Interview questions and answers of WPF

1.) What is WPF ?

Windows Presentation Foundation (WPF) is nothing but it is the wrapper component on the top of Direct X Architecture. WPF is a two -dimension (2-D) and three-Dimension (3-D) graphics engine.
A graphical sub system feature directly related to XAML.
It is a consistent programming model providing clear separation between UI and Business logic.
WPF Application can be deployed on desktop or hosted in web browser.
The coverage of documents,media and applications.
WPF is a two dimensional (2-d) and three dimensional (3-d) graphic engine.

2.) What are the characteristics and capabilities of WPF ?

There are some features and characteristics of wpf which are given below:-
WPF contains many common user interface components including button,text box ,sliders ,labels and edit boxes etc.
WPF supports 2-d and 3-d animations.
WPF supports Documents and media into a single environment.
WPF contains hyperlinks for navigating between documents and tables.
WPF provides various types of grids and panels to assist in layout.
WPF supports tier 0 tier 1 and tier 2 Architecture models.

3.) What is the goal of WPF ?

There are some goals of WPF:-
Unified approach to UI,Document and Media :-It Means Integration as a part of development and experience.
Integrated Vector -based composition engine:-Its goal is Utilize the power of the pc throughout graphics stacks .
Declarative programming :- In This designer and Developers can easily involve in application development.
Ease of Deployment :- It allow the administrator to deploy and manage the application securely.

4.) What is Hardware Acceleration ?

It is a process by which we can use hardware functionality to perform some functionality rather than writing the software logic.

5.) What were those technologies which Microsoft launched before WPF ?

User 32 API
GDI (Graphical device Interface)
GDI+
Direct X

6.) What are three major technologies launched by Microsoft after Direct x engine ?

Windows Communication Foundation (wcf):- All the protocols communications comes under this section.
Windows Work Flow(WWF):-It helps the developers to make the work flow of the application.
Windows Presentation Foundation (WPF):- It is used on the top of Direct X Model.

7.) What do you mean by USER 32 and its problems ?

User 32 :- It provides the windows look and feel for text Boxes ,Buttons and other UI elements.User 32 API Provides the drawing capabilities to the users.32 we can seen this component in window user 32 sub system.The main purpose of user 32 is to give look and feel in UI element in windows.We can find user 32.dll file in our window.
Problems in User 32:-
If we want to draw line ,rectangle and circle then we can't draw it in User 32 API. To overcome this problem Microsoft launch Next Technology GDI (Graphical user Interface).

8.) What is GDI and its problems ?

Graphical User Interface (GDI):-There are two main purpose to introduced this technology.
To improve Drawing capability
To use high level of abstraction of hardware so that programmer/Developers can concentrate only on programming logic not on design part and complexity of hardware is taken care by GDI.
Microsoft Introduced GDI (Graphical Device Interface) to provide drawing capabilities.It is not only provide drawing capabilities but also provide a high level of abstraction on the hard ware display.It encapsulate the all complexity of hardware in GDI API.
Problem in GDI :-
GDI API did not support file JPEG ,PNG and anti-aliasing features etc.
The main issue of GDI was it did not use hardware acceleration.
It did not support animation and 3-D Features.
It is never used in game programming.

9.) Why did Microsoft launched GDI+ After GDI technology ?

To overcome the some problems of GDI Microsoft launched a new technology ,called GDI+.

10.) What are the features and problems of GDI+ Technology ?

GDI+ is a extended version of GDI.
It supported the JPG and PNG files .
It supported anti-aliasing features also.
It supported Gradient and shading features.
Note:-Hardware acceleration is a process in which we use hardware to perform some functionalities like rectangle/circle drawing etc.rather than performing these functionalities by software which is running in CPU Memory.
Problem in GDI and GDI+:-
it did not support hardware acceleration.
It didn't support animation and 3-D Features.
It is never used in game programming.

11.) Why did Microsoft launched Direct X After GDI+ technology ?

To overcome the problems of GDI and GDI + Microsoft launched a new Technology, called Direct X .

12.) What is Direct X ?

Microsoft has introduced Direct X technology to overcome the drawback of GDI and GDI+ technology.
Direct X exploited hardware acceleration.
It support all animation and 3-D Features.
It supports full color graphics also.
It supports media streaming facilities and lot more.
It provide more supports to game developers.
Direct X Technology launched basically for game programming.It is not used for commercial application.Developers couldn't use for commercial purpose .This is the Biggest Disadvantage of Direct X technology.

13.) What is Problem of Direct X and its solution ?

Any Developer couldn't use Direct X technology for commercial purpose.It is only for game programmers.
To overcome this drawback Microsoft launch technology on the Top of Direct X ,called Widows Presentation Foundation (WPF).

14.) What is the main purpose WPF ?

WPF is very power full technology launched by Microsoft which is used for commercial purpose.

15.) What types of application we can build with WPF Technology ?

WPF intended to replace both web forms and windows forms application.Application can be built to run in a browser or a standalone window.
Windows Forms and web pages/windows can co-exist in a browser or a standalone window.
One WPF Page/window can have both type of controls on it.
A New type of web application called XAML browser application XBAP(Formerly web browser application WBA).

16.) What designer tool is used in WPF Technology ?

MS Expression Graphics Designer --> ACRYLIC
MS Expression Interactive designer --> SPARKLE
MS Expression web Designer --> QUARTZ
MS Visual studio Designer --> CIDER

17.) What is three main layer of WPF?

i.)The Managed WPF API Layer
ii.) The Media Integration Layer
ii.) Unmanaged Component Layer(lower level)

18.) What is XAML?

