How to detect the relative grid resolution via API?

[u-u-u]

Hey folks,

when working in arranger, I want to increase/decrease the transport position depending on how deep I zoomed into the arrangement.

So I think I need an observer function which lets me detect the grid resolution. (which is also reflected in the visible in the arrangement grid)

To make it more clear:
When zoomed in like this the callback function should return 1/4 (16th = 1/4 beat):

grid 16th.PNG

When zoomed in like this the callback function should return 1 (1 beat):

grid beats.PNG

When zoomed in like this the callback function should return 8 (2 bars = 8 beats):

grid 2bars.PNG

Does something exist already or do I have to request it?