| Windows Presentation Foundation (WPF) | |
|---|---|
| Original author | Microsoft |
| Developer | .NET Foundation |
| Initial release | November 21, 2006; 19 years ago (2006-11-21) |
| Stable release | |
| Written in | C#,C++,C |
| Operating system | Microsoft Windows |
| Platform | .NET Framework,.NET |
| Type | Software framework |
| License | MIT License |
| Website | learn |
| Repository | |
Windows Presentation Foundation (WPF) is afree and open-sourceuser interface framework forWindows-based desktop applications. WPF applications are based in.NET, and are primarily developed usingC# andXAML.[2]
Originally developed byMicrosoft, WPF was initially released as part of.NET Framework 3.0 in 2006. In 2018, Microsoft released WPF asopen source under theMIT License.[3] WPF's design and its layout language XAML have been adopted by multiple other UI frameworks, such asUWP,.NET MAUI, andAvalonia.
WPF employsXAML, anXML-based language, to define and link various interface elements, and uses C# to define program behavior.[4] WPF applications are deployed as standalone desktop programs.
WPF supports a number of commonuser interface elements, such as 2D/3D rendering, fixed and adaptivedocuments,typography,vector graphics, runtimeanimation, and pre-rendered media. These elements can then be linked and manipulated based on various events, user interactions, anddata bindings.[5]
WPF was developed under the codename "Avalon", as part of the WinFX programming model forWindows "Longhorn". In August 2004, Microsoft announced that components of WinFX would bebackported toWindows XP andWindows Server 2003.[6] It would later be released as part of .NET Framework 3.0, a free download for these operating systems.[7] WPFruntime libraries are included with all versions ofMicrosoft Windows sinceWindows Vista andWindows Server 2008.[8][9]
At the Microsoft Connect event on December 4, 2018,Microsoft announced releasing WPF as open source project onGitHub. It is released under theMIT License. Windows Presentation Foundation has become available for projects targeting the.NET software framework, however, the system is not cross-platform and is still available only on Windows.[3][10]
In WPF, screens and other UI elements are defined using a pair of files: aXAML file and an associatedC# file with the extension.xaml.cs, often referred to as a "code-behind". The XAML file declaratively defines the layout, contents and other properties of the UI element, while the C# file allows exposure of code entry points for interactivity.[4]
A basic example of an interactiveHello, World! program could be created like so:
MainWindow.xaml:
<Windowx:Class="WpfExample.MainWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"Title="MainWindow"Height="200"Width="300"><StackPanelOrientation="Vertical"><TextBlockText="What is your name?"/><TextBoxx:Name="NameInputTextBox"/><Buttonx:Name="SubmitButton"Click="SubmitButton_Click"><TextBlockText="Submit"/></Button><TextBlockx:Name="ResultTextBlock"/></StackPanel></Window>
MainWindow.xaml.cs:
usingSystem.Windows;namespaceWpfExample{publicpartialclassMainWindow:Window{publicMainWindow(){InitializeComponent();}privatevoidSubmitButton_Click(objectsender,RoutedEventArgse){stringname=this.NameInputTextBox.Text;this.ResultTextBlock.Text=$"Hello {name}!";}}}
In the above example, a UI element calledMainWindow is declared as asubclass of the built-inWindow class. The XAML file defines the layout, which in this example is a vertical collection of controls - a textblock outlining instructions to the user, a textbox for the user to type their name, a button to submit, and a results text block. When the button is clicked, the methodSubmitButton_Click is called, which is defined in the.xaml.cs file. This function updates the final textblock to contain a message greeting the user, addressing them by their submitted name.
WPF supports most modern media types, including vector and raster images, audio, video, and can support both 2D and 3D rendering.[11] It also supports implementing graphical effects on visual elements, such asHLSLpixel shaders and built-in effects such asblurs anddrop shadows.[12][13]
WPF mainly relies on vector graphics, which allows most controls and elements to be scaled without loss in quality orpixelization.[14][15]
WPF employsdata binding, a technique of propagating changes between user interface elements and theobject model of the program.[16] For instance, a textblock defined in XAML could bind its contents to astring property stored on a C# object in the following way:
<TextBlockText="{Binding Username}"/>
publicclassExampleViewModel{publicstringUsername{get;set;}}
This would make the textblock display the value of theUsername property.
