Článek
11/18/2011

TextBlock Class

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

Provides a lightweight control for displaying small amounts of text..

Inheritance Hierarchy

System.Object
  System.Windows.DependencyObject
    System.Windows.UIElement
      System.Windows.FrameworkElement
        System.Windows.Controls.TextBlock

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

Syntax

'Declaration
<ContentPropertyAttribute("Inlines", True)> _
Public NotInheritable Class TextBlock _
    Inherits FrameworkElement

[ContentPropertyAttribute("Inlines", true)]
public sealed class TextBlock : FrameworkElement

<TextBlock ...>text</TextBlock>
-or-
<TextBlock>
  oneOrMoreInlineElements
</TextBlock>
-or-
<TextBlock .../>

XAML Values

text
Inner text that is displayed in the TextBlock. This text becomes the value of the Text property. It also creates a single new Run object in the Inlines collection that holds the same text.
oneOrMoreInlineElements
One or more Run or LineBreak elements.

The TextBlock type exposes the following members.

Constructors

	Name	Description
	TextBlock	Initializes a new instance of the TextBlock class.

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Properties

	Name	Description
	ActualHeight	Gets the rendered height of a FrameworkElement. (Inherited from FrameworkElement.)
	ActualWidth	Gets the rendered width of a FrameworkElement. (Inherited from FrameworkElement.)
	AllowDrop	Gets or sets a value that determines whether this UIElement can be a drop target for purposes of Silverlight drag-and-drop operations. (Inherited from UIElement.)
	BaselineOffset	Returns a value by which each line of text is offset from a baseline.
	CacheMode	Gets or sets a value that indicates that rendered content should be cached when possible. (Inherited from UIElement.)
	CharacterSpacing	Gets or sets the distance between characters of text in the control measured in 1000ths of the font size.
	Clip	Gets or sets the Geometry used to define the outline of the contents of a UIElement. (Inherited from UIElement.)
	Cursor	Gets or sets the cursor image that displays while the mouse pointer is over a FrameworkElement. (Inherited from FrameworkElement.)
	DataContext	Gets or sets the data context for a FrameworkElement when it participates in data binding. (Inherited from FrameworkElement.)
	DesiredSize	Gets the size that this UIElement computed during the measure pass of the layout process. (Inherited from UIElement.)
	Dispatcher	Gets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
	Effect	Gets or sets the pixel shader effect to use for rendering this UIElement. (Inherited from UIElement.)
	FlowDirection	Gets or sets the direction that text and other user interface elements flow within any parent element that controls their layout. (Inherited from FrameworkElement.)
	FontFamily	Gets or sets the preferred top-level font family for the text content in this element.
	FontSize	Gets or sets the font size for the text content in this element.
	FontSource	Gets or sets the font source that is applied to the text for rendering content.
	FontStretch	Gets or sets the font stretch for the text content in this element.
	FontStyle	Gets or sets the font style for the content in this element.
	FontWeight	Gets or sets the top-level font weight for the TextBlock.
	Foreground	Gets or sets the Brush to apply to the text contents of the TextBlock.
	Height	Gets or sets the suggested height of a FrameworkElement. (Inherited from FrameworkElement.)
	HorizontalAlignment	Gets 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.)
	Inlines	Gets the collection of inline text elements within a TextBlock.
	IsHitTestVisible	Gets or sets whether the contained area of this UIElement can return true values for hit testing. (Inherited from UIElement.)
	Language	Gets or sets localization/globalization language information that applies to a FrameworkElement. (Inherited from FrameworkElement.)
	LineHeight	Gets or sets the height of each line of content.
	LineStackingStrategy	Gets or sets a value that indicates how a line box is determined for each line of text in the TextBlock.
	Margin	Gets or sets the outer margin of a FrameworkElement. (Inherited from FrameworkElement.)
	MaxHeight	Gets or sets the maximum height constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	MaxWidth	Gets or sets the maximum width constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	MinHeight	Gets or sets the minimum height constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	MinWidth	Gets or sets the minimum width constraint of a FrameworkElement. (Inherited from FrameworkElement.)
	Name	Gets 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	Gets or sets the degree of the object's opacity. (Inherited from UIElement.)
	OpacityMask	Gets or sets the brush used to alter the opacity of regions of this object. (Inherited from UIElement.)
	Padding	Gets or sets a value that indicates the thickness of padding space between the boundaries of the content area and the content displayed by a TextBlock.
	Parent	Gets the parent object of this FrameworkElement in the object tree. (Inherited from FrameworkElement.)
	Projection	Gets or sets the perspective projection (3-D effect) to apply when rendering this UIElement. (Inherited from UIElement.)
	RenderSize	Gets the final render size of a UIElement. (Inherited from UIElement.)
	RenderTransform	Gets or sets transform information that affects the rendering position of a UIElement. (Inherited from UIElement.)
	RenderTransformOrigin	Gets or sets the origin point of any possible render transform declared by RenderTransform, relative to the bounds of the UIElement. (Inherited from UIElement.)
	Resources	Gets 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	Gets or sets an instance Style that is applied for this object during rendering. (Inherited from FrameworkElement.)
	Tag	Gets or sets an arbitrary object value that can be used to store custom information about this object. (Inherited from FrameworkElement.)
	Text	Gets or sets the text contents of a TextBlock.
	TextAlignment	Gets or sets a value that indicates the horizontal alignment of text content.
	TextDecorations	Gets or sets a value that specifies the text decorations that are applied to the content in a TextBlock element.
	TextTrimming	Gets or sets the text trimming behavior to employ when content overflows the content area.
	TextWrapping	Gets or sets how the TextBlock wraps text.
	Triggers	Gets the collection of triggers for animations that are defined for a FrameworkElement. (Inherited from FrameworkElement.)
	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. (Inherited from UIElement.)
	VerticalAlignment	Gets 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.)
	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. (Inherited from UIElement.)
	Width	Gets or sets the width of a FrameworkElement. (Inherited from FrameworkElement.)

