`eles.boundingBox()` options : `includeMainLabels`, `includeSourceLabels`, `includeTargetLabels`

[maxkfranz]

Issue type

Feature request

Description of new feature

Add the following options to eles.boundingBox() (and eles.renderedBoundingBox()):

• includeMainLabels : A boolean, whether to include the main label in the returned bounds.
• includeSourceLabels : A boolean, whether to include the source label of an edge in the returned bounds.
• includeTargetLabels : A boolean, whether to include the target label of an edge in the returned bounds.

Behaviour to maintain compatibility with existing apps:

• The existing includeLabels option acts as an override when false, excluding all the labels in the bounding box result.
• Each flag is true by default.

Motivation for new feature

See #1679. If you can query an element for only the bounding box of a particular label, then it's easy to determine whether an event.position is within the bounds of the label.

By using this feature, a programmer can add features like direct manipulation of labels (e.g. drag on a label to move it). It also allows for features like click-to-type. Those sorts of features would make great extensions.

This proposed feature enables these use-cases with minimal added complexity of the Cytoscape.js API.

[maxkfranz]

The original spec has been updated to be more consistent. Each option is plural.