feat(core): axisMeasure

[razsultana]

Implemented an axisMeasure lazy datasource which can be used to create a visual clue to the level of zoom, publishing the startPos, endPos, centerPos, measureDomainSize, measurePixelSize and measureLabel fields at each scale domain change.
Its behavior can be changed by several parameters: minMeasureSize, hideMeasureThreshold, multiplierValue and alignMeasure.
The parameters and fields usage is shown in two examples in packages/core/example/axes and they are also documented in the lazy.md part of the documentation.
The range of measureValues and measureLabels is determined by querying genome.totalSize, so this feature works only on genomeAxes (to make it more general, the scale #zoomExtent might need to be made available for simple Axes).

[razsultana]

Same comment as for line 118

[tuner]

Awesome! Seems to work and looks pretty good! I added some comments.

The range of measureValues and measureLabels is determined by querying genome.totalSize, so this feature works only on genomeAxes (to make it more general, the scale #zoomExtent might need to be made available for simple Axes).

Instead of precalculating stuff, you could calculate the rule length on the fly. E.g., take Math.floor(Math.log10(domainSpan)) with some paddings, etc. or something like that. This way this.measureValues.find((value) => value > minValueSize); would become unnecessary. Not critical though, as it can be improved later on without breaking any interfaces or schemas.

[tuner]

Hmm. I'm not sure about this. What if someone would like to have 1, 5, 10, 50, 100, 50, etc? No need to implement it now, but how would multiplierValue work with that?

I would be careful when adding nice-to-have options, as they may become a nuisance later on.

[tuner]

These could be class-private variables (i.e., start with #).

On the other hand, you could have just a single variable that stores the object that you might publish when the domain changes. However, when propagating new data objects, it's best to always create a new object, not mutate an existing one.

[tuner]

Local to onDomainChanged(). Shouldn't be here.

[tuner]

Same here and in the following few variables.

[tuner]

When the property and variable names are the same, you can make it more succinct:

{
  startPos,
  endPos,
  centerPos,
  ...
}