Dash-cytoscape, how text-rotation works?

I want to place radially the node labels for a circle layout, but the description
of text-rotation for cytoscape.js:
http://js.cytoscape.org/#style/labels is imprecise, and I cannot figure out how to use text-rotation effectively:

text-rotation : A rotation angle that is applied to the label.
For nodes, the label is rotated along its anchor point on the node, so a label margin may help for some usecases.

I suppose that the label is rotated about (not along) its anchor point (on the node !!!)

My question: how is measured the angle of rotation? In radians or degrees? positive rotation is anti-clockwise or clock-wise?
The angle of rotation can vary between (-90 degs, 90degs] or (-180 degs, 180 degs]?
An example would help a lot.


I addressed this question on the cytoscape forum, too, and I was lucky to get an answer from Max Franz. I paste it here if someone is interested in this topic:

  • It’s a relative transform.

  • All angles in the stylesheet are clockwise, unless otherwise specified.

  • The anchor point is based on how you specify the label alignment. For example, bottom right alignment would have an anchor at the bottom right of the node’s bounds.

  • Angles are measured in radians (e.g. 3.14rad) or degrees (e.g. 180deg).