The direction data binding happens is configurable - it can be defined to go UI-to-source (eg. text entered into atextbox being propagated to a bound string property in code), or source-to-UI (eg. a visual clock being updated to display the current time stored in code), or bi-directional.[16]
Data binding doesn't have any restrictions on types, and it is possible to bindstructs,classes, orcollections. Converters can be used to transpose the values and types being used during binding - for example, binding a textbox to aDateTime property, but using a converter to display the time as a formattedlocalised date string.[16]
Most properties on built-in controls can be databound, and custom-made controls can create bindable properties by defining Dependency Properties.[16][17]
MVVM, the architectural pattern encouraged by Microsoft for WPF developers, relies heavily on data binding.[18]
Using templates and styles, developers can define the visuals and structure of UI elements.
A style is a combination of property settings that can be applied to a UI element with a single property attribute. For example, a "blueradio button" style could be created and then be reused on any number of radio button controls throughout the program. Styles can alter collections of properties of controls, but are not intended for significant structural changes.
Templates are a mechanism for defining alternative UI for portions of a WPF application. There are several template types available in WPF for different scenarios, but they all have the general purpose of defining the contents, layout and structure of a UI element.[19]
In WPF, many visual properties can be animated. This is exposed through dependency properties, which is the same underlying system that data binding relies on. WPF animations are time-based, as opposed to frame-based.[20]
Animation classes are based on the .NET type of property to be animated. For instance, changing the color of an element is done with the ColorAnimation class and animating the width of an element (which is typed as adouble) is done with the DoubleAnimation class.[20]
Animations can be grouped into Storyboards, which are the primary way to start, stop, pause and otherwise manipulate animations.[20]
WPF natively supports paginated documents. It provides theDocumentViewer class, which is for reading fixed layout documents. TheFlowDocumentReader class offers different view modes such as per-page or scrollable and alsoreflows text if the viewing area is resized. It supports both theXML Paper Specification andOpen Packaging Conventions.[21]
WPF includes a number of text rendering features, includingOpenType,TrueType, and OpenType CFF (Compact Font Format) fonts. This means that WPF can support a wide number of text features, includingligatures,old-style numerals,swash variants,fraction,superscript andsubscript,small caps,ruby characters,glyph substitution, multiplebaselines, andkerning.[22]
WPF handles texts inUnicode, and handles texts independent of global settings, such as system locale. In addition, fallback mechanisms are provided to allow writing direction (horizontal versus vertical) handled independent of font name; building international fonts from composite fonts, using a group of single-language fonts; composite fonts embedding. Font linking and font fallback information is stored in a portable XML file, using composite font technology.[23] The XML file has extension.CompositeFont.
The WPF text engine also supports built-inspell checking. It also supports such features as automatic line spacing, enhanced international text, language-guided line breaking,hyphenation, and justification, bitmap effects, transforms, and text effects such as shadows, blur, glow, rotation etc. Animated text is also supported; this refers to animated glyphs, as well as real-time changes in position, size, color, and opacity of the text.
WPF text rendering takes advantage of advances inClearType technology, such as sub-pixel positioning, natural advance widths, Y-direction anti-aliasing,hardware-accelerated text rendering, as well as aggressive caching of pre-rendered text in video memory.[24] ClearType cannot be turned off in older WPF 3.x applications.[25]
Windows Forms features are possible through the use of theElementHost andWindowsFormsHost classes.
