WPF Course, Overview of WPF Application Structure

Windows Presentation Foundation (WPF) is an application framework provided by Microsoft that helps in developing rich desktop applications. WPF uses XAML (Extensible Application Markup Language) to define the UI and leverages the powerful capabilities of the .NET Framework to handle the application’s logic. In this course, we will take an in-depth look at the structure and main components of WPF applications.

1. Basic Concepts of WPF

WPF is a framework designed to enhance the GUI experience, providing a consistent user experience across various devices, regardless of resolution. WPF creates a systematic and maintainable application structure through the MVVM (Model-View-ViewModel) architectural pattern. Simply put, WPF provides all the tools necessary to build the UI, allowing developers to create artistic and intuitive applications.

2. Basic Structure of a WPF Application

A WPF application is fundamentally composed of the following components:

  • Project Structure: A WPF project is generally based on the .NET Framework and consists of various files and folders.
  • XAML Files: An XML-based language that defines the view and sets the appearance of the UI.
  • Code Behind Files: Contains C# code for business logic and event handling.
  • View Model: When following the MVVM pattern, it manages the data and UI state of the view and interacts with the view through data binding.
  • Model: Defines the business logic and data structures.

2.1 Project Structure

The basic structure of a WPF project is set up when you create a new WPF application project in Visual Studio. The main files and folders are as follows:

  • Solution File (.sln): Contains meta information and settings for the project.
  • Properties Folder: Contains the application’s properties and settings files.
  • App.xaml: Defines the entry point of the application and global resources.
  • MainWindow.xaml: Defines the main window where the application starts.
  • ViewModel Folder: Contains various view models that interact with the UI when following the MVVM pattern.
  • Model Folder: Contains model classes that implement business logic.

2.2 XAML Files

XAML is the core language of WPF, an XML-based language that allows UI elements to be declaratively defined. In XAML files, UI elements (buttons, text boxes, etc.) are declared, and individual element styles and behaviors can be defined through properties. Additionally, multiple XAML files can be linked to structure the layout.

2.3 Code Behind Files

The code behind files are linked to XAML files and contain the necessary C# code to handle events for UI elements or execute business logic. For example, they define event handling for button clicks or validate input data.

2.4 View Model

In the MVVM pattern, the View Model acts as a mediator between the view and the model. The View Model manages the state of the UI and enables interaction between the view’s text boxes and buttons, especially through data binding. It is typically designed to implement the INotifyPropertyChanged interface to receive notifications of property changes.

2.5 Model

The model consists of classes that perform the business logic of the application and define the data. It handles data-centric tasks such as interactions with databases, API calls, or file input/output. In WPF, data can be easily accessed through binding when there is data transfer between the model and the view model, or when there are data conditions.

3. Core Components of WPF Applications

WPF applications are comprised of the following core components:

  • Window: The basic user interface component of WPF applications that provides a frame for displaying the UI.
  • Control: Basic UI components that include various interface elements such as buttons, text boxes, and list boxes.
  • Style: A visual element that helps maintain a consistent appearance for UI elements.
  • Data Binding: Enables two-way data connections between the view and the view model.
  • Resource: A variety of reusable design elements in the UI, such as colors, styles, and brushes.

3.1 Window

In a WPF application, the Window is the top-level container for user interaction. A Window defined in XAML provides the application’s basic interface through various properties (title, size, shape) and events (load, close).

3.2 Control

Controls are the basic UI components that are essential for user interaction with the application. There are various controls such as buttons, checkboxes, and radio buttons, and custom controls can be created as needed. The style of controls can be set in both XAML and code behind, allowing users to customize them as desired.

3.3 Style

Styles are one of the powerful features of WPF, allowing the design of specific UI elements to be reusable. Similar to CSS, styles can be defined to give a consistent appearance to a wide variety of UI components, with the option to modify detailed properties to create various variations.

