Annotations are additional objects that can be added to a document. They help to provide clarification to its content or to expand upon what is already present. Annotations are essential in PDFs as the document format is not easily editable to make the text clearer. Many different types of annotation are supported by PDF files including marking text, adding entirely new text and adding sticky notes. .
What types of annotations exist?
Whilst there are many different types they can all be divided into one of three categories.
This group of annotations can be added to text content in some way. They are often used to alert the reader to some desired change or clarification, for instance the Strike Through is used to mark text that should be removed or ignored. As well as applying annotations to existing text you can also add text to the document in the form of a Free Text, theses appear as text on the page of a document. These annotations can also have a pop-up assigned to it allowing you to provide more details.
This group of annotations appear as shapes of the PDF page. These shapes can be used to draw attention of sections of the page. They can be placed anywhere on the page and their usage is much more diverse and allow you to assign a pop-up to provide additional details As well as basic shapes and pop-ups there are special shapes that appear as boxes that you can fill with text.
3. Additional Functionality
This group of annotations adds functionality to the document in some way. This includes functionality such as links, sounds that are played when an icon is clicked, files attached to the document, embedded videos and other forms of rich media. In general these are not used or very rarely used to annotate a document but are more likely to be added as part of the documents main content. They are included here as the PDF specification includes them as annotations.
What would I use annotations for?
Annotations are useful in a whole host of situations, I have mentioned some previously, here I shall detail some cases where they would prove useful.
When writing a draft of something, be it a contract, novel or license, you may be unlikely to want another to freely edit the contents of the draft. By saving the document as a PDF you have a document that others can read and not edit. If they find content of the document that needs to be changed, discussed or removed entirely they can add annotations. In this way others can mark what content needs alteration and provide details of why or how in the related pop-ups and the original text will remain intact.
When viewing an electronic document you can take advantage of annotations to make reading the document much simpler. There are many ways this could be done. An Underline with a pop-up may provide the user some additional information about a subject in case they do not have a full understanding. Links can be used to jump to different sections of the document where two sections reference one another. Arrows with a pop-up may be added over images or diagrams to provide details about different sections.
When you have complex documents, such as technical specifications, annotations are incredibly useful for the reader. For instance the reader can leave notes to themselves of any oddities they have discovered in “real world” examples of the subject of a technical specification. Annotations can also be added to keep track of where you have implemented parts of the technical specification. Annotating a document in this way will give you a guide that would be useful for new members of a team working in a development setting.
Hopefully you found this guide on Annotations, what are they and why use them useful. Next time Ill be taking a look at ‘How to add annotations to PDFs using jPedal’.
IDRsolutions develop a Java PDF library, a PDF forms to HTML5 converter, a PDF to HTML5 or SVG converter and a Java Image Library that doubles as an ImageIO replacement. On the blog our team post about anything interesting they learn about.