Using XSL Formatting Objects
by J. David Eisenberg
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Pages: 1, 2
Page Sequences
Now that the page masters are defined, you may specify the the order in which a given set of these page masters will be used when it's time to generate a sequence of pages.
The document we're building consists of a cover followed by the contents. That is, there are two sequences of pages: the cover page (which happens to be a sequence of exactly one page), followed by the "contents pages", which is a sequence of alternating left and right pages.
While it's possible to define a page sequence that consists of the page master for the cover alone, we don't gain anything by doing so. (If we had several pages of front matter, as many books do, it would definitely be worth the effort.) Instead, we will concentrate on defining the sequence of master pages for the contents of the book. In plain English, the contents of the book consist of even-numbered left-hand pages followed by odd-numbered right-hand pages. This means that the inside front cover will be page two. The specification is shown below, with line numbers added for reference.
1 <fo:page-sequence-master master-reference="contents"> 2 <fo:repeatable-page-master-alternatives> 3 <fo:conditional-page-master-reference 4 master-name="leftPage" 5 odd-or-even="even"/> 6 <fo:conditional-page-master-reference 7 master-name="rightPage" 8 odd-or-even="odd"/> 9 </fo:repeatable-page-master-alternatives> 10 </fo:page-sequence-master>
- Line 1
- Define and name this page sequence master.
- Line 2
- This sequence consists of page masters that should be chosen repeatedly according to the specified conditions as pages are generated.
- Lines 3-5
- Choose the page master named leftPage if the page being generated has an even page number.
- Lines 6-8
- Choose the page master named rightPage if the page being generated has an odd page number.
Extra information
While this is probably the most common page sequence, others are possible. If you had a single-sided document where all the pages looked like a right-hand page, but you wanted to set a maximum number of pages, you would use a page-sequence master as follows:
<fo:page-sequence-master master-reference="example"> <fo:repeatable-page-master-reference maximum-repeats="10" master-name="rightPage"/> </fo:page-sequence-master>The maximum-repeats attribute can also be applied to repeatable-page-master-alternatives.
You may specify a maximum-repeats attribute to limit the number of pages that this sequence can generate. The maximum-repeats also applies to repeatable-page-master-alternatives.
Other conditions that you may use in a conditional-page-master-reference are
page-position Use this page depending upon where it occurs in the page-sequence. Valid values are first, last, rest (i.e., not the first page), or any. blank-or-not-blank Use this page master depending upon whether the page is blank or not. Valid values are blank and not-blank. The blank value is used to maintain parity; for example, to generate a blank page to ensure that a chapter always ends on an odd page number.
The Cover Page
Now that the page masters and sequences are established, you can start putting content into those pages. This is done by specifying which page sequence to use, and which region the information should flow into. Here's the beginning of the cover page. We use the numeric entity code © for the copyright symbol.
1 <fo:page-sequence master-name="cover"> 2 <fo:flow flow-name="xsl-region-body"> 3 <fo:block font-family="Helvetica" font-size="18pt" 4 text-align="end"> 5 Spanish Review Handbook 6 </fo:block> 7 <fo:block font-family="Helvetica" font-size="12pt" 8 text-align="end" space-after="36pt"> 9 Copyright © 2001 J. David Eisenberg 10 </fo:block> 11 <fo:block text-align="end"> 12 A Catcode Production 13 </fo:block> 14 </fo:flow> 15 </fo:page-sequence>
- Line 1
- Specifies the page sequence into which this content will flow. Note: it's easy to confuse this with <fo:page-sequence-master>; the word master is part of the attribute name, not part of the element name!
- Line 2
- The following content goes into the xsl-region-body area of the page.
- Lines 3-6
- This content (Spanish Review Handbook) should begin on a new line (<fo:block>) with the specified font family and size. Note the text-align is at the end edge of the line.
- Lines 7-10
- Another block for the copyright message, using a different font size. Put some empty space-after this block is put into the flow.
- Lines 13-14
- Another block with publisher information.
- Lines 14-15
- That's the end of the content for this page.
Creating the PDF file
Now that we have some content, we can render this page to print. If you'd like to try this yourself, download the Apache Software Foundation's FOP tool and install it according to the instructions you find there. You will need
- Java 1.1.x or later;
- an XML parser which supports SAX and DOM;
- for later articles in this series, you'll also need an XSLT parser (f you download Xalan, you'll get both Xerces, the XML parser, and Xalan, the XSLT parser); and,
- an SVG library, which is in the w3c.jar file that comes with FOP.
For example, on a Linux system, you could put all the .jar files in a convenient directory and create a script named fop.sh that looks like
java -cp \ /usr/local/xml-jar/fop.jar:/usr/local/xml-jar/w3c.jar:\ /usr/local/xml-jar/xml.jar:/usr/local/xml-jar/xerces.jar:\ /usr/local/xml-jar/xalan.jar:/usr/local/xml-jar/bsf.jar \ org.apache.fop.apps.CommandLine $1 $2
Invoking the script by typing fop.sh spanish1.fo spanish1.pdf produces a PDF file. To view the file, you need a PDF viewer; Adobe Acrobat Reader works on Linux, Macintosh, and Windows. Linux users may also use xpdf, an X-Window PDF viewer. The output from the document so far is shown below in a reduced view.
This obviously cries out for a graphic to make it look better. The graphic is added as an external-graphic whose src attribute is a valid URI for the image. The additional elements are shown in bold below.
<fo:block font-family="Helvetica" font-size="12pt"
text-align="end" space-after="36pt">
Copyright #169; 2001 J. David Eisenberg
</fo:block>
<fo:block text-align="end">
<fo:external-graphic src="file:images/catcode_logo.jpg"
width="99px" height="109px"/>
</fo:block>
<fo:block>
A Catcode Production
</fo:block>
There. That's much nicer, isn't it?
Beginning the Content Pages
Before we leave this article, we'll start the content pages. In this case, we have to put information into the xsl-region-before and xsl-region-after as well as the xsl-region-body.
1 <fo:page-sequence master-name="contents" initial-page-number="2"> 2 <fo:static-content flow-name="xsl-region-before"> 3 <fo:block font-family="Helvetica" font-size="10pt" 4 text-align="center"> 5 Spanish Review Handbook 6 </fo:block> 7 </fo:static-content> 8 9 <fo:static-content flow-name="xsl-region-after"> 10 <fo:block font-family="Helvetica" font-size="10pt" 11 text-align="center"> 12 Página <fo:page-number /> 13 </fo:block> 14 </fo:static-content> 15 16 <fo:flow flow-name="xsl-region-body"> 17 <fo:block font-size="14pt"> 18 Watch this space! 19 </fo:block> 20 </fo:flow> 21 </fo:page-sequence>
- Line 1
- Start a new page sequence using the sequence defined by the contents master name. Start page numbers at 2.
- Lines 2-7
- As currently configured, the FO to PDF converter requires the content of the header area to be the same on all pages; thus you must specify <fo:static-content> rather than a variable <fo:flow> to fill the xsl-region-before.
- Lines 9-14
- Footer areas must also have <fo:static-content>. NOTE: Line 12 shows how to insert the current <fo:page-number/>. Entity á represents á.
- Lines 16-20
- Specify the content to fill in the xsl-region-body in this page sequence.
Here's the result:
Watch this space
In the next article, we'll show you how to use XSLT to make it much easier to create the FO elements. You'll also learn how to put lists and tables into your documents.
