Andy De George
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| title | ms.date | ms.topic | dev_langs | helpviewer_keywords | ms.assetid | |||||
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| TextElement Content Model Overview | 03/30/2017 | overview |
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d0a7791c-b090-438c-812f-b9d009d83ee9 |
TextElement Content Model Overview
This content model overview describes the supported content for a xref:System.Windows.Documents.TextElement. The xref:System.Windows.Documents.Paragraph class is a type of xref:System.Windows.Documents.TextElement. A content model describes what objects/elements can be contained in others. This overview summarizes the content model used for objects derived from xref:System.Windows.Documents.TextElement. For more information, see Flow Document Overview.
Content Model Diagram
The following diagram summarizes the content model for classes derived from xref:System.Windows.Documents.TextElement as well as how other non- TextElement classes fit into this model.
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 xref:System.Windows.Documents.Block class or an xref:System.Windows.Documents.Inline class. For example, a xref:System.Windows.Documents.Span (an xref:System.Windows.Documents.Inline-derived class) can only have xref:System.Windows.Documents.Inline child elements, but a xref:System.Windows.Documents.Figure (also an xref:System.Windows.Documents.Inline-derived class) can only have xref:System.Windows.Documents.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 xref:System.Windows.Controls.RichTextBox.
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A xref:System.Windows.Controls.RichTextBox must contain a xref:System.Windows.Documents.FlowDocument which in turn must contain a xref:System.Windows.Documents.Block-derived object. The following is the corresponding segment from the preceding diagram.
Thus far, this is what the markup might look like.
[!code-xamlFlowOvwSnippets_snip#SchemaWalkThrough1]
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According to the diagram, there are several xref:System.Windows.Documents.Block elements to choose from including xref:System.Windows.Documents.Paragraph, xref:System.Windows.Documents.Section, xref:System.Windows.Documents.Table, xref:System.Windows.Documents.List, and xref:System.Windows.Documents.BlockUIContainer (see Block-derived classes in the preceding diagram). Let's say we want a xref:System.Windows.Documents.Table. According to the preceding diagram, a xref:System.Windows.Documents.Table contains a xref:System.Windows.Documents.TableRowGroup containing xref:System.Windows.Documents.TableRow elements, which contain xref:System.Windows.Documents.TableCell elements which contain a xref:System.Windows.Documents.Block-derived object. The following is the corresponding segment for xref:System.Windows.Documents.Table taken from the preceding diagram.
The following is the corresponding markup.
[!code-xamlFlowOvwSnippets_snip#SchemaWalkThrough2]
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Again, one or more xref:System.Windows.Documents.Block elements are required underneath a xref:System.Windows.Documents.TableCell. To make it simple, let's place some text inside the cell. We can do this using a xref:System.Windows.Documents.Paragraph with a xref:System.Windows.Documents.Run element. The following is the corresponding segments from the diagram showing that a xref:System.Windows.Documents.Paragraph can take an xref:System.Windows.Documents.Inline element and that a xref:System.Windows.Documents.Run (an xref:System.Windows.Documents.Inline element) can only take plain text.
The following is the entire example in markup.
[!code-xamlFlowOvwSnippets_snip#SchemaExampleWholePage]
Working with TextElement Content Programmatically
The contents of a xref:System.Windows.Documents.TextElement is made up by collections and so programmatically manipulating the contents of xref:System.Windows.Documents.TextElement objects is done by working with these collections. There are three different collections used by xref:System.Windows.Documents.TextElement -derived classes:
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xref:System.Windows.Documents.InlineCollection: Represents a collection of xref:System.Windows.Documents.Inline elements. xref:System.Windows.Documents.InlineCollection defines the allowable child content of the xref:System.Windows.Documents.Paragraph, xref:System.Windows.Documents.Span, and xref:System.Windows.Controls.TextBlock elements.
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xref:System.Windows.Documents.BlockCollection: Represents a collection of xref:System.Windows.Documents.Block elements. xref:System.Windows.Documents.BlockCollection defines the allowable child content of the xref:System.Windows.Documents.FlowDocument, xref:System.Windows.Documents.Section, xref:System.Windows.Documents.ListItem, xref:System.Windows.Documents.TableCell, xref:System.Windows.Documents.Floater, and xref:System.Windows.Documents.Figure elements.
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xref:System.Windows.Documents.ListItemCollection: A flow content element that represents a particular content item in an ordered or unordered xref:System.Windows.Documents.List.
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 xref:System.Windows.Documents.Span object, and then uses the Add method to add two text runs as content children of the xref:System.Windows.Documents.Span.
[!code-csharpSpanSnippets#_SpanInlinesAdd] [!code-vbSpanSnippets#_SpanInlinesAdd]
The following example creates a new xref:System.Windows.Documents.Run element and inserts it at the beginning of the xref:System.Windows.Documents.Span.
[!code-csharpSpanSnippets#_SpanInlinesInsert] [!code-vbSpanSnippets#_SpanInlinesInsert]
The following example deletes the last xref:System.Windows.Documents.Inline element in the xref:System.Windows.Documents.Span.
[!code-csharpSpanSnippets#_SpanInlinesRemoveLast] [!code-vbSpanSnippets#_SpanInlinesRemoveLast]
The following example clears all of the contents (xref:System.Windows.Documents.Inline elements) from the xref:System.Windows.Documents.Span.
[!code-csharpSpanSnippets#_SpanInlinesClear] [!code-vbSpanSnippets#_SpanInlinesClear]
Types That Share This Content Model
The following types inherit from the xref:System.Windows.Documents.TextElement class and may be used to display the content described in this overview.
xref:System.Windows.Documents.Bold, xref:System.Windows.Documents.Figure, xref:System.Windows.Documents.Floater, xref:System.Windows.Documents.Hyperlink, xref:System.Windows.Documents.InlineUIContainer, xref:System.Windows.Documents.Italic, xref:System.Windows.Documents.LineBreak, xref:System.Windows.Documents.List, xref:System.Windows.Documents.ListItem, xref:System.Windows.Documents.Paragraph, xref:System.Windows.Documents.Run, xref:System.Windows.Documents.Section, xref:System.Windows.Documents.Span, xref:System.Windows.Documents.Table, xref:System.Windows.Documents.Underline.
Note that this list only includes nonabstract types distributed with the Windows SDK. You may use other types that inherit from xref:System.Windows.Documents.TextElement.
Types That Can Contain TextElement Objects
See WPF Content Model.