TextElement Content Model Overview

  • Article

This content model overview describes the supported content for a TextElement. The Paragraph class is a type of TextElement. A content model describes what objects/elements can be contained in others. This overview summarizes the content model used for objects derived from TextElement. For more information, see Flow Document Overview.

Content Model Diagram

The following diagram summarizes the content model for classes derived from TextElement as well as how other non- TextElement classes fit into this model.

Diagram: Flow content containment schema

As can be seen from the preceding diagram, the children allowed for an element are not necessarily determined by whether a class is derived from the Block class or an Inline class. For example, a Span (an Inline-derived class) can only have Inline child elements, but a Figure (also an Inline-derived class) can only have Block child elements. Therefore, a diagram is useful for quickly determining what element can be contained in another. As an example, let's use the diagram to determine how to construct the flow content of a RichTextBox.

  1. A RichTextBox must contain a FlowDocument which in turn must contain a Block-derived object. The following is the corresponding segment from the preceding diagram.

    Diagram: RichTextBox containment rules

    Thus far, this is what the markup might look like.

    <RichTextBox>
  <FlowDocument>
    <!-- One or more Block-derived object… -->
  </FlowDocument>
</RichTextBox>

  2. According to the diagram, there are several Block elements to choose from including Paragraph, Section, Table, List, and BlockUIContainer (see Block-derived classes in the preceding diagram). Let's say we want a Table. According to the preceding diagram, a Table contains a TableRowGroup containing TableRow elements, which contain TableCell elements which contain a Block-derived object. The following is the corresponding segment for Table taken from the preceding diagram.

    Diagram: Parent/child schema for Table

    The following is the corresponding markup.

    <RichTextBox>
  <FlowDocument>
    <Table>
      <TableRowGroup>
        <TableRow>
          <TableCell>
            <!-- One or more Block-derived object… -->
          </TableCell>
        </TableRow>
      </TableRowGroup>
    </Table>
  </FlowDocument>
</RichTextBox>

  3. Again, one or more Block elements are required underneath a TableCell. To make it simple, let's place some text inside the cell. We can do this using a Paragraph with a Run element. The following is the corresponding segments from the diagram showing that a Paragraph can take an Inline element and that a Run (an Inline element) can only take plain text.

    Diagram: Parent/child schema for Paragraph

    Diagram: Parent/Child schema for Run

The following is the entire example in markup.

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <RichTextBox>
    <FlowDocument>
      
      <!-- Normally a table would have multiple rows and multiple
           cells but this code is for demonstration purposes.-->
      <Table>
        <TableRowGroup>
          <TableRow>
            <TableCell>
              <Paragraph>

                <!-- The schema does not actually require
                     explicit use of the Run tag in markup. It 
                     is only included here for clarity. -->
                <Run>Paragraph in a Table Cell.</Run>
              </Paragraph>
            </TableCell>
          </TableRow>
        </TableRowGroup>
      </Table>

    </FlowDocument>
  </RichTextBox>
</Page>

Working with TextElement Content Programmatically

The contents of a TextElement is made up by collections and so programmatically manipulating the contents of TextElement objects is done by working with these collections. There are three different collections used by TextElement -derived classes:

You can manipulate (add or remove items) from these collections using the respective properties of Inlines, Blocks, and ListItems. The following examples show how to manipulate the contents of a Span using the Inlines property.

Note

Table uses several collections to manipulate its contents, but they are not covered here. For more information, see Table Overview.

The following example creates a new Span object, and then uses the Add method to add two text runs as content children of the Span.

Span spanx = new Span();
spanx.Inlines.Add(new Run("A bit of text content..."));
spanx.Inlines.Add(new Run("A bit more text content..."));

Dim spanx As New Span()
spanx.Inlines.Add(New Run("A bit of text content..."))
spanx.Inlines.Add(New Run("A bit more text content..."))

The following example creates a new Run element and inserts it at the beginning of the Span.

Run runx = new Run("Text to insert...");
spanx.Inlines.InsertBefore(spanx.Inlines.FirstInline, runx);

Dim runx As New Run("Text to insert...")
spanx.Inlines.InsertBefore(spanx.Inlines.FirstInline, runx)

The following example deletes the last Inline element in the Span.

spanx.Inlines.Remove(spanx.Inlines.LastInline);

spanx.Inlines.Remove(spanx.Inlines.LastInline)

The following example clears all of the contents (Inline elements) from the Span.

spanx.Inlines.Clear();

spanx.Inlines.Clear()

Types That Share This Content Model

The following types inherit from the TextElement class and may be used to display the content described in this overview.

Bold, Figure, Floater, Hyperlink, InlineUIContainer, Italic, LineBreak, List, ListItem, Paragraph, Run, Section, Span, Table, Underline.

Note that this list only includes nonabstract types distributed with the Windows SDK. You may use other types that inherit from TextElement.

Types That Can Contain TextElement Objects

See WPF Content Model.

See also