MSDN Documentation

Window Class

Represents a top-level window, which is a container for other UI elements.

public class Window : ContentControl, IDisposable { ... }

The Window class is the root element for most WPF applications. It provides the frame for the application's content, handles user input, and manages the window's state (size, position, visibility).

Properties

• Title: string - Gets or sets the text displayed in the window's title bar.
• Width: double - Gets or sets the width of the window.
• Height: double - Gets or sets the height of the window.
• Content: object - Gets or sets the content of the window.
• WindowState: WindowState - Gets or sets the current state of the window (Normal, Minimized, Maximized).

Events

• Activated: RoutedEventHandler - Occurs when the window is activated.
• Closed: EventArgs - Occurs when the window is closed.
• StateChanged: EventArgs - Occurs when the window's state changes.

using System.Windows;

public class MyMainWindow : Window
{
    public MyMainWindow()
    {
        this.Title = "My Application Window";
        this.Width = 400;
        this.Height = 300;

        Button okButton = new Button();
        okButton.Content = "OK";
        okButton.Click += OkButton_Click;
        this.Content = okButton;
    }

    private void OkButton_Click(object sender, RoutedEventArgs e)
    {
        MessageBox.Show("Button clicked!");
    }

    [STAThread]
    public static void Main()
    {
        MyMainWindow mainWindow = new MyMainWindow();
        Application app = new Application();
        app.Run(mainWindow);
    }
}

Application Class

Represents the WPF application and provides properties and methods for managing application-level features.

public class Application : IWeakEventListener { ... }

The Application class is the entry point for most WPF applications. It manages the application's message loop, resources, and the lifetime of its windows. You typically instantiate this class and call its Run() method.

Properties

• Current: Application - Gets the current Application instance.
• MainWindow: Window - Gets or sets the main window of the application.
• Windows: ReadOnlyCollection<Window> - Gets a collection of all windows that are currently open in the application.

Methods

• Run(Window window): void - Initializes a new instance of the Application class, creates a new message loop, and then starts the message loop and listens for incoming messages.

DependencyProperty Class

Represents a property that can be hosted by any dependency object.

public sealed class DependencyProperty { ... }

Dependency properties are a core feature of WPF. They extend the traditional .NET property system by allowing properties to have values derived from various sources, including data binding, styles, templates, and animations. They also provide built-in support for change notification and validation.

Key Concepts

• Property Metadata: Defines behavior like change notification callbacks and coercion functions.
• Value Precedence: Determines which value wins when a property is set from multiple sources.
• CoerceValueCallback: A callback that can modify a property value before it's set.
• PropertyChangedCallback: A callback that is invoked when a property's value changes.

public static readonly DependencyProperty MyCustomProperty =
    DependencyProperty.Register(
        "MyCustom",                      // Property name
        typeof(string),                  // Property type
        typeof(MyDependencyObject),      // Owner type
        new FrameworkPropertyMetadata("Default Value") // Property metadata
    );

public string MyCustom
{
    get { return (string)GetValue(MyCustomProperty); }
    set { SetValue(MyCustomProperty, value); }
}

EventArgs Class

Serves as the base class for classes that contain event data.

public class EventArgs { ... }

In the .NET Framework, event handlers typically follow a convention where they accept two arguments: an object sender and an EventArgs object. The EventArgs class itself is usually used when an event does not need to pass any specific data. Custom event arguments are created by deriving from EventArgs.

Methods

• Empty: EventArgs - Gets an instance of the EventArgs class that has no event data.

Visual Class

Represents an object that can render itself.

public abstract class Visual : DispatcherObject { ... }

The Visual class is the base class for all WPF elements that have a visual representation but are not necessarily UI elements that interact directly with the user. This includes things like drawing primitives, effects, and composition nodes. It provides the fundamental rendering capabilities for WPF.

Methods

• RenderOpen(): DrawingContext - Opens a DrawingContext for drawing on the visual.