I've been playing with the idea for some time and the time has come to
bring this up. I would like to write an FO extension which allows to
insert a multi-page document into an FO document, so each page produces
a new page of exactly the same dimensions as the bitmap image in the
final format (by default). With fo:external-graphic it's only possible
to embed one single image somewhere inline. Of course, it's possible to
position the fo:external-graphic so it takes up the whole page and you
can even address individual pages (<uri>#page=3) with the new image
package but you'd still need to know at least the number of pages at
XSLT time to get this right. Instead, I'd like to do this with a single
extension element on the same level as fo:page-sequence. I've called it
fox:external-document for now. Here's the proposed specification:


Child of: fo:root
Contents of fo:root would be changed to this:

The fo:external-document extension element is used to generate a
(sub-)sequence of pages where each page will contain the necessary areas
to display each page of a potentially multi-page document on a separate

The size of each sub-image will define the size of the page it generates
unless the width, height, content-width, content-height properties are


The following properties apply:
- (Common Accessibility Properties)
- (Common Aural Properties)
- block-progression-dimension
- content-height
- content-type
- content-width
- display-align
- height
- id
- inline-progression-dimension
- overflow
- pages: <page-set> (see below)
- reference-orientation
- scaling
- scaling-method
- src
- text-align
- width

Value: auto | <integer-range>
Default: "auto" which means all pages of the document.
integer-range allows values such as "7" or "1-3"

Benefits of the extension:
- It is mostly useful for multi-page TIFF files (scanned documents and
faxes) and PDFs (with my PDF-in-PDF plug-in).
- It removes the necessity to post-process the generated output file
(for example with PDFBox or iText). It's not necessary to implement this
post-processing for each output format in use and it's not necessary to
manually play with the intermediate format to add this functionality.
- Attaching existing PDF files to PDFs generated by FOP has been a
frequent topic on fop-users.
- FOP could be used this way to convert multi-page TIFF files to PDF or
whatever output formats FOP supports. We could provide a command-line
option for that if we want.

While writing this it occurred to me that this could also be implemented
as an FO-preprocessor (SAX filter). However, since this proprocessor
would have to generate page masters depending on the images which have
to be inserted at the beginning of the FO file, this could be
inefficient. The only benefits I see is that it could be used with other
FO implementations, too, and that it wouldn't add code to FOP which has
to be maintained. So, I would prefer to implement this as a layout

I know this is again something that doesn't really bring FOP closer to
version 1.0. Again, it's simply coming from people using FOP on a
day-to-day basis.


Jeremias Maerki

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