Expand Minimize

Control class

Applies to Windows and Windows Phone

Represents the base class for UI elements that use a ControlTemplate to define their appearance. Parent class for ContentControl, UserControl, ItemsControl and several practical controls.

Inheritance

Object
  DependencyObject
    UIElement
      FrameworkElement
        Control

Syntax


public ref class Control : FrameworkElement

Attributes

[MarshalingBehavior(Agile)]
[Threading(Both)]
[Version(0x06020000)]
[WebHostHidden()]

Members

The Control class has these types of members:

Constructors

The Control class has these constructors.

ConstructorDescription
Control Provides base class initialization behavior for Control derived classes.

 

Events

The Control class has these events.

EventDescription
DataContextChanged Occurs when the value of the FrameworkElement.DataContext property changes. (Inherited from FrameworkElement)
DoubleTapped Occurs when an otherwise unhandled DoubleTap interaction occurs over the hit test area of this element. (Inherited from UIElement)
DragEnter Occurs when the input system reports an underlying drag event with this element as the target. (Inherited from UIElement)
DragLeave Occurs when the input system reports an underlying drag event with this element as the origin. (Inherited from UIElement)
DragOver Occurs when the input system reports an underlying drag event with this element as the potential drop target. (Inherited from UIElement)
Drop Occurs when the input system reports an underlying drop event with this element as the drop target. (Inherited from UIElement)
GotFocus Occurs when a UIElement receives focus. (Inherited from UIElement)
Holding Occurs when an otherwise unhandled Hold interaction occurs over the hit test area of this element. (Inherited from UIElement)
IsEnabledChanged Occurs when the IsEnabled property changes.
KeyDown Occurs when a keyboard key is pressed while the UIElement has focus. (Inherited from UIElement)
KeyUp Occurs when a keyboard key is released while the UIElement has focus. (Inherited from UIElement)
LayoutUpdated Occurs when the layout of the visual tree changes, due to layout-relevant properties changing value or some other action that refreshes the layout. (Inherited from FrameworkElement)
Loaded Occurs when a FrameworkElement has been constructed and added to the object tree, and is ready for interaction. (Inherited from FrameworkElement)
LostFocus Occurs when a UIElement loses focus. (Inherited from UIElement)
ManipulationCompleted Occurs when a manipulation on the UIElement is complete. (Inherited from UIElement)
ManipulationDelta Occurs when the input device changes position during a manipulation. (Inherited from UIElement)
ManipulationInertiaStarting Occurs when the input device loses contact with the UIElement object during a manipulation and inertia begins. (Inherited from UIElement)
ManipulationStarted Occurs when an input device begins a manipulation on the UIElement. (Inherited from UIElement)
ManipulationStarting Occurs when the manipulation processor is first created. (Inherited from UIElement)
PointerCanceled Occurs when a pointer that made contact abnormally loses contact. (Inherited from UIElement)
PointerCaptureLost Occurs when pointer capture previously held by this element moves to another element or elsewhere. (Inherited from UIElement)
PointerEntered Occurs when a pointer enters the hit test area of this element. (Inherited from UIElement)
PointerExited Occurs when a pointer leaves the hit test area of this element. (Inherited from UIElement)
PointerMoved Occurs when a pointer moves while the pointer remains within the hit test area of this element. (Inherited from UIElement)
PointerPressed Occurs when the pointer device initiates a Press action within this element. (Inherited from UIElement)
PointerReleased Occurs when the pointer device that previously initiated a Press action is released, while within this element. (Inherited from UIElement)
PointerWheelChanged Occurs when the delta value of a pointer wheel changes. (Inherited from UIElement)
RightTapped Occurs when a right-tap input stimulus happens while the pointer is over the element. (Inherited from UIElement)
SizeChanged Occurs when either the ActualHeight or the ActualWidth property changes value on a FrameworkElement. (Inherited from FrameworkElement)
Tapped Occurs when an otherwise unhandled Tap interaction occurs over the hit test area of this element. (Inherited from UIElement)
Unloaded Occurs when this object is no longer connected to the main object tree. (Inherited from FrameworkElement)

