The Movable Filter as a User Interface Tool

Summary

• Magic Lens Filters
  • employ a metaphor based on physical lenses;
  • show a modified view in the context of the original view, are bounded (local);
  • are movable.
• Principles of operation:
  • read an underlying model of some data (input), create a new model (output) based on the various operations (filtering);
  • the various operations are composable if 2 or more lenses overlap;
  • click-through editing tools can be combined with these filters to enhance editors.
• Advantages:
  • details in context: detail within lens bounding area, context outside the bounding area;
  • reduce clutter to a local area;
  • enable multiple simultaneous views with 2 or more lenses (with the same filter) in different areas of the global view;
  • good for querying (filtering) geometric attribute of data set by using arbitrary shape of lenses;
  • coordinate alternate views (provide a view of related data or information) in context;
  • support a direct manipulation of complex queries by composing different filter lenses, and such visual macros can be saved as a compound lens
  • safe preview changes of a model without destroying or modifying the underlying data;
  • better editing operation support through local alternate views;
  • Inter-Application tools, separating conceptual effect from implementation (e.g., using the same lens on 2 applications at the same time).
• Implementation:
  • apperance-altering, without modification of the application and its data model (easiest to implement);
  • application-specific, most flexible in lens semantics;
  • multiple-application, same lens share same "conceptual effects", but implementation of lens semantics is application dependent (most difficult).
  • A magic lens user interface system can be either supported by individual applications, or by the windowing system.

Analysis

Questions

• About the built-in geometric attribute of the lens region: it sounds like a very neat idea, but how generalizable is the use of such a technique? Can you think of an example that uses the shape and size of the lens region to modify (enhance) a query?
• What are those "two-view" editing systems (such as Juno and Tweedle)?
• Why are inter-application lenses needed? What are the advantages of using one lens for 2 applications over building or integrating 2 applications?
• The physical lens metaphor gives me the feeling that magic lens is really doing some filtering (of the data model). However, the alternate view function of magic lens is not "filtering" anymore. The examples (in Coordinated Alternate Views part) given seemed more like a "tool-tip" or "tip-window" than a lens filter. Do you agree?
• Are there any real products that systematically employed Magic Lens techniques (especially the composite filter technique)?