Overview of the flashx.textLayout.elements package

The model for the Text Layout Framework is defined mainly by the elements package, which includes classes and interfaces that define the data structure that holds the text. The model uses a hierarchical tree to represent text and each node in the tree is an instance of a class in the elements package.

The root node of the tree is always an instance of the TextFlow class. The TextFlow class represents an entire story, which is a collection of text that is treated as one unit, or flow, even if the flow requires more than one column or text container to display. The remaining elements in the hierarchy are loosely based on XHTML elements. For example, the root node can have children of two types, DivElement and ParagraphElement. DivElements and ParagraphElements are similar, but not identical, to the <div /> and <p /> XHTML elements.

DivElements are more narrowly defined than the <div /> XHTML element in that DivElements contain only ParagraphElements and other DivElements whereas the XHTML element can contain a wider variety of elements, including text. ParagraphElements are grouping elements that cannot directly contain text or graphics. ParagraphElements can, however, contain four types of child elements that do directly contain primitive text and graphics:

• The SpanElement class represents runs of text that share common formatting.
• The InlineGraphicElement class represents graphic elements that are treated as single characters in a line of text.
• The LinkElement class represents hypertext links, and are similar to <a/> XHTML elements. Links can contain one or more SpanElements, InlineGraphicElements or TCYElements.
• The TCYElement class represents short runs of text that are perpendicular to the rest of the line, usually small runs of horizontal text within vertical text lines. For example, you would use a TCYElement to represent a horizontal run of digits in an otherwise vertically oriented run of Japanese characters.

The following diagram illustrates the node hierarchy in the elements package of the Text Layout Framework:

The abstract base classes FlowElement, FlowGroupElement, and FlowLeafElement define the structure of the tree. All the objects in the tree derive from the FlowElement class. FlowElement objects represent paragraphs, groups of paragraphs and spans of text within paragraphs. The FlowGroupElement class is the base class for classes that can have an array of children. These classes include TextFlow, ParagraphElement, DivElement, and LinkElement. The FlowLeafElement class is the base class for classes at the lowest level of the tree, classes that have no children. These classes include InLineGraphicElement and SpanElement.

The remaining classes in the elements package play supporting roles.

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	Interface	Description
	IConfiguration	Read-only interface to a configuration object.

	Class	Description
	BreakElement	The BreakElement class defines a line break, which provides for creating a line break in the text without creating a new paragraph.
	Configuration	The Configuration class is a primary point of integration between the Text Layout Framework and an application.
	ContainerFormattedElement	ContainerFormattedElement is the root class for all container-level block elements, such as DivElement and TextFlow objects.
	DivElement	The DivElement class defines an element for grouping paragraphs (ParagraphElement objects).
	FlowElement	The text in a flow is stored in tree form with the elements of the tree representing logical divisions within the text.
	FlowGroupElement	The FlowGroupElement class is the base class for FlowElement objects that can have an array of children.
	FlowLeafElement	Base class for FlowElements that appear at the lowest level of the flow hierarchy.
	InlineGraphicElement	The InlineGraphicElement class handles graphic objects that display inline in the text.
	InlineGraphicElementStatus	The InlineGraphicElementStatus class defines a set of constants for checking the value of InLineGraphicElement.status.
	LinkElement	The LinkElement class defines a link to a URI, which is executed when the user clicks it.
	LinkState	The LinkState class defines a set of constants for the linkState property of the LinkElement class.
	ParagraphElement	The ParagraphElement class represents a paragraph in the text flow hierarchy.
	ParagraphFormattedElement	The ParagraphFormattedElement is an abstract base class for FlowElement classes that have paragraph properties.
	SpanElement	The SpanElement class represents a run of text that has a single set of formatting attributes applied.
	SpecialCharacterElement	The SpecialCharacterElement class is an abstract base class for elements that represent special characters.
	SubParagraphGroupElement	The SubParagraphGroupElement class groups FlowLeafElements together.
	TabElement	The TabElement class represents a <tab/> in the text flow.
	TCYElement	The TCYElement (Tatechuuyoko - ta-tae-chu-yo-ko) class is a subclass of SubParagraphGroupElement that causes text to draw horizontally within a vertical line.
	TextFlow	The TextFlow class is responsible for managing all the text content of a story.
	TextFlowLine	The TextFlowLine class represents a single line of text in a text flow.
	TextFlowLineLocation	The TextFlowLineLocation class is an enumeration class that defines constants for specifying the location of a line within a paragraph.