Chapter 10. Interactive objects

For the active rendering of changing information in an electronic display, XSL-FO supports interactive, operator-influenced presentation of content. The use of interactive formatting objects enables the operator (i.e. the reader of the document) to select from multiple alternatives prepared by the stylesheet writer, where the interactive object itself reflects previous interaction by its state. This results in a dynamically changing presentation of the information, rather than a single static rendering of the information.

XSL-FO 1.0 provides two areas where interactivity can influence presentation: reflecting the active state of a linked object using different property values, and selecting and switching between alternative available presentations using different sub-trees of formatting objects.

Appearance or other impartation differences can distinguish a link that can be but hasn't yet been traversed (future potential for visitation), from a link that would be traversed (active hover), from a link that is about to be traversed (has the focus), from a link that is in the process of being traversed (is activated), from a link that has been traversed (past visitation).

Switching alternative available renderings can be used to implement interactive presentations such as a dynamically expandable and collapsible table of contents. HTML pages accomplish this in an imperative fashion with scripting in a programming language, whereas XSL-FO 1.0 pages accomplish this in a declarative fashion by describing transition paths in a state machine, without having to implement the imperative logic behind the state machine.

Included in this chapter. This chapter includes discussion of the following XSL-FO objects.

Formatting objects related to dynamic properties:

• multi-properties ( 6.9.6 ):

  • is the collection of candidate property sets from which exactly one set influences the properties of a formatting object based on its status or the status of operator interaction,

• multi-property-set ( 6.9.7 ):

  • is the set of properties associated with a single possible state of a formatting object or operator interaction.

Formatting objects related to dynamic presentation:

• multi-switch ( 6.9.3 ):

  • is the collection of candidate formatting object sequences from which exactly one is rendered at any given time based on an interactive condition that is influenced by the operator while being tracked by the formatter,

• multi-case ( 6.9.4 ):

  • is a single formatting object sequence that is a candidate for rendering based on an interactive condition that is influenced by the operator while being tracked by the formatter,

• multi-toggle ( 6.9.5 ):

  • is the definition of the interaction-sensitive objects within a candidate sequence of formatting objects.