3.4 Data Binding

In WPF, data binding allows UI elements to be directly connected to the data in the View Model. This is an essential part of the MVVM architecture, automatically reflecting changes in the data in the UI. Therefore, it reduces the amount of code and separates the UI from the business logic, making the application easier to manage.

3.5 Resource

Using resources allows for a consistent design across the application. Colors, brushes, styles, and templates can be defined as resources and reused in various parts of the application. It offers flexibility in defining global resources within XAML files or setting resources for specific controls.

4. Key Features of WPF

WPF provides the following key features that facilitate modern application development:

  • High-Resolution Display Support: WPF uses vector-based graphics to provide a consistent UI across various resolutions.
  • Bitmap Effects: Supports bitmap images, textures, gradients, etc., enabling rich and appealing user interfaces.
  • Data Binding: Data bound to the ViewModel is directly displayed in the UI, with changes reflected immediately.
  • Templates: Allows defining layouts and presentation methods for UI elements through ControlTemplate and DataTemplate.
  • Storyboard and Animation: Provides powerful animation capabilities to easily create complex UI animations.

5. Advantages of Developing WPF Applications

The main advantages of developing WPF applications include:

  • Productivity: Efficiently designing the UI through XAML can reduce the time spent on writing code.
  • Maintainability: Using the MVVM pattern allows separation of business logic from UI presentation, enhancing code readability.
  • Scalability: Adding new features or controls to existing WPF applications is easy.
  • Excellent UI/UX: Provides outstanding user experiences, including various media types and animations.
  • Strong Community Support: WPF has an extensive developer community and resources, making it easy to find various information and help.

6. Conclusion

WPF is a modern application development framework with a variety of features and advantages. In this course, we have explored the basic structure and important components of WPF applications. Going forward, leverage the various features of WPF to develop richer and more attractive desktop applications.

In the next course, we will provide a more in-depth explanation of specific WPF controls and their usage.

WPF Course, Defining and Using Custom Events

Windows Presentation Foundation (WPF) is a powerful graphical user interface (GUI) framework for developing desktop applications as part of the .NET Framework. In this tutorial, we will go into detail about how to define and use custom events in WPF. Custom events are useful when you want to handle events that occur under specific conditions or situations.

1. What are Custom Events?

Custom events are events defined by developers as needed, in addition to the built-in events. For example, you can customize events that may occur in situations such as button clicks, data changes, or the completion of a specific process.

1.1 Components of Events

Events typically consist of the following components:

  • Delegate: Defines a reference to a specific method that will handle the event.
  • Event Handler: The method that is called when the event occurs.
  • Event Publisher: The class that raises the event.
  • Event Subscriber: The class that handles the raised event.

2. Defining Custom Events

To define a custom event in WPF, you must first declare a delegate and then declare the event based on that delegate.

2.1 Declaring a Delegate

A delegate is a type that defines a specific method signature. The actual method that will be connected to the event must match the signature of this delegate.

public delegate void MyCustomEventHandler(object sender, EventArgs e);

2.2 Declaring an Event

Once the delegate is ready, you can define an event using the delegate type. Here is an example of a class that includes a custom event:

public class MyClass
{
    public event MyCustomEventHandler MyCustomEvent;

    protected virtual void OnMyCustomEvent(EventArgs e)
    {
        MyCustomEvent?.Invoke(this, e);
    }
}

3. Raising Events

To raise an event, you call the OnMyCustomEvent method. You can call this method to raise the event when specific conditions are met.

public void TriggerEvent()
{
    OnMyCustomEvent(EventArgs.Empty);
}

4. Subscribing to Events

To subscribe to an event, the subscriber class needs to attach a method to the event it wants to subscribe to. The subscription method defines how to respond when the event occurs.

public class Subscriber
{
    public void Subscribe(MyClass publisher)
    {
        publisher.MyCustomEvent += HandleMyCustomEvent;
    }

    private void HandleMyCustomEvent(object sender, EventArgs e)
    {
        // Logic to handle when the event occurs
    }
}