To enable the use of WinForms, the developer executes this from their WPF C# code:[26]
usingSystem.Windows.Forms.Integration;WindowsFormsHost.EnableWindowsFormsInterop();
WPF programs, via theP/Invoke feature of theCLR, can access native functionality such calling functions from Windowslibraries. This allows the ability to communicate and operate other parts of the operating system, includingunmanaged libraries.[27]
WPF supportsWindows Ink forpen-based input,[28] and multi-touch input onWindows 7 and above.[29] It also supportsMicrosoft UI Automation to allow developers to create accessible interfaces, and to expose the UI to automated test frameworks.[30]
Following the success ofmarkup languages for web development, WPF introduced eXtensible Application Markup Language (XAML;/ˈzæməl/), which is based onXML. XAML is designed as a more efficient method of developing application user interfaces.[31] XAML is adeclarative language, meaning the developer (or designer) describes the behavior and integration of components without the use ofprocedural programming. Although it is rare that an entire application will be built completely in XAML, the introduction of XAML allows application designers to more effectively contribute to the application development cycle. UsingXAML to develop user interfaces also allows for separation of model and view, which is considered a good architectural principle.[32] In XAML, elements and attributes map to classes and properties in the underlying APIs.
As in web development, both layouts and specific themes are well suited to markup, butXAML is not required for either. Indeed, all elements of WPF may be coded in a.NET language (C#,VB.NET). The XAML code can ultimately be compiled into a managed assembly in the same way all .NET languages are.
WPF applications are Windows-only standalone desktopexecutables.
Historically, WPF supported compiling toXBAP, a file format intended to be shown inweb browsers via aNPAPI plugin, but NPAPI and XBAP support was phased out of support by browsers, and XBAP compilation is now no longer included for WPF for .NET.[33][34]
WPF is used to developVisual Studio, Microsoft's flagshipIDE, and was used for developing MicrosoftExpression Blend.[35]
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WPF and its layout language, XAML, have influenced multiple other UI frameworks.Silverlight (codenamed WPF/E - WPF Everywhere), released in 2007, is adeprecated cross-browserbrowser plugin. Silverlight had a WPF-based implementation, including using XAML for layouting, that supported video, vector graphics, and animations.[36] Using add-ons, it was supported onMozilla Firefox,Internet Explorer 6 and above,Google Chrome 42 and below andApple Safari. Microsoft encouraged developers to stop using Silverlight in 2015,[37] and support was officially ended in 2021.[38]
After becoming open source in 2018, WPF inspired the development ofAvalonia, an open-source .NET cross-platform XAML-based UI framework, distributed under theMIT License.[39] While WPF only is intended for Windows, Avalonia also supports builds for web (viaWebAssembly),MacOS,Android,iOS, andLinux. Avalonia's name references WPF's in-development codename ("Avalon"), and markets itself as "a spiritual successor to WPF".[40] Avalonia is currently used in tools made byUnity,GitHub andJetBrains.[41]
OpenSilver is framework designed to migrate WPF solutions to web usingWebAssembly. OpenSilver 3.1, released in December 2024, included a XAML designer for use inVisual Studio Code.[42]
XAML, which was first designed for WPF, has been adopted for other similar Microsoft-developed UI libraries, such asUWP,[43] designed forWindows 10,Windows 11,Xbox One andXbox Series S/X applications, and.NET MAUI (formerlyXamarin.Forms), designed for creating cross-platform nativeAndroid andiOS apps.[44]
Developers of WPF applications typically useMicrosoft Visual Studio. Visual Studio contains a combination XAML editor and WPF visual designer, beginning with Visual Studio 2008.[45] Prior to Visual Studio 2008, theWPF designer add-in, codenamed Cider, was the original release of aWYSIWYG editor for creating WPF windows, pages, and user controls. It was available for Visual Studio 2005 as aVisual Studio 2005 extensions for .NET Framework 3.0CTP for the initial release of WPF.[46]
Visual Studio is not strictly required to develop WPF projects, as solutions can be built in the command line usingMSBuild.[47]
Microsoft Blend is a designer-oriented tool that provides an artboard for the creation of WPF applications with 2D and 3D graphics, text and forms content. It generatesXAML that may be exported into other tools and shares solution (sln files) and project formats (csproj, vbproj) with Microsoft Visual Studio.Microsoft Expression Design is a bitmap and 2D-vector graphics tool for exporting toXAML.
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