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Methods

	Name	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 for routed event that had already been marked as handled by another element along the event route. (Inherited from UIElement.)
	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 Silverlight layout. Classes can override this method to define their own Arrange pass behavior. (Inherited from FrameworkElement.)
	CaptureMouse	Sets mouse capture to a UIElement. (Inherited from UIElement.)
	CheckAccess	Determines whether the calling thread has access to this object. (Inherited from DependencyObject.)
	ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject.)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	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.)
	FindName	Retrieves an object that has the specified identifier name. (Inherited from FrameworkElement.)
	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.)
	GetBindingExpression	Retrieves the BindingExpression for a dependency property where a binding is established. (Inherited from FrameworkElement.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	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. (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 Silverlight layout. Classes can override this method to define their own Measure pass behavior. (Inherited from FrameworkElement.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	OnApplyTemplate	When overridden in a derived class, is 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 an application. For more information, see Remarks. (Inherited from FrameworkElement.)
	OnCreateAutomationPeer	When implemented in a derived class, returns class-specific AutomationPeer implementations for the Silverlight automation infrastructure. (Inherited from UIElement.)
	ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
	ReleaseMouseCapture	Removes mouse capture from a UIElement. After this call, typically no object holds mouse capture. (Inherited from UIElement.)
	RemoveHandler	Removes the specified routed event handler from this UIElement. (Inherited from UIElement.)
	SetBinding	Attaches a binding to a FrameworkElement, using the provided binding object, and returns a BindingExpressionBase for possible later use. (Inherited from FrameworkElement.)
	SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	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.)

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Events

	Name	Description
	BindingValidationError	Occurs when a data validation error is reported by a binding source. (Inherited from FrameworkElement.)
	DataContextChanged	Occurs when the data context for this element changes. (Inherited from FrameworkElement.)
	DoubleTap	Occurs when a DoubleTap gesture is committed while over this UIElement. (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.)
	Hold	Occurs when a Hold gesture is committed while over this UIElement. (Inherited from UIElement.)
	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 Silverlight visual tree changes. (Inherited from FrameworkElement.)
	Loaded	Occurs when a FrameworkElement has been constructed and added to the object tree. (Inherited from FrameworkElement.)
	LostFocus	Occurs when a UIElement loses focus. (Inherited from UIElement.)
	LostMouseCapture	Occurs when the UIElement loses mouse capture. (Inherited from UIElement.)
	ManipulationCompleted	Occurs when a manipulation and inertia on the UIElement is complete. (Inherited from UIElement.)
	ManipulationDelta	Occurs when the input device changes position during a manipulation. (Inherited from UIElement.)
	ManipulationStarted	Occurs when an input device begins a manipulation on the UIElement. (Inherited from UIElement.)
	MediaCommand	Occurs when a button is pressed on a remote control. (Inherited from UIElement.)
	MouseEnter	Occurs when the mouse (or a stylus) enters the bounding area of a UIElement. (Inherited from UIElement.)
	MouseLeave	Occurs when the mouse (or the stylus) leaves the bounding area of a UIElement. (Inherited from UIElement.)
	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. (Inherited from UIElement.)
	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). (Inherited from UIElement.)
	MouseMove	Occurs when the coordinate position of the mouse (or stylus) changes while over a UIElement (or while a UIElement holds mouse capture). (Inherited from UIElement.)
	MouseRightButtonDown	Occurs when the right mouse button is pressed while the mouse pointer is over a UIElement. (Inherited from UIElement.)
	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. (Inherited from UIElement.)
	MouseWheel	Occurs when the user rotates the mouse wheel while the mouse pointer is over a UIElement, or the UIElement has focus. (Inherited from UIElement.)
	SizeChanged	Occurs when either the ActualHeight or the ActualWidth properties change value on a FrameworkElement. (Inherited from FrameworkElement.)
	Tap	Occurs when a Tap gesture is committed while over this UIElement. (Inherited from UIElement.)
	TextInput	Occurs when a UI element gets text in a device-independent manner. (Inherited from UIElement.)
	TextInputStart	Occurs when a UI element initially gets text in a device-independent manner. (Inherited from UIElement.)
	TextInputUpdate	Occurs when text continues to be composed via an input method editor (IME). (Inherited from UIElement.)
	Unloaded	Occurs when this object is no longer connected to the main object tree. (Inherited from FrameworkElement.)

