ZGRViewer - chunhualiao/public-docs GitHub Wiki

ZGRViewer typically uses a hierarchical layout or layered layout for visualizing trees and directed acyclic graphs (DAGs) like ASTs and package dependency graphs. This layout is often specifically implemented as:

1. Sugiyama-style layout (also called "layered graph drawing" or "hierarchical graph drawing") - This is the most common algorithm for creating top-to-bottom hierarchical visualizations with:

   • Nodes arranged in horizontal layers
   • Directed edges pointing downward
   • Minimal edge crossings
   • Clear parent-child relationships

2. Dot layout - Since ZGRViewer is designed to work with GraphViz, it likely uses GraphViz's "dot" layout engine, which implements a variant of the Sugiyama algorithm specifically optimized for directed graphs.

The key characteristics of this layout approach are:

• Nodes are assigned to discrete horizontal levels/ranks
• Root nodes appear at the top
• Child nodes appear in lower levels
• Edges are routed to minimize crossings
• The overall flow is top-to-bottom (though it can be configured for other directions)

This layout is particularly well-suited for hierarchical data like syntax trees and dependency graphs because it clearly shows the flow of relationships and makes the hierarchy visually apparent.