Extension inherits from renderer; better to be decoupled

[maxkfranz]

Instead of inheriting from the renderer, it would be more flexible to have this extension decoupled. The renderer may change in future, and there is also a concern with performance: drawNodeText() is synchronous.

That means that doing the DOM manipulation will hold up redraws(), thereby slowing down the "rendering loop" (not quite how it works, but the principle is the same). It would probably be faster to poll using timeouts, and update the labels then. There may be a slight lag in the labels, but that would be an acceptable tradeoff for performance.

[wehriam]

Is there a pluggable callback or an event emitted when the graph is manipulated?

[maxkfranz]

There isn't a single event but several: add, remove, load, viewport and style. All those events originate from or bubble up to the core and so can be bound on cy.