WPF Compatibility

WPF Compatibility

Silverlight

Silverlight offers a subset of the functionality provided by Windows Presentation Foundation (WPF) and enables you to build rich Internet applications that are easy to deploy and quick to install. An additional goal for Silverlight is to enable you to transfer your .NET Framework development experience to Silverlight, and vice versa. You should also be able to port Silverlight applications to the desktop, mainly reusing the XAML. This topic explains some of the main feature differences between WPF and Silverlight.

This topic contains the following sections.

• WPF Features Not in Silverlight
• WPF Features with Limited Support in Silverlight
• Same Feature, Different Approach
• Silverlight-Only Features
• Control Support in Silverlight vs. WPF
• Other API Differences
• Related Topics

WPF Features Not in Silverlight

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Flow Document

There is no Flow Document support in Silverlight. For more information, see Flow Document Overview in the WPF documentation.

Dynamic Resources

Silverlight does not support dynamic resources. All resource references to keyed resources in XAML are static. For more information, see Resources Overview.

Miscellaneous

In addition to the features previously listed, the following are supported in WPF but not in Silverlight:

• TileMode property for TileBrush objects.
• ValueConversion attribute.
• ITyped list, InstanceFactory, or BindingList(T).
• Electronic Documentation Management (EDM).
• MarkupExtension base class.

WPF Features with Limited Support in Silverlight

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Data Binding

The basics of Silverlight and WPF data binding are the same. However, there are some data-binding features offered in WPF that are not available in Silverlight. Silverlight supports binding the DependencyProperty of a FrameworkElement (and in some cases a DependencyObject) to any CLR object. Silverlight does not provide any of the following:

• Datasets.
• ICustomTypeDescriptor , IListSource, or IBindingList.
• Binding directly to XML data or XPath binding. (The recommended alternative is to use the System.Xml.Linq API for XML business objects.)
• BindingMode.OneWayToSource binding.
• Discrete notification for source and target updates with dedicated NotifyOnSourceUpdated or NotifyOnTargetUpdated properties (and related events) on a binding.
• Bindable Run.

Additionally, Silverlight does not support some of the binding options that WPF supports. For more information, see Binding Markup Extension and Property Path Syntax.

Silverlight does provide value converters and support for data validation. This includes support for the INotifyDataErrorInfo interface, which WPF does not support.

For more information, see Data Binding.

Triggers

WPF (particularly in .NET Framework 3.5) uses the concept of triggers. Triggers enable you to make property changes or start actions when events occur or properties change. Silverlight support for triggers is limited to using the EventTrigger object for the Loaded event and the BeginStoryboard action. However, everything that triggers were used for in previous WPF XAML can be accomplished by using the VisualStateManager model. For more information, see Customizing the Appearance of an Existing Control by Using a ControlTemplate or Creating a New Control by Creating a ControlTemplate.

Routed Events

WPF introduced the concept of routed events, where an event can be handled by multiple handlers in the element tree instead of just the object that initiated the event. For more information about routed events from the WPF perspective, see Routed Events Overview in the WPF documentation.

Silverlight includes the concept of routed events for a small subset of events. However, Silverlight does not enable you to create a new routed event. In addition, Silverlight does not include Preview events or class-handling of routed events. Silverlight user code can re-handle a routed event already marked handled, but only through code. For more information about routed events in Silverlight, see Events Overview for Silverlight.

Commanding

WPF introduced the concept of commanding. Only a few Silverlight classes in Silverlight 4 support the commanding infrastructure. ButtonBase and Hyperlink provide Command and CommandParameter properties. Silverlight does not provide command libraries as part of the runtime, or specific built-in behaviors of the core types or Silverlight SDK controls that interface with the commands. However, the Silverlight input system interprets the commands. The design intention is that the command implementations exist as a component of the data source itself, as part of a view model relationship. Commands are hooked to the Command properties through binding to the same source that generates the UI-visible data.

3-D Graphics

3-D drawing support in Silverlight is limited. For more information, see 3-D Effects (Perspective Transforms).

Dependency Properties

WPF and Silverlight have similar property systems that both use the concept of a dependency property. You can define a custom dependency property, but there are some important differences. Most notably, Silverlight does not have separate registration methods for read-only dependency properties, does not use metadata flags, and does not have an explicit coercion system or callback. For more information, see Custom Dependency Objects and Dependency Properties.

Visual and Logical Trees

Silverlight does not include the concept of separate runtime-accessible visual and logical trees that are included in WPF. Also, Silverlight have the LogicalTreeHelper API. Silverlight does provide the VisualTreeHelper class in case you need to navigate the rendered objects in the object tree. For more information, see Silverlight Object Trees.

In WPF, all visual elements derive from the Visual class, which does not exist in Silverlight. However, a subset of Visual-analogous capabilities exist in other Silverlight base classes.

Freezables

Silverlight does not include Freezable objects in its object model. For more information, see Freezable Objects Overview in the WPF documentation.

