The fo:float formatting object is used for two distinct purposes. First, so that during the normal placement of content, some related content is formatted into a separate area at the beginning of a page where it is available to be read without immediately intruding on the reader. The areas generated by this kind of fo:float are called before-floats. An fo:float is specified to generate before-floats if it has a "float" property value of "before". The constraints on placing before-floats on a page are described in the [pg-out-of-line] section of this introduction and in the description of the fo:float formatting object.

Second, the fo:float formatting object is used when an area is intended to float to one side, with normal content flowing alongside the floated area. The areas generated by this kind of fo:float are called side-floats. A side-float is always made a child of the nearest ancestor reference-area. The edge of the reference-area towards which the side-float floats is controlled by the value of the "float" property.

Flowing normal content flowing alongside side-floats is realized by increasing the start-intrusion-adjustment or the end-intrusion-adjustment of normal child areas of the parent reference-area of the side-float.

The "clear" property applies to any block-level formatting object. If the value of this property for a particular formatting object is any value other than "none", then the areas generated by the block will be positioned to ensure that their border-rectangles do not overlap the allocation-rectangles of the applicable side-floats as determined by the "clear" property value.

Footnotes[top]

Footnotes

The fo:footnote formatting object is used to generate both a footnote and its citation. The fo:footnote has two children, which are both required to be present. The first child is an fo:inline formatting object, which is formatted to produce the footnote citation. The second child is an fo:footnote-body formatting object which generates the content (or body) of the footnote.

The actual areas generated by the descendants of the fo:footnote-body formatting object are determined by the formatting objects that comprise the descendant subtree. For example, the footnote could be formatted with a label and an indented body by using the fo:list-block formatting object within the fo:footnote-body.

Conditional Sub-Regions[top]

Conditional Sub-Regions

The region-body has two conditional sub-regions which implicitly specify corresponding reference-areas called before-float-reference-area and footnote-reference-area. These reference-areas are conditionally generated as children of the region-reference-area. The before-float-reference-area is generated only if the page contains one or more areas with area-class "xsl-before-float". The footnote-reference-area is generated only if the page contains one or more areas with area-class "xsl-footnote".

The conditionally generated areas borrow space in the block-progression-dimension (this is "height" when the writing-mode is "lr-tb") within the region-reference-area, at the expense of the main-reference-area. Whether or not a conditionally generated area is actually generated depends, additionally, on whether there is sufficient space left in the main-reference-area.

There may be limits on how much space conditionally generated areas can borrow from the region-reference-area. It is left to the user agent to decide these limits.

The block-progression-dimension of the main-reference-area is set equal to the block-progression-dimension of the allocation-rectangle of the region-reference-area minus the sum of the sizes in the block-progression-direction of the allocation-rectangles of the conditionally generated reference-areas that were actually generated. The main-reference-area is positioned to immediately follow the after-edge of the allocation-rectangle of the before-float-reference-area. This positions the after-edge of the main-reference-area to coincide with the before-edge of the allocation-rectangle of the footnote-reference-area. In addition to the constraints normally determined by the region-reference-area, the inline-progression-dimension (this is "width" when the writing-mode is "lr-tb") of a conditionally generated reference-area is constrained to match the inline-progression-dimension of the main-reference-area.

Each conditionally generated reference-area may additionally contain a sequence of areas used to separate the reference-area from the main-reference-area. The sequence of areas is the sequence returned by formatting a fo:static-content specified in the page-sequence that is being used to format the page.

If there is an fo:static-content in a page-sequence whose "flow-name" property value is "xsl-before-float-separator", then the areas returned by formatting the fo:static-content are inserted in the proper order as the last children of a before-float-reference-area that is generated using the same page-master, provided the main-reference-area on the page is not empty.

If there is an fo:static-content whose "flow-name" property value is "xsl-footnote-separator", then the areas returned by formatting the fo:static-content are inserted in the proper order as the initial children of a footnote-reference-area that is generated using the same page-master.

An interactive user agent may choose to create "hot links" to the footnotes from the footnote-citation, or create "hot links" to the before-floats from an implicit citation, instead of realizing conditional sub-regions.

