Semantic zooming of code change history

Previously, we presented our technique for visualizing fine-grained code changes in a timeline view, designed to facilitate reviewing and interacting with the code change history. During user evaluations, it became evident that users often wanted to see the code changes at a higher level of abstraction. Therefore, we developed a novel approach to automatically summarize fine-grained code changes into more conceptual, higher-level changes in real time. Our system provides four collapse levels, which are integrated with the timeline via semantic zooming: raw level (no collapsing), statement level, method level, and type level. Compared to the raw level, the number of code changes shown in the timeline at each level is reduced by 55%, 77%, and 83%, respectively. This implies that the semantic zooming would help users better understand and interact with the history by minimizing the potential information overload.