XFA Specification
Chapter 2, Template Features for Designing Static Forms
Form Structural Building Blocks
30
Page Set
A
pageSet
element represents an ordered set of display surfaces, for example a series of printed pages. A
pageSet
element may contain any number of child
pageSet
elements. For example, consider the
following template fragment:
<pageSet>
<pageSet>
<pageArea
<pageArea
</pageSet>
<pageSet>
<pageArea
<pageArea
</pageSet>
</pageSet>
... />
... />
... />
... />
In the above example each inner
pageSet
element contains two
pageArea
elements to represent the
two sides of a duplex-printed page. The outer
pageSet
element groups all the duplex-printed pages
together. In this case there are two pages, each printed on both sides, for a total of four printed surfaces.
Types of Layout Elements
Layout operates on layout elements. There are two general classes of layout elements. Any layout element
corresponding to a
pageSet
element, a
pageArea
element or a
contentArea
element represents a
physical
display object or a region of a physical display object.All other layout objects are
layout content.
The function of the layout processor is to apportion layout content to and position layout content upon
physical display objects.
Layout content can be further subdivided into
displayable entities
and
structure.
●
Displayable layout elements includes those elements which have no other function than to be visually
presented upon the display, such as text, images, and geometric figures. Elements descended from
draw
elements are also classified as displayable because
draw
elements merely provide packaging
around one of the other types of displayable entities. Displayable entities may originate either from the
template (boilerplate) or from user-supplied data.
Structural layout elements embody relationships between displayable entities and/or other structural
layout elements. Subform elements and exclusion group elements are examples of structural layout
elements. Note that structural layout elements may also be visually presented upon the display, as for
example a subform that has a border and/or a fill color.
●
In the context of layout, displayable layout elements are generally passive. That is, generally they are acted
upon by other layout elements but have no effect upon other layout elements except by the simple act of
taking up space. Physical layout elements, by contrast, are always active; they both act directly upon and
set constraints upon other layout elements. For example, a block of text may flow across multiple
contentArea
elements and be split up by them. Structural layout elements become active when they
possess non-default
breakBefore
or
breakAfter
properties. For example, usingthe
breakBefore
property a structural layout element may state that it must be kept intact, or that it must be displayed on
the front surface of a page.
The
w
(width) and
h
(height) properties of layout elements are particularly likely to be a source of
confusion. The height of a
contentArea
is a constraint. For example when text being placed into a
contentArea
crosses the lower edge of the
contentArea
, the text may be split and only a fragment
placed into the
contentArea
. By contrast if a height is specified for a subform, it is not a physical
constraint but a logical property. Hence the supplied height does not affect the layout or actual size of the