 

Methods

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

MethodDescription
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. (Inherited from UIElement)
ApplyTemplate Loads the relevant control template so that its parts can be referenced.
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. (Inherited from UIElement)
ArrangeOverride Provides the behavior for the Arrange pass of layout. Classes can override this method to define their own Arrange pass behavior. (Inherited from FrameworkElement)
CancelDirectManipulations Cancels ongoing direct manipulation processing (system-defined panning/zooming) on any ScrollViewer parent that contains the current UIElement. (Inherited from UIElement)
CapturePointer Sets pointer capture to a UIElement. Once captured, only the element that has capture will fire pointer-related events. (Inherited from UIElement)
ClearValue Clears the local value of a dependency property. (Inherited from DependencyObject)
FindName Retrieves an object that has the specified identifier name. (Inherited from FrameworkElement)
FindSubElementsForTouchTargeting Enables a UIElement subclass to expose child elements that assist with resolving touch targeting. (Inherited from UIElement)
Focus Attempts to set the focus on the control.
GetAnimationBaseValue Returns any base value established for a dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject)
GetBindingExpression Returns the BindingExpression that represents the binding on the specified property. (Inherited from FrameworkElement)
GetTemplateChild Retrieves the named element in the instantiated ControlTemplate visual tree.
GetValue Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject)
GoToElementStateCore When implemented in a derived class, enables per-state construction of a visual tree for a control template in code, rather than by loading XAML for all states at control startup. (Inherited from FrameworkElement)
InvalidateArrange Invalidates the arrange state (layout) for a UIElement. After the invalidation, the UIElement will have its layout updated, which will occur asynchronously. (Inherited from UIElement)
InvalidateMeasure Invalidates the measurement state (layout) for a UIElement. (Inherited from 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. (Inherited from UIElement)
MeasureOverride Provides the behavior for the Measure pass of the layout cycle. Classes can override this method to define their own Measure pass behavior. (Inherited from FrameworkElement)
OnApplyTemplate Invoked whenever application code or internal processes (such as a rebuilding layout pass) call ApplyTemplate. In simplest terms, this means the method is called just before a UI element displays in your app. Override this method to influence the default post-template logic of a class. (Inherited from FrameworkElement)
OnCreateAutomationPeer When implemented in a derived class, returns class-specific AutomationPeer implementations for the Microsoft UI Automation infrastructure. (Inherited from UIElement)
OnDisconnectVisualChildren Override this method to implement how layout and logic should behave when items are removed from a class-specific content or children property. (Inherited from UIElement)
OnDoubleTapped Called before the DoubleTapped event occurs.
OnDragEnter Called before the DragEnter event occurs.
OnDragLeave Called before the DragLeave event occurs.
OnDragOver Called before the DragOver event occurs.
OnDrop Called before the Drop event occurs.
OnGotFocus Called before the GotFocus event occurs.
OnHolding Called before the Holding event occurs.
OnKeyDown Called before the KeyDown event occurs.
OnKeyUp Called before the KeyUp event occurs.
OnLostFocus Called before the LostFocus event occurs.
OnManipulationCompleted Called before the ManipulationCompleted event occurs.
OnManipulationDelta Called before the ManipulationDelta event occurs.
OnManipulationInertiaStarting Called before the ManipulationInertiaStarting event occurs.
OnManipulationStarted Called before the ManipulationStarted event occurs.
OnManipulationStarting Called before the ManipulationStarting event occurs.
OnPointerCanceled Called before the PointerCanceled event occurs.
OnPointerCaptureLost Called before the PointerCaptureLost event occurs.
OnPointerEntered Called before the PointerEntered event occurs.
OnPointerExited Called before the PointerExited event occurs.
OnPointerMoved Called before the PointerMoved event occurs.
OnPointerPressed Called before the PointerPressed event occurs.
OnPointerReleased Called before the PointerReleased event occurs.
OnPointerWheelChanged Called before the PointerWheelChanged event occurs.
OnRightTapped Called before the RightTapped event occurs.
OnTapped Called before the Tapped event occurs.
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. (Inherited from UIElement)
ReleasePointerCaptures Releases all pointer captures held by this element. (Inherited from UIElement)
RemoveHandler Removes the specified routed event handler from this UIElement. Typically the handler in question was added by AddHandler. (Inherited from UIElement)
SetBinding Attaches a binding to a FrameworkElement, using the provided binding object. (Inherited from FrameworkElement)
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. (Inherited from UIElement)
UpdateLayout Ensures that all positions of child objects of a UIElement are properly updated for layout. (Inherited from UIElement)

