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Unit 12: Portable Document Format

Notes
Figure 12.12: Pattern Filling a Circle

12.4.4 Templates

It is common to have parts of a document, such as header/footer sections or background
watermarks, repeated on multiple pages. It would be trivial to write a little PHP function to
generate such things on each page, but if you did this the final PDF file would end up containing
the same sequence of PDF calls on every page. PDF has built-in functionality known as “Form
XObjects” (renamed “Templates” in pdflib) to more efficiently handle repeating elements.
To create a template, simply call pdf_begin_template( ), perform the various operations to create
the PDF components you want this template to contain, then call pdf_end_template( ). It is a
good idea to do a pdf_save( ) right after beginning the template and a pdf_restore( ) just before
ending it to make sure that any context changes you perform in your template don’t leak out
of this template into the rest of the document.

The pdf_begin_template( ) function takes the dimensions of the template and returns a handle
for the template:

$template = pdf_begin_template(pdf, width, height);
The pdf_end_template( ), pdf_save( ), and pdf_restore( ) functions take no arguments beyond
the pdf handle:

pdf_end_template(pdf); pdf_save(pdf); pdf_restore(pdf);
The below Example uses templates to create a two-page document with the PHP logo in the
top-left and top-right corners and the title “pdf Template Example” and a line at the top of each
page. If you wanted to add something like a page number to your header, you would need to
do that on each page. There is no way to put variable content in a template.

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