5. Example: Custom Button Click Event

Below is a complete example of implementing a custom button click event. In this example, when the button called MyButton is clicked, it raises a custom event, which is handled by the subscribed Subscriber class.

public class MyButton
{
    public event MyCustomEventHandler ButtonClicked;

    protected virtual void OnButtonClicked(EventArgs e)
    {
        ButtonClicked?.Invoke(this, e);
    }

    public void Click()
    {
        // Button click logic
        OnButtonClicked(EventArgs.Empty);
    }
}

public class Subscriber
{
    public void Subscribe(MyButton button)
    {
        button.ButtonClicked += HandleButtonClicked;
    }

    private void HandleButtonClicked(object sender, EventArgs e)
    {
        // Logic to handle button click
        Console.WriteLine("Button has been clicked!");
    }
}

// Usage example
MyButton myButton = new MyButton();
Subscriber subscriber = new Subscriber();
subscriber.Subscribe(myButton);

// Raising the button click event
myButton.Click();

6. Defining Event Args

If you want to include additional information in the event, you can create custom event args like UsernameEventArgs. This event args class can inherit from EventArgs and add the necessary properties.

public class MyEventArgs : EventArgs
{
    public string Message { get; set; }
    
    public MyEventArgs(string message)
    {
        Message = message;
    }
}

You can use custom event args by modifying the event handler and the event raising method.

public class MyClass
{
    public event MyCustomEventHandler MyCustomEvent;

    protected virtual void OnMyCustomEvent(MyEventArgs e)
    {
        MyCustomEvent?.Invoke(this, e);
    }

    public void TriggerEvent()
    {
        OnMyCustomEvent(new MyEventArgs("An event has occurred."));
    }
}

7. Using Custom Events in WPF

In WPF, custom events are useful when interacting with the GUI. You can raise custom events in conjunction with WPF components such as buttons and text boxes.

7.1 Integrating with XAML

To use custom events in XAML, you need to declare the event in XAML and attach an event handler.

<Button Content="Click Me" MyCustomEvent="Button_MyCustomEvent"></Button>

7.2 Handling Events in Code Behind

You can define event handlers in the corresponding code-behind file.

private void Button_MyCustomEvent(object sender, MyEventArgs e)
{
    MessageBox.Show(e.Message);
}

8. Conclusion

We have explored how to define and use custom events in WPF. Custom events allow you to effectively handle various situations that arise in applications. By interacting with delegates, events, and event args, you can build powerful event-driven applications.

I hope this tutorial has helped you understand custom events in WPF. The next lesson will delve into a deeper discussion of the event system.

WPF Course, Event Handling Using the Command Pattern

Windows Presentation Foundation (WPF) is a powerful UI framework based on the .NET Framework, allowing for the creation of complex user interfaces. WPF supports the MVVM (Model-View-ViewModel) pattern, which effectively separates the UI from the business logic. Among its features, the Command pattern is an important technique that makes event handling clearer and more manageable. In this article, we will explore how to use the Command pattern in WPF to handle events.

1. Overview of the Command Pattern

The Command pattern is one of the behavioral design patterns that encapsulates a request as an object, separating the request sender from the receiver. This pattern allows requests to be stored in a queue and adds the ability to log or replay requests. In WPF, commands can be used to implement event handling logic for actions like button clicks and menu selections.

2. The Necessity of the Command Pattern in WPF

Directly handling events in WPF can increase the coupling between UI components and business logic. This can lead to reduced maintainability of the code and make testing difficult. By using the Command pattern, UI and business logic can be completely separated, making development and maintenance easier.

3. Understanding the Command System in WPF

In WPF, commands are implemented through the ICommand interface. This interface includes the Execute and CanExecute methods. The Execute method performs the actual logic of the command, while CanExecute determines whether the command can be executed.

