Format your content in HTML and then transform it into PDF.

HTML pages are easy to create on the fly. PDF pages are hard. One simple way to create dynamic PDF is to first create the document in HTML and then use HTMLDOC to transform it into PDF. This works for single pages and long documents.

HTMLDOC creates PDF documents from HTML 3.2 data. It provides document layout options, such as running headers and footers. It can add PDF features, such as bookmarks, links, metadata, and encryption. Invoke HTMLDOC from the command line or use its GUI. Visit http://www.easysw.com/htmldoc/software.php to download Windows binaries or source that can be compiled on Linux, Mac OS X, or a variety of other operating systems.

The detailed documentation that comes with HTMLDOC also is available online at http://www.easysw.com/htmldoc/documentation.php.

In Perl, you can automate PDF generation with HTMLDOC by using the HTML::HTMLDoc module to interface with HTMLDOC.

How to Combine PDF and FDF URLs to Fill Forms?

Another way to automatically fill an online PDF form is to append an FDF file reference to the PDF form's URL. In this case the FDF file must omit the PDF form reference (the /F key). When the user follows the link, Acrobat/Reader opens the PDF and fills the form fields using the FDF data. The FDF file reference must be a full URL:

http://localhost/fine_form.pdf#FDF=http://localhost/fine_data.fdf

Or, it must reference an FDF-generating script instead of a file. For example:

http://localhost/fine_form.pdf#FDF=http://localhost/fdf_data.php?t=42

You should use this technique of referencing both the form PDF and the FDF data in a single URL when displaying filled-in forms inside of HTML frames.

You really must use a web server to test these techniques. Windows users can download IndigoPerl from http://www.indigostar.com. IndigoPerl is an Apache installer for Windows that includes PHP and Perl support.

FDF can also contain PDF annotation (e.g., sticky note) information. Use the preceding techniques to dynamically add annotations to online PDF. Create example FDF or XFDF files by opening a PDF in Acrobat and adding some annotations. Then, select Document Export Comments . . . (Acrobat 6) or File Export Comments . . . (Acrobat 5).

How to Serve FDF to Fill Forms?

One way to automatically fill an online PDF form is to serve a data-packed FDF file (with MIME type application/vnd.fdf). The user's browser will open Acrobat/Reader and pass it the FDF data. Acrobat/Reader will read the FDF data to locate the PDF form. It will load and display this PDF and then populate its fields from the FDF. The PDF form in question should be available from your web server and the FDF data should reference it by URL using the /F key, as we do in our preceding example.

Check your web server to make sure it sends the appropriate Content-type: application/vnd.fdf header when serving FDF files. Or, send the header directly from your script.

This technique is simple, but it has limitations. First, not all browsers know how to handle FDF data. Second, this technique does not always work inside of HTML frames. The next technique overcomes both of these problems.

FDF, the Forms Data Format

Populate online PDF forms with known data.
To maintain form data, you must display the current state of the data to the user. This enables the user to review the data, update a single field, and submit this change back to the server. With HTML forms, you can set field values as the form is served to the user. With PDF forms, you can use the Forms Data Format (FDF) to populate a form's fields with data.

The PDF Reference describes the FDF file format. Its syntax uses PDF objects Section 6.8 to organize data. To see an example, open your PDF form in Acrobat and fill in some fields. Export this data as FDF by selecting Advanced Forms Export Forms Data . . . (Acrobat 6) or File Export Form Data . . . (Acrobat 5). Our basic PDF form yields an FDF file that lists fields in name/value pairs and then references the PDF form by filename:

%FDF-1.2

1 0 obj

<< /FDF << /Fields [ << /T (text_field_1) /V (Here is some text) >>

<< /T (text_field_2) /V (More nice text) >> ]

/F (http://localhost/fine_form.pdf)

>>

>>

endobj

trailer

<< /Root 1 0 R >>

%%EOF

For XML fans, XFDF is an XML-based subset of FDF features. Acrobat Versions 5 and 6 support XFDF. Its MIME type is application/vnd.adobe.xfdf.

Users can store and manage PDF form data using FDF files. Visit http://segraves.tripod.com/index3.htm for some examples. For our purpose of serving filled-out PDF forms, the user never sees or handles the FDF file directly.

You have two options for automatically filling an online PDF form with data. You can serve FDF data that references the PDF form, or you can create a URL that references both the PDF form and the FDF data together.

How to Test Your PDF Form?

