PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Solution Overview
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There are a few different ways you can deal with this situation.You could go through
each of these placeholders and delete the formatting codes. Deleting them actually makes
little difference to how the document looks in the end because the codes embedded in the
previous template indicate how much space should be left between the letters of the placeholders
that you are going to replace anyhow. However, if you take this approach, you must
go through and hand-edit the PDF file and repeat this each time you change or update the
file. Doing all this work is not a big deal when you’re dealing with only four placeholders,
but it becomes a nightmare when, for example, you have multiple documents with many
placeholders, and you decide to change the letterhead on all the documents.
You can avoid this problem by using a different technique.You can use Adobe
Acrobat to create a PDF form—similar to an HTML form with blank, named fields.You
can then use a PHP script to create what is called an FDF (Forms Data Format) file,
which is basically a set of data to be merged with a template.You can create FDFs using
PHP’s FDF function library: specifically, the fdf_create() function to create a file, the
fdf_set_value() function to set the field values, and the fdf_set_file() function to
set the associated template form file.You can then pass this file back to the browser with
the appropriate MIME type—in this case, vnd.fdf—and the browser’s Acrobat Reader
plug-in should substitute the data into the form.
This way of doing things is neat, but it has two limitations. First, it assumes that you
own a copy of Acrobat Professional (the full version, not the free reader, or even the
Standard edition). Second, it is difficult to substitute in text that is inline rather than text
that looks like a form field.This might or might not be a problem, depending on what
you are trying to do.We largely use PDF generation for generating letters where many
things must be substituted inline. FDFs do not work well for this purpose. If you are
auto-filling, for example, a tax form online, this will not be a problem.
You can read more about the FDF format at Adobe’s site: http://www.adobe.com/
devnet/acrobat/fdftoolkit.html.
You should also look at the FDF documentation in the PHP manual if you decide to
use this approach: http://www.php.net/manual/en/ref.fdf.php.
We turn now to the PDF solution to the previous problem.
You can still find and replace the placeholders in the PDF file if you recognize that
the additional format codes consist solely of hyphens, digits, and parentheses and can
therefore be matched via a regular expression.We wrote a function, pdf_replace(), to
automatically generate a matching regular expression for a placeholder and replace that
placeholder with the appropriate text.
Note that with some versions of Acrobat, the placeholders are in plain text, and you
can replace them with str_replace(), as you did before.
Other than this addition, the code for generating the certificate via a PDF template is
similar to the RTF version.This script is shown in Listing 32.4.