Zoomable Graphical Sketchpad
To adequately explore the effectiveness of the Pad++ substrate and the informational physics design strategy discussed here will require development of a wide range of applications. One domain we plan to investigate is construction of active documents. Most tools for interacting with documents (like World-Wide Web browsers such as Mosaic and Netscape) predefine all of the interactive widgets within the client. Hooks are provided so that documents may access those widgets but there is no method to provide new ones, except to re-define the standards, modify the client and distribute the client to enough of the user population so it becomes the new standard in practice.
Pad++'s extensibility ensures that new widgets can be defined by scripts which can be included with a document. This will allow documents to provide new forms of interactivity without depending on the client to supply it. We are currently in the design stages of an extension to HTML we call the MultiScale Markup Language (MSML), that will be the markup language to describe documents within Pad++. MSML will allow logical formatting of documents with different sized components, and will provide a method for allowing Pad++ scripts to be included with documents -- allowing truly active documents.
In addition to data visualizations, we are investigating the use of Pad++ as a replacement for standard windowing system. PadWin currently consists of a few basic semantically zoomable gauges which display statistics such as the list of tasks being scheduled, the state of the printer queue, or the names of people who are logged on. We intend to extend these tools so that most of the computers resources and facilities are accessible through navigation within PadWin. We are also producing a suite of zoomable applications for use in PadWin.
In order to support existing non-zoomable applications, PadWin will incorporate a mechanism to control the placement of application windows on the screen to make them blend into the Pad++ surface. By mapping, unmapping, and moving these windows appropriately, PadWin will act as an extended virtual window manager where the effective screen size is huge, and where zoomable and non-zoomable applications reside side by side.
Pad++ also seems well-suited to a collaborative work environment. While the original Pad implementation allowed some basic shared workspaces (running from a single process displaying on multiple X servers), we are designing a more sophisticated approach. The goal is to be able to use portals to look remotely on to any Pad++ surfaces on the network (assuming that the right permissions are set). Each user's system will contain a spatial database server that will send updates to all other systems that have portals looking on to it. With this approach, there may be a lag in retrieving others' data, but once it arrives, it will be cached within the local system so the high-speed interactivity of Pad++ won't be lost.
Finally, we are building a completely visual interface to Pad++ for creation of an interactive visual dataspace. Multimedia authoring tools such as MacroMedia DirectorTM and Apple's Multimedia Authoring ToolTM are letting visual designers without programming experience create beautiful and complex interactive hypertext data retrieval systems. As we discussed with the layout of HTML however, having a huge data surface potentially alleviates some of the problems of navigating within a large hypertext document. To this end, we are building a set of tools that will allow non-technical visual designers to create interactive zoomable multimedia systems.
Copyright Computer Science Department, The University of New Mexico