 

Properties

The Control class has these properties.

PropertyAccess typeDescription

ActualHeight

Read-onlyGets the rendered height of a FrameworkElement. (Inherited from FrameworkElement)

ActualWidth

Read-onlyGets the rendered width of a FrameworkElement. (Inherited from FrameworkElement)

AllowDrop

Read/writeGets or sets a value that determines whether this UIElement can be a drop target for purposes of drag-and-drop operations. (Inherited from UIElement)

Background

Read/writeGets or sets a brush that provides the background of the control.

BackgroundProperty

Read-onlyIdentifies the Background dependency property.

BaseUri

Read-onlyGets a Uniform Resource Identifier (URI) that represents the base Uniform Resource Identifier (URI) for an XAML-constructed object at XAML load time. This property is useful for Uniform Resource Identifier (URI) resolution at run time. (Inherited from FrameworkElement)

BorderBrush

Read/writeGets or sets a brush that describes the border fill of a control.

BorderBrushProperty

Read-onlyIdentifies the BorderBrush dependency property.

BorderThickness

Read/writeGets or sets the border thickness of a control.

BorderThicknessProperty

Read-onlyIdentifies the BorderThickness dependency property.

CacheMode

Read/writeGets or sets a value that indicates that rendered content should be cached as a composited bitmap when possible. (Inherited from UIElement)

CharacterSpacing

Read/writeGets or sets the uniform spacing between characters, in units of 1/1000 of an em.

CharacterSpacingProperty

Read-onlyIdentifies the CharacterSpacing dependency property.

Clip

Read/writeGets or sets the RectangleGeometry used to define the outline of the contents of a UIElement. (Inherited from UIElement)

CompositeMode

Read/writeGets or sets a property that declares alternate composition and blending modes for the element in its parent layout and window. This is relevant for elements that are involved in a mixed XAML / Microsoft DirectX UI. (Inherited from UIElement)

DataContext

Read/writeGets or sets the data context for a FrameworkElement when it participates in data binding. (Inherited from FrameworkElement)

DefaultStyleKey

Read/writeGets or sets the key that references the default style for the control. Authors of custom controls use this property to change the default for the style that their control uses.

DefaultStyleKeyProperty

Read-onlyIdentifies the DefaultStyleKey dependency property.

DesiredSize

Read-onlyGets the size that this UIElement computed during the measure pass of the layout process. (Inherited from UIElement)

Dispatcher

Read-onlyGets the CoreDispatcher that this object is associated with. The CoreDispatcher represents a facility that can access the DependencyObject on the UI thread even if the code is initiated by a non-UI thread. (Inherited from DependencyObject)

FlowDirection

Read/writeGets or sets the direction in which text and other UI elements flow within any parent element that controls their layout. This property can be set to either LeftToRight or RightToLeft. Setting FlowDirection to RightToLeft on any element sets the alignment to the right, the reading order to right-to-left and the layout of the control to flow from right to left. (Inherited from FrameworkElement)

FocusState

Read-onlyGets a value that specifies whether this control has focus, and the mode by which focus was obtained.

FocusStateProperty

Read-onlyIdentifies the FocusState dependency property.

FontFamily

Read/writeGets or sets the font used to display text in the control.

FontFamilyProperty

Read-onlyIdentifies the FontFamily dependency property.

FontSize

Read/writeGets or sets the size of the text in this control.