3.1 ICommand Interface

public interface ICommand
{
    event EventHandler CanExecuteChanged;
    bool CanExecute(object parameter);
    void Execute(object parameter);
}

3.1.1 CanExecute Method

This method defines the logic that determines whether a command can be executed under certain conditions. A return value of true indicates that the command is executable.

3.1.2 Execute Method

This is the method called when the command is executed, implementing the actual business logic. This method defines the tasks that the command will perform.

4. Implementing a Command

Now, let’s implement a command in a real WPF application. Below is a simple example of defining a command.

4.1 Writing a Command Class

public class RelayCommand : ICommand
{
    private readonly Action _execute;
    private readonly Func _canExecute;

    public RelayCommand(Action execute, Func canExecute = null)
    {
        _execute = execute ?? throw new ArgumentNullException(nameof(execute));
        _canExecute = canExecute;
    }

    public event EventHandler CanExecuteChanged;

    public bool CanExecute(object parameter)
    {
        return _canExecute == null || _canExecute(parameter);
    }

    public void Execute(object parameter)
    {
        _execute(parameter);
    }

    public void RaiseCanExecuteChanged()
    {
        CanExecuteChanged?.Invoke(this, EventArgs.Empty);
    }
}


4.2 Using Commands in ViewModel


You can use the RelayCommand class defined above in the ViewModel. The example below shows how to set up a command to handle a button click event.


public class MainViewModel
{
    public ICommand MyCommand { get; }

    public MainViewModel()
    {
        MyCommand = new RelayCommand(ExecuteMyCommand, CanExecuteMyCommand);
    }

    private void ExecuteMyCommand(object parameter)
    {
        // Perform business logic
    }

    private bool CanExecuteMyCommand(object parameter)
    {
        // Determine executability
        return true;
    }
}



5. Connecting WPF UI and Commands


To connect a command to the View, you use the Command property in XAML. Below is an example of binding a button’s Command property to the ViewModel’s command.


<Button Content="Click Me" Command="{Binding MyCommand}" />


With this setup, the MyCommand command will execute when the button is clicked.


6. Advantages of the Command Pattern


    

  • Structural Separation: Separating the UI and business logic enhances code maintainability.
    • 

  • Reusability: Commands can be reused, reducing code duplication.
    • 

  • Testability: The encapsulation of business logic within commands makes unit testing easier.
    • 



7. Conclusion


In this lecture, we learned about handling events in WPF using the Command pattern. The Command pattern is a very useful tool for creating complex user interfaces. It helps improve code structure and enhances maintainability. Moving forward, consider applying the Command pattern in various projects using WPF.


8. Additional Resources


If you wish to learn more deeply, refer to the following materials:



	

	




	

		
		
WPF Tutorial, Designing WPF Applications Using MVVM
	


	
	
	

		
Windows Presentation Foundation (WPF) is a framework provided by Microsoft for developing desktop applications. WPF offers powerful features that allow for the creation of excellent user interfaces, and we will explore in detail how to effectively design applications using the MVVM (Model-View-ViewModel) pattern.


1. Overview of MVVM Pattern


MVVM stands for Model-View-ViewModel, a design pattern created to separate user interface and business logic. This pattern consists of three main components:


    

  • Model: Responsible for the application’s data and business logic. The model includes interactions with the database, data validation, and business rules.
    • 

  • View: Responsible for the visual elements shown to the user. In WPF, XAML (Extensible Application Markup Language) is used to define the view, displaying the UI elements with which users can interact.
    • 

  • ViewModel: Acts as an intermediary between the view and model. It includes business logic, handling events that occur in the view, and reflecting changes in model data to the view.
    • 



2. Advantages of the MVVM Pattern


Using the MVVM pattern provides the following benefits:


    

  • Maintainability: The code is clearly separated, making it easier to maintain and extend.
    • 

  • Testability: The ViewModel can be tested independently, allowing for the validation of business logic without tying it to the UI.
    • 

  • Reusability: ViewModel and Model can be reused in different views, improving productivity.
    • 

  • Data Binding: Taking advantage of WPF’s powerful data binding capabilities, synchronization between UI elements and the data model can be implemented easily.
    • 



3. Designing the Structure of WPF Applications


When designing a WPF application using the MVVM pattern, the basic project structure is organized as follows:


- MyApplication
    - Models
    - Views
    - ViewModels
    - Resources
    - App.xaml
    - MainWindow.xaml



Each folder contains classes for the respective components, allowing for clear separation of each element.


