The versatility of a PDF viewer
Almost every user knows: a PDF viewer is not just a display tool for a well known document format. It provides many more functions, runs on many platforms, offers interfaces in many technologies and serves as an important component of many applications. When you look closer it is a true miracle.
The majority of the traditional viewers are standalone interactive programs running on a personal computer. But meanwhile viewers are also available as seamlessly integrated controls in a user dialog of applications such as MS Access etc. Or, viewers can be found in embedded systems such as a display unit of an airplane. Some viewers are specialized tools in digital signature applications called "secure viewer". And nowadays viewers are part of web applications running on a the HTML and Java Script platform of a common web browser.
Most navigation functions such as scrolling pages, jumping to bookmarks, zooming, rotating etc. are self-evident. On top of these basic functions some viewers provide a wide variety of tools of more or less useful functions to manipulate a PDF document. The most requested functions, however, are:
adding annotations
filling out forms
applying digital signatures
There are more complex functions such as assembling documents from different source documents but this function is usually out of the scope of a simple viewer application and is provided as specialized tool.
A viewer component which is meant to be part of an software application must provide interfaces for at least the .NET and Java technologies. And, the COM technology ActiveX is still widely used in a variety of development environments. But if even if a viewer component concentrates on .NET and Java it has to provide interfaces for the various GUI flavors such as WPF vs. Windows Forms on one side and AWT Swing vs. SWT on the other side.
In order to cover the needs of our customers we have developed viewer components for various technologies such as .NET, Java and ActiveX. Based on these viewer components we also provide a PDF Document Assembler Tool. The newest component is a pure Java Script viewer running in web browsers. I will post separate articles on some of these topics.