FontSizeProperty

Read-onlyIdentifies the FontSize dependency property.

FontStretch

Read/writeGets or sets the degree to which a font is condensed or expanded on the screen.

FontStretchProperty

Read-onlyIdentifies the FontStretch dependency property.

FontStyle

Read/writeGets or sets the style in which the text is rendered.

FontStyleProperty

Read-onlyIdentifies the FontStyle dependency property.

FontWeight

Read/writeGets or sets the thickness of the specified font.

FontWeightProperty

Read-onlyIdentifies the FontWeight dependency property.

Foreground

Read/writeGets or sets a brush that describes the foreground color.

ForegroundProperty

Read-onlyIdentifies the Foreground dependency property.

Height

Read/writeGets or sets the suggested height of a FrameworkElement. (Inherited from FrameworkElement)

HorizontalAlignment

Read/writeGets or sets the horizontal alignment characteristics that are applied to a FrameworkElement when it is composed in a layout parent, such as a panel or items control. (Inherited from FrameworkElement)

HorizontalContentAlignment

Read/writeGets or sets the horizontal alignment of the control's content.

HorizontalContentAlignmentProperty

Read-onlyIdentifies the HorizontalContentAlignment dependency property.

IsDoubleTapEnabled

Read/writeGets or sets a value that determines whether the DoubleTapped event can originate from that element. (Inherited from UIElement)

IsEnabled

Read/writeGets or sets a value indicating whether the user can interact with the control.

IsEnabledProperty

Read-onlyIdentifies the IsEnabled dependency property.

IsHitTestVisible

Read/writeGets or sets whether the contained area of this UIElement can return true values for hit testing. (Inherited from UIElement)

IsHoldingEnabled

Read/writeGets or sets a value that determines whether the Holding event can originate from that element. (Inherited from UIElement)

IsRightTapEnabled

Read/writeGets or sets a value that determines whether the RightTapped event can originate from that element. (Inherited from UIElement)

IsTabStop

Read/writeGets or sets a value that indicates whether a control is included in tab navigation.

IsTabStopProperty

Read-onlyIdentifies the IsTabStop dependency property.

IsTapEnabled

Read/writeGets or sets a value that determines whether the Tapped event can originate from that element. (Inherited from UIElement)

IsTextScaleFactorEnabled

Read/writeGets or sets whether automatic text enlargement, to reflect the system text size setting, is enabled.

IsTextScaleFactorEnabledProperty

Read-onlyIdentifies the IsTextScaleFactorEnabled dependency property.

Language

Read/writeGets or sets localization/globalization language information that applies to a FrameworkElement, and also to all child elements of the current FrameworkElement in the object representation and in UI. (Inherited from FrameworkElement)

ManipulationMode

Read/writeGets or sets the ManipulationModes value used for UIElement behavior and interaction with gestures. Setting this value enables handling the manipulation events from this element in app code. (Inherited from UIElement)

Margin

Read/writeGets or sets the outer margin of a FrameworkElement. (Inherited from FrameworkElement)

MaxHeight

Read/writeGets or sets the maximum height constraint of a FrameworkElement. (Inherited from FrameworkElement)

MaxWidth

Read/writeGets or sets the maximum width constraint of a FrameworkElement. (Inherited from FrameworkElement)

MinHeight

Read/writeGets or sets the minimum height constraint of a FrameworkElement. (Inherited from FrameworkElement)

MinWidth

Read/writeGets or sets the minimum width constraint of a FrameworkElement. (Inherited from FrameworkElement)

Name

Read/writeGets or sets the identifying name of the object. When a XAML processor creates the object tree from XAML markup, run-time code can refer to the XAML-declared object by this name. (Inherited from FrameworkElement)

Opacity

Read/writeGets or sets the degree of the object's opacity. (Inherited from UIElement)

Padding

Read/writeGets or sets the padding inside a control.

PaddingProperty

Read-onlyIdentifies the Padding dependency property.