4. Defining the Model


The model part contains the data and business logic of the application. For example, let’s define a model for storing user information:


public class User
{
    public string Name { get; set; }
    public string Email { get; set; }
}



This model includes fields for the user’s name and email address, with potential methods for interacting with the database.


5. Defining the View


The view consists of the UI elements displayed to the user. In WPF, views are defined using XAML. Below is XAML code defining a simple UI:



    
        
        
        
    




This example includes text boxes for entering the user’s name and email, along with a submit button.


6. Defining the ViewModel


The ViewModel serves as the linking mechanism between the view and model. It includes methods for storing user input in the model and updating model data when specific events (e.g., button clicks) occur:


public class UserViewModel : INotifyPropertyChanged
{
    private User _user;
    
    public UserViewModel()
    {
        _user = new User();
    }
    
    public string Name
    {
        get { return _user.Name; }
        set
        {
            _user.Name = value;
            OnPropertyChanged(nameof(Name));
        }
    }
    
    public string Email
    {
        get { return _user.Email; }
        set
        {
            _user.Email = value;
            OnPropertyChanged(nameof(Email));
        }
    }
    
    public void Submit()
    {
        // Logic for saving user data
    }
    
    public event PropertyChangedEventHandler PropertyChanged;
    
    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}



The ViewModel above includes properties for the user’s name and email, as well as a Submit method for submitting the data.


7. Setting Up Data Binding


We implement interaction between the view and ViewModel using WPF’s data binding feature. Binding can be set up in XAML as follows:



    




Then, the Text properties of the TextBox can be bound as follows:







Now, the values entered by the user in the text boxes automatically update the ViewModel’s Name and Email properties.


8. Handling Events


We implement handling the button click event to call the ViewModel’s Submit method:






The above code configures the Command pattern so that the ViewModel’s Submit method is called upon button click.


9. Implementing Commands


We implement commands in the application to handle user interactions.


public ICommand SubmitCommand => new RelayCommand(Submit);



Here, RelayCommand is a simple class that implements the ICommand interface.


10. Defining the Command Class


We define the RelayCommand class to implement commands:


public class RelayCommand : ICommand
{
    private readonly Action _execute;
    private readonly Predicate _canExecute;

    public RelayCommand(Action execute, Predicate canExecute = null)
    {
        _execute = execute ?? throw new ArgumentNullException(nameof(execute));
        _canExecute = canExecute;
    }

    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }

    public bool CanExecute(object parameter)
    {
        return _canExecute == null || _canExecute(parameter);
    }

    public void Execute(object parameter)
    {
        _execute(parameter);
    }
}


This RelayCommand class allows for easy implementation of various commands.


11. Linking View and ViewModel


We ensure that the View and ViewModel are well connected, checking that data binding and commands work properly to reflect changes in the user interface in real-time.


12. Dependency Injection and MVVM


To implement MVVM efficiently, it is advisable to use the Dependency Injection pattern to inject necessary dependencies into the ViewModel.


This approach enhances testability and flexibility of the code.


Conclusion


By designing WPF applications in the MVVM pattern, we can enhance code readability and reusability while improving maintainability. The separation of business logic and UI through the MVVM pattern is a crucial aspect when crafting complex applications.


Now we have effectively learned how to design and implement WPF applications using MVVM, allowing us to actively apply the MVVM pattern in real application development. We hope this article aids you in your WPF application development.

