fop/docs/examples/keeps_and_breaks/pagelevel1.fo

<?xml version="1.0" encoding="utf-8"?>

<!--
This file addresses breaks in page context.
-->

<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
  <fo:layout-master-set>
    <!-- layout for all pages -->
    <fo:simple-page-master master-name="all"
                  page-height="29.7cm"
                  page-width="21cm"
                  margin-top="1cm"
                  margin-bottom="2cm"
                  margin-left="2.5cm"
                  margin-right="2.5cm">
      <fo:region-body
      margin-top="3cm" margin-bottom="2cm"/>
      <fo:region-before extent="3cm"/>
      <fo:region-after extent="2cm"/>
    </fo:simple-page-master>
  </fo:layout-master-set>

  <fo:page-sequence master-reference="all">
    <fo:static-content flow-name="xsl-region-after">
    <fo:block font-size="10pt" text-align="start"
      border-style="solid" border-color="blue" border-width="0.5pt">
    Text excerpt from XSL Candidate Recommendation, 21 Nov 2000.
    </fo:block>
  </fo:static-content>

    <fo:flow flow-name="xsl-region-body">
      <fo:block
      font-size="14pt" font-family="sans-serif"
    line-height="18pt" space-after.optimum="15pt">
Keep and break conditions apply to a class of areas, which are typically
page-reference-areas, column-areas, and line-areas. The appropriate class
for a given condition is referred to as a context and an area in this
class is a context-area. As defined in Section 6.4.1, page-reference-areas
are areas generated by an fo:page-sequence using the specifications in a
fo:page-master, and column-areas are normal-flow-reference-areas generated
from a region-body, or region-reference-areas generated from other types
of region-master.
      </fo:block>

      <fo:block
      font-size="14pt" font-family="sans-serif"
    line-height="18pt" space-after.optimum="15pt">
A keep or break condition is an open statement about a formatting object
and the tree relationships of the areas it generates with the relevant
context-areas. These tree relationships are defined mainly in terms of
leading or trailing areas. If A is a descendant of P, then A is defined
to be leading in P if A has no preceding sibling which is a normal area,
nor does any of its ancestor areas up to but not including P. Similarly,
A is defined to be trailing in P if A has no following sibling which is
a normal area, nor does any of its ancestor areas up to but not including P.
For any given formatting object, the next formatting object in the flow is
the first formatting object following (in the pre-order traversal order)
which generates and returns normal areas.
    </fo:block>

      <fo:block
      font-size="14pt" font-family="sans-serif"
    line-height="18pt" space-after.optimum="15pt"
    break-after="page">
<fo:inline color="red">break-after="page"</fo:inline>
Break conditions are either break-before or break-after conditions.
A break-before condition is satisfied if the first area generated and
returned by the formatting object is leading within a context-area. A
break-after condition depends on the next formatting object in the flow;
it is satisfied if either there is no such next formatting object, or
if the first normal area generated and returned by that formatting
object is leading in a context-area.
      </fo:block>

      <fo:block
      font-size="14pt" font-family="sans-serif"
    line-height="18pt" space-after.optimum="15pt">
Break conditions are imposed by the break-before and break-after
properties. A refined value of page for these traits imposes a break
condition with a context consisting of the page-reference-areas; a
value of even-page or odd-page imposes a break condition with a
context of even-numbered page-reference-areas or odd-numbered page
reference-areas, respectively; a value of column imposes a break
condition with a context of column-areas. A value of auto in a
break-before or break-after trait imposes no break condition.
      </fo:block>

      <fo:block
      font-size="14pt" font-family="sans-serif"
    line-height="18pt" space-after.optimum="15pt">
Keep conditions are either keep-with-previous, keep-with-next, or
keep-together conditions. A keep-with-previous condition on an
object is satisfied if the first area generated and returned by
the formatting object is not leading within a context-area, or
if there are no preceding areas in a post-order traversal of the
area tree. A keep-with-next condition is satisfied if the last
area generated and returned by the formatting object is not
trailing within a context-area, or if there are no following
areas in a pre-order traversal of the area tree. A keep-together
condition is satisfied if all areas generated and returned by
the formatting object are descendants of a single context-area.
      </fo:block>

      <fo:block
      font-size="14pt" font-family="sans-serif"
    line-height="18pt" space-after.optimum="15pt">
Keep conditions are imposed by the "within-page", "within-column",
and "within-line" components of the "keep-with-previous",
"keep-with-next", and "keep-together" properties. The refined value
of each component specifies the strength of the keep condition
imposed, with higher numbers being stronger than lower numbers and
the value always being stronger than all numeric values. A component
with value auto does not impose a keep condition. A "within-page"
component imposes a keep-condition with context consisting of the
page-reference-areas; "within-column", with context consisting of
the column-areas; and "within-line" with context consisting of the
line-areas.
      </fo:block>

      <fo:block
      font-size="14pt" font-family="sans-serif"
    line-height="18pt" space-after.optimum="15pt"
    break-before="page">
<fo:inline color="red">break-before="page"</fo:inline>
The area tree is constrained to satisfy all break conditions imposed.
Each keep condition must also be satisfied, except when this would
cause a break condition or a stronger keep condition to fail to be
satisfied. If not all of a set of keep conditions of equal strength
can be satisfied, then some maximal satisfiable subset of conditions
of that strength must be satisfied (together with all break conditions
and maximal subsets of stronger keep conditions, if any).
      </fo:block>

    </fo:flow>
  </fo:page-sequence>
</fo:root>