Parent

Read-onlyGets the parent object of this FrameworkElement in the object tree. (Inherited from FrameworkElement)

PointerCaptures

Read-onlyGets the set of all captured pointers, represented as Pointer values. (Inherited from UIElement)

Projection

Read/writeGets or sets the perspective projection (3-D effect) to apply when rendering this element. (Inherited from UIElement)

RenderSize

Read-onlyGets the final render size of a UIElement. (Inherited from UIElement)

RenderTransform

Read/writeGets or sets transform information that affects the rendering position of a UIElement. (Inherited from UIElement)

RenderTransformOrigin

Read/writeGets or sets the origin point of any possible render transform declared by RenderTransform, relative to the bounds of the UIElement. (Inherited from UIElement)

RequestedTheme

Read/writeGets or sets the UI theme that is used by the UIElement (and its child elements) for resource determination. The UI theme you specify with RequestedTheme can override the app-level RequestedTheme. (Inherited from FrameworkElement)

Resources

Read/writeGets the locally defined resource dictionary. In XAML, you can establish resource items as child object elements of a frameworkElement.Resources property element, through XAML implicit collection syntax. (Inherited from FrameworkElement)

Style

Read/writeGets or sets an instance Style that is applied for this object during layout and rendering. (Inherited from FrameworkElement)

TabIndex

Read/writeGets or sets a value that determines the order in which elements receive focus when the user navigates through controls by pressing the Tab key.

TabIndexProperty

Read-onlyIdentifies the TabIndex dependency property.

TabNavigation

Read/writeGets or sets a value that modifies how tabbing and TabIndex work for this control.

TabNavigationProperty

Read-onlyIdentifies the TabNavigation dependency property.

Tag

Read/writeGets or sets an arbitrary object value that can be used to store custom information about this object. (Inherited from FrameworkElement)

Template

Read/writeGets or sets a control template. The control template defines the visual appearance of a control in UI, and is defined in XAML markup.

TemplateProperty

Read-onlyIdentifies the Template dependency property.

Transitions

Read/writeGets or sets the collection of Transition style elements that apply to a UIElement. (Inherited from UIElement)

Triggers

Read-onlyGets the collection of triggers for animations that are defined for a FrameworkElement. Not commonly used. (Inherited from FrameworkElement)

UseLayoutRounding

Read/writeGets 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. (Inherited from UIElement)

VerticalAlignment

Read/writeGets or sets the vertical alignment characteristics that are applied to a FrameworkElement when it is composed in a parent object such as a panel or items control. (Inherited from FrameworkElement)

VerticalContentAlignment

Read/writeGets or sets the vertical alignment of the control's content.

VerticalContentAlignmentProperty

Read-onlyIdentifies the VerticalContentAlignment dependency property.

Visibility

Read/writeGets 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. (Inherited from UIElement)

Width

Read/writeGets or sets the width of a FrameworkElement. (Inherited from FrameworkElement)

 

Remarks

The Control class is the base class for many of the controls you add to an app and its UI. The Control class defines very little behavior; you can add an actual Control element to XAML for UI but you typically add something that inherits from Control directly or indirectly, such as a Button or ListBox. For a list of controls you can use, see Controls by function.

The Template property, which uses the type ControlTemplate, specifies the visual appearance of a control. If you want to change the appearance of a control but retain its functionality, you should consider creating a new ControlTemplate instead of defining a new Control-based class. For more info, see Quickstart: Control templates.

Control is the parent of UserControl. UserControl is the intended base class for lightweight controls that don't need visual states. Although the UserControl technically inherits the Template property, you cannot apply a template to a UserControl.

Implicit styles for controls

Each practical control that's defined for XAML has a default style that contains its default control template. Controls can have an implicit style, meaning that the FrameworkElement.Style property isn't set explicitly. Once that implicit style is available, almost all other properties of a control can be set with Setter elements in that Style. The Style can initialize the control separately from the rest of the control logic, and can set values that aren't the code-based defaults for each property.

