The same effect can be created programmatically using the Datalogics PDF Java Toolkit as is demonstrated in the Gist referenced lower in this article. Acrobat will then create Highlight annotations and use the bounding rectangle of the selection as the bounding rectangle of the highlight. However, when you are over a word, the highlighter will act as a selection tool and you can highlight specific words. For example, in Acrobat DC, you can draw on the page with the highlighter tool and when you are not over a word, an Ink annotation gets created and is defaulted to yellow just like a highlighter. All are annotations but this article only covers the annotations that appear in the Comments panel of Adobe Acrobat.Īll of the annotation types can appear anywhere on the PDF page but some of them only make sense when they are associated with words. The Datalogics PDF Java Toolkit allows developers to create, modify, extract and manage these annotations in a way that is completely interoperable with Adobe Acrobat.Įvery object on a PDF page that isnt content is, technically, an annotation links, printer marks, some types of watermarks, embedded movies and 3D models, as well as lines, arrows, highlights. These are stored as annotation on top of the PDF pages. Acrobat gives you a highlighter, a sticky note tool, even a paperclip to attach additional documents or files. One of the more interesting features of Adobe Acrobat is the ability to review and markup documents using electronic versions of common tools used to mark up paper documents.