	

	




	

		
		
WPF Course, Differences Between WPF and WinForms
	


	
	
	

		
Windows Presentation Foundation (WPF) and Windows Forms (WinForms) are both UI technologies provided by Microsoft’s .NET technology stack. These two technologies each have their own advantages and disadvantages, and can be selected according to the needs of the developers. Here, we will introduce the basic concepts of WPF and WinForms and detail their main differences.


1. Basic Concepts


1.1 Windows Forms (WinForms)


WinForms is a technology available in the early versions of the Microsoft .NET Framework, used for developing desktop applications for the Windows operating system. WinForms comes with a very intuitive drag-and-drop design environment, optimized for control and event-based programming. However, WinForms lacks flexibility in UI design and user experience (UI/UX), which imposes many limitations in implementing complex applications.


1.2 Windows Presentation Foundation (WPF)


WPF is a more advanced technology compared to WinForms, offering a more powerful and flexible framework. WPF uses vector-based graphics to create more vibrant and responsive UIs and defines UI elements using a markup language called XAML (Extensible Application Markup Language). WPF allows the construction of very complex UIs through features like data binding, styling, animation, and custom controls.


2. Key Differences between WPF and WinForms


2.1 Graphics Handling


WPF uses vector-based graphics instead of bitmap, providing better resolution and quality across various display scales. In contrast, WinForms is centered around bitmap-based forms and controls, making it less adaptable to changes in DPI (resolution). In fact, WPF applications offer a clearer and more consistent UI across various screen sizes and resolutions.


2.2 UI Design and Layout


WinForms provides a classic form-based interface, where the programmer must directly specify the position and size of controls. This can impose significant constraints when collaborating between designers and developers. In contrast, WPF allows for smooth layouts and UI design using XAML, enabling designers to work separately from the code. XAML allows UI elements to be defined declaratively, making it easily understandable and modifiable even for non-experts.


2.3 Data Binding


WPF provides robust data binding capabilities. This feature makes it easy to manage complex relationships between UI elements and data sources. With WPF, the MVVM (Model-View-ViewModel) pattern separates UI and business logic, automatically reflecting data changes in the UI. However, WinForms has limited data binding, requiring manual event handling, which increases complexity in large applications.


2.4 Animation and Effects


WPF offers strong support for animations and transitions. Developers can easily apply various animations to UI elements, greatly enhancing the user experience. In contrast, implementing animations in WinForms requires more complex code and manual work, resulting in limited basic effects.


2.5 Styles and Templates


WPF’s complex customization of styles and templates allows for different appearances even from the same base control. In WPF, Styles and ControlTemplates enable easy modification and customization of UI elements. Conversely, WinForms has restricted capabilities in this area, often making customization difficult.


2.6 Resource Management


WPF uses resource dictionaries to create and manage various reusable resources (e.g., styles, brushes, shapes, etc.). This enhances code reusability and makes maintenance easier. In comparison, WinForms requires direct management of resources through code, which can reduce efficiency.


2.7 Platform Support


WPF has evolved to support cross-platform capabilities in .NET Core and .NET 5 and above, considering the possibility of running on platforms other than Windows. In contrast, WinForms primarily operates optimized for Windows, making its platform compatibility more limited than WPF.


3. Criteria for Choosing between WPF and WinForms


The choice between WPF and WinForms depends on the goals and needs of the project. WinForms is suitable for simple and intuitive projects or when integration with existing systems is required. On the other hand, WPF is appropriate when complex UIs or user experience is important. It is crucial to understand the characteristics of each technology well and clarify the requirements to make the appropriate choice.


4. Conclusion


WPF and WinForms are technologies with their own characteristics and advantages. While WinForms allows rapid application development due to its simplicity, WPF offers a higher level of UI and user experience, enabling the creation of more advanced applications. It is important for developers to choose each technology appropriately according to the project’s requirements to achieve optimal results.


5. References