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TextRun Class

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

Namespace: System.Windows.Media.TextFormatting
Assembly: PresentationCore (in presentationcore.dll)
XML Namespace:  http://schemas.microsoft.com/winfx/2006/xaml/presentation

public abstract class TextRun
public abstract class TextRun
public abstract class TextRun
This class is abstract; see Inheritance Hierarchy for derived non-abstract classes usable in XAML.

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.

Series of text runs that comprise a text string


Sequence of text runs

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.

Class

Description

TextRun

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

TextCharacters

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

TextEmbeddedObject

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.

TextEndOfLine

Defines a line-break character code.

TextEndOfParagraph

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

TextEndOfSegment

Defines a segment break marker.

TextHidden

Defines a range of non-visible characters.

TextModifier

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);
}

System.Object
  System.Windows.Media.TextFormatting.TextRun
     Derived Classes

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

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0

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