The generation of areas with area-class "xsl-before-float" or "xsl-footnote" is specified in the descriptions of the formatting objects that initially return areas with those area-classes.

Examples[top]

Examples

Floating Figure[top]

Floating Figure

Input sample:

<doc>
  <p>C'ieng pieces were made in northern towns, such as C'ieng Mai.
They were typically of tamlung weight.</p>
  <figure>
    <photo image="TH0317A.jpg"/>
    <caption>C'ieng Tamlung of C'ieng Mai</caption>
  </figure>
</doc>

In this example the figures are placed as floats at the before side (top in a lr-tb writing-mode).

XSL Stylesheet:

<?xml version='1.0'?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:fo="http://www.w3.org/1999/XSL/Format"
                version='1.0'>

<xsl:template match="p">
  <fo:block>
    <xsl:apply-templates/>
  </fo:block>
</xsl:template>

<xsl:template match="figure">
  <fo:float float="before">
    <xsl:apply-templates/>
  </fo:float>
</xsl:template>

<xsl:template match="photo">
  <fo:block text-align="center">
    <fo:external-graphic src="{@image}"/>
  </fo:block>
</xsl:template>

<xsl:template match="caption">
  <fo:block space-before="3pt" text-align="center"
    start-indent="10mm" end-indent="10mm">
    <xsl:apply-templates/>
  </fo:block>
</xsl:template>

</xsl:stylesheet>

Result Instance: elements and attributes in the fo: namespace

<fo:block>C'ieng pieces were made in northern towns,
such as C'ieng Mai. They were typically of tamlung weight.
</fo:block>

<fo:float float="before">

  <fo:block text-align="center">
    <fo:external-graphic src="TH0317A.jpg">
    </fo:external-graphic>
  </fo:block>

  <fo:block space-before="3pt" text-align="center" start-indent="10mm"
    end-indent="10mm">C'ieng Tamlung of C'ieng Mai
  </fo:block>

</fo:float>

Footnote[top]

Footnote

Input sample:

<doc>
  <p>Some Pod Duang were restruck<fn>Berglund, A., Thai Money, from
Earliest Times to King Rama V, p. 203.</fn> during the reign of King Rama V.</p>
</doc>

In this example the footnotes are numbered consecutively throughout the document. The footnote callout is the number of the footnote, followed by a ")", as a superscript. The footnote itself is formatted using list formatting objects with the footnote number as the label and the footnote text as the body.

XSL Stylesheet:

<?xml version='1.0'?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:fo="http://www.w3.org/1999/XSL/Format"
                version='1.0'>

<xsl:template match="p">
  <fo:block>
    <xsl:apply-templates/>
  </fo:block>
</xsl:template>

<xsl:template match="fn">
  <fo:footnote>
    <fo:inline font-size="0.83em" baseline-shift="super">
      <xsl:number level="any" count="fn" format="1)"/>
    </fo:inline>
    <fo:footnote-body>
      <fo:list-block provisional-distance-between-starts="20pt"
          provisional-label-separation="5pt">
        <fo:list-item>
          <fo:list-item-label end-indent="label-end()">
            <fo:block  font-size="0.83em"
                       line-height="0.9em">
              <xsl:number level="any" count="fn" format="1)"/>
            </fo:block>
          </fo:list-item-label>
          <fo:list-item-body start-indent="body-start()">
            <fo:block  font-size="0.83em"
                       line-height="0.9em">
              <xsl:apply-templates/>
            </fo:block>
          </fo:list-item-body>
        </fo:list-item>
      </fo:list-block>
    </fo:footnote-body>
  </fo:footnote>
</xsl:template>

</xsl:stylesheet>

Result Instance: elements and attributes in the fo: namespace

<fo:block>Some Pod Duang were restruck
  <fo:footnote>
    <fo:inline font-size="0.83em" baseline-shift="super">1)
    </fo:inline>
    <fo:footnote-body>
    <fo:list-block provisional-distance-between-starts="20pt"
      provisional-label-separation="5pt">
    <fo:list-item>
    <fo:list-item-label end-indent="label-end()">
    <fo:block font-size="0.83em" line-height="0.9em">1)
    </fo:block>
    </fo:list-item-label>
    <fo:list-item-body start-indent="body-start()">
    <fo:block font-size="0.83em" line-height="0.9em">Berglund, A.,
Thai Money, from Earliest Times to King Rama V, p. 203.
    </fo:block>
    </fo:list-item-body>
    </fo:list-item>
    </fo:list-block>
    </fo:footnote-body>
  </fo:footnote> during the reign of King Rama V.
</fo:block>

fo:float[top]

fo:float

Common Usage:

