@ WP Thank you for the instructions!
@Arioch: This is true.
and thank you for the code snipets. I will compare them with mine.
Many charts I draw like this in Delphi. I use(d) TeeChart Pro there.
Cross fingers for their migration, which I have not started yet.
TeeChart Pro is great, but they want more money for every update of Delphi. Sure, this is ok, they have a lot of work with every new Delphi version. Nevertheless, it does not pay for me as person to invest so much money. I am no software-reseller.
What is NOT ok to me, that I have to pay Embarcadero for a new version of Delphi just to get a version with the most severe bugs removed. Working with Lazarus now, I am aware how much afford it was to use workarounds of the Delphi IDE bugs. They do not even think of upgrading the software as they delivered poor quality! They want to sell me a new version.
e.g. my Delphi IDE freezes every some hours because of RAM overrun, which is caused by a setting of the IDE, which I need. Bugs in components are corrected in Lazarus within some days, - they (Embarcadero) keep them for years or do provide no update at all. So the free thing is much better than the high-price one?!
When this policy leads to a shutdown of Embarcadero one day, - I do not want to be dependent on Delphi anymore.