This documentation is archived and is not being maintained.

TextRun Class

Represents a sequence of characters that share a single property set.

Namespace:  System.Windows.Media.TextFormatting
Assembly:  PresentationCore (in PresentationCore.dll)

public abstract class TextRun

The TextRun type exposes the following members.

Protected methodTextRunCreates an instance of a TextRun object.

Public propertyCharacterBufferReferenceGets a reference to the text run character buffer.
Public propertyLengthGets the number of characters in the text run.
Public propertyPropertiesGets the set of text properties that are shared by every character in the text run, such as typeface or foreground brush.

Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)

A text run is a sequence of characters sharing a single property set. Any change to the format, such as font style, foreground color, font family, or any other formatting effect, breaks the text run. The following example illustrates how changes in formatting to a text string results in a series of text runs—each text run has a common set of formatting properties.

The TextRun class is the root of a type hierarchy representing several types of text content processed by TextFormatter. Each class that is derived from TextRun represents a distinct type of text content.




Root of the hierarchy. Defines a group of characters that share the same set of character properties.


Defines a collection of character glyphs from a distinct physical typeface.


Defines a type of text content in which measuring, hit testing, and drawing of the entire content is done as a distinct entity. An example of this type of content is a button in the middle of the line of text.


Defines a line-break character code.


Defines a paragraph-break character code. Derives from TextEndOfLine.


Defines a segment break marker.


Defines a range of non-visible characters.


Defines the beginning of a modification scope.

In the following example, an override for the GetTextRun method is implemented.

// Retrieve the next formatted text run for the text source.
public override TextRun GetTextRun(int textSourceCharacterIndex)
    // Determine whether the text source index is in bounds.
    if (textSourceCharacterIndex < 0)
        throw new ArgumentOutOfRangeException("textSourceCharacterIndex", "Value must be greater than 0.");

    // Determine whether the text source index has exceeded or equaled the text source length.
    if (textSourceCharacterIndex >= _text.Length)
        // Return an end-of-paragraph indicator -- a TextEndOfParagraph object is a special type of text run.
        return new TextEndOfParagraph(1);

    // Create and return a TextCharacters object, which is formatted according to
    // the current layout and rendering properties.
    if (textSourceCharacterIndex < _text.Length)
        // The TextCharacters object is a special type of text run that contains formatted text.
        return new TextCharacters(
           _text,                                       // The text store
           textSourceCharacterIndex,                    // The text store index
           _text.Length - textSourceCharacterIndex,     // The text store length
           new CustomTextRunProperties());              // The layout and rendering properties

    // Return an end-of-paragraph indicator if there is no more text source.
    return new TextEndOfParagraph(1);

.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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