Interactive PDF files: A wonderfull way for E- learning

The author: Professor Yasser Metwally

http://yassermetwally.com

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INTRODUCTION

February  6, 2010 — JavaScript for Acrobat is an extension of core JavaScript, version 1.5 of ISO-16262, formerly known as ECMAScript, an object-oriented scripting language developed by Netscape Communications.

JavaScript was created to offload web page processing from a server onto a client in web-based applications. Acrobat extends the core language by adding new objects and their accompanying methods and properties, to the JavaScript language. These Acrobat-specific objects enable a developer to manage document security, communicate with a database, handle file attachments, manipulate a PDF file so that it behaves as an interactive, web-enabled form, and so on. Because the Acrobat-specific objects are added on top of core JavaScript, you still have access to its standard classes, including Math, String, Date, and RegExp.

PDF documents have great versatility since they can be displayed both within the Acrobat software as well as a web browser. Therefore, it is important to be aware of the differences between JavaScript used in a PDF file and JavaScript used in a web page:

1. JavaScript in a PDF file does not have access to objects within an HTML page. Similarly, JavaScript in a web page cannot access objects within a PDF file.
2. In HTML, JavaScript is able to manipulate such objects as Window. JavaScript for Acrobat cannot access this particular object but it can manipulate PDF-specific objects.

Most people know Acrobat as a medium for exchanging and viewing electronic documents easily and reliably, independent of the environment in which they were created; however, Acrobat provides far more capabilities than a simple document viewer.

You can enhance a PDF document so that it contains form fields to capture user-entered data as well as buttons to initiate user actions. This type of PDF document can replace existing paper forms, allowing employees within a company to fill out forms and submit them via PDF files, and connect their solutions to enterprise workflows by virtue of their XML-based structure and the accompanying support for SOAP-based web services. 

Acrobat also contains functionality to support online team review. Documents that are ready for review are converted to PDF. When a reviewer views a PDF document in Acrobat and adds comments to it, those comments (or annotations) constitute an additional layer of information on top of the base document. Acrobat supports a wide variety of standard comment types, such as a note, graphic, sound, or movie. To share comments on a document with others, such as the author and other reviewers, a reviewer can export just the comment "layer" to a separate comment repository.

In either of these scenarios, as well as others that are not mentioned here, you can customize the behavior of a particular PDF document, implement security policies, interact with databases and web services, and dynamically alter the appearance of a PDF document by using JavaScript. You can tie JavaScript code to a specific PDF document, a particular page within a PDF document, or a form field or button in a PDF file. When an end user interacts with Acrobat or a PDF file displayed in Acrobat that contains JavaScript, Acrobat monitors the interaction and executes the appropriate JavaScript code.

Not only can you customize the behavior of PDF documents in Acrobat, you can customize Acrobat itself. In earlier versions of Acrobat (prior to Acrobat 5), this type of customization could only be done by writing Acrobat plug-ins in a high-level language like C or C++. Now, much of that same functionality is available through Acrobat extensions to JavaScript. You will find that using JavaScript to perform a task such as adding a menu to Acrobat's user interface is much easier than writing a plug-in.