way Binding. Earlier, the command property on the inputbinding class was not a Dependency property – so binding to it was out of question. Binding and the. I also defined ICommands in my ViewModel which I data bind the Command attribute of various WPF element to. WPF Bind commands on Expander events, Expander is defined in controltemplate for GroupItem - gist:6387870. Add command handlers (in code-behind or ViewModel). CanExecute(object param) is called. WPF: Copying Hyperlink with command binding in Flowdocument / Richtextbox throw exception Problem In my product we use a label containing flow document and there have a link to switch to another window. In fact, the implementation of ICommand. Routed Commands Trap Bubbling Events I recently started working at the New York Times on the extremely cool Times Reader application. Like so: var myFos =. An event object is a class that inherits from the abstract Microsoft. In a modern user interface, it's typical for a function to be reachable from several places though, invoked by different user actions. CommandParameter="{Binding ElementName=XTextBlock, Path=Text}" How to implement XCommand for Windows 8 Store Application. The sender parameter in the Executed or CanExecute handlers is the object that owns the event handler. Binding Command to Ancestor View Model from View in WPF MVVM 11/06/13 on. Windows Presentation Foundation or WPF (formerly Avalon) is the UI subsystem of. So … what would happen if the XAML parser would come across a property in the native control (which derives from either UIView or Android. Hi, I did quite some googling now but did not find an answer. RequerySuggested. Q and A - Windows 8 Button Command Binding in UWP "XAML with C#" sample in C#, XAML for Visual Studio 2015. Abstract: Walkthrough for using WPF commanding for enabling / disabling Button with Command Property Commanding is a very useful feature in XAML based technologies (WPF, Windows Phone, Windows Store Apps, Silverlight). A command is an object that represents an action to be taken and is bound to a particular method that performs the action. This need not be a disadvantage as it makes the code self-explanatory, but especially in simple cases as the one shown above (simple event-to-command binding without additional actions), I find it unnecessarily lengthy – the full Button declaration now takes 7 lines of XAML code, making the View code unnecessarily complex and more difficult. WPF Binding of DataGrid Column Header in XAML Setting the Background of a WPF TextBox depending on Validation in a Template/Style using TemplateBinding Setting the DataContext of a View to a ViewModel in MVVM. In the sample which I got,the commands were just bound to the Button. No it is a bug. Unfortunately, the WPF DataGrid doesn’t support this functionality out of the box. MainWindowViewModel. Wpf Caliburn Micro: binding click event of faked c How can play video as a wallpaper like dreamscreen user control numeric pad; How to determine whether two FlowDocuments have th WPF Textbox TwoWay binding in datatemplate not upd Add Button on Each Row in DataGrid WPF in Code Beh Maintaining same recent colours list for WPF RadCo. Most devs use an MVVM framework such as MVVM Light or PRISM which offer developer friendly wrappers for iCommand. Join a community of over 2. You have to right code to call command for load and close event. Use the command to save, and the event handler to close the view directly. /// Creates a new command. xaml' file or in the code behind C# code file. Here the click event is registered by calling the ButtonCommandBinding class to bind. The idea of this pattern build an universal command, that takes two delegates: One that is called, when ICommand. Broadly speaking, this substitutes the "/" binding symbol for the dot. WEBINAR: On-Demand. T1 and T2 are the arguments of the event handler. CanExecuteChanged in RoutedCommand is just a forwarder: public event EventHandler CanExecuteChanged {. Join a community of over 2. This need not be a disadvantage as it makes the code self-explanatory, but especially in simple cases as the one shown above (simple event-to-command binding without additional actions), I find it unnecessarily lengthy – the full Button declaration now takes 7 lines of XAML code, making the View code unnecessarily complex and more difficult. Most of the described rules apply for all types of XAML projects - Windows Store, Windows Phone, Silverlight and WPF projects. Thus you can have the command as a separation layer between the ui and the presentation model. This property should be always updated with the New value, so that you would get an call back on SelectedItemChanged when a new item in the tree is selected. , close buttons are used to close a dialog. it should be possible to bind Events to Commands in the ViewModel. Today I've tried to find a way how to pass EventArgs as CommandParameter to DelegateCommand triggered by EventTrigger. RequerySuggested. To create a command class we need to implement the “ICommand” interface. WPF routed events and commands When controls are added to a form, the event gets hooked up to the XAML markup and the handlers are added to the code behind. You can check this by calling FocusManager. Sample code: The source code of the application Visual JSON Editor contains sample implementations for most of the discussed recommendations. RemoveItemCommand } ". Interactivity library to make a command respond to an event on WPF controls without using any code-behind. Interactivity. However it can be hard sometimes and in this post I will describe how you can create something I first thought it will be easy : a wrapping text with hyperlinks in it. Our MainWindowViewModel class will be used to bind the 'left mouse button down' EventName command defined in the MainWindow. But in reality, routed events are not events. Basically RoutedCommands works great in certain scenarios, and are prevalent in WPF. The WPF Command Model has four key parts: Commands - Command objects represent a unit of work and keep track of whether or not it can be executed; Command Bindings - binds the command to the associated application code; Command Sources - for menu, this is the MenuItem control that triggered. With that all set up, now the command is available in every window of the program, without having to actually add anything to the window's XAML. Learn more. Recently I finally and completely stopped to use ICommandSource directly (I mean. Command Binding. This is essentially a specialised version of the generic approach described here for binding an ICommand to any event. , close buttons are used to close a dialog. An event object is a class that inherits from the abstract Microsoft. Routed command can bubble through the element hierarchy. So an important thing to know, in order for command binding to make sense, is that (like many things in WPF) commands bubble. Commands provide a mechanism for the view to update the model in MVVM architecture. when the user clicks on a button or a menu item. iv Contents at a Glance About the Author xxvi. A dependency property to bind to TreeView Item Selected. While searching on the internet I found this answer. Whenever an event takes place, the application will be notified and the program can react to them, e. It’s a WPF application which allows you to read the New York Times using WPF’s high-fidelity flow document support, along with many other slick features. The command property is available for action based elements for e. The ICommand is what the Control in xaml is binding to. This is part of a series on New WPF Features We got a lot of feedback to improve the way a developer could set binding to the input keys and modifiers. In this article, we will learn about button click event in WPF with MVVM concept. This article provides an example on how you can use a three-state Checkbox control to set the IsChecked property of several other related CheckBoxes in a data-bound ItemsControl, or any other control that derives from the ItemsControl such as the DataGrid, ListView or TreeView controls, in WPF using the MVVM pattern. [WPF] Using InputBindings with the MVVM pattern March 17, 2009 Thomas Levesque 30 Comments If you develop WPF applications according to the Model-View-ViewModel pattern, you may have faced this issue : in XAML, how to bind a key or mouse gesture to a ViewModel command ?. Execute(object param) is invoked, and one that evalues the state of the command when ICommand. Interactivity 16 Jan 2011 As mentioned previously , I recently used System. The DataBinding is great, but what about binding events. A similar type of input binding can be used with mouse actions, allowing you to detect when the user clicks any of the three main mouse buttons, double-clicks a button or moves the mouse wheel. MainWindowViewModel. I detect which rectangle has been clicked using Event Command. If we want two-way binding, things get a little more messy.