Refactor visualization code

[laike9m]

Refactor visualization code

[laike9m]

Potentially we can reuse:

Cyberbrain/cyberbrain-vsc/src/trace_data.js

Lines 279 to 309 in cfb91ac

	// Remove nodes that should not appear in the trace graph, if the following two
	// conditions are met:
	// - It has a source which is an invisible node
	// - It is not a source of any visible node
	let visibleEventIDs = new Set();
	let sourceEventIDs = new Set();
	for (const event of this.visibleEvents.values()) {
	visibleEventIDs.add(event.id);
	const sourceIDs = this.tracingResult.get(event.id);
	if (sourceIDs !== undefined) {
	for (const sourceID of sourceIDs) {
	sourceEventIDs.add(sourceID);
	}
	}
	}
	for (const event of this.visibleEvents.values()) {
	const sourceIDs = this.tracingResult.get(event.id);
	if (sourceIDs === undefined) {
	continue;
	}
	for (const sourceID of sourceIDs) {
	if (!visibleEventIDs.has(sourceID) && !sourceEventIDs.has(event.id)) {
	// Delete while iterating is safe, see https://stackoverflow.com/a/35943995
	this.visibleEvents.delete(event.offset);
	break;
	}
	}
	}