onzoom not working?

[ghost]

I am trying to grab the visible x-axis after a zoom has occurred, but I cannot figure out how. chart.axis.min() and max(), as well as .range() returns is undefined, and chart.zoom() does not reflect the actual zoom but shows the original data.
I tried to use on-zoom-end (in the c3chart directive), but that also does not appear to fire.

Any suggestions?