Secondary TGAxis NDC coordinates for following zoom of primary axis

[ferdymercury]

Explain what you would like to see improved and how.

From: https://root-forum.cern.ch/t/automatic-repositioning-of-tgaxis-after-zooming/61906/11

It would be nice if there was an option to let TGaxis behave in "NDC" coordinates, as if it were a TLegend. In order to follow the zooming of the primary axes.

According to couet, the inherited function TGaxis::SetNDC() exists but does not yet behave correctly.

ROOT version

ROOT v6.32.04
Built for linuxx8664gcc on Aug 14 2024, 04:13:21
From tags/v6-32-04@v6-32-04
With c++ (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
Binary directory: /opt/root/bin

Installation method

Binary Release

Operating system

Ubuntu 22.04

Additional context

An alternative / workaround is to have a TTimer modifying the axes every 0.5 seconds to reflect zoom updates. Or to connect the Modified() signal with a modify-slot.

Just for the record, I currently use this fully functional workaround with the signal-slot mechanism:

https://igit.ific.uv.es/ferhue/pulse-surfer/-/compare/db3486d6...b4800032?from_project_id=256

[couet]

Indeed it is not as easy as it seems. It needs some developments.