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Fields

	Name	Description
	CharacterSpacingProperty	Identifies the CharacterSpacing dependency property.
	FontFamilyProperty	Identifies the FontFamily dependency property.
	FontSizeProperty	Identifies the FontSize dependency property.
	FontStretchProperty	Identifies the FontStretch dependency property.
	FontStyleProperty	Identifies the FontStyle dependency property.
	FontWeightProperty	Identifies the FontWeight dependency property.
	ForegroundProperty	Identifies the Foreground dependency property.
	LineHeightProperty	Identifies the LineHeight dependency property.
	LineStackingStrategyProperty	Identifies the LineStackingStrategy dependency property.
	PaddingProperty	Identifies the Padding dependency property.
	TextAlignmentProperty	Identifies the TextAlignment dependency property.
	TextDecorationsProperty	Identifies the TextDecorations dependency property.
	TextProperty	Identifies the Text dependency property.
	TextTrimmingProperty	Identifies the TextTrimming dependency property.
	TextWrappingProperty	Identifies the TextWrapping dependency property.

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Remarks

The TextBlock control is the primary element for displaying text in Silverlight based applications. If you need to display caption for another control that includes required field or validation error indicators, use the Label control.

When you set text in a TextBlock, it is not necessary in XAML to explicitly specify the Text property. You can put text in the TextBlock container as its content, or inner text, as in the following example:

<TextBlock>Hello, world!</TextBlock>

Note:
Leading or trailing whitespace is not preserved when you set the Text property. For details on whitespace handling in XAML, see XAML Overview.

You can align the TextBlock within the layout of a parent container with the TextAlignment, HorizontalAlignment, and VerticalAlignment properties.

The Run and LineBreak objects can also be used to render formatted text, as child elements of a TextBlock in XAML (or as items of Inlines in code). The Run object is a text element that represents a discrete section of formatted or unformatted text. The LineBreak object represents an explicit new line in a TextBlock.

The default value of the FontSize property of a rendered TextBlock is 11 (measured in pixels).

The default value of the FontFamily property of a rendered TextBlock is "Portable User Interface". For more information on the "Portable User Interface" concept, see Text and Fonts.

TextBlock Text Model

Rather than presenting a single string, a TextBlock can also present a series of strings contained in different Run elements, where each element can have different character-level font attributes. The LineBreak object represents an explicit new line in a TextBlock, and is generally used between surrounding Run elements. LineBreak and Run share a base class (Inline), which makes it possible for a TextBlock to hold a strongly typed InlineCollection of its text model content. That InlineCollection is also the TextBlock XAML content property, and the end result is that to specify items in the TextBlock model you simply specify various Run and LineBreak elements as child elements of the TextBlock.

The following XAML example shows how to define several differently formatted text strings in a TextBlock by using Run objects, separated with LineBreak.

<!-- Display formatted text as Run objects within a TextBlock. -->
<Canvas>
<TextBlock
  FontFamily="Arial" Width="400" Text="Sample text formatting runs">
  <LineBreak/>
  <Run Foreground="Maroon" FontFamily="Courier New" FontSize="24">Courier New 24</Run>
  <LineBreak/>
  <Run Foreground="Teal" FontFamily="Times New Roman" FontSize="18" FontStyle="Italic">Times New Roman Italic 18</Run>
  <LineBreak/>
  <Run Foreground="SteelBlue" FontFamily="Verdana" FontSize="14" FontWeight="Bold">Verdana Bold 14</Run>
</TextBlock>
</Canvas>

The following illustration shows the rendered formatted text from the previous XAML content example.

TextBlock rendering multiple Run objects

Sample of text formatting runs.

LineBreak forces the text in each Run to display on a separate line. Without the LineBreak, the text in each Run would flow together as one line and would often be clipped due to exceeding the TextBlock object width or the width of the Silverlight content area. The following illustration shows how the formatted text would render without using LineBreak objects.

TextBlock rendering multiple Run objects without LineBreak objects

Sample text formatting runs.

Accessing the TextBlock Text Model in Code

There are really two properties involved in the TextBlock text model: Text, and Inlines. Changing the value of Text is not always advisable, because it can flatten any existing font element formatting on the individual Run items as well as strip the LineBreak elements for a TextBlock that was originally constructed with inlines and not just Text. For details, see Inlines.

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.

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