Main Ideas

Relo focuses on supporting users to understand parts of large codebases:

by reducing the high cognitive overhead found in many software visualization tools; and
by allowing developers to incrementally explore the code and build a visualization representing their mental model (avoiding overloading the user with information not relevant to his/her goals).

1. Cognitive Overhead: Program understanding tools need to manage large amounts of information available in codebases. They need to therefore reduce the cognitive overhead (in program comprehension). Relo thus intuitively supports:

Visualizing code components like fields, methods, classes, and packages, in a manner similar to UML class-diagrams.
Editing method implementations in embedded text editors.
Visualizing code relationships through their automatic layout as topological constraints. For example, (as per people’s typical expectations) inheritance relations are shown vertically, method calls horizontally and containment by visual nesting.
Accessing varying levels of detail of the code by providing automatic fisheye semantic zooming of the code graph.

2. Incremental Browsing: Program understanding tools need to help programmers understand code features that are scattered throughout the program text. Developers should be able to browse and find related code snippets. Support for bottom-up exploration by allowing incremental building and refining of visualizations, helps developers’ build a mental model and maintain context. Relo supports bottom-up comprehension by allowing developers to select relationships they want to follow and using the traversed paths in building a visualization.