TextSource.GetTextRun(Int32) Method

Definition

Namespace:

System.Windows.Media.TextFormatting

Assembly:

PresentationCore.dll

Retrieves a TextRun starting at a specified TextSource position.

public:
 abstract System::Windows::Media::TextFormatting::TextRun ^ GetTextRun(int textSourceCharacterIndex);

public abstract System.Windows.Media.TextFormatting.TextRun GetTextRun (int textSourceCharacterIndex);

abstract member GetTextRun : int -> System.Windows.Media.TextFormatting.TextRun

Public MustOverride Function GetTextRun (textSourceCharacterIndex As Integer) As TextRun

Parameters

textSourceCharacterIndex

Int32

Specifies the character index position in the TextSource where the TextRun is retrieved.

Returns

TextRun

A value that represents a TextRun, or an object derived from TextRun.

Examples

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);
}

' Retrieve the next formatted text run for the text source.
Public Overrides Function GetTextRun(ByVal textSourceCharacterIndex As Integer) As TextRun
    ' Determine whether the text source index is in bounds.
    If textSourceCharacterIndex < 0 Then
        Throw New ArgumentOutOfRangeException("textSourceCharacterIndex", "Value must be greater than 0.")
    End If

    ' Determine whether the text source index has exceeded or equaled the text source length.
    If textSourceCharacterIndex >= _text.Length Then
        ' Return an end-of-paragraph indicator -- a TextEndOfParagraph object is a special type of text run.
        Return New TextEndOfParagraph(1)
    End If

    ' Create and return a TextCharacters object, which is formatted according to
    ' the current layout and rendering properties.
    If textSourceCharacterIndex < _text.Length Then
        ' The TextCharacters object is a special type of text run that contains formatted text.
        Return New TextCharacters(_text, textSourceCharacterIndex, _text.Length - textSourceCharacterIndex, New CustomTextRunProperties()) ' The layout and rendering properties -  The text store length -  The text store index -  The text store
    End If

    ' Return an end-of-paragraph indicator if there is no more text source.
    Return New TextEndOfParagraph(1)
End Function

Remarks

A text run is a sequence of characters sharing a single property set. Any change to the format, such as font family, font style, foreground color, text decoration, or any other formatting effect, breaks the text run. 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.