Touch API

Silverlight 4 supports some of the multitouch API from WPF. However, the Silverlight 4 client as a whole is registered for touch messages, and the multitouch events are handled through a client-level Touch service class. In contrast, WPF has element-level support for multitouch events on its UIElement class. Also, the Silverlight 4 version of multitouch does not provide native gesture handling or manipulation/inertia handling. If you need this multitouch support in Silverlight 4, you have to handle the raw messages and implement this functionality yourself.

Same Feature, Different Approach

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Subpixel Rendering

Both WPF and Silverlight allow subpixel rendering. However, in some cases, subpixel rendering can result in blurry text, images, and other displayed objects when antialiasing is applied to the object. For more information about subpixel rendering, see Pixel Snapping in WPF Applications in the WPF documentation. WPF handles subpixel rendering issues by using a feature called pixel snapping, which snaps lines to the nearest device pixel. Silverlight introduces the concept of layout rounding, which rounds object dimensions to the nearest whole integer. This feature can be turned off by setting the UseLayoutRounding flag to false. For more information, see Layout Rounding. Silverlight also has a TextHintingMode property for overriding certain text display optimizations so that they work better if the text is being repositioned or animated dynamically.

Printing

The printing support in Silverlight is designed to allow users to print a UIElement that is contained in the Silverlight application, which varies substantially from the document-focused printing in WPF. For more information about printing support in Silverlight see, Printing. For more information about printing with WPF, see Printing Overview in the WPF documentation.

XAML Processing

There are a few XAML processing differences between WPF and Silverlight. For more information about these differences, see XAML Processing Differences Between Silverlight Versions and WPF.

Out-of-Browser Support

WPF has an XBAP deployment model that runs in a browser. Silverlight uses a different deployment technique where an application can be configured to run outside the browser after being installed from a host Web page. In addition, the out-of-browser application can request elevated permissions, and can thus access features that the default sandbox of a WPF XBAP cannot. For more information, see Out-of-Browser Support.

Resource Dictionaries

Silverlight and WPF both use resource dictionaries as a technique for sharing resource content, but there are some implementation differences. The following is a list of the most notable issues.

• Silverlight has a different list of which types are shareable.
• UIElement derived classes are never usable as resources, even if they are only referenced once. This is enforced at run time.
• Silverlight does not have a FindResource API. Instead, you use the ResourceDictionary indexer against a specific ResourceDictionary instance. The behavior difference here is that using the indexer does not step through the entire resource lookup sequence as is used for load-time XAML, it only checks that instance.
• For XAML references to resources, only StaticResource is available, because Silverlight does not support DynamicResource.
• Silverlight supports an x:Name on a ResourceDictionary item and can use x:Name as a substitute for x:Key. WPF does not support this behavior.

For more information, see Resource Dictionaries.

Screen Coordinate System and Measurements

Silverlight uses a slightly different behavior for how it interprets coordinates and measurement units for layout and display APIs.

• WPF supports a measurement system that by default is based on Device Independent Pixel (DIP) units. Silverlight supports a measurement system that is always based on pixel units.
• WPF measurement properties specified in XAML can include a unit measure string suffix that changes the interpretation of the preceding numeric value. For example, in WPF you can specify 10cm, where the cm indicates centimeter units. As part of XAML processing in WPF, that value is converted to a device independent pixel value at run time. Silverlight does not support this behavior; any XAML that includes a unit suffix such as px,pt,in or cm is invalid in Silverlight and throws a parse error. Silverlight measurements are always pixel units.
• Certain measurement properties in both WPF and Silverlight support setting a value "Auto" if specified in XAML, or Double.NaN if specified in code. The behavior is the same in either WPF or Silverlight. The difference is that WPF uses an explicit LengthConverter to enable the XAML usage. Silverlight uses a native XAML conversion behavior. Properties that can accept "Auto" for XAML in Silverlight are specifically indicated as part of their XAML syntax section in reference documentation.
• WPF has a theoretically unbounded coordinate system. Silverlight has a bounded coordinate system. The maximum value for a coordinate component in Silverlight is approximately +32678. APIs that represent a Silverlight coordinate might throw a native-level error or raise an exception if this maximum value is exceeded. This is true even for values that might be temporary and not intended for the final rendering value. 32678 is well beyond the maximum screen size, so this should only be an issue if you are performing math or applying transforms to coordinate values.

Silverlight-Only Features

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Deep Zoom

Silverlight introduces the Deep Zoom feature, which allows zooming in and out of high-resolution images or collections of images. For more information, see Deep Zoom.

Control Support in Silverlight vs. WPF

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The following table lists the control support for Silverlight and WPF.

