WPF (Windows Presentation Foundation) Interview Questions
This section covers frequently asked WPF interview questions.
1. What is WPF?
WPF (Windows Presentation Foundation) is a Microsoft framework for building Windows desktop applications with rich user interfaces. It's a powerful tool for creating visually appealing and interactive applications.
2. Capabilities of WPF.
- Standard UI controls (buttons, text boxes, etc.)
- 2D and 3D graphics capabilities
- Support for various document formats
- Data binding
- Animation
- Multimedia support
3. Resources in WPF.
Resources in WPF provide a mechanism to reuse objects and values. This simplifies the creation and maintenance of consistent and reusable UI elements.
4. What is XAML?
XAML (Extensible Application Markup Language) is an XML-based declarative language used to define the user interface (UI) in WPF applications. It's a concise and efficient way to describe UI elements and their properties.
5. Uses of XAML.
XAML is used to create both graphical and non-graphical UI elements. It's used to define the structure and appearance of WPF applications and simplifies the separation of UI design from backend development.
6. Routed Events.
Routed events in WPF allow an event to travel up or down the element tree, enabling handlers on parent or ancestor elements to respond to events triggered on their child elements.
7. Document Types Supported by WPF.
- Flow Document: Content adapts to the window size.
- Fixed Document: Content remains fixed; doesn't change based on window size.
8. Content Alignment in WPF.
Properties like HorizontalContentAlignment and VerticalContentAlignment control the alignment of content within UI elements.
9. Resource Syntax in WPF.
Example
<Style x:Key="myStyle" TargetType="{x:Type Button}">
<Setter Property="Background" Value="Red"/>
</Style>
10. Types of WPF Resources.
- StaticResource: Resolved only once during initialization.
- DynamicResource: Resolved every time the property is accessed.
11. Namespace for 3D Graphics.
System.Windows.Media.Media3D.
12. WPF as a DirectX Replacement.
No, WPF is not a direct replacement for DirectX. While WPF offers 2D and 3D graphics capabilities, DirectX is better suited for high-performance 3D graphics and gaming.
13. Dependency Properties.
Dependency properties are a special type of property system in WPF. They provide advanced features like data binding, styling, and animation.
14. CLR (Common Language Runtime).
The CLR is the runtime environment for .NET applications.
15. Freezable Objects.
Freezable objects are immutable after they are frozen. This improves performance and thread safety.
16. Value Converters.
Value converters transform values between a source and a target (often used with data binding). They implement the IValueConverter interface.
17. Silverlight vs. WPF Browser Applications.
| Feature | Silverlight | WPF Browser Application |
|---|---|---|
| Client-Side Requirements | Plugin | .NET Framework |
| Operating System | Cross-platform | Windows only |
18. SketchFlow for WPF Mockups.
SketchFlow (now discontinued) was a tool for creating interactive prototypes of WPF applications.
19. Layout Controls.
(This section would list various layout panels in WPF: Grid, DockPanel, WrapPanel, Canvas, UniformGrid, StackPanel.)
20. PRISM (Prism Library).
PRISM (Prism Library) is a framework assisting in building WPF, Silverlight, and Windows Phone applications using design patterns like MVVM.
21. Custom Controls.
Custom controls extend existing controls. They're commonly used for building reusable UI components.
22. Path Animations.
Path animations move UI elements along a defined path.
23. BAML (Binary Application Markup Language).
BAML is a compiled version of XAML.
24. XAML vs. BAML.
BAML is a compiled binary form of XAML, generally resulting in faster loading times.
25. Page vs. Window Controls.
| Control Type | Usage |
|---|---|
| Page | Browser applications |
| Window | Standard window applications |
26. Parent Class of Control.
FrameworkElement.
27. StaticResource vs. DynamicResource.
| Resource Type | Resolution Timing |
|---|---|
StaticResource |
Once during loading |
DynamicResource |
Every time the property is accessed |
28. MDI (Multiple Document Interface) Support in WPF.
WPF does not directly support MDI; similar functionality can be achieved using UserControls or other techniques.
29. Serialization.
Serialization converts an object's state into a stream of bytes for storage or transmission.
30. MVVM (Model-View-ViewModel).
MVVM is a design pattern separating data (Model), presentation (View), and presentation logic (ViewModel) in WPF applications. It leverages data binding and commands for cleaner code and improved testability.
31. When Was MVVM Introduced?
2005 by John Gossman.
32. Advantages of MVVM.
- Improved code organization (separation of concerns).
- Testability.
- Code reusability.
- Simplified maintenance.
33. Key Features of MVVM.
(This section would list key MVVM features, such as data binding, commands, and the separation of concerns between the Model, View, and ViewModel.)
34. MVVM vs. MVC.
MVVM uses a ViewModel to manage UI logic, replacing the Controller in MVC.