UIElement class (Windows)

1 out of 3 rated this helpful - Rate this topic

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

Inheritance

Object
DependencyObject
UIElement

Syntax

C++


public class UIElement : DependencyObject

Attributes

MarshalingBehaviorAttribute(Agile)
StaticAttribute(Windows.UI.Xaml.IUIElementStatics, NTDDI_WIN8)
ThreadingAttribute(Both)
VersionAttribute(NTDDI_WIN8)
WebHostHiddenAttribute()

Members

The UIElement class has these types of members:

Events
Methods
Properties

Events

The UIElement class has these events.

Event	Description
DoubleTapped	Occurs when an otherwise unhandled DoubleTap interaction occurs over the hit test area of this element.
DragEnter	Occurs when the input system reports an underlying drag event with this element as the target.
DragLeave	Occurs when the input system reports an underlying drag event with this element as the origin.
DragOver	Occurs when the input system reports an underlying drag event with this element as the potential drop target.
Drop	Occurs when the input system reports an underlying drop event with this element as the drop target.
GotFocus	Occurs when a UIElement receives focus.
Holding	Occurs when an otherwise unhandled Hold interaction occurs over the hit test area of this element.
KeyDown	Occurs when a keyboard key is pressed while the UIElement has focus.
KeyUp	Occurs when a keyboard key is released while the UIElement has focus.
LostFocus	Occurs when a UIElement loses focus.
ManipulationCompleted	Occurs when a manipulation on the UIElement is complete.
ManipulationDelta	Occurs when the input device changes position during a manipulation.
ManipulationInertiaStarting	Occurs when the input device loses contact with the UIElement object during a manipulation and inertia begins.
ManipulationStarted	Occurs when an input device begins a manipulation on the UIElement.
ManipulationStarting	Occurs when the manipulation processor is first created.
PointerCanceled	Occurs when a pointer that made contact abnormally loses contact.
PointerCaptureLost	Occurs when pointer capture previously held by this element moves to another element or elsewhere.
PointerEntered	Occurs when a pointer enters the hit test area of this element.
PointerExited	Occurs when a pointer leaves the hit test area of this element.
PointerMoved	Occurs when a pointer moves while the pointer remains within the hit test area of this element.
PointerPressed	Occurs when the pointer device initiates a Press action within this element.
PointerReleased	Occurs when the pointer device that previously initiated a Press action is released, while within this element.
PointerWheelChanged	Occurs when the delta value of a pointer wheel changes.
RightTapped	Occurs when a right-tap input stimulus happens while the pointer is over the element.
Tapped	Occurs when an otherwise unhandled Tap interaction occurs over the hit test area of this element.

Methods

The UIElement class has these methods. It also inherits methods from the Object class.

Method	Description
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 even if the event is handled elsewhere.
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.
CapturePointer	Sets pointer capture to a UIElement. Once captured, only the element that has capture will fire pointer-related events.
ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject)
FindSubElementsForTouchTargeting	Enables a UIElement subclass to expose child elements that assist with resolving touch targeting.
GetAnimationBaseValue	Returns any base value established for a dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject)
GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject)
InvalidateArrange	Invalidates the arrange state (layout) for a UIElement. After the invalidation, the UIElement will have its layout updated, which will occur asynchronously.
InvalidateMeasure	Invalidates the measurement state (layout) for a UIElement.
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.
OnCreateAutomationPeer	When implemented in a derived class, returns class-specific AutomationPeer implementations for the Microsoft UI Automation infrastructure.
OnDisconnectVisualChildren	Override this method to implement how layout and logic should behave when items are removed from a class-specific content or children property.
ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject)
ReleasePointerCapture	Releases pointer captures for capture of one specific pointer by this UIElement.
ReleasePointerCaptures	Releases all pointer captures held by this element.
RemoveHandler	Removes the specified routed event handler from this UIElement. Typically the handler in question was added by AddHandler.
SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject)
TransformToVisual	Returns a transform object that can be used to transform coordinates from the UIElement to the specified object.
UpdateLayout	Ensures that all positions of child objects of a UIElement are properly updated for layout.

Properties

The UIElement class has these properties.

