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UIElement Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

UIElement is a base class for most of the objects that have visual appearance and can process basic input in Silverlight.

Inheritance Hierarchy

System.Object
System.Windows.DependencyObject
System.Windows.UIElement
System.Windows.FrameworkElement

Namespace: System.Windows
Assembly: System.Windows (in System.Windows.dll)

Syntax

'Declaration
Public MustInherit Class UIElement _
 Inherits DependencyObject

public abstract class UIElement : DependencyObject

The UIElement type exposes the following members.

Properties

Name	Description
Public propertySupported by Silverlight for Windows Phone	AllowDrop	Gets or sets a value that determines whether this UIElement can be a drop target for purposes of Silverlight drag-and-drop operations.
Public propertySupported by Silverlight for Windows Phone	CacheMode	Gets or sets a value that indicates that rendered content should be cached when possible.
Public propertySupported by Silverlight for Windows Phone	Clip	Gets or sets the Geometry used to define the outline of the contents of a UIElement.
Public propertySupported by Silverlight for Windows Phone	DesiredSize	Gets the size that this UIElement computed during the measure pass of the layout process.
Public propertySupported by Silverlight for Windows Phone	Dispatcher	Gets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
Public property	Effect	Gets or sets the pixel shader effect to use for rendering this UIElement.
Public propertySupported by Silverlight for Windows Phone	IsHitTestVisible	Gets or sets whether the contained area of this UIElement can return true values for hit testing.
Public propertySupported by Silverlight for Windows Phone	Opacity	Gets or sets the degree of the object's opacity.
Public propertySupported by Silverlight for Windows Phone	OpacityMask	Gets or sets the brush used to alter the opacity of regions of this object.
Public propertySupported by Silverlight for Windows Phone	Projection	Gets or sets the perspective projection (3-D effect) to apply when rendering this UIElement.
Public propertySupported by Silverlight for Windows Phone	RenderSize	Gets the final render size of a UIElement.
Public propertySupported by Silverlight for Windows Phone	RenderTransform	Gets or sets transform information that affects the rendering position of a UIElement.
Public propertySupported by Silverlight for Windows Phone	RenderTransformOrigin	Gets or sets the origin point of any possible render transform declared by RenderTransform, relative to the bounds of the UIElement.
Public propertySupported by Silverlight for Windows Phone	UseLayoutRounding	Gets or sets a value that determines whether rendering for the object and its visual subtree should use rounding behavior that aligns rendering to whole pixels.
Public propertySupported by Silverlight for Windows Phone	Visibility	Gets or sets the visibility of a UIElement. A UIElement that is not visible does not render and does not communicate its desired size to layout.

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Methods

Name	Description
Public methodSupported by Silverlight for Windows Phone	AddHandler	Adds a routed event handler for a specified routed event, adding the handler to the handler collection on the current element. Specify handledEventsToo as true to have the provided handler be invoked for routed event that had already been marked as handled by another element along the event route.
Public methodSupported by Silverlight for Windows Phone	Arrange	Positions child objects and determines a size for a UIElement. Parent objects that implement custom layout for their child elements should call this method from their layout override implementations to form a recursive layout update.
Public methodSupported by Silverlight for Windows Phone	CaptureMouse	Sets mouse capture to a UIElement.
Public methodSupported by Silverlight for Windows Phone	CheckAccess	Determines whether the calling thread has access to this object. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows Phone	ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows Phone	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows Phone	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by Silverlight for Windows Phone	GetAnimationBaseValue	Returns any base value established for a Silverlight dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows Phone	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by Silverlight for Windows Phone	GetType	Gets the Type of the current instance. (Inherited from Object.)
Public methodSupported by Silverlight for Windows Phone	GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows Phone	InvalidateArrange	Invalidates the arrange state (layout) for a UIElement. After the invalidation, the UIElement will have its layout updated, which will occur asynchronously.
Public methodSupported by Silverlight for Windows Phone	InvalidateMeasure	Invalidates the measurement state (layout) for a UIElement.
Public methodSupported by Silverlight for Windows Phone	Measure	Updates the DesiredSize of a UIElement. Typically, objects that implement custom layout for their layout children call this method from their own MeasureOverride implementations to form a recursive layout update.
Protected methodSupported by Silverlight for Windows Phone	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows Phone	OnCreateAutomationPeer	When implemented in a derived class, returns class-specific AutomationPeer implementations for the Silverlight automation infrastructure.
Public methodSupported by Silverlight for Windows Phone	ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows Phone	ReleaseMouseCapture	Removes mouse capture from a UIElement. After this call, typically no object holds mouse capture.
Public methodSupported by Silverlight for Windows Phone	RemoveHandler	Removes the specified routed event handler from this UIElement.
Public methodSupported by Silverlight for Windows Phone	SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
Public methodSupported by Silverlight for Windows Phone	ToString	Returns a string that represents the current object. (Inherited from Object.)
Public methodSupported by Silverlight for Windows Phone	TransformToVisual	Returns a transform object that can be used to transform coordinates from the UIElement to the specified object.
Public methodSupported by Silverlight for Windows Phone	UpdateLayout	Ensures that all positions of child objects of a UIElement are properly updated for layout.