XAML Stands for Extensible Application Markup Language.
XAML is a declarative XML- based Language that defines objects and their Properties in XML.
XAML can be used to create visible UI elements in the declarative XAML markup.
XAML files are xml files that generally represent the .xaml extension.
XAML is a flexible Language that can be used designing and programming purpose at a time.
XAML Parser instantiates and writes up the objects using appropriate API and sets their properties.
If we use XAML with Avalon then Procedural code (code behind) is separate from user interface (UI).
We can use XAML Language in WPF,SilverLight and WF .NET Technologies.
XAML is Very powerful binding Technologies.

19.) What is the advantage of XAML?

Graphical designer tools are used XAML language (ex. Blend).
XAML Code is flexible and short.
XAML code is used for designing and Business logic codes.

20.) What are the two main techniques to write the xaml syntax ?

Property syntax
Attribute element syntax

21.) What is BAML in WPF ?

BAML stands for Binary Application Markup Language
It is the Binary representation of XAML.
It is more efficient than other.
BAML is not like Microsoft intermediate Language(MSIL).It is a Compressed declarative format that is faster to load and parse than plain XAML.
BAML is just an implementation detail without any direct public Exposure,so it could be replaced with different in the Future.
BAML is very smaller in size than XAML.

22.) What is tree concepts in WPF ?

All elements of a WPF UI (User Interface) are hierarchically related.The template of WPF contains two types of tree concepts.
Logical Tree
Visual Tree

23.) What is Logical tree in WPF ?

Each Element that we explicitly add to window ,be it layout control or content will be part of the window's logical tree.This tree is the exact representation of what you have specified to be display.
The Logical Tree describes the relationship between elements of UI (user interface).

24.) What is Advantage of Logical tree in WPF ?

There are some advantage of Logical tree as given below:-
It inherit the dependency property values.
It is used to binding the elements.
It is used for forwarding the Routing events.
It is helpful to resolve the dynamic resources.
It is used as a root element in any template.

25.) What is Visual tree in WPF ?

The Visual tree Contains all the rendering information needed to compose the output to a display device (computer).These are harder to visualize by looking at codes.
The Visual tree contains all the Logical elements + Visual elements of the UI (Template) of each element.

26.) What is advantage Visual tree in WPF ?

There are some advantage of visual tree in wpf.
It is helpful to rendering (displaying) the visual elements.
It contains number of additional UI element classes for each entry in the logical tree.
It propagate the IsEnabled Properties.
It propagate the ambiguity.

27.) What is XBAP in WPF ?

XAML Browser Applications (XBAPs) are a variant of WPF application which can run over the internet. XABPs will only run on windows.It requires .NET 3.0/3.5/4.0/4.5 Framework.

28.) What is core assemblies used in WPF ?

There are three main assemblies used in wpf.
WindowsBase.dll
Presentationcore.dll
PresentationFoundation.dll

29.) What are two main Namespace classes used in WPF ?

Application class
Windows class

30.) What is a BAML in WPF ?

This is known as Binary Application Markup Language (BAML).
It is a Binary representation of XAML.
It is more efficient.

31.) What is Data binding in WPF ?

Data binding is the process that establishes a connection between the application UI and business logic. A typical use of data binding is to place server or local configuration data into forms or other UI controls. In Windows Presentation Foundation, this concept is expanded to include the binding of a broad range of properties to a variety of data sources.

32.) What are the types of data binding in WPF ?

There are two types of data binding in WPF.
Unidirectional (source ---> target or vice versa)
Bidirectional (source <---> target)

33.) What is Data context ?

Data context is the dependency property which contains the data.The data may be following type like:
Data set
Collection object
CLR Object
XML Data Provider etc.
Every WPF Control derived from framework element that is part of a Data Context property.

34.) What are the Characteristics of Data Binding In WPF ?

There are some characteristics of data binding in wpf.
User Interface(UI) can be bound to CLR objects or XML .
Dependency properties can also be bound to ado.net and objects associated with web services and web properties.
Data templates can be applied to data.
Filter,sort and group views can be generated on the top of the data.

35.) What are the elements used for Data Binding In WPF ?

Source
Source Path
Target Dependency Property
Target Dependency object

36.) What are the types of Binding modes In WPF ?

There are four binding modes in wpf.
One Way
One Time
Two Way
OneWayToSource

37.) What is Event Routing in WPF ?

The Event routing allows an event to originate in one element but be raised by another one.

38.) What are the types of Routed Events in WPF ?

There are mainly three types of Routed events in wpf as given below:-
Direct Events
Bubbling events
Tunnelling events

39.) What is Direct Events in WPF ?

Direct events are like ordinary .NET events. They originate in one element and don’t pass to any other.
Example:-
MouseEnter (which fires when the mouse pointer moves over an element) is a direct event

40.) What is Bubbling Events in WPF ?

Bubbling events are events that travel up the containment hierarchy.
Example:-
MouseDown is a bubbling event. It’s raised first by the element that is clicked. Next, it’s raised by that element’s parent, and then by that element’s parent, and so on, until WPF reaches the top of the element tree.

41.) What is Tunnelling Events in WPF ?

Tunnelling events are events that travel down the containment hierarchy.
Example:-
It give chance to preview (and possibly stop) an event before it are eaches the appropriate control.