Property	Access type	Description
AllowDrop	Read/write	Gets or sets a value that determines whether this UIElement can be a drop target for purposes of drag-and-drop operations.
AllowDropProperty	Read-only	Identifies the AllowDrop dependency property.
CacheMode	Read/write	Gets or sets a value that indicates that rendered content should be cached as a composited bitmap when possible.
CacheModeProperty	Read-only	Identifies the CacheMode dependency property.
Clip	Read/write	Gets or sets the RectangleGeometry used to define the outline of the contents of a UIElement.
ClipProperty	Read-only	Identifies the Clip dependency property.
DesiredSize	Read-only	Gets the size that this UIElement computed during the measure pass of the layout process.
Dispatcher	Read-only	Gets the CoreDispatcher that this object is associated with. (Inherited from DependencyObject)
DoubleTappedEvent	Read-only	Gets the identifier for the DoubleTapped routed event.
DragEnterEvent	Read-only	Gets the identifier for the DragEnter routed event.
DragLeaveEvent	Read-only	Gets the identifier for the DragLeave routed event.
DragOverEvent	Read-only	Gets the identifier for the DragOver routed event.
DropEvent	Read-only	Gets the identifier for the Drop routed event.
HoldingEvent	Read-only	Gets the identifier for the Holding routed event.
IsDoubleTapEnabled	Read/write	Gets or sets a value that determines whether the DoubleTapped event can originate from that element.
IsDoubleTapEnabledProperty	Read-only	Identifies the IsDoubleTapEnabled dependency property.
IsHitTestVisible	Read/write	Gets or sets whether the contained area of this UIElement can return true values for hit testing.
IsHitTestVisibleProperty	Read-only	Identifies the IsHitTestVisible dependency property.
IsHoldingEnabled	Read/write	Gets or sets a value that determines whether the Holding event can originate from that element.
IsHoldingEnabledProperty	Read-only	Identifies the IsHoldingEnabled dependency property.
IsRightTapEnabled	Read/write	Gets or sets a value that determines whether the RightTapped event can originate from that element.
IsRightTapEnabledProperty	Read-only	Identifies the IsRightTapEnabled dependency property.
IsTapEnabled	Read/write	Gets or sets a value that determines whether the Tapped event can originate from that element.
IsTapEnabledProperty	Read-only	Identifies the IsTapEnabled dependency property.
KeyDownEvent	Read-only	Gets the identifier for the KeyDown routed event.
KeyUpEvent	Read-only	Gets the identifier for the KeyUp routed event.
ManipulationCompletedEvent	Read-only	Gets the identifier for the ManipulationCompleted routed event.
ManipulationDeltaEvent	Read-only	Gets the identifier for the ManipulationDelta routed event.
ManipulationInertiaStartingEvent	Read-only	Gets the identifier for the ManipulationInertiaStarting routed event.
ManipulationMode	Read/write	Gets or sets the ManipulationModes value used for UIElement behavior and interaction with gestures.
ManipulationModeProperty	Read-only	Identifies the ManipulationMode dependency property.
ManipulationStartedEvent	Read-only	Gets the identifier for the ManipulationStarted routed event.
ManipulationStartingEvent	Read-only	Gets the identifier for the ManipulationStarting routed event.
Opacity	Read/write	Gets or sets the degree of the object's opacity.
OpacityProperty	Read-only	Identifies the IsHitTestVisible dependency property.
PointerCanceledEvent	Read-only	Gets the identifier for the PointerCanceled routed event.
PointerCaptureLostEvent	Read-only	Gets the identifier for the PointerCaptureLost routed event.
PointerCaptures	Read-only	Gets the set of all captured pointers, represented as Pointer values.
PointerCapturesProperty	Read-only	Identifies the PointerCaptures dependency property.
PointerEnteredEvent	Read-only	Gets the identifier for the PointerEntered routed event.
PointerExitedEvent	Read-only	Gets the identifier for the PointerExited routed event.
PointerMovedEvent	Read-only	Gets the identifier for the PointerMoved routed event.
PointerPressedEvent	Read-only	Gets the identifier for the PointerPressed routed event.
PointerReleasedEvent	Read-only	Gets the identifier for the PointerReleased routed event.
PointerWheelChangedEvent	Read-only	Gets the identifier for the PointerWheelChanged routed event.
Projection	Read/write	Gets or sets the perspective projection (3-D effect) to apply when rendering this element.
ProjectionProperty	Read-only	Identifies the Projection dependency property.
RenderSize	Read-only	Gets the final render size of a UIElement.
RenderTransform	Read/write	Gets or sets transform information that affects the rendering position of a UIElement.
RenderTransformOrigin	Read/write	Gets or sets the origin point of any possible render transform declared by RenderTransform, relative to the bounds of the UIElement.
RenderTransformOriginProperty	Read-only	Identifies the RenderTransformOrigin dependency property.
RenderTransformProperty	Read-only	Identifies the RenderTransform dependency property.
RightTappedEvent	Read-only	Gets the identifier for the RightTapped routed event.
TappedEvent	Read-only	Gets the identifier for the Tapped routed event.
Transitions	Read/write	Gets or sets the collection of Transition style elements that apply to a UIElement.
TransitionsProperty	Read-only	Identifies the Transitions dependency property.
UseLayoutRounding	Read/write	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.
UseLayoutRoundingProperty	Read-only	Identifies the UseLayoutRounding dependency property.
Visibility	Read/write	Gets or sets the visibility of a UIElement. A UIElement that is not visible is not rendered and does not communicate its desired size to layout.
VisibilityProperty	Read-only	Identifies the Visibility dependency property.

Remarks

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

Much of the input behavior for visible elements in a UI is defined in the UIElement class. This includes the events for keyboard, pointers, touch, manipulations, 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. For more info, see Events and routed events overview.

UIElement has properties that can influence the element's preferences for processing input. For example, you can enable the element to be a drop target with AllowDrop, or disable tap response with IsTapEnabled.

Although UIElement defines the events for focus reporting (GotFocus, LostFocus), UIElement does not define an API for programmatically setting the focus. This capability is defined by the Control class.

UIElement does not expose a public constructor. Typically, you don't derive classes from either UIElement or FrameworkElement directly. More typically used base classes for derived custom classes are these classes:

Specific controls that are not sealed (for example, TextBox)
Control base classes (Control, ContentControl, UserControl)
Navigation elements (Page, Frame)
Panel classes (the base class Panel, or specific non-sealed implementations such as Grid)

Requirements

Minimum supported client	Windows 8 [Windows Store apps only]
Minimum supported server	Windows Server 2012 [Windows Store apps only]
Namespace	Windows.UI.Xaml Windows::UI::Xaml [C++]
Metadata	Windows.winmd

UIElement class