The Reader's Helper: A Personalized Document Reading Environment
If the document is resized, the Thumbar is resized to represent the same screenful depicted in the document area. The use of a thumb-nail icon to represent a page in a document is of course not a new idea. Adobe Systems, for instance, uses a similar method of displaying icons for the individual pages in a document [1]. The Adobe method, however, portrays a static representation of the document (i.e., the thumb-nail image does not automatically change when the document is edited) and does not support using a lens for navigation throughout the document. The Adobe method is also based on a formally paginated document with distinct thumb-nails for each page. In the Thumbar, there is no pagination and therefore, the document is viewed as a continuous stream of text and images by which one can navigate to any location in the document.
If the document cannot be fully contained in the Thumbar (because the document is too long), a green line is drawn across the bottom of the Thumbar. Dragging the lens down to the green line causes the entire thumb-nail image to scroll upwards, thereby revealing more of the document. Once the document has been scrolled in this way, a green line will also appear at the top of the Thumbar indicating that more of the document is available above. To go back to the beginning of the document, the reader may again drag the lens upward to the green line which, thereby causing the thumb-nail image to scroll back down. Alternatively, there are buttons at the top of the Thumbar for repositioning the lens at either the top or the bottom of the document. The user may also choose to view the entire document in the Thumbar. This has the disadvantage, however, of reducing the clarity of thumb-nail information.
With the help of a Thumbar attached to the document browser, the reader can look ahead in the document to evaluate its content and structure. This is not possible in most document browsing systems available today where readers are restricted to one page or screenful at a time. This ability to look ahead in a document is quite useful for reading documents as it leverages off of the design principle of providing a global (macro) and local (micro) representation of information [23]. The global representation portrays coarse information while the local representation portrays fine grained information. In this instance, the Thumbar presents an overview (macro) of the document and the document area presents the detailed (micro) information. This particular innovation adds value to the document reading and browsing experience.