The implicit style exists as a keyed resource that's part of the Windows Runtime, stored internally as a binary representation of XAML. You can get a copy of either a particular control's style or of the full set of styles to look at how the styles and control templates are defined. Also, each XAML control has a documentation topic that explains its control template. For example, if you want to know more about the default control template for an AppBar, you'd look at AppBar styles and templates.

The association between a particular control type and the key/name of the implicit style it uses by default is established by the value of the DefaultStyleKey property. The DefaultStyleKey property is protected, so only someone that subclasses a control class can change the value. If you're just creating a control instance, for example declaring controls in a XAML UI, then the default style is the implicit style that's based on the control's type. For more info, see Remarks in DefaultStyleKey. You don't need to change the DefaultStyleKey value to use a different style, you just need to define your own XAML Style that has the same TargetType that matches the implicit style lookup and exists as a XAML resource. For more info, see Quickstart: Control templates.

The visual state model

The visual state model is a technique where you modify just a few of the properties defined in a control's template. You change property values in order to provide visual feedback to the user that indicates what the control is doing and hints at further UI interactions that are possible. The controls are modified by applying zero-duration or short-duration storyboarded animations to some of the properties in the template. You also can define short-duration animations that apply for the transitions between states.

The visual states themselves are defined as part of the control template. Each visual state has a name, so that the control logic can invoke the GoToState method that loads up each visual state when it's needed for a particular logic state. Visual states are declared within visual state groups, so that visual states that are exclusive to each other can ensure that only one such state is active at a time. As soon as another visual state from the same group is loaded, the animations for the previous state stop being applied, but animations in another group might still be running and applying their changes and visual behavior. For example, a control might have a visual indicator for keyboard focus and a visual indicator for pointer-over. Because these are UI modes that can be adjusted independently of each other and can happen at the same time, they're each defined in a different visual state group.

Because it's defined in XAML as part of the control template, you can change the visual state behavior for any XAML control that you use in your UI. However, the logic is still based on the control expecting to find certain visual state groups and named visual states within. So you have to be very careful that you're providing the correctly named and structured visual states that are showing all aspects of a control's behavior to the user. For more info, see Storyboarded animations for visual states. Visual states are also briefly introduced in Quickstart: Control templates.

Default visual states for controls sometimes use the library animations. You should try to preserve the library animations when you replace control templates or visual states because these animations are an important part of the control's look and feel in the UI. For more info, see Animating your UI.

Controls and focus

The Control class defines several APIs that influence the keyboard focus behavior for a UI: the Focus method, the FocusState property, and the IsEnabled and IsTabStop properties. Enabling keyboard focus is an important part of assuring that a UI is accessible, because each focusable element becomes part of the tab order for the UI. Only UI elements that are interactive are typically enabled to receive keyboard focus. For example, a TextBox is interactive because the user can type text, whereas a TextBlock is not interactive because the text is read-only. Most of the classes that derive from Control are legitimately interactive and so it makes sense that they can be focused and should be in the tab order.

In order to be focusable, each of these must be true:

  • Visibility is Visible
  • IsEnabled is true
  • IsTabStop is true
  • The control must be instantiated with its template loaded (Loaded fired, control connected to app's root visual)
If you want a control to not be focusable, you can set IsTabStop to false. However, if the reason you don't want the control to have focus is because it's not interactive in your UI, you might want to set IsEnabled to false to make the lack of interaction obvious to everyone. Many controls have predefined visual states that are invoked for IsEnabled=false, such as "graying out" text in labels.

Focus changes can fire GotFocus or LostFocus events. Although the "FocusedElement" value (exposed via GetFocusedElement method) is updated immediately, the change notifications of GotFocus or LostFocus occur asynchronously. This asynchronous focusing design is intended to avoid flickering on visual state transitions when control logic reacts to focus change too quickly.

The Focus method enables bringing keyboard focus to a control programmatically. Be judicious when calling this method, it can be intrusive to move the keyboard focus when the user doesn't expect it. The main scenarios for Focus are either setting the very first keyboard focus point when an entire page of UI is loaded, or setting focus to a specific part of a control once the parent control container has received top-level focus (like focusing the textbox in a combobox). For more info, see Focus. FocusState tracks whether focus is programmatic or user-driven, which makes a difference for visual states, notably the visual focus indicator for keyboard focus that all controls should have.