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Events

Name	Description
Public eventSupported by Silverlight for Windows Phone	DoubleTap	Occurs when a DoubleTap gesture is committed while over this UIElement.
Public event	DragEnter	Occurs when the input system reports an underlying drag event with this element as the target.
Public event	DragLeave	Occurs when the input system reports an underlying drag event with this element as the origin.
Public event	DragOver	Occurs when the input system reports an underlying drag event with this element as the potential drop target.
Public event	Drop	Occurs when the input system reports an underlying drop event with this element as the drop target.
Public eventSupported by Silverlight for Windows Phone	GotFocus	Occurs when a UIElement receives focus.
Public eventSupported by Silverlight for Windows Phone	Hold	Occurs when a Hold gesture is committed while over this UIElement.
Public eventSupported by Silverlight for Windows Phone	KeyDown	Occurs when a keyboard key is pressed while the UIElement has focus.
Public eventSupported by Silverlight for Windows Phone	KeyUp	Occurs when a keyboard key is released while the UIElement has focus.
Public eventSupported by Silverlight for Windows Phone	LostFocus	Occurs when a UIElement loses focus.
Public eventSupported by Silverlight for Windows Phone	LostMouseCapture	Occurs when the UIElement loses mouse capture.
Public eventSupported by Silverlight for Windows Phone	ManipulationCompleted	Occurs when a manipulation and inertia on the UIElement is complete.
Public eventSupported by Silverlight for Windows Phone	ManipulationDelta	Occurs when the input device changes position during a manipulation.
Public eventSupported by Silverlight for Windows Phone	ManipulationStarted	Occurs when an input device begins a manipulation on the UIElement.
Public event	MediaCommand	Occurs when a button is pressed on a remote control.
Public eventSupported by Silverlight for Windows Phone	MouseEnter	Occurs when the mouse (or a stylus) enters the bounding area of a UIElement.
Public eventSupported by Silverlight for Windows Phone	MouseLeave	Occurs when the mouse (or the stylus) leaves the bounding area of a UIElement.
Public eventSupported by Silverlight for Windows Phone	MouseLeftButtonDown	Occurs when the left mouse button is pressed (or when the tip of the stylus touches the tablet) while the mouse pointer is over a UIElement.
Public eventSupported by Silverlight for Windows Phone	MouseLeftButtonUp	Occurs when the left mouse button is released (or the tip of the stylus is removed from the tablet) while the mouse (or the stylus) is over a UIElement (or while a UIElement holds mouse capture).
Public eventSupported by Silverlight for Windows Phone	MouseMove	Occurs when the coordinate position of the mouse (or stylus) changes while over a UIElement (or while a UIElement holds mouse capture).
Public event	MouseRightButtonDown	Occurs when the right mouse button is pressed while the mouse pointer is over a UIElement.
Public event	MouseRightButtonUp	Occurs when the right mouse button is released while the mouse pointer is over a UIElement. However, this event will only be raised if a caller marks the preceding MouseRightButtonDown event as handled; see Remarks.
Public eventSupported by Silverlight for Windows Phone	MouseWheel	Occurs when the user rotates the mouse wheel while the mouse pointer is over a UIElement, or the UIElement has focus.
Public eventSupported by Silverlight for Windows Phone	Tap	Occurs when a Tap gesture is committed while over this UIElement.
Public eventSupported by Silverlight for Windows Phone	TextInput	Occurs when a UI element gets text in a device-independent manner.
Public eventSupported by Silverlight for Windows Phone	TextInputStart	Occurs when a UI element initially gets text in a device-independent manner.
Public eventSupported by Silverlight for Windows Phone	TextInputUpdate	Occurs when text continues to be composed via an input method editor (IME).

