Windows Presentation Foundation (WPF) remains a powerful framework for building desktop applications with rich UI capabilities. Whether you’re a beginner or an experienced developer, mastering WPF interview questions is essential for landing your dream job.
This guide covers 20 essential WPF interview questions, including performance optimization, architecture, and real-world scenarios.
1. What is WPF?
Answer:
WPF (Windows Presentation Foundation) is a UI framework for building Windows desktop applications. It uses XAML for declarative UI design and supports advanced features like data binding, animations, and styling.
2. Is WPF Still in Demand?
Answer:
Yes, WPF is still in demand for enterprise applications, legacy system upgrades, and specialized desktop software. While newer frameworks like MAUI and Blazor are emerging, WPF remains relevant due to its stability and rich feature set.
3. What Are the Key Features of WPF?
Answer:
- XAML-based UI design
- Data binding (One-way, Two-way)
- Templating & Styling (ControlTemplate, DataTemplate)
- Animation & Multimedia support
- Resolution independence (Vector graphics)
4. What Are the Different Types of WPF Documents?
Answer:
WPF supports two types of documents:
- Flow Documents: Adjust content dynamically (e.g., eBooks, articles).
- Fixed Documents: Preserve exact layout (e.g., PDFs, printed reports).
5. Explain WPF Architecture
Answer:
WPF follows a layered architecture:
- PresentationFramework.dll (High-level controls)
- PresentationCore.dll (Base types like
UIElement) - Milcore.dll (Media Integration Layer, connects to DirectX)
6. What is XAML in WPF?
Answer:
XAML (Extensible Application Markup Language) is a declarative XML-based language used to design WPF UIs. It separates UI logic from business logic.
7. What Are Dependency Properties?
Answer:
Dependency properties extend CLR properties with data binding, animation, and styling support. They are registered using DependencyProperty.Register().
Example:
public static readonly DependencyProperty TitleProperty =
DependencyProperty.Register("Title", typeof(string), typeof(MyControl));
8. What is Data Binding in WPF?
Answer:
Data binding connects UI elements to data sources (OneWay, TwoWay, OneTime). It reduces manual UI updates.
Example:
<TextBlock Text="{Binding UserName, Mode=TwoWay}" />
9. How Can I Improve My WPF Application Performance?
Answer:
- Use Virtualization (
VirtualizingStackPanel) for large lists. - Optimize Data Binding (Avoid
Mode=TwoWayunnecessarily). - Freeze Freezable objects (Brushes, Geometries).
- Reduce Visual Tree complexity.
- Use Async/Await for long-running tasks.
10. What is MVVM in WPF?
Answer:
MVVM (Model-View-ViewModel) is a design pattern that separates:
- Model (Data logic)
- View (UI)
- ViewModel (Business logic, binds View & Model)
Benefits: Testability, maintainability, and clean separation.
11. What is a Routed Event in WPF?
Answer:
A routed event can travel through the visual tree (Bubbling, Tunneling, Direct). Example: Button.Click (bubbles up from button to parent).
12. Difference Between StaticResource and DynamicResource
Answer:
- StaticResource: Resolved at load time (faster).
- DynamicResource: Re-evaluated at runtime (supports themes).
13. What is a Command in WPF?
Answer:
Commands (ICommand) decouple UI actions from logic (e.g., RelayCommand in MVVM).
Example:
public ICommand SaveCommand => new RelayCommand(() => SaveData());
14. How to Handle Exceptions in WPF?
Answer:
- Use
Dispatcher.UnhandledExceptionfor UI thread errors. - Wrap async code in
try-catch.
15. What is a UserControl vs Custom Control?
Answer:
- UserControl: Reusable XAML-based component.
- Custom Control: Extends
Controlclass with templating support.
16. What is Prism in WPF?
Answer:
Prism is a framework for modular WPF apps (MVVM, DI, event aggregation).
17. How to Implement Themes in WPF?
Answer:
- Use
ResourceDictionaryfor styles. - Switch themes dynamically using
DynamicResource.
18. What is the Role of Dispatcher in WPF?
Answer:
The Dispatcher manages the UI thread queue, ensuring thread-safe updates.
Example:
Dispatcher.Invoke(() => { StatusText = "Updated"; });
19. How to Debug Data Binding Issues?
Answer:
- Check Output Window for binding errors.
- Use
PresentationTraceSources.TraceLevel=High.
20. What’s New in the Latest WPF Updates?
Answer:
Recent WPF updates include:
- .NET 6/7/8 support
- Performance improvements (Hardware acceleration)
- Better high-DPI handling
People Also Ask
Is WPF Still in Demand?
Yes, especially in enterprise and legacy applications.
What Are the Different Types of WPF Documents?
Flow documents (dynamic) and fixed documents (static).
How Can I Improve My WPF Application Performance?
Use virtualization, optimize bindings, and freeze resources.
Conclusion
Mastering these WPF interview questions will boost your confidence in technical interviews. Whether you’re discussing MVVM, performance tuning, or XAML, this guide covers key concepts to help you succeed.
Stay updated with WPF trends and keep coding! 🚀