Supposedly moving from v1 to v2, the newest one is 2.1.4, from January 2014: pChart 2.0 - a PHP charting library
I understand that the one currently being used, which is in vendor but not with composer, already has custom code.
Corrected the essentials for PHP 8.3 directly on the version available.

https://github.com/LimeSurvey/LimeSurvey/pull/3959

@gabrieljenik : pchart is not deprecated ? We still use it ?

No security issue in pchart ? upset …

Did you test moving to pchart2 ?
Used for pdf statistics ? We use only 2 charts if i don't make error.

@DenisChenu, if I remember correctly, years ago it was discussed switching to pchart 2.x But there were issues with the license. It had changed and we not be able to use it for free, see http://www.pchart.net/license

Oh ! Yes right !

And complex …

The pChart library is released under two different licenses. If your application is not a commercial one (eg: you make no money by redistributing it) then the GNU GPLv3 license (General Public License) applies. This license allows you to freely integrate this library in your applications, modify the code and redistribute it in bundled packages as long as your application is also distributed with the GPL license.

@gabrieljenik can you please make this PR to master?

https://github.com/LimeSurvey/LimeSurvey/pull/3967

round(intval($value) and not intval(round($value))

Or just remove the rouind here ?