Create a text file named echo.php and program it with the following script. IndigoPerl users can save it to C:\indigoperl\apache\htdocs\pdf_hacks\echo.php. This PHP script simply reports submitted form data back to your browser. Create a PDF Submit button that posts data to this script's URL (e.g., http://localhost/pdf_hacks/echo.php#FDF) as we described earlier.

Download echo.php here: http://mihd.net/7nzemdj

A PDF form interacts properly with a web server only when viewed inside a web browser. So, drag and drop your form into a browser, fill some fields, and then click the Submit button. The PDF should be replaced with an echoed data report.

If dragging and dropping PDF into Mozilla causes the PDF to open outside of the browser window, make sure Mozilla's Java is enabled (Edit >Preferences... >Advanced). After enabling Java, restart Mozilla and try again.

How to Install the Apache Web Server on Windows?

To test your interactive PDF form, you must have access to a web server. Many of these hacks use server-side PHP scripts, so your web server should also run PHP (http://www.php.net). Windows users can download an Apache (http://www.apache.org) web server installer called IndigoPerl from IndigoSTAR (http://www.indigostar.com). This installer includes PHP (and Perl) modules, so you can run our hacks right out of the box. Apache and PHP are free software.

Visit http://www.indigostar.com/indigoperl.htm and download indigoperl-2004.02.zip. Unzip this file into a temporary directory and then double-click setup.bat to run the installer. When the installer asks for an installation directory, press Enter to choose the default: C:\indigoperl\. In our discussions, we'll assume IndigoPerl is installed in this location.

After installing IndigoPerl, open a web browser and point it at http://localhost/. This is the URL of your local web server, and your browser should display a Web Server Test Page with links to documentation. When you request http://localhost/, Apache serves you index.html from C:\indigoperl\apache\htdocs\. Create a pdf_hacks directory in the htdocs directory, and use this location for our PHP scripts. Access this location from your browser with the URL: http://localhost/pdf_hacks/.

How to Create the Form?

Open the form's source document and print to PDF or scan a paper copy and create a PDF using OCR. Open the PDF in Acrobat to add form fields.

PDF forms can be powerful JavaScript programs, but we won't be using any PDF JavaScript. Instead, we will create PDF forms that let the web server do all the work. This gives you the freedom to program the form's logic with any language or database interface you desire.

PDF form fields correspond closely to HTML form fields. Add them to your PDF using one or more Acrobat tools.

input type="text"
Text

input type="password"
Text with Password Option

input type="checkbox"
Checkbox

input type="radio"
Radio Button

input type="submit"
Button with Submit Form Action

input type="reset"
Button with Reset Form Action

input type="hidden"
Text with Hidden Appearance

input type="image"
Button with Icon Option

input type="button"
Button

textarea
Text with Multiline Option

select
Combo Box or List Box

In Acrobat 6, you have one tool for each form field type. Open this toolbar by selecting Tools Advanced Editing Forms Show Forms Toolbar. Select a tool (e.g., Text Field tool), click, and drag out a rectangle where the field goes. Release the rectangle and a Field Properties dialog opens. Select the General tab and enter the field Name. This name will identify the field's data when it is submitted to your web server. Set the field's appearance and behavior using the other tabs. Click Close and the field is done.

In Acrobat 5, use the Form tool to create any form field. Click, and drag out a rectangle where the field goes. Release the rectangle and a Field Properties dialog opens. Select the desired field Type (e.g., Text) and enter the field Name. This name will identify the field's data when it is submitted to your web server. Set the field's appearance and behavior using the other tabs. Click OK and the field is done. Using the Form tool, double-click a field at any time to change its properties.

Take care to maximize your PDF form's compatibility with older versions of Acrobat and Reader.

To upload form data to your web server, the PDF must have a Submit Form button. Create a PDF button, open the Actions tab, and then add the Submit a Form (Acrobat 6) or Submit Form (Acrobat 5) action to the Mouse Up event.

Edit the action's properties to include your script's URL; this would be an HTML form's action attribute. Append #FDF to the end of this URL, like this:

http://localhost/pdf_hacks/echo.php#FDF

Set the Field Selection to include the fields you want this button to submit; All Fields is safest, to start. Set the Export Format to HTML and the PDF form will submit the form data using HTTP's post method.

When you are done, save your PDF form and test it.

Buttons look funny on paper. If users will be printing your form, consider making buttons unprintable. Open the button properties and select the General tab (Acrobat 6) or the Appearance tab (Acrobat 5). Under Common Properties set Form Field: to Visible but Doesn't Print. Click OK.