Avoid double Update when editing Hybrid Annotations

[fm3]

Hybrid Annotations have a skeletonTracing and a volumeTracing object. When moving around (possibly upon other interactions too), update actions for both are generated.

Since editPosition/editRotation of the skeletonTracing always take precedence (if I remember correctly), could we avoid updating both tracings, if there is not actually a change to both?

Currently, both update requests will show up in analytics.

[philippotto]

Just thinking out loud here:

Let's assume, we would only send updateTracing for skeleton if it exists (I'm only referring to the case where no volume-relevant metadata changed). What would happen if the user deletes the skeleton layer at some point? I think, there are two scenarios:

• after deleting the layer and reopening the annotation, no up-to-date edit position and zoom level would exist anymore. to circumvent this, the front-end could send one updateTracing action for the volume layer before deleting the skeleton layer.
• when reverting to an older version of the annotation, the skeleton layer will exist again and will contain the necessary metadata.

so, if we take care for the first point, this should be relatively simple, I think 🤔

[fm3]

Yes, good point!

We could also update the other layers directly in the backend when a layer is deleted.

Note that this also includes the bounding boxes. Currently, when a new layer is added, the redundant properties are copied to it. Compare

webknossos/app/models/annotation/AnnotationLayerPrecedence.scala

Line 24 in fd97cd5

case class RedundantTracingProperties(

and

webknossos/app/models/annotation/AnnotationService.scala

Line 205 in fd97cd5

Note that the tracings have redundant properties, with a precedence logic selecting a layer

Or, we take this comment to heart and disallow deleting the skeleton layer entirely. This would have various new implications that we would have to think through. (e.g. skeleton tools may need to be disabled according to task type). We would also still have to handle legacy annotations that don’t have a skeleton layer (or lazily add it on loading…)