On* event handler overrides

The Control class defines several protected virtual methods that are each associated with a framework-level input event. These methods are intended to provide a pre-wired event handler for input events such that a control can enforce that certain input behaviors are used by that control and all instances of it. For example, there's a PointerPressed event defined by UIElement. Control defines the OnPointerPressed method, with an empty definition. Within the base Control constructor, event wiring for all the relevant input events includes the On* method as a listener/handler, which initially does nothing. But all it takes now for you as the control author to change the behavior for an input event is to give a new override definition for an On* method (also, make sure your constructor calls base). That behavior gets inherited to all instances or subclasses, unless another subclasser overrides it again. Because the On* events are first in sequence, before any UI definition XAML, they can adjust the event data and potentially change the conditions that other listeners see about the event.

The existing On* definitions in a particular control class can affect you as the consumer of the control even if you haven't overridden any On* methods yourself. This is because the existing On* definitions may have provided handling for an event that sets a Handled property value to false in some event's event data. That will prevent your instance-based event handling from even seeing the event, and will prevent your handler from being invoked. What's happening here is that there's an intentional control design that is enforcing that certain events shouldn't matter to the control, either because they're low-level events that clash with control logic or because the control has replacement logic. A prominent example of this is the ButtonBase class. The ButtonBase class has two behaviors that it enforces through a native override of OnPointerPressed and OnKeyDown. It's doing this because it's combining various input modes at a low level and reporting them instead as the control-specific Click event. In the case of a PointerPressed event handler, if you tried to handle this on a Button instance, your handler doesn't get invoked. That's because the native OnPointerPressed set Handled to true and that prevented PointerPressed from propagating to your instance and app code. For OnKeyDown, the logic was just looking for certain keys (Ctrl and Enter) so an instance handler can still invoke as long as it isn't also looking for those keys.

Note  There's actually a way to get around native handling of On* methods for input, for some of the input events. To do this you need to wire your handlers using the AddHandler method with handledEventsToo. For more info see AddHandler or Events and routed events overview.

Text properties that inherit to text element parts

Control defines several properties that are relevant to presentation of text. These are:

Obviously, not every control is intended to display text within it. For example, setting FontFamily on an AppBarSeparator is legal but has absolutely no effect. The reason that Control defines these properties at the base class level is to make it easy for control templates to use TemplateBinding to apply top-level text properties to one or more text element parts that exist within the template. For example, if you look at the control template for a DatePicker, you'll see that the root is a container and more deeply within that container are several ComboBox parts that actually take the text input. Each of these uses statements like FontWeight="{TemplateBinding FontWeight}" to have the top-level FontWeight as set on a DatePicker be used by various parts within.

Text properties on Control also inherit implicitly for a control that has a ContentPresenter within it that displays text. For example, if you set FontSize on a Button, there's no explicit TemplateBinding in its template or ContentPresenter part that controls what the template does with a top-level FontSize value. But the Control.FontSize value is implicitly inherited by ContentPresenter.FontSize based on the context within the template's definition, so the text within the Button will be presented using the Control.FontSize you set.

Control derived classes

Control is the parent class for these immediately derived control classes. Some of these are practical controls. Others are intermediate base classes for various controls that share characteristics.

Requirements

Minimum supported client

Windows 8 [Windows Store apps only]

Minimum supported server

Windows Server 2012 [Windows Store apps only]

Minimum supported phone

Windows Phone 8.1 [Windows Runtime apps only]

Namespace

Windows.UI.Xaml.Controls
Windows::UI::Xaml::Controls [C++]

Metadata

Windows.winmd

See also

FrameworkElement
Controls by function
Quickstart: Control templates
Quickstart: Styling controls
Storyboarded animations for visual states

 

 

Show:
© 2014 Microsoft