Note:
The controls in the Silverlight Toolkit are regularly updated. For the current list of controls in the Silverlight Toolkit, see Silverlight Toolkit on CodePlex.
Control	Silverlight or WPF	Available for Silverlight
AccessText	WPF	Not available
AdornedElementPlaceholder	WPF	Not available
AdornerDecorator	WPF	Not available
AutoCompleteBox	Silverlight	Silverlight SDK
Border	Both	Runtime
BulletChrome	WPF	Not available
BulletDecorator	WPF	Not available
Button	Both	Runtime
ButtonChrome	WPF	Not available
Calendar	Both	Silverlight SDK
Canvas	Both	Runtime
CheckBox	Both	Runtime
ClassicBorderDecorator	WPF	Not available
ComboBox	Both	Runtime
ComboBoxItem	Both	Runtime
ContentControl	Both	Runtime
ContentPresenter	Both	Runtime
ContextMenu	WPF	Not available
Control	Both	Silverlight SDK
DataPager	Silverlight	Silverlight SDK
DataGrid	Both	Silverlight SDK
DatePicker	Both	Silverlight SDK
Decorator	WPF	Not available
DescriptionViewer	Silverlight	Silverlight SDK
DockPanel	Both	Silverlight Toolkit
DocumentPageView	WPF	Not available
DocumentReference	WPF	Not available
DocumentViewer	WPF	Not available
Ellipse	Both	Runtime
Expander	Both	Silverlight Toolkit
FixedPage	WPF	Not available
FlowDocumentPageViewer	WPF	Not available
FlowDocumentReader	WPF	Not available
FlowDocumentScrollViewer	WPF	Not available
Frame	Both	Silverlight SDK
FrameworkElement	Both	Runtime
Glyphs	Both	Runtime
Grid	Both	Runtime
GridSplitter	Both	Silverlight SDK
GridViewColumnHeader	WPF	Not available
GridViewHeaderRowPresenter	WPF	Not available
GridViewRowPresenter	WPF	Not available
GroupBox	WPF	Not available
GroupItem	WPF	Not available
HeaderedContentControl	Both	Silverlight Toolkit
HeaderedItemsControl	Both	Silverlight SDK
Hyperlink	Both	Runtime
HyperlinkButton	Silverlight	Runtime
Image	Both	Runtime
InkCanvas	WPF	Not available
InkPresenter	Both	Runtime
ItemsControl	Both	Runtime
ItemsPresenter	Both	Runtime
Label	Both	Silverlight SDK
Line	Both	Runtime
ListBox	Both	Runtime
ListBoxChrome	WPF	Not available
ListBoxItem	Both	Runtime
ListView	WPF	Not available
ListViewItem	WPF	Not available
MediaElement	Both	Runtime
Menu	WPF	Not available
MenuItem	WPF	Not available
MultiScaleImage	Silverlight	Runtime
NavigationWindow	WPF	Not available, but see Frame
NumericUpDown	Silverlight	Silverlight Toolkit
Page	Both	Silverlight SDK
PageContent	WPF	Not available
PageFunction	WPF	Not available
PasswordBox	Both	Runtime
Path	Both	Runtime
Polygon	Both	Runtime
Polyline	Both	Runtime
Popup	Both	Runtime
ProgressBar	Both	Runtime
RadioButton	Both	Runtime
Rectangle	Both	Runtime
RepeatButton	Both	Runtime
ResizeGrip	WPF	Not available
Ribbon	WPF	Not available
RibbonWindow	WPF	Not available
RichTextBox	Both	Runtime
ScrollBar	Both	Runtime
ScrollChrome	WPF	Not available
ScrollContentPresenter	Both	Runtime
ScrollViewer	Both	Runtime
Separator	WPF	Not available
Slider	Both	Runtime
StackPanel	Both	Runtime
StatusBar	WPF	Not available
StatusBarItem	WPF	Not available
SystemDropShadowChrome	WPF	Not available
TabControl	Both	Silverlight SDK
TabItem	Both	Silverlight SDK
TabPanel	WPF	Silverlight SDK
TextBlock	Both	Runtime
TextBox	Both	Runtime
Thumb	Both	Runtime
TickBar	WPF	Not available
ToggleButton	Both	Runtime
ToolBar	WPF	Not available
ToolBarOverflowPanel	WPF	Not available
ToolBarPanel	WPF	Not available
ToolBarTray	WPF	Not available
ToolTip	Both	Runtime
Track	WPF	Not available
TreeView	Both	Silverlight SDK
TreeViewItem	Both	Silverlight SDK
UniformGrid	WPF	Not available
UserControl	Both	Runtime
ValidationSummary	Silverlight	Silverlight SDK
ViewBox	Both	Runtime
Viewport3D	WPF	Not available, but see PlaneProjection
VirtualizingStackPanel	Both	Runtime
WebBrowserBrush	Silverlight	Runtime
WebBrowser	Both	Runtime
Window	Both	Runtime (out-of-browser only)
WindowsFormsHost	WPF	Not available
WrapPanel	Both	Silverlight Toolkit

Other API Differences

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The following table lists some of the API differences between Silverlight and WPF.

API	Silverlight or WPF	Available for Silverlight
MediaSampleAttributeKeys	Silverlight	Runtime
MediaSourceAttributesKeys	Silverlight	Runtime
MediaStreamAttributeKeys	Silverlight	Runtime
MediaStreamDescription	Silverlight	Runtime
MediaStreamSample	Silverlight	Runtime
MediaStreamSource	Silverlight	Runtime
MediaStreamSourceDiagnosticKind	Silverlight	Runtime
MediaStreamType	Silverlight	Runtime