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Fields

Name	Description
Public fieldStatic memberSupported by Silverlight for Windows Phone	AllowDropProperty	Identifies the AllowDrop dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	CacheModeProperty	Identifies the CacheMode dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	ClipProperty	Identifies the Clip dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	DoubleTapEvent	Identifies the DoubleTap routed event.
Public fieldStatic member	EffectProperty	Identifies the Effect dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	HoldEvent	Identifies the Hold routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	IsHitTestVisibleProperty	Identifies the IsHitTestVisible dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	KeyDownEvent	Identifies the KeyDown routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	KeyUpEvent	Identifies the KeyUp routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	ManipulationCompletedEvent	Identifies the ManipulationCompleted routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	ManipulationDeltaEvent	Identifies the ManipulationDelta routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	ManipulationStartedEvent	Identifies the ManipulationStarted routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	MouseLeftButtonDownEvent	Identifies the MouseLeftButtonDown routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	MouseLeftButtonUpEvent	Identifies the MouseLeftButtonUp routed event.
Public fieldStatic member	MouseRightButtonDownEvent	Identifies the MouseRightButtonDown routed event.
Public fieldStatic member	MouseRightButtonUpEvent	Identifies the MouseRightButtonUp routed event.
Public fieldStatic member	MouseWheelEvent	Identifies the MouseWheel routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	OpacityMaskProperty	Identifies the IsHitTestVisible dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	OpacityProperty	Identifies the IsHitTestVisible dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	ProjectionProperty	Identifies the Projection dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	RenderTransformOriginProperty	Identifies the RenderTransformOrigin dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	RenderTransformProperty	Identifies the RenderTransform dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	TapEvent	Identifies the Tap routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	TextInputEvent	Identifies the TextInput routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	TextInputStartEvent	Identifies the TextInputStart routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	TextInputUpdateEvent	Identifies the TextInputUpdate routed event.
Public fieldStatic memberSupported by Silverlight for Windows Phone	UseLayoutRoundingProperty	Identifies the UseLayoutRounding dependency property.
Public fieldStatic memberSupported by Silverlight for Windows Phone	VisibilityProperty	Identifies the Visibility dependency property.

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Remarks

UIElement provides a starting point for Silverlight layout characteristics; FrameworkElement adds more layout capabilities.

Much of the input behavior for visible elements in a Silverlight UI is defined in the UIElement class. This includes the events for keyboard, mouse and stylus input, and focus events. Some of these events are routed events. A routed event enables a built-in event handling notification system, so that a parent object can handle input events from child objects in the object tree if the event remains unhandled. This input event behavior is useful for input area grouping, and for control compositing.

Although UIElement defines the events for focus reporting (GotFocus, LostFocus), UIElement does not define an API for programmatically setting the focus. However, this capability is defined by the Control class and is thus present for many of the Silverlight elements in a UI.

UIElement does not expose a public constructor. It is not typical to derive from either UIElement or FrameworkElement directly. More typically used base classes for derived custom classes in Silverlight are these classes:

Specific controls that are not sealed (for example, TextBox)
Control base classes (Control, ContentControl, UserControl)
Panel classes (the base class Panel, or specific non-sealed panel implementations, for example Grid)

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.