The fo:float formatting object is typically used either to cause an image to be positioned in a separate area at the beginning of a page, or to cause an image to be positioned to one side, with normal content flowing around and along-side the image.

Areas:

The fo:float generates an optional single area with area-class "xsl-anchor", and one or more block-areas that all share the same area-class, which is either "xsl-before-float", "xsl-side-float" or "xsl-normal" as specified by the "float" property. (An fo:float generates normal block-areas if its "float" property value is "none".)

Areas with area-class "xsl-side-float" are reference areas.

An area with area-class "xsl-before-float" is placed as a child of a before-float-reference-area.

The optional area with area-class "xsl-anchor" is not generated if the "float" property value is "none", or if, due to an error as described in the constraints section, the fo:float shall be formatted as though its "float" property was "none". Otherwise, the area with area-class "xsl-anchor" shall be generated.

The area with area-class "xsl-anchor" has no children, and is an inline-area, except where this would violate the constraints that (a.) any area's children must be either block-areas or inline-areas, but not a mixture, and (b.) the children of a line-area may not consist only of anchor areas. In the case where an inline-area would violate these constraints, the fo:float must instead generate a block-area.

Constraints:

The normal inline-area generated by the fo:float shall be placed in the area tree as though the fo:float had a "keep-with-previous" property with value "always". The inline-area has a length of zero for both the inline-progression-dimension and block-progression-dimension.

The term anchor-area is used here to mean the area with area-class "xsl-anchor" generated by the fo:float. An area with area-class "xsl-side-float" is a side-float.

No area may have more than one child block-area with the same area-class returned by the same fo:float formatting object.

Areas with area-class "xsl-before-float" must be properly ordered within the area tree relative to other areas with the same area-class.

The padding-, border-, and content-rectangles of the block-areas generated by fo:float all coincide. That is, the padding and border are zero at all edges of the area.

The following constraints apply to fo:float formatting objects that generate areas with area-class "xsl-before-float":

It is an error if the fo:float occurs as a descendant of a flow that is not assigned to a region-body, or of an fo:block-container that generates absolutely positioned areas. In either case, the fo:float shall be formatted as though its "float" property was "none".
A block-area with area-class "xsl-before-float" generated by the fo:float may only be descendant from a before-float-reference-area that is (a) descendant from a "region-reference-area" generated using the region-master for the region to which the flow that has the fo:float as a descendant is assigned, and (b) is descendant from the same page containing the anchor-area, or from a page following that page.
The fo:float may not generate any additional block-areas with area-class "xsl-before-float" unless the page containing the preceding block-area generated by the fo:float contains no other areas with area-class "xsl-before-float", has an empty main-reference-area, and does not contain a footnote-reference-area.
The "clear" property does not apply.

The following constraints apply to fo:float formatting objects that generate areas with area-class "xsl-side-float":

Each side-float is placed either as a child of the nearest ancestor reference-area of the anchor-area or as a child of a later reference-area in the same reference-area chain.
Side-floats that are siblings in the area-tree may overlap their content rectangles.
The description in section 9.5 of [CSS2] shall be used to determine the formatting of the fo:float and the rendering of normal line-areas and side-floats that are inline-overlapping, with these modifications:
- All references to left and right shall be interpreted as their corresponding writing-mode relative directions "start" and "end". The "float" property will additionally have the writing-mode relative values "start" and "end".
- All references to top and bottom shall be interpreted as their corresponding writing-mode relative directions "before" and "after".
- The phrase "current line box" shall be interpreted to mean the line-area containing the anchor-area generated by the float. If the anchor-area is a block-area then the "current line box" does not exist.
- Side-floats derive their length in the inline-progression-dimension intrinsically from their child areas; the length is not determined by an explicit property value.
- A side-float may add to the intrusion adjustment of any inline-overlapping block-area whose nearest ancestor reference-area is the parent of the side-float. See [intrusadjust] for the description of intrusion adjustments.
- The user agent may make its own determination, after taking into account the intrusion adjustments caused by one or more overlapping side-floats, that the remaining space in the inline-progression-direction is insufficient for the next side-float or normal block-area. The user agent may address this by causing the next side-float or normal block-area to "clear" one of the relevant side-floats, as described in the "clear" property description, so the intrusion adjustment is sufficiently reduced. Of the side-floats that could be cleared to meet this constraint, the side-float that is actually cleared must be the one whose after-edge is closest to the before-edge of the parent reference-area.
  
  NOTE:
  The user agent may determine sufficiency of space by using a fixed length, or by some heuristic such as whether an entire word fits into the available space, or by some combination, in order to handle text and images.

Contents:

(%block;)+

An fo:float is not permitted to have an fo:float, fo:footnote or fo:marker as a descendant.

Additionally, an fo:float is not permitted to have as a descendant an fo:block-container that generates an absolutely positioned area.

The following properties apply to this formatting object:

[float]
[clear]

fo:footnote[top]

fo:footnote

Common Usage:

The fo:footnote is typically used to produce footnote-citations within the region-body of a page and the corresponding footnote in a separate area nearer the after-edge of the page.

Areas:

The fo:footnote formatting object does not generate any areas. The fo:footnote formatting object returns the areas generated and returned by its child fo:inline formatting object.

Additionally the fo:footnote formatting object returns the block-areas with area class "xsl-footnote" generated by its fo:footnote-body child. An area with area-class "xsl-footnote" is placed as a child of a footnote-reference-area.

Constraints:

The term anchor-area is defined to mean the last area that is generated and returned by the fo:inline child of the fo:footnote.

A block-area returned by the fo:footnote is only permitted as a descendant from a footnote-reference-area that is (a) descendant from a "region-reference-area" generated using the region-master for the region to which the flow that has the fo:footnote as a descendant is assigned, and (b) is descendant from the same page that contains the anchor-area, or from a page following the page that contains the anchor-area.

The second block-area and any additional block-areas returned by an fo:footnote must be placed on the immediately subsequent pages to the page containing the first block-area returned by the fo:footnote, before any other content is placed. If a subsequent page does not contain a region-body, the user agent must use the region-master of the last page that did contain a region-body to hold the additional block-areas.

It is an error if the fo:footnote occurs as a descendant of a flow that is not assigned to a region-body, or of an fo:block-container that generates absolutely positioned areas. In either case, the block-areas generated by the fo:footnote-body child of the fo:footnote shall be returned to the parent of the fo:footnote and placed in the area tree as though they were normal block-level areas.

Contents:

(inline,footnote-body)

An fo:footnote is not permitted to have an fo:float, fo:footnote, or fo:marker as a descendant.

Additionally, an fo:footnote is not permitted to have as a descendant an fo:block-container that generates an absolutely positioned area.

The following properties apply to this formatting object:

[common-accessibility-properties]

fo:footnote-body[top]

fo:footnote-body

Common Usage:

The fo:footnote-body is used to generate the footnote content.

Areas:

The fo:footnote-body generates and returns one or more block-level areas with area-class "xsl-footnote".

Constraints:

The fo:footnote-body is only permitted as a child of an fo:footnote.

No area may have more than one child block-area returned by the same fo:footnote-body formatting object.

Areas with area-class "xsl-footnote" must be properly ordered within the area tree relative to other areas with the same area-class.

Contents:

(%block;)+

The following properties apply to this formatting object:

[common-accessibility-properties]

[Next Chapter] [Home]

Table of contents

Appendices

6.10 Out-of-Line Formatting Objects

Introduction[top]

Floats[top]

Footnotes[top]

Conditional Sub-Regions[top]

Examples[top]

Floating Figure[top]

Footnote[top]

fo:float[top]

fo:footnote[top]

fo:footnote-body[top]